/*jshint esversion: 6 */
"use strict";

const assert = require('assert');

const lstate  = require('./lstate.js');
const lapi    = require('./lapi.js');
const lua     = require('./lua.js');
const ldebug  = require('./ldebug.js');
const lobject = require('./lobject.js');
const CT      = lua.constant_types;

const LUA_LOADED_TABLE = "_LOADED";


class luaL_Buffer {
    constructor(L) {
        this.L = L;
        this.b = "";
    }
}

/*
** search for 'objidx' in table at index -1.
** return 1 + string at top if find a good name.
*/
const findfield = function(L, objidx, level) {
    if (level === 0 || !lapi.lua_istable(L, -1))
        return 0;  /* not found */

    lapi.lua_pushnil(L);  /* start 'next' loop */

    while (lapi.lua_next(L, -2)) {  /* for each pair in table */
        if (lapi.lua_type(L, -2) === CT.LUA_TSTRING) {  /* ignore non-string keys */
            if (lapi.lua_rawequal(L, objidx, -1)) {  /* found object? */
                lapi.lua_pop(L, 1);  /* remove value (but keep name) */
                return 1;
            } else if (findfield(L, objidx, level - 1)) {  /* try recursively */
                lapi.lua_remove(L, -2);  /* remove table (but keep name) */
                lapi.lua_pushliteral(L, ".");
                lapi.lua_insert(L, -2);  /* place '.' between the two names */
                lapi.lua_concat(L, 3);
                return 1;
            }
        }
        lapi.lua_pop(L, 1);  /* remove value */
    }

    return 0;  /* not found */
};

/*
** Search for a name for a function in all loaded modules
*/
const pushglobalfuncname = function(L, ar) {
    let top = lapi.lua_gettop(L);
    ldebug.lua_getinfo(L, 'f', ar);  /* push function */
    lapi.lua_getfield(L, lua.LUA_REGISTRYINDEX, lua.to_luastring(LUA_LOADED_TABLE));
    if (findfield(L, top + 1, 2)) {
        let name = lapi.lua_tostring(L, -1);
        if (name.jsstring().startsWith("_G.")) {
            lapi.lua_pushstring(L, name.slice(3));  /* name start with '_G.'? */
            lapi.lua_remove(L, -2);  /* name start with '_G.'? */
        }
        lapi.lua_copy(L, -1, top + 1);  /* name start with '_G.'? */
        lapi.lua_pop(L, 2);  /* name start with '_G.'? */
    } else {
        lapi.lua_settop(L, top);  /* remove function and global table */
        return 0;
    }
};

const panic = function(L) {
    throw new Error(`PANIC: unprotected error in call to Lua API (${lapi.lua_tojsstring(L, -1)})`);
};

const luaL_argerror = function(L, arg, extramsg) {
    let ar = new lua.lua_Debug();

    if (!ldebug.lua_getstack(L, 0, ar))  /* no stack frame? */
        return luaL_error(L, lua.to_luastring(`bad argument #${arg} (${lobject.jsstring(extramsg)})`));

    ldebug.lua_getinfo(L, 'n', ar);

    if (ar.namewhat === 'method') {
        arg--;  /* do not count 'self' */
        if (arg === 0)  /* error is in the self argument itself? */
            return luaL_error(L, lua.to_luastring(`calling '${lobject.jsstring(ar.name)}' on  bad self (${lobject.jsstring(extramsg)})`));
    }

    if (ar.name === null)
        ar.name = pushglobalfuncname(L, ar) ? lapi.lua_tostring(L, -1) : [lua.char["?"]];

    return luaL_error(L, lua.to_luastring(`bad argument #${arg} to '${lobject.jsstring(ar.name)}' (${lobject.jsstring(extramsg)})`));
};

const typeerror = function(L, arg, tname) {
    let typearg;
    if (luaL_getmetafield(L, arg, lua.to_luastring("__name")) === CT.LUA_TSTRING)
        typearg = lapi.lua_tostring(L, -1);
    else if (lapi.lua_type(L, arg) === CT.LUA_TLIGHTUSERDATA)
        typearg = lua.to_luastring("light userdata");
    else
        typearg = luaL_typename(L, arg);

    let msg = lapi.lua_pushstring(L, lua.to_luastring(`${lobject.jsstring(tname)} expected, got ${lobject.jsstring(typearg)}`));
    return luaL_argerror(L, arg, msg);
};

const luaL_where = function(L, level) {
    let ar = new lua.lua_Debug();
    if (ldebug.lua_getstack(L, level, ar)) {
        ldebug.lua_getinfo(L, lua.to_luastring("Sl"), ar);
        if (ar.currentline > 0) {
            lapi.lua_pushstring(L, lua.to_luastring(`${lobject.jsstring(ar.short_src)}:${ar.currentline}:`));
            return;
        }
    }
    lapi.lua_pushstring(L, []);
};

const luaL_error = function(L, fmt, ...args) {
    let i = 0;

    fmt = lobject.jsstring(fmt);
    // TODO: bypassing lua_pushvstring for now
    fmt = fmt.replace(/(^%[sfIpdcU]|([^%])%[sfIpdcU])/g, function (m, p1, p2, off) {
        return p2 ? p2 + args[i++] : args[i++];
    });
    fmt = lua.to_luastring(fmt);

    lapi.lua_pushstring(L, fmt);

    return lapi.lua_error(L);
};

const tag_error = function(L, arg, tag) {
    typeerror(L, arg, lapi.lua_typename(L, tag));
};

const luaL_newstate = function() {
    let L = lstate.lua_newstate();
    if (L) lapi.lua_atpanic(L, panic);
    return L;
};


const luaL_typename = function(L, i) {
    return lapi.lua_typename(L, lapi.lua_type(L, i));
};

const luaL_argcheck = function(L, cond, arg, extramsg) {
    if (!cond) luaL_argerror(L, arg, extramsg);
};

const luaL_checkany = function(L, arg) {
    if (lapi.lua_type(L, arg) === CT.LUA_TNONE)
        luaL_argerror(L, arg, lua.to_luastring("value expected"));
};

const luaL_checktype = function(L, arg, t) {
    if (lapi.lua_type(L, arg) !== t)
        tag_error(L, arg, t);
};

const luaL_checkstring = function(L, n) {
    return luaL_checklstring(L, n, null);
};

const luaL_checklstring = function(L, arg) {
    let s = lapi.lua_tolstring(L, arg);
    if (s === null || s === undefined) tag_error(L, arg, CT.LUA_TSTRING);
    return s;
};

const luaL_optlstring = function(L, arg, def) {
    if (lapi.lua_type(L, arg) <= 0) {
        return def;
    } else return luaL_checklstring(L, arg);
};

const luaL_optstring = luaL_optlstring;

const interror = function(L, arg) {
    if (lapi.lua_isnumber(L, arg))
        luaL_argerror(L, arg, lua.to_luastring("number has no integer representation"));
    else
        tag_error(L, arg, CT.LUA_TNUMBER);
};

const luaL_checknumber = function(L, arg) {
    let d = lapi.lua_tonumber(L, arg);
    if (d === false)
        tag_error(L, arg, CT.LUA_TNUMBER);
    return d;
};

const luaL_checkinteger = function(L, arg) {
    let d = lapi.lua_tointeger(L, arg);
    if (d === false)
        interror(L, arg);
    return d;
};

const luaL_optinteger = function(L, arg, def) {
    return luaL_opt(L, luaL_checkinteger, arg, def);
};

const luaL_prepbuffsize = function(B, sz) {
    return B;
};

const luaL_buffinit = function(L, B) {
    B.L = L;
    B.b = [];
};

const luaL_buffinitsize = function(L, B, sz) {
    luaL_buffinit(L, B);
    return B;
};

const luaL_addlstring = function(B, s, l) {
    B.b = B.b.concat(s.slice(0, l));
};

const luaL_addstring = luaL_addlstring;

const luaL_pushresult = function(B) {
    let L = B.L;
    lapi.lua_pushstring(L, B.b);
};

const luaL_addchar = function(B, c) {
    B.b.push(c);
};

const luaL_addvalue = function(B) {
    let L = B.L;
    let s = lapi.lua_tostring(L, -1);
    // TODO: buffonstack ? necessary ?
    luaL_addstring(B, s);
    lapi.lua_remove(L, -1);
};

const luaL_opt = function(L, f, n, d) {
    return lapi.lua_type(L, n) <= 0 ? d : f(L, n);
};

const getS = function(L, ud) {
    let s = ud.string;
    ud.string = null;
    return s;
};

const luaL_loadbufferx = function(L, buff, size, name, mode) {
    return lapi.lua_load(L, getS, {string: buff}, name, mode);
};

const luaL_loadbuffer = function(L, s, sz, n) {
    return luaL_loadbufferx(L, s, sz, n, null);
};

const luaL_loadstring = function(L, s) {
    return luaL_loadbuffer(L, s, s.length, s);
};

const luaL_getmetafield = function(L, obj, event) {
    if (!lapi.lua_getmetatable(L, obj))
        return CT.LUA_TNIL;
    else {
        lapi.lua_pushstring(L, event);
        let tt = lapi.lua_rawget(L, -2);
        if (tt === CT.LUA_TNIL)
            lapi.lua_pop(L, 2);
        return tt;
    }
};

const luaL_callmeta = function(L, obj, event) {
    obj = lapi.lua_absindex(L, obj);
    if (luaL_getmetafield(L, obj, event) === CT.LUA_TNIL)
        return false;

    lapi.lua_pushvalue(L, obj);
    lapi.lua_call(L, 1, 1);

    return true;
};

const luaL_len = function(L, idx) {
    lapi.lua_len(L, idx);
    let l = lapi.lua_tointegerx(L, -1);
    if (l === false)
        luaL_error(L, "object length is not an integer");
    lapi.lua_pop(L, 1);  /* remove object */
    return l;
};

const luaL_tolstring = function(L, idx) {
    if (luaL_callmeta(L, idx, "__tostring")) {
        if (!lapi.lua_isstring(L, -1))
            luaL_error(L, "'__tostring' must return a string");
    } else {
        switch(lapi.lua_type(L, idx)) {
            case CT.LUA_TNUMBER:
            case CT.LUA_TBOOLEAN:
                lapi.lua_pushstring(L, lua.to_luastring(`${lapi.index2addr(L, idx).value}`));
                break;
            case CT.LUA_TSTRING:
                lapi.lua_pushstring(L, lapi.index2addr(L, idx).value);
                break;
            case CT.LUA_TNIL:
                lapi.lua_pushstring(L, lua.to_luastring(`nil`));
                break;
            default:
                let tt = luaL_getmetafield(L, idx, lua.to_luastring("__name"));
                let kind = tt === CT.LUA_TSTRING ? lapi.lua_tostring(L, -1) : luaL_typename(L, idx);
                lapi.lua_pushstring(L, lua.to_luastring(`${lobject.jsstring(kind)}: 0x${lapi.index2addr(L, -1).id.toString(16)}`));
                if (tt !== CT.LUA_TNIL)
                    lapi.lua_remove(L, -2);
                break;
        }
    }

    return lapi.lua_tolstring(L, -1);
};

/*
** Stripped-down 'require': After checking "loaded" table, calls 'openf'
** to open a module, registers the result in 'package.loaded' table and,
** if 'glb' is true, also registers the result in the global table.
** Leaves resulting module on the top.
*/
const luaL_requiref = function(L, modname, openf, glb) {
    luaL_getsubtable(L, lua.LUA_REGISTRYINDEX, lua.to_luastring(LUA_LOADED_TABLE));
    lapi.lua_getfield(L, -1, modname); /* LOADED[modname] */
    if (!lapi.lua_toboolean(L, -1)) {  /* package not already loaded? */
        lapi.lua_pop(L, 1);  /* remove field */
        lapi.lua_pushcfunction(L, openf);
        lapi.lua_pushstring(L, modname);  /* argument to open function */
        lapi.lua_call(L, 1, 1);  /* call 'openf' to open module */
        lapi.lua_pushvalue(L, -1);  /* make copy of module (call result) */
        lapi.lua_setfield(L, -3, modname);  /* LOADED[modname] = module */
    }
    lapi.lua_remove(L, -2);  /* remove LOADED table */
    if (glb) {
        lapi.lua_pushvalue(L, -1);  /* copy of module */
        lapi.lua_setglobal(L, modname);  /* _G[modname] = module */
    }
};

/*
** ensure that stack[idx][fname] has a table and push that table
** into the stack
*/
const luaL_getsubtable = function(L, idx, fname) {
    if (lapi.lua_getfield(L, idx, fname) === CT.LUA_TTABLE)
        return true;  /* table already there */
    else {
        lapi.lua_pop(L, 1);  /* remove previous result */
        idx = lapi.lua_absindex(L, idx);
        lapi.lua_newtable(L);
        lapi.lua_pushvalue(L, -1);  /* copy to be left at top */
        lapi.lua_setfield(L, idx, fname);  /* assign new table to field */
        return false;  /* false, because did not find table there */
    }
};

/*
** set functions from list 'l' into table at top - 'nup'; each
** function gets the 'nup' elements at the top as upvalues.
** Returns with only the table at the stack.
*/
const luaL_setfuncs = function(L, l, nup) {
    luaL_checkstack(L, nup, lua.to_luastring("too many upvalues"));
    for (let lib in l) {  /* fill the table with given functions */
        for (let i = 0; i < nup; i++)  /* copy upvalues to the top */
            lapi.lua_pushvalue(L, -nup);
        lapi.lua_pushcclosure(L, l[lib], nup);  /* closure with those upvalues */
        lapi.lua_setfield(L, -(nup + 2), lua.to_luastring(lib));
    }
    lapi.lua_pop(L, nup);  /* remove upvalues */
};

/*
** Ensures the stack has at least 'space' extra slots, raising an error
** if it cannot fulfill the request. (The error handling needs a few
** extra slots to format the error message. In case of an error without
** this extra space, Lua will generate the same 'stack overflow' error,
** but without 'msg'.)
*/
const luaL_checkstack = function(L, space, msg) {
    if (!lapi.lua_checkstack(L, space)) {
        if (msg)
            luaL_error(L, lua.to_luastring(`stack overflow (${lobject.jsstring(msg)})`));
        else
            luaL_error(L, lua.to_luastring('stack overflow'));
    }
};

const luaL_newlib = function(L, l) {
    lapi.lua_createtable(L);
    luaL_setfuncs(L, l, 0);
};

// Only with Node
if (typeof require === "function") {
    let fs = false;
    try {
        fs = require('fs');
    } catch (e) {}

    if (fs) {
        class LoadF {
            constructor() {
                this.n = NaN;  /* number of pre-read characters */
                this.f = null;  /* file being read */
                this.buff = new Buffer(1024);  /* area for reading file */
                this.pos = 0;  /* current position in file */
                this.binary = false;
            }
        }

        const toDataView = function(buffer) {
            let ab = new ArrayBuffer(buffer.length);
            let au = new Uint8Array(ab);
            for (let i = 0; i < buffer.length; i++)
                au[i] = buffer[i];
            return new DataView(ab);
        };

        const getF = function(L, ud) {
            let lf = ud;
            let bytes = 0;
            if (lf.n > 0) {  /* are there pre-read characters to be read? */
                lf.n = 0;  /* no more pre-read characters */
            } else {  /* read a block from file */
                lf.buff.fill(0);
                bytes = fs.readSync(lf.f, lf.buff, 0, lf.buff.length, lf.pos); /* read block */
                lf.pos += bytes;
            }
            if (bytes > 0)
                return lf.binary ? toDataView(lf.buff) : lf.buff.slice(0, bytes);
            else return null;
        };

        const errfile = function(L, what, fnameindex, error) {
            let serr = error.message;
            let filename = lapi.lua_tostring(L, fnameindex).slice(1);
            lapi.lua_pushstring(L, lua.to_luastring(`cannot ${lobject.jsstring(what)} ${lobject.jsstring(filename)}: ${lobject.jsstring(serr)}`));
            lapi.lua_remove(L, fnameindex);
            return lua.thread_status.LUA_ERRFILE;
        };

        const getc = function(lf) {
            let b = new Buffer(1);
            let bytes = fs.readSync(lf.f, b, 0, 1, lf.pos);
            lf.pos += bytes;
            return bytes > 0 ? b.readUInt8() : null;
        };

        const skipBOM = function(lf) {
            let p = [0XEF, 0XBB, 0XBF];  /* UTF-8 BOM mark */
            lf.n = 0;
            let c;
            do {
                c = getc(lf);
                if (c === null || c !== p[0]) return c;
                p = p.slice(1);
                lf.buff[lf.n++] = c;  /* to be read by the parser */
            } while (p.length > 0);
            lf.n = 0;  /* prefix matched; discard it */
            return getc(lf);  /* return next character */
        };

        /*
        ** reads the first character of file 'f' and skips an optional BOM mark
        ** in its beginning plus its first line if it starts with '#'. Returns
        ** true if it skipped the first line.  In any case, '*cp' has the
        ** first "valid" character of the file (after the optional BOM and
        ** a first-line comment).
        */
        const skipcomment = function(lf) {
            let c = skipBOM(lf);
            if (c === '#'.charCodeAt(0)) {  /* first line is a comment (Unix exec. file)? */
                do {  /* skip first line */
                    c = getc(lf);
                } while (c && c !== '\n'.charCodeAt(0));

                return {
                    skipped: true,
                    c: getc(lf)  /* skip end-of-line, if present */
                };
            } else {
                lf.pos--;
                return {
                    skipped: false,
                    c: c
                };
            }
        };

        const luaL_loadfilex = function(L, filename, mode) {
            let jsfilename = lobject.jsstring(filename);
            let lf = new LoadF();
            let fnameindex = lapi.lua_gettop(L) + 1;  /* index of filename on the stack */
            if (filename === null) {
                lapi.lua_pushliteral(L, "=stdin");
                lf.f = process.stdin.fd;
            } else {
                lapi.lua_pushliteral(L, `@${jsfilename}`);
                try {
                    lf.f = fs.openSync(jsfilename, "r");
                } catch (e) {
                    return errfile(L, lua.to_luastring("open"), fnameindex, e);
                }
            }

            try {
                let com;
                if ((com = skipcomment(lf)).skipped)  /* read initial portion */
                    lf.buff[lf.n++] = '\n'.charCodeAt(0);  /* add line to correct line numbers */

                if (com.c === lua.LUA_SIGNATURE.charCodeAt(0) && filename) {  /* binary file? */
                    lf.binary = true;
                }

                let status = lapi.lua_load(L, getF, lf, lapi.lua_tostring(L, -1), mode);
                if (filename) fs.closeSync(lf.f);  /* close file (even in case of errors) */
                lapi.lua_remove(L, fnameindex);
                return status;
            } catch (err) {
                lapi.lua_settop(L, fnameindex);  /* ignore results from 'lua_load' */
                return errfile(L, lua.to_luastring("read"), fnameindex);
            }
        };

        const luaL_loadfile = function(L, filename) {
            return luaL_loadfilex(L, filename, null);
        };

        module.exports.luaL_loadfilex = luaL_loadfilex;
        module.exports.luaL_loadfile  = luaL_loadfile;
    }
}

module.exports.LUA_LOADED_TABLE  = LUA_LOADED_TABLE;
module.exports.luaL_Buffer       = luaL_Buffer;
module.exports.luaL_addchar      = luaL_addchar;
module.exports.luaL_addlstring   = luaL_addlstring;
module.exports.luaL_addstring    = luaL_addstring;
module.exports.luaL_addvalue     = luaL_addvalue;
module.exports.luaL_argcheck     = luaL_argcheck;
module.exports.luaL_argerror     = luaL_argerror;
module.exports.luaL_buffinit     = luaL_buffinit;
module.exports.luaL_buffinitsize = luaL_buffinitsize;
module.exports.luaL_callmeta     = luaL_callmeta;
module.exports.luaL_checkany     = luaL_checkany;
module.exports.luaL_checkinteger = luaL_checkinteger;
module.exports.luaL_checklstring = luaL_checklstring;
module.exports.luaL_checknumber  = luaL_checknumber;
module.exports.luaL_checkstack   = luaL_checkstack;
module.exports.luaL_checkstring  = luaL_checkstring;
module.exports.luaL_checktype    = luaL_checktype;
module.exports.luaL_error        = luaL_error;
module.exports.luaL_getmetafield = luaL_getmetafield;
module.exports.luaL_getsubtable  = luaL_getsubtable;
module.exports.luaL_len          = luaL_len;
module.exports.luaL_loadbuffer   = luaL_loadbuffer;
module.exports.luaL_loadbufferx  = luaL_loadbufferx;
module.exports.luaL_loadstring   = luaL_loadstring;
module.exports.luaL_newlib       = luaL_newlib;
module.exports.luaL_newstate     = luaL_newstate;
module.exports.luaL_opt          = luaL_opt;
module.exports.luaL_optinteger   = luaL_optinteger;
module.exports.luaL_optlstring   = luaL_optlstring;
module.exports.luaL_optstring    = luaL_optstring;
module.exports.luaL_prepbuffsize = luaL_prepbuffsize;
module.exports.luaL_pushresult   = luaL_pushresult;
module.exports.luaL_requiref     = luaL_requiref;
module.exports.luaL_setfuncs     = luaL_setfuncs;
module.exports.luaL_tolstring    = luaL_tolstring;
module.exports.luaL_typename     = luaL_typename;
module.exports.luaL_where        = luaL_where;