"use strict";

const conf = (process.env.FENGARICONF ? JSON.parse(process.env.FENGARICONF) : {});

const {
    LUA_VERSION_MAJOR,
    LUA_VERSION_MINOR,
    to_luastring
} = require('./defs.js');

/*
** LUA_PATH_SEP is the character that separates templates in a path.
** LUA_PATH_MARK is the string that marks the substitution points in a
** template.
** LUA_EXEC_DIR in a Windows path is replaced by the executable's
** directory.
*/
const LUA_PATH_SEP  = ";";
module.exports.LUA_PATH_SEP = LUA_PATH_SEP;

const LUA_PATH_MARK = "?";
module.exports.LUA_PATH_MARK = LUA_PATH_MARK;

const LUA_EXEC_DIR  = "!";
module.exports.LUA_EXEC_DIR = LUA_EXEC_DIR;

/*
@@ LUA_PATH_DEFAULT is the default path that Lua uses to look for
** Lua libraries.
@@ LUA_JSPATH_DEFAULT is the default path that Lua uses to look for
** JS libraries.
** CHANGE them if your machine has a non-conventional directory
** hierarchy or if you want to install your libraries in
** non-conventional directories.
*/
const LUA_VDIR = LUA_VERSION_MAJOR + "." + LUA_VERSION_MINOR;
module.exports.LUA_VDIR = LUA_VDIR;

if (typeof process === "undefined") {
    const LUA_DIRSEP = "/";
    module.exports.LUA_DIRSEP = LUA_DIRSEP;

    const LUA_LDIR = "./lua/" + LUA_VDIR + "/";
    module.exports.LUA_LDIR = LUA_LDIR;

    const LUA_JSDIR = LUA_LDIR;
    module.exports.LUA_JSDIR = LUA_JSDIR;

    const LUA_PATH_DEFAULT = to_luastring(
        LUA_LDIR + "?.lua;" + LUA_LDIR + "?/init.lua;" +
        /* LUA_JSDIR excluded as it is equal to LUA_LDIR */
        "./?.lua;./?/init.lua"
    );
    module.exports.LUA_PATH_DEFAULT = LUA_PATH_DEFAULT;

    const LUA_JSPATH_DEFAULT = to_luastring(
        LUA_JSDIR + "?.js;" + LUA_JSDIR + "loadall.js;./?.js"
    );
    module.exports.LUA_JSPATH_DEFAULT = LUA_JSPATH_DEFAULT;
} else if (require('os').platform() === 'win32') {
    const LUA_DIRSEP = "\\";
    module.exports.LUA_DIRSEP = LUA_DIRSEP;

    /*
    ** In Windows, any exclamation mark ('!') in the path is replaced by the
    ** path of the directory of the executable file of the current process.
    */
    const LUA_LDIR = "!\\lua\\";
    module.exports.LUA_LDIR = LUA_LDIR;

    const LUA_JSDIR = "!\\";
    module.exports.LUA_JSDIR = LUA_JSDIR;

    const LUA_SHRDIR = "!\\..\\share\\lua\\" + LUA_VDIR + "\\";
    module.exports.LUA_SHRDIR = LUA_SHRDIR;

    const LUA_PATH_DEFAULT = to_luastring(
        LUA_LDIR + "?.lua;" + LUA_LDIR + "?\\init.lua;" +
        LUA_JSDIR + "?.lua;" + LUA_JSDIR + "?\\init.lua;" +
        LUA_SHRDIR + "?.lua;" + LUA_SHRDIR + "?\\init.lua;" +
        ".\\?.lua;.\\?\\init.lua"
    );
    module.exports.LUA_PATH_DEFAULT = LUA_PATH_DEFAULT;

    const LUA_JSPATH_DEFAULT = to_luastring(
        LUA_JSDIR + "?.js;" +
        LUA_JSDIR + "..\\share\\lua\\" + LUA_VDIR + "\\?.js;" +
        LUA_JSDIR + "loadall.js;.\\?.js"
    );
    module.exports.LUA_JSPATH_DEFAULT = LUA_JSPATH_DEFAULT;
} else {
    const LUA_DIRSEP = "/";
    module.exports.LUA_DIRSEP = LUA_DIRSEP;

    const LUA_ROOT = "/usr/local/";
    module.exports.LUA_ROOT = LUA_ROOT;
    const LUA_ROOT2 = "/usr/";

    const LUA_LDIR = LUA_ROOT + "share/lua/" + LUA_VDIR + "/";
    const LUA_LDIR2 = LUA_ROOT2 + "share/lua/" + LUA_VDIR + "/";
    module.exports.LUA_LDIR = LUA_LDIR;

    const LUA_JSDIR = LUA_LDIR;
    module.exports.LUA_JSDIR = LUA_JSDIR;
    const LUA_JSDIR2 = LUA_LDIR2;

    const LUA_PATH_DEFAULT = to_luastring(
        LUA_LDIR + "?.lua;" + LUA_LDIR + "?/init.lua;" +
        LUA_LDIR2 + "?.lua;" + LUA_LDIR2 + "?/init.lua;" +
        /* LUA_JSDIR(2) excluded as it is equal to LUA_LDIR(2) */
        "./?.lua;./?/init.lua"
    );
    module.exports.LUA_PATH_DEFAULT = LUA_PATH_DEFAULT;

    const LUA_JSPATH_DEFAULT = to_luastring(
        LUA_JSDIR + "?.js;" + LUA_JSDIR + "loadall.js;" +
        LUA_JSDIR2 + "?.js;" + LUA_JSDIR2 + "loadall.js;" +
        "./?.js"
    );
    module.exports.LUA_JSPATH_DEFAULT = LUA_JSPATH_DEFAULT;
}

/*
@@ LUA_COMPAT_FLOATSTRING makes Lua format integral floats without a
@@ a float mark ('.0').
** This macro is not on by default even in compatibility mode,
** because this is not really an incompatibility.
*/
const LUA_COMPAT_FLOATSTRING = conf.LUA_COMPAT_FLOATSTRING || false;

const LUA_MAXINTEGER = 2147483647;
const LUA_MININTEGER = -2147483648;

/*
@@ LUAI_MAXSTACK limits the size of the Lua stack.
** CHANGE it if you need a different limit. This limit is arbitrary;
** its only purpose is to stop Lua from consuming unlimited stack
** space (and to reserve some numbers for pseudo-indices).
*/
const LUAI_MAXSTACK = conf.LUAI_MAXSTACK || 1000000;

/*
@@ LUA_IDSIZE gives the maximum size for the description of the source
@@ of a function in debug information.
** CHANGE it if you want a different size.
*/
const LUA_IDSIZE = conf.LUA_IDSIZE || (60-1); /* fengari uses 1 less than lua as we don't embed the null byte */

const lua_integer2str = function(n) {
    return String(n); /* should match behaviour of LUA_INTEGER_FMT */
};

const lua_number2str = function(n) {
    return String(Number(n.toPrecision(14))); /* should match behaviour of LUA_NUMBER_FMT */
};

const lua_numbertointeger = function(n) {
    return n >= LUA_MININTEGER && n < -LUA_MININTEGER ? n : false;
};

const LUA_INTEGER_FRMLEN = "";
const LUA_NUMBER_FRMLEN = "";

const LUA_INTEGER_FMT = `%${LUA_INTEGER_FRMLEN}d`;
const LUA_NUMBER_FMT  = "%.14g";

const lua_getlocaledecpoint = function() {
    return (1.1).toLocaleString().charCodeAt(1);
};

const luai_apicheck = function(l, e) {
    if (!e) throw Error(e);
};

/*
@@ LUAL_BUFFERSIZE is the buffer size used by the lauxlib buffer system.
*/
const LUAL_BUFFERSIZE = conf.LUAL_BUFFERSIZE || 8192;

// See: http://croquetweak.blogspot.fr/2014/08/deconstructing-floats-frexp-and-ldexp.html
const frexp = function(value) {
    if (value === 0) return [value, 0];
    var data = new DataView(new ArrayBuffer(8));
    data.setFloat64(0, value);
    var bits = (data.getUint32(0) >>> 20) & 0x7FF;
    if (bits === 0) { // denormal
        data.setFloat64(0, value * Math.pow(2, 64));  // exp + 64
        bits = ((data.getUint32(0) >>> 20) & 0x7FF) - 64;
    }
    var exponent = bits - 1022;
    var mantissa = ldexp(value, -exponent);
    return [mantissa, exponent];
};

const ldexp = function(mantissa, exponent) {
    var steps = Math.min(3, Math.ceil(Math.abs(exponent) / 1023));
    var result = mantissa;
    for (var i = 0; i < steps; i++)
        result *= Math.pow(2, Math.floor((exponent + i) / steps));
    return result;
};

module.exports.LUAI_MAXSTACK          = LUAI_MAXSTACK;
module.exports.LUA_COMPAT_FLOATSTRING = LUA_COMPAT_FLOATSTRING;
module.exports.LUA_IDSIZE             = LUA_IDSIZE;
module.exports.LUA_INTEGER_FMT        = LUA_INTEGER_FMT;
module.exports.LUA_INTEGER_FRMLEN     = LUA_INTEGER_FRMLEN;
module.exports.LUA_MAXINTEGER         = LUA_MAXINTEGER;
module.exports.LUA_MININTEGER         = LUA_MININTEGER;
module.exports.LUA_NUMBER_FMT         = LUA_NUMBER_FMT;
module.exports.LUA_NUMBER_FRMLEN      = LUA_NUMBER_FRMLEN;
module.exports.LUAL_BUFFERSIZE        = LUAL_BUFFERSIZE;
module.exports.frexp                  = frexp;
module.exports.ldexp                  = ldexp;
module.exports.lua_getlocaledecpoint  = lua_getlocaledecpoint;
module.exports.lua_integer2str        = lua_integer2str;
module.exports.lua_number2str         = lua_number2str;
module.exports.lua_numbertointeger    = lua_numbertointeger;
module.exports.luai_apicheck          = luai_apicheck;