-- INTERNAL
-- definitions of BUILD and game types for the Lunatic Interpreter

local require = require
local ffi = require("ffi")
local ffiC = ffi.C

local bit = bit
local string = string
local table = table
local math = math

local assert = assert
local error = error
local ipairs = ipairs
local loadstring = loadstring
local pairs = pairs
local rawget = rawget
local rawset = rawset
local setmetatable = setmetatable
local setfenv = setfenv
local tonumber = tonumber
local type = type

local print = print
local tostring = tostring


--== First, load the definitions common to the game's and editor's Lua interface.

-- The "gv" global will provide access to C global *scalars* and safe functions.
-- XXX: still exposes C library functions etc. contained in ffi.C, problem?
local gv_ = {
    -- All non-scalars need to be explicitly listed here and access to them is
    -- redirected to the dummy empty table...
}

local dummy_empty_table = {}

-- This is for declarations of arrays or pointers which should not be
-- accessible through the "gv" global. The "defs_common" module will
-- use this function.
--
-- Notes: do not declare multiple pointers on one line (this is bad:
-- "int32_t *a, *b"). Do not name array arguments (or add a space
-- between the identifier and the '[' instead).
function decl(str)
    -- NOTE that the regexp also catches non-array/non-function identifiers
    -- like "user_defs ud;"
    for varname in string.gmatch(str, "([%a_][%w_]*)[[(;]") do
--        print("DUMMY "..varname)
        gv_[varname] = dummy_empty_table
    end

    ffi.cdef(str)
end

-- load the common definitions!
local defs_c = require("defs_common")
local cansee = defs_c.cansee
local strip_const = defs_c.strip_const
local setmtonce = defs_c.setmtonce


---=== EDuke32 game definitions ===---

---- game structs ----
ffi.cdef[[
enum dukeinv_t {
    GET_STEROIDS,
    GET_SHIELD,
    GET_SCUBA,
    GET_HOLODUKE,
    GET_JETPACK,
    GET_DUMMY1,
    GET_ACCESS,
    GET_HEATS,
    GET_DUMMY2,
    GET_FIRSTAID,
    GET_BOOTS,
    GET_MAX
};

enum dukeweapon_t {
    KNEE_WEAPON,
    PISTOL_WEAPON,
    SHOTGUN_WEAPON,
    CHAINGUN_WEAPON,
    RPG_WEAPON,
    HANDBOMB_WEAPON,
    SHRINKER_WEAPON,
    DEVISTATOR_WEAPON,
    TRIPBOMB_WEAPON,
    FREEZE_WEAPON,
    HANDREMOTE_WEAPON,
    GROW_WEAPON,
    MAX_WEAPONS
};

enum {
    MAXPLAYERS = 16,
};
]]

ffi.cdef[[
#pragma pack(push,1)
struct action {
    int16_t startframe, numframes;
    int16_t viewtype, incval, delay;
};

struct move {
    int16_t hvel, vvel;
};

typedef struct { int32_t id; struct move mv; } con_move_t;
typedef struct { int32_t id; struct action ac; } con_action_t;

typedef struct {
    int32_t id;
    con_action_t act;
    con_move_t mov;
    int32_t movflags;
} con_ai_t;
#pragma pack(pop)
]]

-- Struct template for actor_t. It already has 'const' fields (TODO: might need
-- to make more 'const'), but still has array members exposed, so is unsuited
-- for external exposure.
local ACTOR_STRUCT = [[
{
    const int32_t t_data[10];  // 56b sometimes used to hold offsets to con code
    const struct move mv;
    const struct action ac;
    const int16_t _padding[1];

    int32_t flags; //4b
    vec3_t bpos; //12b
    int32_t floorz,ceilingz,lastvx,lastvy; //16b
    int32_t lasttransport; //4b

    const int16_t picnum;
    int16_t ang, extra;
    const int16_t owner;
    int16_t movflag,tempang,timetosleep; //6b

    const int16_t lightId, lightcount, lightmaxrange, cgg; //8b
    int16_t actorstayput;
    const int16_t dispicnum;
    int16_t shootzvel;
    const int8_t _do_not_use[8];
}
]]

local DUKEPLAYER_STRUCT = [[
{
    vec3_t pos, opos, vel, npos;
    int32_t bobposx, bobposy;
    int32_t truefz, truecz, player_par;
    int32_t randomflamex, exitx, exity;
    int32_t runspeed, max_player_health, max_shield_amount;
    int32_t autostep, autostep_sbw;

    uint32_t interface_toggle_flag;

    uint8_t palette;

    uint16_t max_actors_killed, actors_killed;
    uint16_t gotweapon, zoom;

    const int16_t loogiex[64];
    const int16_t loogiey[64];
    int16_t sbs, sound_pitch;

    int16_t ang, oang, angvel;
    const int16_t cursectnum;
    int16_t look_ang, last_extra, subweapon;
    const int16_t max_ammo_amount[MAX_WEAPONS];
    const int16_t ammo_amount[MAX_WEAPONS];
    const int16_t inv_amount[GET_MAX];
    int16_t wackedbyactor, pyoff, opyoff;

    int16_t horiz, horizoff, ohoriz, ohorizoff;
    const int16_t newowner;
    int16_t jumping_counter, airleft;
    int16_t fta, ftq, access_wallnum, access_spritenum;
    int16_t got_access, weapon_ang, visibility;
    int16_t somethingonplayer, on_crane;
    const int16_t i;
    const int16_t one_parallax_sectnum;
    int16_t random_club_frame, one_eighty_count;
    const int16_t dummyplayersprite;
    int16_t extra_extra8;
    int16_t actorsqu, timebeforeexit;
    const int16_t customexitsound;
    int16_t last_pissed_time;

    const int16_t weaprecs[MAX_WEAPONS];
    int16_t weapon_sway, crack_time, bobcounter;

    int16_t orotscrnang, rotscrnang, dead_flag;   // JBF 20031220: added orotscrnang
    int16_t holoduke_on, pycount;
    int16_t transporter_hold;

    uint8_t max_secret_rooms, secret_rooms;
    uint8_t frag, fraggedself, quick_kick, last_quick_kick;
    uint8_t return_to_center, reloading, weapreccnt;
    uint8_t aim_mode, auto_aim, weaponswitch, movement_lock, team;
    uint8_t tipincs, hbomb_hold_delay, frag_ps, kickback_pic;

    uint8_t gm, on_warping_sector, footprintcount, hurt_delay;
    uint8_t hbomb_on, jumping_toggle, rapid_fire_hold, on_ground;
    uint8_t inven_icon, buttonpalette, over_shoulder_on, show_empty_weapon;

    uint8_t jetpack_on, spritebridge, lastrandomspot;
    uint8_t scuba_on, footprintpal, heat_on, invdisptime;

    uint8_t holster_weapon, falling_counter, footprintshade;
    uint8_t refresh_inventory, last_full_weapon;

    uint8_t toggle_key_flag, knuckle_incs, knee_incs, access_incs;
    uint8_t walking_snd_toggle, palookup, hard_landing, fist_incs;

    int8_t numloogs, loogcnt, scream_voice;
    int8_t last_weapon, cheat_phase, weapon_pos, wantweaponfire;
    int8_t const curr_weapon;

    palette_t pals;

    const char name[32];

    const int8_t padding_[1];
}
]]

local randgen = require("randgen")
local geom = require("geom")

local ma_rand = randgen.new(true)  -- initialize to "random" (time-based) seed
local ma_count = nil

local function ma_replace_array(typestr, neltstr)
    local nelts = tonumber(neltstr)
    if (nelts==nil) then
        nelts = ffiC[neltstr]
        assert(type(nelts)=="number")
    end

    local strtab = { "const ", typestr.." " }
    for i=1,nelts do
        local ch1 = 97 + (ma_rand:getu32() % 25)  -- 'a'..'z'
        strtab[i+2] = string.format("_%c%x%s", ch1, ma_count, (i<nelts) and "," or "")
        ma_count = ma_count+1
    end
    strtab[#strtab+1] = ";"

    return table.concat(strtab)
end

-- Converts a template struct definition to an external one, in which arrays
-- have been substituted by randomly named scalar fields.
local function mangle_arrays(structstr)
    ma_count = 0
    -- NOTE: regexp only works for non-nested arrays and for one array per line.
    return (string.gsub(structstr, "const%s+([%w_]+)[^\n]+%[([%w_]+)%];", ma_replace_array))
end

--print(mangle_arrays(ACTOR_STRUCT))

ffi.cdef([[
#pragma pack(push, 1)
typedef struct
]].. mangle_arrays(ACTOR_STRUCT) ..[[
actor_t;

typedef struct
]].. strip_const(ACTOR_STRUCT).. [[
actor_u_t;  // The _u_t versions are unrestricted variants for internal use.

typedef struct
]].. mangle_arrays(DUKEPLAYER_STRUCT) ..[[
DukePlayer_t;

typedef struct
]].. strip_const(DUKEPLAYER_STRUCT) ..[[
DukePlayer_u_t;

typedef struct {
    uint32_t bits; // 4b
    int16_t fvel, svel; // 4b
    int8_t avel, horz; // 2b
    int8_t extbits, filler; // 2b
} input_t;

typedef struct {
    DukePlayer_t *ps;
    input_t *sync;

    int32_t netsynctime;
    int16_t ping, filler;
    int32_t pcolor, pteam;
    uint8_t frags[MAXPLAYERS], wchoice[MAX_WEAPONS];

    char vote, gotvote, pingcnt, playerquitflag, ready;
    char user_name[32];
    uint32_t revision;
} playerdata_t;

typedef struct {
    int32_t workslike, cstat; // 8b
    int32_t hitradius, range, flashcolor; // 12b
    int16_t spawns, sound, isound, vel; // 8b
    int16_t decal, trail, tnum, drop; // 8b
    int16_t offset, bounces, bsound; // 6b
    int16_t toffset; // 2b
    int16_t extra, extra_rand; // 4b
    int8_t sxrepeat, syrepeat, txrepeat, tyrepeat; // 4b
    int8_t shade, xrepeat, yrepeat, pal; // 4b
    int8_t movecnt; // 1b
    uint8_t clipdist; // 1b
    int8_t filler[6]; // 6b
} projectile_t;

typedef struct {
    intptr_t *execPtr;
    intptr_t *loadPtr;

    uint32_t flags;

    int16_t cacherange;

    projectile_t defproj;
} tiledata_t;
#pragma pack(pop)

enum
{
    MAXMOUSEBUTTONS = 10,
    MAXMOUSEAXES = 2,
    MAXJOYBUTTONS = (32+4),
    MAXJOYAXES = 8,
    NUMGAMEFUNCTIONS = 56,
};

// NOTE: not packed!
typedef struct {
    vec3_t camera;
    int32_t const_visibility,uw_framerate;
    int32_t camera_time,folfvel,folavel,folx,foly,fola;
    int32_t reccnt,crosshairscale;

    int32_t runkey_mode,statusbarscale,mouseaiming,weaponswitch,drawweapon;   // JBF 20031125
    int32_t democams,color,msgdisptime,statusbarmode;
    int32_t m_noexits,noexits,autovote,automsg,idplayers;
    int32_t team, viewbob, weaponsway, althud, weaponscale, textscale;

    int32_t entered_name,screen_tilting,shadows,fta_on,executions,auto_run;
    int32_t coords,tickrate,levelstats,m_coop,coop,screen_size,lockout,crosshair;
    int32_t playerai,angleinterpolation,obituaries;

    int32_t respawn_monsters,respawn_items,respawn_inventory,recstat,monsters_off,brightness;
    int32_t m_respawn_items,m_respawn_monsters,m_respawn_inventory,m_recstat,m_monsters_off,detail;
    int32_t m_ffire,ffire,m_player_skill,m_level_number,m_volume_number,multimode;
    int32_t player_skill,level_number,volume_number,m_marker,marker,mouseflip;

    int32_t configversion;

    int16_t cameraang, camerasect, camerahoriz;
    int16_t pause_on,from_bonus;
    int16_t camerasprite,last_camsprite;
    int16_t last_level,secretlevel, bgstretch;

    struct {
        int32_t UseJoystick;
        int32_t UseMouse;
        int32_t AutoAim;
        int32_t ShowOpponentWeapons;
        int32_t MouseDeadZone,MouseBias;
        int32_t SmoothInput;

        // JBF 20031211: Store the input settings because
        // (currently) jmact can't regurgitate them
        int32_t MouseFunctions[MAXMOUSEBUTTONS][2];
        int32_t MouseDigitalFunctions[MAXMOUSEAXES][2];
        int32_t MouseAnalogueAxes[MAXMOUSEAXES];
        int32_t MouseAnalogueScale[MAXMOUSEAXES];
        int32_t JoystickFunctions[MAXJOYBUTTONS][2];
        int32_t JoystickDigitalFunctions[MAXJOYAXES][2];
        int32_t JoystickAnalogueAxes[MAXJOYAXES];
        int32_t JoystickAnalogueScale[MAXJOYAXES];
        int32_t JoystickAnalogueDead[MAXJOYAXES];
        int32_t JoystickAnalogueSaturate[MAXJOYAXES];
        uint8_t KeyboardKeys[NUMGAMEFUNCTIONS][2];

        //
        // Sound variables
        //
        int32_t FXDevice;
        int32_t MusicDevice;
        int32_t FXVolume;
        int32_t MusicVolume;
        int32_t SoundToggle;
        int32_t MusicToggle;
        int32_t VoiceToggle;
        int32_t AmbienceToggle;

        int32_t NumVoices;
        int32_t NumChannels;
        int32_t NumBits;
        int32_t MixRate;

        int32_t ReverseStereo;

        //
        // Screen variables
        //

        int32_t ScreenMode;

        int32_t ScreenWidth;
        int32_t ScreenHeight;
        int32_t ScreenBPP;

        int32_t ForceSetup;
        int32_t NoAutoLoad;

        int32_t scripthandle;
        int32_t setupread;

        int32_t CheckForUpdates;
        int32_t LastUpdateCheck;
        int32_t useprecache;
    } config;

    char overhead_on,last_overhead,showweapons;
    char god,warp_on,cashman,eog,showallmap;
    char show_help,scrollmode,noclip;
    char ridecule[10][40];
    char savegame[10][22];
    char pwlockout[128],rtsname[128];
    char display_bonus_screen;
    char show_level_text;
} user_defs;
]])

decl[[
const char *g_sizes_of_what[];
int32_t g_sizes_of[];
actor_t actor[MAXSPRITES];
user_defs ud;
playerdata_t g_player[MAXPLAYERS];

const int32_t playerswhenstarted;
int32_t lastvisinc;

int32_t A_IncurDamage(int32_t sn);  // not bound-checked!
void P_AddWeaponMaybeSwitch(DukePlayer_t *ps, int32_t weap);
int32_t A_Shoot(int32_t i, int32_t atwith);
int32_t A_IncurDamage(int32_t sn);
int32_t A_Spawn(int32_t j, int32_t pn);
void VM_FallSprite(int32_t i);
int32_t VM_ResetPlayer2(int32_t snum);
void A_RadiusDamage(int32_t i, int32_t r, int32_t, int32_t, int32_t, int32_t);
void G_OperateSectors(int32_t sn, int32_t ii);
int32_t A_Dodge(spritetype *s);
]]

-- functions
decl[[
int32_t kopen4loadfrommod(const char *filename, char searchfirst);
int32_t kfilelength(int32_t handle);
void kclose(int32_t handle);
int32_t kread(int32_t handle, void *buffer, int32_t leng);
]]


-- http://lua-users.org/wiki/SandBoxes says "potentially unsafe"
-- as it allows to see implementations of functions.
--local string_dump = string.dump
string.dump = nil


-- sanity-check struct type sizes
local good = true
for i=0,7 do
    local what = ffi.string(ffiC.g_sizes_of_what[i])
    local fsz = ffi.sizeof(what)
    local csz = ffiC.g_sizes_of[i]
--    print(i..": "..what..": C sizeof = "..tostring(csz)..", FFI sizeof = "..tostring(fsz))
    if (fsz ~= csz) then
        good = false;
    end
end

if (not good) then
    error("Some sizes don't match between C and LuaJIT/FFI.")
end

-- Add game-side metamethods to "spritetype" and register it with "metatype"
defs_c.spritetype_mt.__index.isenemy = function(s)
    return (bit.band(ffiC.g_tile[s.picnum], ffiC.SFLAG_BADGUY)~=0)
end
ffi.metatype("spritetype", defs_c.spritetype_mt)

-- "player" global, needed by the "control" module
local tmpmt = {
    __index = function(tab, key)
                  if (key >= 0 and key < ffiC.playerswhenstarted) then
                      return ffiC.g_player[key].ps[0]
                  end
                  error('out-of-bounds player[] read access', 2)
              end,

    __newindex = function(tab, key, val) error('cannot write directly to player[] struct', 2) end,
}
player = setmtonce({}, tmpmt)

--== Custom operations for BUILD data structures ==--
-- declares struct action and struct move, and their ID-wrapped types
-- con_action_t and con_move_t
local con = require("control")
local MV, AC, AI = con.MV, con.AC, con.AI

-- All-zero action and move
local nullac, nullmv = ffi.new("const struct action"), ffi.new("const struct move")

local function check_literal_am(am, typename)
    if (type(am) ~= "number") then
        error("bad argument: expected number or "..typename, 3)
    end

    if (not (am >= 0 and am <= 32767)) then
        error("bad argument: expected number in [0 .. 32767]", 3)
    end
end

local actor_ptr_ct = ffi.typeof("actor_u_t *")  -- an unrestricted actor_t pointer
local player_ptr_ct = ffi.typeof("DukePlayer_u_t *")
local con_action_ct = ffi.typeof("con_action_t")
local con_move_ct = ffi.typeof("con_move_t")
local con_ai_ct = ffi.typeof("con_ai_t")

local actor_mt = {
    __index = {
        -- action
        set_action = function(a, act)
            a = ffi.cast(actor_ptr_ct, a)
            if (type(act)=="string") then
                act = AC[act];
            end
            -- TODO: disallow passing the FFI types altogether, in favor of
            -- strings (also move, ai)?
            if (ffi.istype(con_action_ct, act)) then
                a.t_data[4] = act.id
                a.ac = act.ac
            else
                check_literal_am(act, "action")
                a.t_data[4] = act
                a.ac = nullac
            end

            a.t_data[2] = 0
            a.t_data[3] = 0
        end,

        has_action = function(a, act)
            a = ffi.cast(actor_ptr_ct, a)
            if (type(act)=="string") then
                act = AC[act];
            end
            if (ffi.istype(con_action_ct, act)) then
                return (a.t_data[4]==act.id)
            else
                check_literal_am(act, "action")
                return (a.t_data[4]==act)
            end
        end,

        -- count
        set_count = function(a)
            ffi.cast(actor_ptr_ct, a).t_data[0] = 0
        end,

        get_count = function(a)
            return ffi.cast(actor_ptr_ct, a).t_data[0]
        end,

        -- action count
        reset_acount = function(a)
            ffi.cast(actor_ptr_ct, a).t_data[2] = 0
        end,

        get_acount = function(a)
            return ffi.cast(actor_ptr_ct, a).t_data[2]
        end,

        -- move
        set_move = function(a, mov, movflags)
            a = ffi.cast(actor_ptr_ct, a)
            if (type(mov)=="string") then
                mov = MV[mov];
            end
            if (ffi.istype(con_move_ct, mov)) then
                a.t_data[1] = mov.id
                a.mv = mov.mv
            else
                check_literal_am(mov, "move")
                a.t_data[1] = mov
                a.mv = nullmv
            end

            a.t_data[0] = 0
            local i = a-ffi.cast(actor_ptr_ct, ffiC.actor[0])
            ffiC.sprite[i].hitag = movflags or 0

            -- TODO: random angle moveflag
        end,

        has_move = function(a, mov)
            a = ffi.cast(actor_ptr_ct, a)
            if (type(mov)=="string") then
                mov = MV[mov];
            end
            if (ffi.istype(con_move_ct, mov)) then
                return (a.t_data[1]==mov.id)
            else
                check_literal_am(mov, "move")
                return (a.t_data[1]==mov)
            end
        end,

        -- ai
        set_ai = function(a, ai)
            local oa = a
            a = ffi.cast(actor_ptr_ct, a)

            if (type(ai)=="string") then
                ai = AI[ai];
            end
            -- TODO: literal number AIs?
            if (not ffi.istype(con_ai_ct, ai)) then
                error("bad argument: expected ai", 2)
            end

            -- NOTE: compare with gameexec.c
            a.t_data[5] = ai.id

            oa:set_action(ai.act)
            oa:set_move(ai.mov, ai.movflags)

            a.t_data[0] = 0
        end,

        has_ai = function(a, ai)
            a = ffi.cast(actor_ptr_ct, a)

            if (type(ai)=="string") then
                ai = AI[ai];
            end
            if (ffi.istype(con_ai_ct, ai)) then
                return (a.t_data[5]==ai.id)
            else
                check_literal_am(ai, "ai")
                return (a.t_data[5]==ai)
            end
        end,

        -- Getters/setters.
        get_t_data = function(a, idx)
            if (idx >= 10ULL) then
                error("Invalid t_data index "..idx, 2)
            end
            return ffi.cast(actor_ptr_ct, a).t_data[idx]
        end,
    },
}
ffi.metatype("actor_t", actor_mt)


--- default defines etc.
local con_lang = require("con_lang")

local function check_weapon_idx(weap)
    if (weap >= ffiC.MAX_WEAPONS+0ULL) then
        error("Invalid weapon ID "..weap, 3)
    end
end

local function check_inventory_idx(inv)
    if (inv >= ffiC.GET_MAX+0ULL) then
        error("Invalid inventory ID "..inv, 3)
    end
end

local player_mt = {
    __index = {
        --- Getters/setters
        get_ammo_amount = function(p, weap)
            check_weapon_idx(weap)
            return ffi.cast(player_ptr_ct, p).ammo_amount[weap]
        end,

        set_ammo_amount = function(p, weap, amount)
            check_weapon_idx(weap)
            ffi.cast(player_ptr_ct, p).ammo_amount[weap] = amount
        end,

        get_max_ammo_amount = function(p, weap)
            check_weapon_idx(weap)
            return ffi.cast(player_ptr_ct, p).max_ammo_amount[weap]
        end,

        set_max_ammo_amount = function(p, weap, amount)
            check_weapon_idx(weap)
            ffi.cast(player_ptr_ct, p).max_ammo_amount[weap] = amount
        end,

        set_curr_weapon = function(p, weap)
            check_weapon_idx(weap)
            ffi.cast(player_ptr_ct, p).curr_weapon = weap
        end,

        get_inv_amount = function(p, inv)
            check_inventory_idx(inv)
            return ffi.cast(player_ptr_ct, p).inv_amount[inv]
        end,

        set_inv_amount = function(p, inv, amount)
            check_inventory_idx(inv)
            ffi.cast(player_ptr_ct, p).inv_amount[inv] = amount
        end,

        set_customexitsound = function(p, soundnum)
            if (soundnum >= con_lang.MAXSOUNDS+0ULL) then
                error("Invalid sound number "..soundnum, 2)
            end
            ffi.cast(player_ptr_ct, p).customexitsound = soundnum
        end,

        -- CON-like addammo/addweapon, but without the non-local control flow
        -- (returns true if weapon's ammo was at the max. instead).
        addammo = con._addammo,
        addweapon = con._addweapon,

        addinventory = con._addinventory,

        pstomp = con._pstomp,

        wack = function(p)
            p.horiz = p.horiz + 64
            p.return_to_center = 9
            local n = bit.arshift(128-bit.band(ffiC.krand(),255), 1)
            p.rotscrnang = n
            p.look_ang = n
        end,

        --- Not fully specified, off-limits to users.  Might disappear, change
        --- signature, etc...
        _palfrom = function(p, f, r,g,b)
            local pals = p.pals
            pals.f = f
            pals.r, pals.g, pals.b = r, g, b
        end,

        -- XXX: is this so useful without z offset?
        _cansee = function(p, otherpos, othersect)
            return cansee(p.pos, sprite[p.i].sectnum, otherpos, othersect)
        end,
    },
}
ffi.metatype("DukePlayer_t", player_mt)


for i=1,#con_lang.labels do
    local strbuf = {"enum {"}

    for label, val in pairs(con_lang.labels[i]) do
        strbuf[#strbuf+1] = string.format("%s = %d,", label, val)
    end
    strbuf[#strbuf+1] = "};"

    ffi.cdef(table.concat(strbuf))
end


---=== Set up restricted global environment ===---

local allowed_modules = {
    coroutine=coroutine, bit=bit, table=table, math=math, string=string,

    os = {
        clock = function() return gv_.gethitickms()*0.001 end,
    },

    randgen = randgen,
    geom = geom,
    stat = require("stat"),
    bitar = require("bitar"),

    con = con,
}

for modname, themodule in pairs(allowed_modules) do
    local mt = {
        __index = themodule,
        __newindex = function(tab,idx,val)
            error("modifying base module table forbidden", 2)
        end,
        __metatable = true,
    }

    -- Comment out to make base modules not protected:
    allowed_modules[modname] = setmetatable({}, mt)
end

local function check_valid_modname(modname, errlev)
    if (type(modname) ~= "string") then
        error("module name must be a string", errlev+1)
    end

    -- TODO: restrict valid names?
end

local function errorf(level, fmt, ...)
    local errmsg = string.format(fmt, ...)
    error(errmsg, level+1)
end


local package_loaded = {}
local modname_stack = {}
local ERRLEV = 5

local function readintostr(fn)
    -- XXX: this is pretty much the same as the code in El_RunOnce()

    local fd = ffiC.kopen4loadfrommod(fn, 0)  -- TODO: g_loadFromGroupOnly
    if (fd < 0) then
        errorf(ERRLEV, "Couldn't open file \"%s\"", fn)
    end

    local sz = ffiC.kfilelength(fd)
    if (sz == 0) then
        ffiC.kclose(fd)
        errorf(ERRLEV, "Didn't load module \"%s\": zero-length file", fn)
    end

    if (sz < 0) then
        ffi.kclose(fd)
        error("INTERNAL ERROR: kfilelength() returned negative length", ERRLEV)
    end

    local str = ffi.new("char [?]", sz)  -- XXX: what does it do on out of mem?
    local readlen = ffiC.kread(fd, str, sz)

    ffiC.kclose(fd); fd=-1

    if (readlen ~= sz) then
        errorf(ERRLEV, "INTERNAL ERROR: couldn't read \"%s\" wholly", fn)
    end

    return ffi.string(str, sz)
end

-- The "require" function accessible to Lunatic code.
-- Base modules in allowed_modules are wrapped so that they cannot be
-- modified, user modules are searched in the EDuke32 search
-- path.  Also, our require never messes with the global environment,
-- it only returns the module.
local function our_require(modname)
    check_valid_modname(modname, 2)

    -- see whether it's a base module name first
    if (allowed_modules[modname] ~= nil) then
        return allowed_modules[modname]
    end

    --- search user modules

    if (package_loaded[modname] ~= nil) then
        -- already loaded
        return package_loaded[modname]
    end

    -- TODO: better pattern-matching (permit "", ".lua", ".elua" ?)
    local str = readintostr(modname .. ".lua")

    local modfunc, errmsg = loadstring(str)
    if (modfunc == nil) then
        errorf(ERRLEV-1, "Couldn't load \"%s\": %s", modname, errmsg)
    end

    package_loaded[modname] = true
    table.insert(modname_stack, modname)

    -- Run the module code!
    modfunc(modname)  -- TODO: call protected and report errors here later

    table.remove(modname_stack)

    local modtab = package_loaded[modname]

    if (type(modtab) == "table") then
        -- Protect module table if there is one...
        local mt = {
            __index = modtab,
            __newindex = function(tab,idx,val)
                error("modifying module table forbidden", 2)
            end,
        }

        setmetatable(modtab, mt)
    end

    return modtab
end


-- _G tweaks -- pull in only 'safe' stuff
local G_ = {}  -- our soon-to-be global environment

local module_mt = {
    __index = function (_, n)
        error("attempt to read undeclared variable '"..n.."'", 2)
    end,
}

-- Our 'module' replacement doesn't get the module name from the function args
-- since a malicious user could remove other loaded modules this way.
-- TODO: make transactional?
local function our_module()
    local modname = modname_stack[#modname_stack]
    if (type(modname) ~= "string") then
        error("'module' must be called at the top level of a require'd file", 2)
    end

    local M = setmetatable({}, module_mt)
    package_loaded[modname] = M
    -- change the environment of the function which called us:
    setfenv(2, M)
end

-- overridden 'error' that always passes a string to the base 'error'
local function our_error(errmsg, level)
    if (type(errmsg) ~= "string") then
        error("error using 'error': error message must be a string", 2)
    end

    if (level) then
        if (type(level) ~= "number") then
            error("error using 'error': error level must be a number", 2)
        end

        error(errmsg, level==0 and 0 or level+1)
    end

    error(errmsg, 2)
end

G_.assert = assert
G_.error = our_error
G_.ipairs = ipairs
G_.pairs = pairs
G_.pcall = pcall
G_.print = print  -- TODO: --> initprintf or OSD_Printf; why not needed on linux?
G_.module = our_module
G_.next = next
G_.require = our_require
G_.select = select
G_.tostring = tostring
G_.tonumber = tonumber
G_.type = type
G_.unpack = unpack
G_.xpcall = xpcall
G_._VERSION = _VERSION

-- Available through our 'require':
-- bit, coroutine, math, string, table

-- Not available:
-- collectgarbage, debug, dofile, gcinfo (DEPRECATED), getfenv, getmetatable,
-- jit, load, loadfile, loadstring, newproxy (NOT STD?), package, rawequal,
-- rawget, rawset, setfenv, setmetatable

G_._G = G_

--- non-default data and functions
G_.gameevent = gameevent  -- included in lunatic.c
G_.gameactor = gameactor  -- included in lunatic.c
G_.player = player  -- from above


---=== Lunatic interpreter setup ===---

local lunacon = require("lunacon")


-- change the environment of this chunk to the table G_
-- NOTE: all references to global variables from this point on
-- (also in functions created after this point) refer to G_ !
setfenv(1, G_)

-- Print keys and values of a table.
-- REMEMBER special position of 'tostring' (it's looked up and used as a global
-- from 'print')
local function printkv(label, table)
    print("========== Keys and values of "..label.." ("..tostring(table)..")")
    for k,v in pairs(table) do
        print(k .. ': ' .. tostring(v))
    end
    print('----------')
end

--printkv('_G AFTER SETFENV', _G)


---=== Restricted access to C variables from Lunatic ===---

-- error(..., 2) is to blame the caller and get its line numbers

local tmpmt = {
    __index = function() error('dummy variable: read access forbidden', 2) end,
    __newindex = function() error('dummy variable: write access forbidden', 2) end,
}
setmtonce(dummy_empty_table, tmpmt)

gv = gv_
local tmpmt = {
    __index = ffiC,
    __newindex = function() error("cannot create new or write into existing fields of 'gv'", 2) end,
}
setmtonce(gv, tmpmt)

-- This will create 'sprite', 'wall', etc. HERE, i.e. in the environment of this chunk
defs_c.create_globals(_G)

---- indirect C array access ----
actor = defs_c.creategtab(ffiC.actor, ffiC.MAXSPRITES, 'actor[]')

function TEMP_getvollev()  -- REMOVE
    return ffiC.ud.volume_number+1, ffiC.ud.level_number+1
end


---=== Game variables ===---

-- gamevarNames[name] is true if that gamevar was declared
local gamevarNames = {}

-- code for prohibiting initial assignments to create new variables,
-- based on 14.2 of PiL
function gamevar(name, initval)  -- aka 'declare'
    if (type(name) ~= "string") then
        error("First argument to 'gamevar' must be a string", 2)
    end

    if (not string.match(name, "^[%a_][%w_]*$")) then
        error("First argument to 'gamevar' must be a valid identifier", 2)
    end

    if (string.match(name, "^_")) then
        error("Identifier names starting with an underscore are reserved", 2)
    end

    if (gamevarNames[name]) then
        error(string.format("Duplicate declaration of identifier '%s'", name), 2)
    end

    if (rawget(G_, name) ~= nil) then
        error(string.format("Identifier name '%s' is already used in the global environment", name), 2)
    end

    gamevarNames[name] = true
    rawset(G_, name, initval or false)
end


---=== Serialization, from PiL with modifications ===---
local function basicSerialize(o)
    if (type(o) == "number") then
        if (o ~= o) then return "0/0" end  -- nan
        if (o == 1/0) then return "1/0" end  -- inf
        if (o == -1/0) then return "-1/0" end  -- -inf

        return tostring(o)
    elseif (type(o) == "boolean") then
        return tostring(o)
    elseif (type(o) == "string") then
        return string.format("%q", o)
    end
end

-- will contain all gamevar tables as keys (and true as value)
local tmpgvtabs = {}

local function save(name, value, saved, strings)
    saved = saved or {}       -- initial value

    strings[#strings+1] = name .. "="

    local str = basicSerialize(value)

    if (str ~= nil) then
        strings[#strings+1] = str .. "\n"
    elseif (type(value) == "table") then
        if (saved[value]) then    -- value already saved?
            strings[#strings+1] = saved[value] .. "\n"  -- use its previous name
        else
            saved[value] = name   -- save name for next time
            strings[#strings+1] = "{}\n"  -- create a new table

            for k,v in pairs(value) do      -- save its fields
                local keystr = basicSerialize(k)
                if (keystr == nil) then
                    error("cannot save a " .. type(k) .. " as key of a table", 2);
                end
                local fieldname = string.format("%s[%s]", name, keystr)
                if (type(v)=="table" and not tmpgvtabs[v]) then
                    error("cannot save \""..name..
                          "\": gamevar tables may only contain tables that are also gamevars", 2)
                end
                save(fieldname, v, saved, strings)
            end
        end
    else
        error("cannot save \""..name.."\", a " .. type(value), 2)
    end
end

local function serializeGamevars()
    local saved = {}
    local strings = {}

    for gvname,_ in pairs(gamevarNames) do
        if (type(G_[gvname])=="table") then
            tmpgvtabs[G_[gvname]] = true
        end
    end

    -- TODO: catch errors in save()
    for gvname,_ in pairs(gamevarNames) do
        save(gvname, G_[gvname], saved, strings)
    end
    strings[#strings+1] = "\n"

    tmpgvtabs = {}

    return table.concat(strings)
end

local function loadGamevarsString(string)
--[=[
    for gvname,_ in pairs(gamevarNames) do
        G_[gvname] = nil;
    end
    gamevarNames = {};  -- clear gamevars
--]=]

    assert(loadstring(string))()
end


-- REMOVE this for release
DBG_ = {}
DBG_.printkv = printkv
DBG_.loadstring = loadstring
DBG_.serializeGamevars = serializeGamevars
DBG_.loadGamevarsString = loadGamevarsString


---=== Finishing environment setup ===---

--printkv('_G AFTER DECLS', _G)


-- PiL 14.2 continued
-- We need this at the end because we were previously doing just that!
setmetatable(
    G_, {
        __newindex = function (_1, n, _2)
            error("attempt to write to undeclared variable '"..n.."'", 2)
        end,
        __index = function (_, n)
            error("attempt to read undeclared variable '"..n.."'", 2)
        end,
        })

-- Change the environment of the running Lua thread so that everything
-- what we've set up will be available when this chunk is left.
-- In particular, we need the functions defined after setting this chunk's
-- environment earlier.
setfenv(0, _G)