if not modules then modules = { } end modules ['data-res'] = {
    version   = 1.001,
    comment   = "companion to luat-lib.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files",
}

-- In practice we will work within one tds tree, but i want to keep
-- the option open to build tools that look at multiple trees, which is
-- why we keep the tree specific data in a table. We used to pass the
-- instance but for practical purposes we now avoid this and use a
-- instance variable. We always have one instance active (sort of global).

-- todo: cache:/// home:/// selfautoparent:/// (sometime end 2012)

local format, gsub, find, lower, upper, match, gmatch = string.format, string.gsub, string.find, string.lower, string.upper, string.match, string.gmatch
local concat, insert, sortedkeys = table.concat, table.insert, table.sortedkeys
local next, type, rawget = next, type, rawget
local os = os

local P, S, R, C, Cc, Cs, Ct, Carg = lpeg.P, lpeg.S, lpeg.R, lpeg.C, lpeg.Cc, lpeg.Cs, lpeg.Ct, lpeg.Carg
local lpegmatch, lpegpatterns = lpeg.match, lpeg.patterns

local filedirname       = file.dirname
local filebasename      = file.basename
local suffixonly        = file.suffixonly
local filejoin          = file.join
local collapsepath      = file.collapsepath
local joinpath          = file.joinpath
local allocate          = utilities.storage.allocate
local settings_to_array = utilities.parsers.settings_to_array
local setmetatableindex = table.setmetatableindex

local trace_locating   = false  trackers.register("resolvers.locating",   function(v) trace_locating   = v end)
local trace_detail     = false  trackers.register("resolvers.details",    function(v) trace_detail     = v end)
local trace_expansions = false  trackers.register("resolvers.expansions", function(v) trace_expansions = v end)

local report_resolving = logs.reporter("resolvers","resolving")

local resolvers = resolvers

local expandedpathfromlist   = resolvers.expandedpathfromlist
local checkedvariable        = resolvers.checkedvariable
local splitconfigurationpath = resolvers.splitconfigurationpath
local methodhandler          = resolvers.methodhandler

local initializesetter = utilities.setters.initialize

local ostype, osname, osenv, ossetenv, osgetenv = os.type, os.name, os.env, os.setenv, os.getenv

resolvers.cacheversion  = '1.0.1'
resolvers.configbanner  = ''
resolvers.homedir       = environment.homedir
resolvers.criticalvars  = allocate { "SELFAUTOLOC", "SELFAUTODIR", "SELFAUTOPARENT", "TEXMFCNF", "TEXMF", "TEXOS" }
resolvers.luacnfname    = "texmfcnf.lua"
resolvers.luacnfstate   = "unknown"

-- The web2c tex binaries as well as kpse have built in paths for the configuration
-- files and there can be a depressing truckload of them. This is actually the weak
-- spot of a distribution. So we don't want:
--
-- resolvers.luacnfspec = '{$SELFAUTODIR,$SELFAUTOPARENT}{,{/share,}/texmf{-local,}/web2c}'
--
-- but instead use:
--
-- resolvers.luacnfspec = 'selfautoparent:{/texmf{-local,}{,/web2c}}'
--
-- which does not make texlive happy as there is a texmf-local tree one level up
-- (sigh), so we need this. We can assume web2c as mkiv does not run on older
-- texlives anyway.
--
-- texlive:
--
-- selfautodir:
-- selfautoparent:
-- selfautodir:share/texmf-local/web2c
-- selfautodir:share/texmf/web2c
-- selfautodir:texmf-local/web2c
-- selfautodir:texmf/web2c
-- selfautoparent:share/texmf-local/web2c
-- selfautoparent:share/texmf/web2c
-- selfautoparent:texmf-local/web2c
-- selfautoparent:texmf/web2c
--
-- minimals:
--
-- home:texmf/web2c
-- selfautoparent:texmf-local/web2c
-- selfautoparent:texmf-context/web2c
-- selfautoparent:texmf/web2c

if environment.default_texmfcnf then
    -- unfortunately we now have quite some overkill in the spec (not so nice on a network)
    resolvers.luacnfspec = environment.default_texmfcnf
else
 -- resolvers.luacnfspec = "selfautoparent:texmf{-local,-context,}/web2c"
    resolvers.luacnfspec = "{selfautoloc:,selfautodir:,selfautoparent:}{,/texmf{-local,}/web2c}"
end

resolvers.luacnfspec = 'home:texmf/web2c;' .. resolvers.luacnfspec

-- which (as we want users to use the web2c path) be can be simplified to this:
--
-- if environment and environment.ownpath and string.find(environment.ownpath,"[\\/]texlive[\\/]") then
--     resolvers.luacnfspec = 'selfautodir:/texmf-local/web2c,selfautoparent:/texmf-local/web2c,selfautoparent:/texmf/web2c'
-- else
--     resolvers.luacnfspec = 'selfautoparent:/texmf-local/web2c,selfautoparent:/texmf/web2c'
-- end

--~ -- not yet, some reporters expect strings

--~ resolvers.luacnfspec    = {
--~     "selfautoparent:/texmf-local",       -- is actually a user mistake
--~     "selfautoparent:/texmf-local/web2c",
--~     "selfautoparent:/texmf",             -- idem
--~     "selfautoparent:/texmf/web2c",
--~     "selfautoparent:",                   -- idem
--~ }

local unset_variable = "unset"

local formats   = resolvers.formats
local suffixes  = resolvers.suffixes
local dangerous = resolvers.dangerous
local suffixmap = resolvers.suffixmap

resolvers.defaultsuffixes = { "tex" } --  "mkiv", "cld" -- too tricky

resolvers.instance = resolvers.instance or nil -- the current one (slow access)
local     instance = resolvers.instance or nil -- the current one (fast access)

-- An instance has an environment (coming from the outside, kept raw), variables
-- (coming from the configuration file), and expansions (variables with nested
-- variables replaced). One can push something into the outer environment and
-- its internal copy, but only the later one will be the raw unprefixed variant.

function resolvers.setenv(key,value,raw)
    if instance then
        -- this one will be consulted first when we stay inside
        -- the current environment (prefixes are not resolved here)
        instance.environment[key] = value
        -- we feed back into the environment, and as this is used
        -- by other applications (via os.execute) we need to make
        -- sure that prefixes are resolve
        ossetenv(key,raw and value or resolvers.resolve(value))
    end
end

-- Beware we don't want empty here as this one can be called early on
-- and therefore we use rawget.

local function getenv(key)
    local value = rawget(instance.environment,key)
    if value and value ~= "" then
        return value
    else
        local e = osgetenv(key)
        return e ~= nil and e ~= "" and checkedvariable(e) or ""
    end
end

resolvers.getenv = getenv
resolvers.env    = getenv

-- We are going to use some metatable trickery where we backtrack from
-- expansion to variable to environment.

local function resolve(k)
    return instance.expansions[k]
end

local dollarstripper   = lpeg.stripper("$")
local inhibitstripper  = P("!")^0 * Cs(P(1)^0)
local backslashswapper = lpeg.replacer("\\","/")

local somevariable     = P("$") / ""
local somekey          = C(R("az","AZ","09","__","--")^1)
local somethingelse    = P(";") * ((1-S("!{}/\\"))^1 * P(";") / "")
                       + P(";") * (P(";") / "")
                       + P(1)
local variableexpander = Cs( (somevariable * (somekey/resolve) + somethingelse)^1 )

local cleaner          = P("\\") / "/" + P(";") * S("!{}/\\")^0 * P(";")^1 / ";"
local variablecleaner  = Cs((cleaner  + P(1))^0)

local somevariable     = R("az","AZ","09","__","--")^1 / resolve
local variable         = (P("$")/"") * (somevariable + (P("{")/"") * somevariable * (P("}")/""))
local variableresolver = Cs((variable + P(1))^0)

local function expandedvariable(var)
    return lpegmatch(variableexpander,var) or var
end

function resolvers.newinstance() -- todo: all vars will become lowercase and alphanum only

     if trace_locating then
        report_resolving("creating instance")
     end

    local environment, variables, expansions, order = allocate(), allocate(), allocate(), allocate()

    local newinstance = {
        environment     = environment,
        variables       = variables,
        expansions      = expansions,
        order           = order,
        files           = allocate(),
        setups          = allocate(),
        found           = allocate(),
        foundintrees    = allocate(),
        hashes          = allocate(),
        hashed          = allocate(),
        specification   = allocate(),
        lists           = allocate(),
        data            = allocate(), -- only for loading
        fakepaths       = allocate(),
        remember        = true,
        diskcache       = true,
        renewcache      = false,
        renewtree       = false,
        loaderror       = false,
        savelists       = true,
        pattern         = nil, -- lists
        force_suffixes  = true,
    }

    setmetatableindex(variables,function(t,k)
        local v
        for i=1,#order do
            v = order[i][k]
            if v ~= nil then
                t[k] = v
                return v
            end
        end
        if v == nil then
            v = ""
        end
        t[k] = v
        return v
    end)

    setmetatableindex(environment, function(t,k)
        local v = osgetenv(k)
        if v == nil then
            v = variables[k]
        end
        if v ~= nil then
            v = checkedvariable(v) or ""
        end
        v = resolvers.repath(v) -- for taco who has a : separated osfontdir
        t[k] = v
        return v
    end)

    setmetatableindex(expansions, function(t,k)
        local v = environment[k]
        if type(v) == "string" then
            v = lpegmatch(variableresolver,v)
            v = lpegmatch(variablecleaner,v)
        end
        t[k] = v
        return v
    end)

    return newinstance

end

function resolvers.setinstance(someinstance) -- only one instance is active
    instance = someinstance
    resolvers.instance = someinstance
    return someinstance
end

function resolvers.reset()
    return resolvers.setinstance(resolvers.newinstance())
end

local function reset_hashes()
    instance.lists = { }
    instance.found = { }
end

local slash = P("/")

local pathexpressionpattern = Cs (
    Cc("^") * (
        Cc("%") * S(".-")
      + slash^2 * P(-1) / "/.*"
      + slash^2 / "/.-/"
      + (1-slash) * P(-1) * Cc("/")
      + P(1)
    )^1 * Cc("$") -- yes or no $
)

local cache = { }

local function makepathexpression(str)
    if str == "." then
        return "^%./$"
    else
        local c = cache[str]
        if not c then
            c = lpegmatch(pathexpressionpattern,str)
            cache[str] = c
        end
        return c
    end
end

local function reportcriticalvariables(cnfspec)
    if trace_locating then
        for i=1,#resolvers.criticalvars do
            local k = resolvers.criticalvars[i]
            local v = resolvers.getenv(k) or "unknown" -- this one will not resolve !
            report_resolving("variable '%s' set to '%s'",k,v)
        end
        report_resolving()
        if cnfspec then
            if type(cnfspec) == "table" then
                report_resolving("using configuration specification '%s'",concat(cnfspec,","))
            else
                report_resolving("using configuration specification '%s'",cnfspec)
            end
        end
        report_resolving()
    end
    reportcriticalvariables = function() end
end

local function identify_configuration_files()
    local specification = instance.specification
    if #specification == 0 then
        local cnfspec = getenv("TEXMFCNF")
        if cnfspec == "" then
            cnfspec = resolvers.luacnfspec
            resolvers.luacnfstate = "default"
        else
            resolvers.luacnfstate = "environment"
        end
        reportcriticalvariables(cnfspec)
        local cnfpaths = expandedpathfromlist(resolvers.splitpath(cnfspec))
        local luacnfname = resolvers.luacnfname
        for i=1,#cnfpaths do
            local filename = collapsepath(filejoin(cnfpaths[i],luacnfname))
            local realname = resolvers.resolve(filename)
            if lfs.isfile(realname) then
                specification[#specification+1] = filename
                if trace_locating then
                    report_resolving("found configuration file '%s'",realname)
                end
            elseif trace_locating then
                report_resolving("unknown configuration file '%s'",realname)
            end
        end
        if trace_locating then
            report_resolving()
        end
    elseif trace_locating then
        report_resolving("configuration files already identified")
    end
end

local function load_configuration_files()
    local specification = instance.specification
    if #specification > 0 then
        local luacnfname = resolvers.luacnfname
        for i=1,#specification do
            local filename = specification[i]
            local pathname = filedirname(filename)
            local filename = filejoin(pathname,luacnfname)
            local realname = resolvers.resolve(filename) -- no shortcut
            local blob = loadfile(realname)
            if blob then
                local setups = instance.setups
                local data = blob()
                local parent = data and data.parent
                if parent then
                    local filename = filejoin(pathname,parent)
                    local realname = resolvers.resolve(filename) -- no shortcut
                    local blob = loadfile(realname)
                    if blob then
                        local parentdata = blob()
                        if parentdata then
                            report_resolving("loading configuration file '%s'",filename)
                            data = table.merged(parentdata,data)
                        end
                    end
                end
                data = data and data.content
                if data then
                    if trace_locating then
                        report_resolving("loading configuration file '%s'",filename)
                        report_resolving()
                    end
                    local variables = data.variables or { }
                    local warning = false
                    for k, v in next, data do
                        local variant = type(v)
                        if variant == "table" then
                            initializesetter(filename,k,v)
                        elseif variables[k] == nil then
                            if trace_locating and not warning then
                                report_resolving("variables like '%s' in configuration file '%s' should move to the 'variables' subtable",
                                    k,resolvers.resolve(filename))
                                warning = true
                            end
                            variables[k] = v
                        end
                    end
                    setups[pathname] = variables
                    if resolvers.luacnfstate == "default" then
                        -- the following code is not tested
                        local cnfspec = variables["TEXMFCNF"]
                        if cnfspec then
                            if trace_locating then
                                report_resolving("reloading configuration due to TEXMF redefinition")
                            end
                            -- we push the value into the main environment (osenv) so
                            -- that it takes precedence over the default one and therefore
                            -- also over following definitions
                            resolvers.setenv("TEXMFCNF",cnfspec) -- resolves prefixes
                            -- we now identify and load the specified configuration files
                            instance.specification = { }
                            identify_configuration_files()
                            load_configuration_files()
                            -- we prevent further overload of the configuration variable
                            resolvers.luacnfstate = "configuration"
                            -- we quit the outer loop
                            break
                        end
                    end

                else
                    if trace_locating then
                        report_resolving("skipping configuration file '%s' (no content)",filename)
                    end
                    setups[pathname] = { }
                    instance.loaderror = true
                end
            elseif trace_locating then
                report_resolving("skipping configuration file '%s' (no valid format)",filename)
            end
            instance.order[#instance.order+1] = instance.setups[pathname]
            if instance.loaderror then
                break
            end
        end
    elseif trace_locating then
        report_resolving("warning: no lua configuration files found")
    end
end

-- scheme magic ... database loading

local function load_file_databases()
    instance.loaderror, instance.files = false, allocate()
    if not instance.renewcache then
        local hashes = instance.hashes
        for k=1,#hashes do
            local hash = hashes[k]
            resolvers.hashers.byscheme(hash.type,hash.name)
            if instance.loaderror then break end
        end
    end
end

local function locate_file_databases()
    -- todo: cache:// and tree:// (runtime)
    local texmfpaths = resolvers.expandedpathlist("TEXMF")
    if #texmfpaths > 0 then
        for i=1,#texmfpaths do
            local path = collapsepath(texmfpaths[i])
            path = gsub(path,"/+$","") -- in case $HOME expands to something with a trailing /
            local stripped = lpegmatch(inhibitstripper,path) -- the !! thing
            if stripped ~= "" then
                local runtime = stripped == path
                path = resolvers.cleanpath(path)
                local spec = resolvers.splitmethod(stripped)
                if runtime and (spec.noscheme or spec.scheme == "file") then
                    stripped = "tree:///" .. stripped
                elseif spec.scheme == "cache" or spec.scheme == "file" then
                    stripped = spec.path
                end
                if trace_locating then
                    if runtime then
                        report_resolving("locating list of '%s' (runtime) (%s)",path,stripped)
                    else
                        report_resolving("locating list of '%s' (cached)",path)
                    end
                end
                methodhandler('locators',stripped)
            end
        end
        if trace_locating then
            report_resolving()
        end
    elseif trace_locating then
        report_resolving("no texmf paths are defined (using TEXMF)")
    end
end

local function generate_file_databases()
    local hashes = instance.hashes
    for k=1,#hashes do
        local hash = hashes[k]
        methodhandler('generators',hash.name)
    end
    if trace_locating then
        report_resolving()
    end
end

local function save_file_databases() -- will become cachers
    for i=1,#instance.hashes do
        local hash = instance.hashes[i]
        local cachename = hash.name
        if hash.cache then
            local content = instance.files[cachename]
            caches.collapsecontent(content)
            if trace_locating then
                report_resolving("saving tree '%s'",cachename)
            end
            caches.savecontent(cachename,"files",content)
        elseif trace_locating then
            report_resolving("not saving runtime tree '%s'",cachename)
        end
    end
end

function resolvers.renew(hashname)
    if hashname and hashname ~= "" then
        local expanded = resolvers.expansion(hashname) or ""
        if expanded ~= "" then
            if trace_locating then
                report_resolving("identifying tree '%s' from '%s'",expanded,hashname)
            end
            hashname = expanded
        else
            if trace_locating then
                report_resolving("identifying tree '%s'",hashname)
            end
        end
        local realpath = resolvers.resolve(hashname)
        if lfs.isdir(realpath) then
            if trace_locating then
                report_resolving("using path '%s'",realpath)
            end
            methodhandler('generators',hashname)
            -- could be shared
            local content = instance.files[hashname]
            caches.collapsecontent(content)
            if trace_locating then
                report_resolving("saving tree '%s'",hashname)
            end
            caches.savecontent(hashname,"files",content)
            -- till here
        else
            report_resolving("invalid path '%s'",realpath)
        end
    end
end

local function load_databases()
    locate_file_databases()
    if instance.diskcache and not instance.renewcache then
        load_file_databases()
        if instance.loaderror then
            generate_file_databases()
            save_file_databases()
        end
    else
        generate_file_databases()
        if instance.renewcache then
            save_file_databases()
        end
    end
end

function resolvers.appendhash(type,name,cache)
    -- safeguard ... tricky as it's actually a bug when seen twice
    if not instance.hashed[name] then
        if trace_locating then
            report_resolving("hash '%s' appended",name)
        end
        insert(instance.hashes, { type = type, name = name, cache = cache } )
        instance.hashed[name] = cache
    end
end

function resolvers.prependhash(type,name,cache)
    -- safeguard ... tricky as it's actually a bug when seen twice
    if not instance.hashed[name] then
        if trace_locating then
            report_resolving("hash '%s' prepended",name)
        end
        insert(instance.hashes, 1, { type = type, name = name, cache = cache } )
        instance.hashed[name] = cache
    end
end

function resolvers.extendtexmfvariable(specification) -- crap, we could better prepend the hash
    local t = resolvers.splitpath(getenv("TEXMF")) -- okay?
    insert(t,1,specification)
    local newspec = concat(t,",") -- not ;
    if instance.environment["TEXMF"] then
        instance.environment["TEXMF"] = newspec
    elseif instance.variables["TEXMF"] then
        instance.variables["TEXMF"] = newspec
    else
        -- weird
    end
    reset_hashes()
end

function resolvers.splitexpansions()
    local ie = instance.expansions
    for k,v in next, ie do
        local t, tn, h, p = { }, 0, { }, splitconfigurationpath(v)
        for kk=1,#p do
            local vv = p[kk]
            if vv ~= "" and not h[vv] then
                tn = tn + 1
                t[tn] = vv
                h[vv] = true
            end
        end
        if #t > 1 then
            ie[k] = t
        else
            ie[k] = t[1]
        end
    end
end

-- end of split/join code

-- we used to have 'files' and 'configurations' so therefore the following
-- shared function

function resolvers.datastate()
    return caches.contentstate()
end

function resolvers.variable(name)
    local name = name and lpegmatch(dollarstripper,name)
    local result = name and instance.variables[name]
    return result ~= nil and result or ""
end

function resolvers.expansion(name)
    local name = name and lpegmatch(dollarstripper,name)
    local result = name and instance.expansions[name]
    return result ~= nil and result or ""
end

function resolvers.unexpandedpathlist(str)
    local pth = resolvers.variable(str)
    local lst = resolvers.splitpath(pth)
    return expandedpathfromlist(lst)
end

function resolvers.unexpandedpath(str)
    return joinpath(resolvers.unexpandedpathlist(str))
end

local done = { }

function resolvers.resetextrapath()
    local ep = instance.extra_paths
    if not ep then
        ep, done = { }, { }
        instance.extra_paths = ep
    elseif #ep > 0 then
        instance.lists, done = { }, { }
    end
end

function resolvers.registerextrapath(paths,subpaths)
    paths = settings_to_array(paths)
    subpaths = settings_to_array(subpaths)
    local ep = instance.extra_paths or { }
    local oldn = #ep
    local newn = oldn
    local nofpaths = #paths
    local nofsubpaths = #subpaths
    if nofpaths > 0 then
        if nofsubpaths > 0 then
            for i=1,nofpaths do
                local p = paths[i]
                for j=1,nofsubpaths do
                    local s = subpaths[j]
                    local ps = p .. "/" .. s
                    if not done[ps] then
                        newn = newn + 1
                        ep[newn] = resolvers.cleanpath(ps)
                        done[ps] = true
                    end
                end
            end
        else
            for i=1,nofpaths do
                local p = paths[i]
                if not done[p] then
                    newn = newn + 1
                    ep[newn] = resolvers.cleanpath(p)
                    done[p] = true
                end
            end
        end
    elseif nofsubpaths > 0 then
        for i=1,oldn do
            for j=1,nofsubpaths do
                local s = subpaths[j]
                local ps = ep[i] .. "/" .. s
                if not done[ps] then
                    newn = newn + 1
                    ep[newn] = resolvers.cleanpath(ps)
                    done[ps] = true
                end
            end
        end
    end
    if newn > 0 then
        instance.extra_paths = ep -- register paths
    end
    if newn > oldn then
        instance.lists = { } -- erase the cache
    end
end

local function made_list(instance,list)
    local ep = instance.extra_paths
    if not ep or #ep == 0 then
        return list
    else
        local done, new, newn = { }, { }, 0
        -- honour . .. ../.. but only when at the start
        for k=1,#list do
            local v = list[k]
            if not done[v] then
                if find(v,"^[%.%/]$") then
                    done[v] = true
                    newn = newn + 1
                    new[newn] = v
                else
                    break
                end
            end
        end
        -- first the extra paths
        for k=1,#ep do
            local v = ep[k]
            if not done[v] then
                done[v] = true
                newn = newn + 1
                new[newn] = v
            end
        end
        -- next the formal paths
        for k=1,#list do
            local v = list[k]
            if not done[v] then
                done[v] = true
                newn = newn + 1
                new[newn] = v
            end
        end
        return new
    end
end

function resolvers.cleanpathlist(str)
    local t = resolvers.expandedpathlist(str)
    if t then
        for i=1,#t do
            t[i] = collapsepath(resolvers.cleanpath(t[i]))
        end
    end
    return t
end

function resolvers.expandpath(str)
    return joinpath(resolvers.expandedpathlist(str))
end

function resolvers.expandedpathlist(str)
    if not str then
        return { }
    elseif instance.savelists then
        str = lpegmatch(dollarstripper,str)
        local lists = instance.lists
        local lst = lists[str]
        if not lst then
            local l = made_list(instance,resolvers.splitpath(resolvers.expansion(str)))
            lst = expandedpathfromlist(l)
            lists[str] = lst
        end
        return lst
    else
        local lst = resolvers.splitpath(resolvers.expansion(str))
        return made_list(instance,expandedpathfromlist(lst))
    end
end

function resolvers.expandedpathlistfromvariable(str) -- brrr / could also have cleaner ^!! /$ //
    str = lpegmatch(dollarstripper,str)
    local tmp = resolvers.variableofformatorsuffix(str)
    return resolvers.expandedpathlist(tmp ~= "" and tmp or str)
end

function resolvers.expandpathfromvariable(str)
    return joinpath(resolvers.expandedpathlistfromvariable(str))
end

function resolvers.expandbraces(str) -- output variable and brace expansion of STRING
--     local ori = resolvers.variable(str)
--     if ori == "" then
        local ori = str
--     end
    local pth = expandedpathfromlist(resolvers.splitpath(ori))
    return joinpath(pth)
end

function resolvers.registerfilehash(name,content,someerror)
    if content then
        instance.files[name] = content
    else
        instance.files[name] = { }
        if somerror == true then -- can be unset
            instance.loaderror = someerror
        end
    end
end

local function isreadable(name)
    local readable = lfs.isfile(name) -- not file.is_readable(name) asit can be a dir
    if trace_detail then
        if readable then
            report_resolving("file '%s' is readable",name)
        else
            report_resolving("file '%s' is not readable", name)
        end
    end
    return readable
end

-- name
-- name/name

local function collect_files(names)
    local filelist, noffiles = { }, 0
    for k=1,#names do
        local fname = names[k]
        if trace_detail then
            report_resolving("checking name '%s'",fname)
        end
        local bname = filebasename(fname)
        local dname = filedirname(fname)
        if dname == "" or find(dname,"^%.") then
            dname = false
        else
dname = gsub(dname,"*","%.*")
            dname = "/" .. dname .. "$"
        end
        local hashes = instance.hashes
        for h=1,#hashes do
            local hash = hashes[h]
            local blobpath = hash.name
            local files = blobpath and instance.files[blobpath]
            if files then
                if trace_detail then
                    report_resolving("deep checking '%s' (%s)",blobpath,bname)
                end
                local blobfile = files[bname]
                if not blobfile then
                    local rname = "remap:"..bname
                    blobfile = files[rname]
                    if blobfile then
                        bname = files[rname]
                        blobfile = files[bname]
                    end
                end
                if blobfile then
                    local blobroot = files.__path__ or blobpath
                    if type(blobfile) == 'string' then
                        if not dname or find(blobfile,dname) then
                            local variant = hash.type
                         -- local search  = filejoin(blobpath,blobfile,bname)
                            local search  = filejoin(blobroot,blobfile,bname)
                            local result  = methodhandler('concatinators',hash.type,blobroot,blobfile,bname)
                            if trace_detail then
                                report_resolving("match: variant '%s', search '%s', result '%s'",variant,search,result)
                            end
                            noffiles = noffiles + 1
                            filelist[noffiles] = { variant, search, result }
                        end
                    else
                        for kk=1,#blobfile do
                            local vv = blobfile[kk]
                            if not dname or find(vv,dname) then
                                local variant = hash.type
                             -- local search  = filejoin(blobpath,vv,bname)
                                local search  = filejoin(blobroot,vv,bname)
                                local result  = methodhandler('concatinators',hash.type,blobroot,vv,bname)
                                if trace_detail then
                                    report_resolving("match: variant '%s', search '%s', result '%s'",variant,search,result)
                                end
                                noffiles = noffiles + 1
                                filelist[noffiles] = { variant, search, result }
                            end
                        end
                    end
                end
            elseif trace_locating then
                report_resolving("no match in '%s' (%s)",blobpath,bname)
            end
        end
    end
    return noffiles > 0 and filelist or nil
end

local fit = { }

function resolvers.registerintrees(filename,format,filetype,usedmethod,foundname)
    local foundintrees = instance.foundintrees
    if usedmethod == "direct" and filename == foundname and fit[foundname] then
        -- just an extra lookup after a test on presence
    else
        local t = {
            filename   = filename,
            format     = format ~= "" and format or nil,
            filetype   = filetype  ~= "" and filetype or nil,
            usedmethod = usedmethod,
            foundname  = foundname,
        }
        fit[foundname] = t
        foundintrees[#foundintrees+1] = t
    end
end

-- split the next one up for readability (but this module needs a cleanup anyway)

local function can_be_dir(name) -- can become local
    local fakepaths = instance.fakepaths
    if not fakepaths[name] then
        if lfs.isdir(name) then
            fakepaths[name] = 1 -- directory
        else
            fakepaths[name] = 2 -- no directory
        end
    end
    return fakepaths[name] == 1
end

local preparetreepattern = Cs((P(".")/"%%." + P("-")/"%%-" + P(1))^0 * Cc("$"))

-- -- -- begin of main file search routing -- -- -- needs checking as previous has been patched

local collect_instance_files

local function find_analyze(filename,askedformat,allresults)
    local filetype, wantedfiles, ext = '', { }, suffixonly(filename)
    -- too tricky as filename can be bla.1.2.3:
    --
    -- if not suffixmap[ext] then
    --     wantedfiles[#wantedfiles+1] = filename
    -- end
    wantedfiles[#wantedfiles+1] = filename
    if askedformat == "" then
        if ext == "" or not suffixmap[ext] then
            local defaultsuffixes = resolvers.defaultsuffixes
            for i=1,#defaultsuffixes do
                local forcedname = filename .. '.' .. defaultsuffixes[i]
                wantedfiles[#wantedfiles+1] = forcedname
                filetype = resolvers.formatofsuffix(forcedname)
                if trace_locating then
                    report_resolving("forcing filetype '%s'",filetype)
                end
            end
        else
            filetype = resolvers.formatofsuffix(filename)
            if trace_locating then
                report_resolving("using suffix based filetype '%s'",filetype)
            end
        end
    else
        if ext == "" or not suffixmap[ext] then
            local format_suffixes = suffixes[askedformat]
            if format_suffixes then
                for i=1,#format_suffixes do
                    wantedfiles[#wantedfiles+1] = filename .. "." .. format_suffixes[i]
                end
            end
        end
        filetype = askedformat
        if trace_locating then
            report_resolving("using given filetype '%s'",filetype)
        end
    end
    return filetype, wantedfiles
end

local function find_direct(filename,allresults)
    if not dangerous[askedformat] and isreadable(filename) then
        if trace_detail then
            report_resolving("file '%s' found directly",filename)
        end
        return "direct", { filename }
    end
end

local function find_wildcard(filename,allresults)
    if find(filename,'%*') then
        if trace_locating then
            report_resolving("checking wildcard '%s'", filename)
        end
        local method, result = resolvers.findwildcardfiles(filename)
        if result then
            return "wildcard", result
        end
    end
end

local function find_qualified(filename,allresults) -- this one will be split too
    if not file.is_qualified_path(filename) then
        return
    end
    if trace_locating then
        report_resolving("checking qualified name '%s'", filename)
    end
    if isreadable(filename) then
        if trace_detail then
            report_resolving("qualified file '%s' found", filename)
        end
        return "qualified", { filename }
    end
    if trace_detail then
        report_resolving("locating qualified file '%s'", filename)
    end
    local forcedname, suffix = "", suffixonly(filename)
    if suffix == "" then -- why
        local format_suffixes = askedformat == "" and resolvers.defaultsuffixes or suffixes[askedformat]
        if format_suffixes then
            for i=1,#format_suffixes do
                local s = format_suffixes[i]
                forcedname = filename .. "." .. s
                if isreadable(forcedname) then
                    if trace_locating then
                        report_resolving("no suffix, forcing format filetype '%s'", s)
                    end
                    return "qualified", { forcedname }
                end
            end
        end
    end
    if suffix and suffix ~= "" then
        -- try to find in tree (no suffix manipulation), here we search for the
        -- matching last part of the name
        local basename = filebasename(filename)
        local pattern = lpegmatch(preparetreepattern,filename)
        -- messy .. to be sorted out
        local savedformat = askedformat
        local format = savedformat or ""
        if format == "" then
            askedformat = resolvers.formatofsuffix(suffix)
        end
        if not format then
            askedformat = "othertextfiles" -- kind of everything, maybe all
        end
        --
        if basename ~= filename then
            local resolved = collect_instance_files(basename,askedformat,allresults)
            if #resolved == 0 then
                local lowered = lower(basename)
                if filename ~= lowered then
                    resolved = collect_instance_files(lowered,askedformat,allresults)
                end
            end
            resolvers.format = savedformat
            --
            if #resolved > 0 then
                local result = { }
                for r=1,#resolved do
                    local rr = resolved[r]
                    if find(rr,pattern) then
                        result[#result+1] = rr
                    end
                end
                if #result > 0 then
                    return "qualified", result
                end
            end
        end
        -- a real wildcard:
        --
        -- local filelist = collect_files({basename})
        -- result = { }
        -- for f=1,#filelist do
        --     local ff = filelist[f][3] or ""
        --     if find(ff,pattern) then
        --         result[#result+1], ok = ff, true
        --     end
        -- end
        -- if #result > 0 then
        --     return "qualified", result
        -- end
    end
end

local function check_subpath(fname)
    if isreadable(fname) then
        if trace_detail then
            report_resolving("found '%s' by deep scanning",fname)
        end
        return fname
    end
end

local function find_intree(filename,filetype,wantedfiles,allresults)
    local typespec = resolvers.variableofformat(filetype)
    local pathlist = resolvers.expandedpathlist(typespec)
    local method = "intree"
    if pathlist and #pathlist > 0 then
        -- list search
        local filelist = collect_files(wantedfiles)
        local dirlist = { }
        if filelist then
            for i=1,#filelist do
                dirlist[i] = filedirname(filelist[i][3]) .. "/" -- was [2] .. gamble
            end
        end
        if trace_detail then
            report_resolving("checking filename '%s'",filename)
        end
        local result = { }
        for k=1,#pathlist do
            local path = pathlist[k]
            local pathname = lpegmatch(inhibitstripper,path)
            local doscan = path == pathname -- no ^!!
            if not find (pathname,'//$') then
                doscan = false -- we check directly on the path
            end
            local done = false
            -- using file list
            if filelist then -- database
                -- compare list entries with permitted pattern -- /xx /xx//
                local expression = makepathexpression(pathname)
                if trace_detail then
                    report_resolving("using pattern '%s' for path '%s'",expression,pathname)
                end
                for k=1,#filelist do
                    local fl = filelist[k]
                    local f = fl[2]
                    local d = dirlist[k]
                    if find(d,expression) then
                        -- todo, test for readable
                        result[#result+1] = resolvers.resolve(fl[3]) -- no shortcut
                        done = true
                        if allresults then
                            if trace_detail then
                                report_resolving("match to '%s' in hash for file '%s' and path '%s', continue scanning",expression,f,d)
                            end
                        else
                            if trace_detail then
                                report_resolving("match to '%s' in hash for file '%s' and path '%s', quit scanning",expression,f,d)
                            end
                            break
                        end
                    elseif trace_detail then
                        report_resolving("no match to '%s' in hash for file '%s' and path '%s'",expression,f,d)
                    end
                end
            end
            if done then
                method = "database"
            else
                method = "filesystem" -- bonus, even when !! is specified
                pathname = gsub(pathname,"/+$","")
                pathname = resolvers.resolve(pathname)
                local scheme = url.hasscheme(pathname)
                if not scheme or scheme == "file" then
                    local pname = gsub(pathname,"%.%*$",'')
                    if not find(pname,"%*") then
                        if can_be_dir(pname) then
                            -- quick root scan first
                            for k=1,#wantedfiles do
                                local w = wantedfiles[k]
                                local fname = check_subpath(filejoin(pname,w))
                                if fname then
                                    result[#result+1] = fname
                                    done = true
                                    if not allresults then
                                        break
                                    end
                                end
                            end
                            if not done and doscan then
                                -- collect files in path (and cache the result)
                                local files = resolvers.simplescanfiles(pname,false,true)
                                for k=1,#wantedfiles do
                                    local w = wantedfiles[k]
                                    local subpath = files[w]
                                    if not subpath or subpath == "" then
                                        -- rootscan already done
                                    elseif type(subpath) == "string" then
                                        local fname = check_subpath(filejoin(pname,subpath,w))
                                        if fname then
                                            result[#result+1] = fname
                                            done = true
                                            if not allresults then
                                                break
                                            end
                                        end
                                    else
                                        for i=1,#subpath do
                                            local sp = subpath[i]
                                            if sp == "" then
                                                -- roottest already done
                                            else
                                                local fname = check_subpath(filejoin(pname,sp,w))
                                                if fname then
                                                    result[#result+1] = fname
                                                    done = true
                                                    if not allresults then
                                                        break
                                                    end
                                                end
                                            end
                                        end
                                        if done and not allresults then
                                            break
                                        end
                                    end
                                end
                            end
                        end
                    else
                        -- no access needed for non existing path, speedup (esp in large tree with lots of fake)
                    end
                end
            end
            -- todo recursive scanning
            if done and not allresults then
                break
            end
        end
        if #result > 0 then
            return method, result
        end
    end
end

local function find_onpath(filename,filetype,wantedfiles,allresults)
    if trace_detail then
        report_resolving("checking filename '%s', filetype '%s', wanted files '%s'",filename, filetype or '?',concat(wantedfiles," | "))
    end
    local result = { }
    for k=1,#wantedfiles do
        local fname = wantedfiles[k]
        if fname and isreadable(fname) then
            filename = fname
            result[#result+1] = filejoin('.',fname)
            if not allresults then
                break
            end
        end
    end
    if #result > 0 then
        return "onpath", result
    end
end

local function find_otherwise(filename,filetype,wantedfiles,allresults) -- other text files | any | whatever
    local filelist = collect_files(wantedfiles)
    local fl = filelist and filelist[1]
    if fl then
        return "otherwise", { resolvers.resolve(fl[3]) } -- filename
    end
end

-- we could have a loop over the 6 functions but then we'd have to
-- always analyze

collect_instance_files = function(filename,askedformat,allresults) -- uses nested
    askedformat = askedformat or ""
    filename = collapsepath(filename)
    if allresults then
        -- no need for caching, only used for tracing
        local filetype, wantedfiles = find_analyze(filename,askedformat)
        local results = {
            { find_direct   (filename,true) },
            { find_wildcard (filename,true) },
            { find_qualified(filename,true) },
            { find_intree   (filename,filetype,wantedfiles,true) },
            { find_onpath   (filename,filetype,wantedfiles,true) },
            { find_otherwise(filename,filetype,wantedfiles,true) },
        }
        local result, status, done = { }, { }, { }
        for k, r in next, results do
            local method, list = r[1], r[2]
            if method and list then
                for i=1,#list do
                    local c = collapsepath(list[i])
                    if not done[c] then
                        result[#result+1] = c
                        done[c] = true
                    end
                    status[#status+1] = format("%-10s: %s",method,c)
                end
            end
        end
        if trace_detail then
            report_resolving("lookup status: %s",table.serialize(status,filename))
        end
        return result, status
    else
        local method, result, stamp, filetype, wantedfiles
        if instance.remember then
            stamp = format("%s--%s", filename, askedformat)
            result = stamp and instance.found[stamp]
            if result then
                if trace_locating then
                    report_resolving("remembered file '%s'",filename)
                end
                return result
            end
        end
        method, result = find_direct(filename)
        if not result then
            method, result = find_wildcard(filename)
            if not result then
                method, result = find_qualified(filename)
                if not result then
                    filetype, wantedfiles = find_analyze(filename,askedformat)
                    method, result = find_intree(filename,filetype,wantedfiles)
                    if not result then
                        method, result = find_onpath(filename,filetype,wantedfiles)
                        if not result then
                            method, result = find_otherwise(filename,filetype,wantedfiles)
                        end
                    end
                end
            end
        end
        if result and #result > 0 then
            local foundname = collapsepath(result[1])
            resolvers.registerintrees(filename,askedformat,filetype,method,foundname)
            result = { foundname }
        else
            result = { } -- maybe false
        end
        if stamp then
            if trace_locating then
                report_resolving("remembering file '%s'",filename)
            end
            instance.found[stamp] = result
        end
        return result
    end
end

-- -- -- end of main file search routing -- -- --


local function findfiles(filename,filetype,allresults)
    local result, status = collect_instance_files(filename,filetype or "",allresults)
    if not result or #result == 0 then
        local lowered = lower(filename)
        if filename ~= lowered then
            result, status = collect_instance_files(lowered,filetype or "",allresults)
        end
    end
    return result or { }, status
end

function resolvers.findfiles(filename,filetype)
    return findfiles(filename,filetype,true)
end

function resolvers.findfile(filename,filetype)
    return findfiles(filename,filetype,false)[1] or ""
end

function resolvers.findpath(filename,filetype)
    return filedirname(findfiles(filename,filetype,false)[1] or "")
end

local function findgivenfiles(filename,allresults)
    local bname, result = filebasename(filename), { }
    local hashes = instance.hashes
    local noffound = 0
    for k=1,#hashes do
        local hash = hashes[k]
        local files = instance.files[hash.name] or { }
        local blist = files[bname]
        if not blist then
            local rname = "remap:"..bname
            blist = files[rname]
            if blist then
                bname = files[rname]
                blist = files[bname]
            end
        end
        if blist then
            if type(blist) == 'string' then
                local found = methodhandler('concatinators',hash.type,hash.name,blist,bname) or ""
                if found ~= "" then
                    noffound = noffound + 1
                    result[noffound] = resolvers.resolve(found)
                    if not allresults then break end
                end
            else
                for kk=1,#blist do
                    local vv = blist[kk]
                    local found = methodhandler('concatinators',hash.type,hash.name,vv,bname) or ""
                    if found ~= "" then
                        noffound = noffound + 1
                        result[noffound] = resolvers.resolve(found)
                        if not allresults then break end
                    end
                end
            end
        end
    end
    return result
end

function resolvers.findgivenfiles(filename)
    return findgivenfiles(filename,true)
end

function resolvers.findgivenfile(filename)
    return findgivenfiles(filename,false)[1] or ""
end

local function doit(path,blist,bname,tag,variant,result,allresults)
    local done = false
    if blist and variant then
        local resolve = resolvers.resolve -- added
        if type(blist) == 'string' then
            -- make function and share code
            if find(lower(blist),path) then
                local full = methodhandler('concatinators',variant,tag,blist,bname) or ""
                result[#result+1] = resolve(full)
                done = true
            end
        else
            for kk=1,#blist do
                local vv = blist[kk]
                if find(lower(vv),path) then
                    local full = methodhandler('concatinators',variant,tag,vv,bname) or ""
                    result[#result+1] = resolve(full)
                    done = true
                    if not allresults then break end
                end
            end
        end
    end
    return done
end

--~ local makewildcard = Cs(
--~     (P("^")^0 * P("/") * P(-1) + P(-1)) /".*"
--~   + (P("^")^0 * P("/") / "") * (P("*")/".*" + P("-")/"%%-" + P("?")/"."+ P("\\")/"/" + P(1))^0
--~ )

local makewildcard = Cs(
    (P("^")^0 * P("/") * P(-1) + P(-1)) /".*"
  + (P("^")^0 * P("/") / "")^0 * (P("*")/".*" + P("-")/"%%-" + P(".")/"%%." + P("?")/"."+ P("\\")/"/" + P(1))^0
)

function resolvers.wildcardpattern(pattern)
    return lpegmatch(makewildcard,pattern) or pattern
end

local function findwildcardfiles(filename,allresults,result) -- todo: remap: and lpeg
    result = result or { }
--~     local path = lower(lpegmatch(makewildcard,filedirname (filename)))
--~     local name = lower(lpegmatch(makewildcard,filebasename(filename)))
    local base = filebasename(filename)
    local dirn = filedirname(filename)
    local path = lower(lpegmatch(makewildcard,dirn) or dirn)
    local name = lower(lpegmatch(makewildcard,base) or base)
    local files, done = instance.files, false
    if find(name,"%*") then
        local hashes = instance.hashes
        for k=1,#hashes do
            local hash = hashes[k]
            local hashname, hashtype = hash.name, hash.type
            for kk, hh in next, files[hashname] do
                if not find(kk,"^remap:") then
                    if find(lower(kk),name) then
                        if doit(path,hh,kk,hashname,hashtype,result,allresults) then done = true end
                        if done and not allresults then break end
                    end
                end
            end
        end
    else
        local hashes = instance.hashes
        for k=1,#hashes do
            local hash = hashes[k]
            local hashname, hashtype = hash.name, hash.type
            if doit(path,files[hashname][bname],bname,hashname,hashtype,result,allresults) then done = true end
            if done and not allresults then break end
        end
    end
    -- we can consider also searching the paths not in the database, but then
    -- we end up with a messy search (all // in all path specs)
    return result
end

function resolvers.findwildcardfiles(filename,result)
    return findwildcardfiles(filename,true,result)
end

function resolvers.findwildcardfile(filename)
    return findwildcardfiles(filename,false)[1] or ""
end

-- main user functions

function resolvers.automount()
    -- implemented later
end

function resolvers.load(option)
    statistics.starttiming(instance)
    identify_configuration_files()
    load_configuration_files()
    if option ~= "nofiles" then
        load_databases()
        resolvers.automount()
    end
    statistics.stoptiming(instance)
    local files = instance.files
    return files and next(files) and true
end

function resolvers.loadtime()
    return statistics.elapsedtime(instance)
end

local function report(str)
    if trace_locating then
        report_resolving(str) -- has already verbose
    else
        print(str)
    end
end

function resolvers.dowithfilesandreport(command, files, ...) -- will move
    if files and #files > 0 then
        if trace_locating then
            report('') -- ?
        end
        if type(files) == "string" then
            files = { files }
        end
        for f=1,#files do
            local file = files[f]
            local result = command(file,...)
            if type(result) == 'string' then
                report(result)
            else
                for i=1,#result do
                    report(result[i]) -- could be unpack
                end
            end
        end
    end
end

-- obsolete

-- resolvers.varvalue  = resolvers.variable   -- output the value of variable $STRING.
-- resolvers.expandvar = resolvers.expansion  -- output variable expansion of STRING.

function resolvers.showpath(str)     -- output search path for file type NAME
    return joinpath(resolvers.expandedpathlist(resolvers.formatofvariable(str)))
end

function resolvers.registerfile(files, name, path)
    if files[name] then
        if type(files[name]) == 'string' then
            files[name] = { files[name], path }
        else
            files[name] = path
        end
    else
        files[name] = path
    end
end

function resolvers.dowithpath(name,func)
    local pathlist = resolvers.expandedpathlist(name)
    for i=1,#pathlist do
        func("^"..resolvers.cleanpath(pathlist[i]))
    end
end

function resolvers.dowithvariable(name,func)
    func(expandedvariable(name))
end

function resolvers.locateformat(name)
    local barename = file.removesuffix(name) -- gsub(name,"%.%a+$","")
    local fmtname = caches.getfirstreadablefile(barename..".fmt","formats") or ""
    if fmtname == "" then
        fmtname = resolvers.findfile(barename..".fmt")
        fmtname = resolvers.cleanpath(fmtname)
    end
    if fmtname ~= "" then
        local barename = file.removesuffix(fmtname)
        local luaname, lucname, luiname = barename .. ".lua", barename .. ".luc", barename .. ".lui"
        if lfs.isfile(luiname) then
            return barename, luiname
        elseif lfs.isfile(lucname) then
            return barename, lucname
        elseif lfs.isfile(luaname) then
            return barename, luaname
        end
    end
    return nil, nil
end

function resolvers.booleanvariable(str,default)
    local b = resolvers.expansion(str)
    if b == "" then
        return default
    else
        b = toboolean(b)
        return (b == nil and default) or b
    end
end

function resolvers.dowithfilesintree(pattern,handle,before,after) -- will move, can be a nice iterator instead
    local instance = resolvers.instance
    local hashes = instance.hashes
    for i=1,#hashes do
        local hash = hashes[i]
        local blobtype = hash.type
        local blobpath = hash.name
        if blobpath then
            if before then
                before(blobtype,blobpath,pattern)
            end
            local files = instance.files[blobpath]
            local total, checked, done = 0, 0, 0
            if files then
                for k,v in next, files do
                    total = total + 1
                    if find(k,"^remap:") then
                        k = files[k]
                        v = k -- files[k] -- chained
                    end
                    if find(k,pattern) then
                        if type(v) == "string" then
                            checked = checked + 1
                            if handle(blobtype,blobpath,v,k) then
                                done = done + 1
                            end
                        else
                            checked = checked + #v
                            for i=1,#v do
                                if handle(blobtype,blobpath,v[i],k) then
                                    done = done + 1
                                end
                            end
                        end
                    end
                end
            end
            if after then
                after(blobtype,blobpath,pattern,total,checked,done)
            end
        end
    end
end

resolvers.obsolete = resolvers.obsolete or { }
local obsolete     = resolvers.obsolete

resolvers.find_file  = resolvers.findfile    obsolete.find_file  = resolvers.findfile
resolvers.find_files = resolvers.findfiles   obsolete.find_files = resolvers.findfiles