if not modules then modules = { } end modules ['util-env'] = {
    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"
}

local allocate, mark = utilities.storage.allocate, utilities.storage.mark

local format, sub, match, gsub, find = string.format, string.sub, string.match, string.gsub, string.find
local unquoted, quoted, optionalquoted = string.unquoted, string.quoted, string.optionalquoted
local concat, insert, remove = table.concat, table.insert, table.remove
local globfiles = dir.glob

environment         = environment or { }
local environment   = environment

-- -- These locales are a useless feature in and even dangerous for luatex, so
-- -- we just ignore them. We used to warn but I assume no one needs it anyway
-- -- so let's save some bytes.

-- local setlocale = os.setlocale
--
-- setlocale(nil,nil) -- setlocale("all","C")
--
-- function os.resetlocale()
--     setlocale(nil,nil)
-- end
--
-- function os.pushlocale(l,...)
--     insert(stack, {
--         collate  = setlocale(nil,"collate"),
--         ctype    = setlocale(nil,"ctype"),
--         monetary = setlocale(nil,"monetary"),
--         numeric  = setlocale(nil,"numeric"),
--         time     = setlocale(nil,"time"),
--     })
--     if l then
--         setlocale(l,...)
--     else
--         setlocale(status.lc_collate ,"collate"),
--         setlocale(status.lc_ctype   ,"ctype"),
--         setlocale(status.lc_monetary,"monetary"),
--         setlocale(status.lc_numeric ,"numeric"),
--         setlocale(status.lc_time    ,"time"),
--     end
-- end
--
-- function os.poplocale()
--     local l = remove(stack)
--     if l then
--         setlocale(unpack(l))
--     else
--         resetlocale()
--     end
-- end

-- local report = logs.reporter("system")
--
-- function os.setlocale(a,b)
--     if a or b then
--         if report then
--             report()
--             report("You're messing with os.setlocale in a supposedly locale neutral enviroment. From")
--             report("now on are on your own and without support. Crashes or unexpected side effects")
--             report("can happen but don't bother the luatex and context developer team with it.")
--             report()
--             report = nil
--         end
--         setlocale(a,b)
--     end
-- end

-- It's time to get rid of it:

os.setlocale(nil,nil) function os.setlocale() end

-- dirty tricks (we will replace the texlua call by luatex --luaonly)

local validengines = allocate {
    ["luatex"]    = true,
    ["luajittex"] = true,
}

local basicengines = allocate {
    ["luatex"]    = "luatex",
    ["texlua"]    = "luatex",    -- obsolete
    ["texluac"]   = "luatex",    -- obsolete
    ["luajittex"] = "luajittex",
    ["texluajit"] = "luajittex", -- obsolete
}

local luaengines = allocate {
    ["lua"]    = true,
    ["luajit"] = true,
}

environment.validengines = validengines
environment.basicengines = basicengines

-- [-1] = binary
-- [ 0] = self
-- [ 1] = argument 1 ...

-- instead we could set ranges

if not arg then
    environment.used_as_library = true
    -- used as library
elseif luaengines[file.removesuffix(arg[-1])] then
--     arg[-1] = arg[0]
--     arg[ 0] = arg[1]
--     for k=2,#arg do
--         arg[k-1] = arg[k]
--     end
--     remove(arg) -- last
--
--    environment.used_as_library = true
elseif validengines[file.removesuffix(arg[0])] then
    if arg[1] == "--luaonly" then
        arg[-1] = arg[0]
        arg[ 0] = arg[2]
        for k=3,#arg do
            arg[k-2] = arg[k]
        end
        remove(arg) -- last
        remove(arg) -- pre-last
    else
        -- tex run
    end

    -- This is an ugly hack but it permits symlinking a script (say 'context') to 'mtxrun' as in:
    --
    --   ln -s /opt/minimals/tex/texmf-linux-64/bin/mtxrun context
    --
    -- The special mapping hack is needed because 'luatools' boils down to 'mtxrun --script base'
    -- but it's unlikely that there will be more of this

    local originalzero   = file.basename(arg[0])
    local specialmapping = { luatools == "base" }

    if originalzero ~= "mtxrun" and originalzero ~= "mtxrun.lua" then
       arg[0] = specialmapping[originalzero] or originalzero
       insert(arg,0,"--script")
       insert(arg,0,"mtxrun")
    end

end

-- environment

environment.arguments   = allocate()
environment.files       = allocate()
environment.sortedflags = nil

-- context specific arguments (in order not to confuse the engine)

function environment.initializearguments(arg)
    local arguments = { }
    local files     = { }
    environment.arguments   = arguments
    environment.files       = files
    environment.sortedflags = nil
    for index=1,#arg do
        local argument = arg[index]
        if index > 0 then
            local flag, value = match(argument,"^%-+(.-)=(.-)$")
            if flag then
                flag = gsub(flag,"^c:","")
                arguments[flag] = unquoted(value or "")
            else
                flag = match(argument,"^%-+(.+)")
                if flag then
                    flag = gsub(flag,"^c:","")
                    arguments[flag] = true
                else
                    files[#files+1] = argument
                end
            end
        end
    end
    if not environment.ownname then
        if os.selfpath and os.selfname then
            environment.ownname = file.addsuffix(file.join(os.selfpath,os.selfname),"lua")
        end
    end
    environment.ownname = file.reslash(environment.ownname or arg[0] or 'unknown.lua')
end

function environment.setargument(name,value)
    environment.arguments[name] = value
end

-- todo: defaults, better checks e.g on type (boolean versus string)
--
-- tricky: too many hits when we support partials unless we add
-- a registration of arguments so from now on we have 'partial'

function environment.getargument(name,partial)
    local arguments   = environment.arguments
    local sortedflags = environment.sortedflags
    if arguments[name] then
        return arguments[name]
    elseif partial then
        if not sortedflags then
            sortedflags = allocate(table.sortedkeys(arguments))
            for k=1,#sortedflags do
                sortedflags[k] = "^" .. sortedflags[k]
            end
            environment.sortedflags = sortedflags
        end
        -- example of potential clash: ^mode ^modefile
        for k=1,#sortedflags do
            local v = sortedflags[k]
            if find(name,v) then
                return arguments[sub(v,2,#v)]
            end
        end
    end
    return nil
end

environment.argument = environment.getargument

function environment.splitarguments(separator) -- rather special, cut-off before separator
    local done, before, after = false, { }, { }
    local originalarguments = environment.originalarguments
    for k=1,#originalarguments do
        local v = originalarguments[k]
        if not done and v == separator then
            done = true
        elseif done then
            after[#after+1] = v
        else
            before[#before+1] = v
        end
    end
    return before, after
end

function environment.reconstructcommandline(arg,noquote)
    local resolveprefix = resolvers.resolve -- something rather special
    arg = arg or environment.originalarguments
    if noquote and #arg == 1 then
        return unquoted(resolveprefix and resolveprefix(arg[1]) or arg[1])
    elseif #arg > 0 then
        local result = { }
        for i=1,#arg do
            result[i] = optionalquoted(resolveprefix and resolveprefix(arg[i]) or resolveprefix)
        end
        return concat(result," ")
    else
        return ""
    end
end

-- handy in e.g. package.addluapath(environment.relativepath("scripts"))

function environment.relativepath(path,root)
    if not path then
        path = ""
    end
    if not file.is_rootbased_path(path) then
        if not root then
            root = file.pathpart(environment.ownscript or environment.ownname or ".")
        end
        if root == "" then
            root = "."
        end
        path = root .. "/" .. path
    end
    return file.collapsepath(path,true)
end

-- -- when script lives on e:/tmp we get this:
--
-- print(environment.relativepath("x/y/z","c:/w")) -- c:/w/x/y/z
-- print(environment.relativepath("x"))            -- e:/tmp/x
-- print(environment.relativepath("../x"))         -- e:/x
-- print(environment.relativepath("./x"))          -- e:/tmp/x
-- print(environment.relativepath("/x"))           -- /x
-- print(environment.relativepath("c:/x"))         -- c:/x
-- print(environment.relativepath("//x"))          -- //x
-- print(environment.relativepath())               -- e:/tmp

if arg then

    -- new, reconstruct quoted snippets (maybe better just remove the " then and add them later)

    local newarg, instring = { }, false

    for index=1,#arg do
        local argument = arg[index]
        if find(argument,"^\"") then
            if find(argument,"\"$") then
                newarg[#newarg+1] = gsub(argument,"^\"(.-)\"$","%1")
                instring = false
            else
                newarg[#newarg+1] = gsub(argument,"^\"","")
                instring = true
            end
        elseif find(argument,"\"$") then
            if instring then
                newarg[#newarg] = newarg[#newarg] .. " " .. gsub(argument,"\"$","")
                instring = false
            else
                newarg[#newarg+1] = argument
            end
        elseif instring then
            newarg[#newarg] = newarg[#newarg] .. " " .. argument
        else
            newarg[#newarg+1] = argument
        end
    end
    for i=1,-5,-1 do
        newarg[i] = arg[i]
    end

    environment.initializearguments(newarg)

    environment.originalarguments = mark(newarg)
    environment.rawarguments      = mark(arg)

    arg = { } -- prevent duplicate handling

end

function environment.globfiles(files)
    if not files then
        files = environment.files
    end
    if files then
        local globbed = { }
        for i=1,#files do
            local f = files[i]
            if find(f,"%*") then
                local g = globfiles(f)
                if g then
                    for i=1,#g do
                        globbed[#globbed+1] = g[i]
                    end
                end
            else
                globbed[#globbed+1] = f
            end
        end
        return globbed
    end
end