luapp -- Lua Preprocessor

--LuaPreProcessor by Admicos

os.loadAPI("getopt")

local incdir  = "/etc/luapp/include/"

local version = "1.2.0"
local outType = "normal"

local prefix = "--pp:"
local output = shell.resolve("a.out")

local oBuf = ""

local _defines = {}
local _ignblck = false

local function _print(verbose, ...)
    if outType == "silent" then return end
    if (outType ~= "verbose") and (outType ~= "verboser") and verbose then return end
    if outType ~= "verboser" and verbose == "v" then return end

    print(table.unpack({ ... }))
end

local function _err(err)
    error("ERROR: " .. err, math.huge)
end

function _trim(s)
    return (s:gsub("^%s*(.-)%s*$", "%1"))
end

local function _split(str, splitter)
    local t = {}
    local function helper(line) table.insert(t, line) return "" end
        helper((str:gsub("(.-)" .. splitter, helper)))
    return t
end

local processFile = function(_) end;
local pprocop = {
    include = function(file)
        local incfile = ""
        _print("v", "Including file " .. file)

        if fs.exists(shell.resolve(file)) then
            incfile = shell.resolve(file)
        elseif fs.exists(fs.combine(incdir, file)) then
            incfile = fs.combine(incdir, file)
        elseif fs.exists(file) then
            incfile = file
        else
            _err("Couldn't find a include for '" .. file .. "'")
        end

        processFile(incfile)
    end;

    define = function(thing, ...)
        _print("v", "Defining " .. thing)
        _defines[thing] = table.concat(arg, " ")
    end;

    ifdef = function(defined)
        if _defines[defined] == nil then
            _print("v", "Starting a ignore block")
            _ignblck = true
        end
    end;

    ifndef = function(defined)
        if _defines[defined] ~= nil then
            _print("v", "Starting a ignore block")
            _ignblck = true
        end
    end;

    ["if"] = function(...)
        local lstr = table.concat(arg, " ")
        for def, val in pairs(_defines) do
            lstr = lstr:gsub(def, val)
        end

        if not loadstring("return " .. lstr)() then
            _print("v", "Starting a ignore block")
            _ignblck = true
        end
    end;

    ["ifn"] = function(...)
        local lstr = table.concat(arg, " ")
        for def, val in pairs(_defines) do
            lstr = lstr:gsub(def, val)
        end

        if loadstring("return " .. lstr)() then
            _print("v", "Starting a ignore block")
            _ignblck = true
        end
    end;

    ["else"] = function()
        _ignblck = not _ignblck
    end;

    ignorestart = function()
        _print("v", "Starting a ignore block")
        _ignblck = true
    end;

    ignoreend = function()
        _print("v", "Ending a ignore block")
        _ignblck = false
    end;
}

processFile = function(file)
    if not fs.exists(file) then error("File " .. file .. " doesn't exist") end
    _print(true, "@@ /" .. file .. " @@")

    local ls = {}
    local lIsPreprocessed = false;
    for line in io.lines(file) do
        lIsPreprocessed = false
        ls = _split(_trim(line), " ")
        if #ls >= 1 then
            for _, line in ipairs(ls) do
                if line:sub(1, #prefix) == prefix then
                    local proc = table.remove(ls, 1):sub(#prefix + 1)

                    if not pprocop[proc] then _err("'" .. proc .. "': not found") end

                    if _ignblck then
                        if (proc == "ignoreend") or (proc == "else") then
                            pprocop[proc](table.unpack(ls))
                        end
                    else
                        pprocop[proc](table.unpack(ls))
                    end

                    lIsPreprocessed = true
                end
            end
        end

        if (not lIsPreprocessed) and (not _ignblck) then
            for def, val in pairs(_defines) do
                _print("v", "Replaced defined value " .. def)

                line = line:gsub(def, val)
            end

            oBuf = oBuf .. line .. "\n"
        end
    end

    local f = fs.open(output, "w")
        f.write(oBuf)
    f.close()
end

local function main(args)
    if args == nil then return end
    if args["opt-1"] == nil then print("'luapp -h' for help") return end

    if args["verbose"]  then outType = "verbose" end
    if args["verboser"] then outType = "verboser" end
    if args["silent"]   then outType = "silent" end

    if args["prefix"] then prefix = args["prefix"] end
    if args["output"] then output = shell.resolve(args["output"]) end

    local file = shell.resolve(args["opt-1"])

    _print(false, "luapp " .. version)
    _print(true, "Prefix set as: " .. prefix)

    _print(false, "")

    processFile(file)
    _print(false, "DONE: /" .. output)
end

main(getopt.init("luapp", "Lua Preprocessor", {
    ["prefix"] = {"Preprocessor Line Prefix", "p", "prefix"};
    ["output"] = {"Processed file out", "o", "output"};
    ["verbose"] = {"More output", "v", nil};
    ["verboser"] = {"Even more output", "vv", nil};
    ["silent"] = {"Less output", "s", nil};
}, { ... }))