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

local ffi = require("ffi")

---- sector, wall, sprite, ... ----
ffi.cdef[[
#pragma pack(push,1)
typedef struct
{
    const int16_t wallptr, wallnum;
    int32_t ceilingz, floorz;
    int16_t ceilingstat, floorstat;
    int16_t ceilingpicnum, ceilingheinum;
    int8_t ceilingshade;
    uint8_t ceilingpal, ceilingxpanning, ceilingypanning;
    int16_t floorpicnum, floorheinum;
    int8_t floorshade;
    uint8_t floorpal, floorxpanning, floorypanning;
    uint8_t visibility, filler;
    int16_t lotag, hitag, extra;
} sectortype;

typedef struct
{
    int32_t x, y;
    const int16_t point2, nextwall, nextsector; int16_t cstat;
    int16_t picnum, overpicnum;
    int8_t shade;
    uint8_t pal, xrepeat, yrepeat, xpanning, ypanning;
    int16_t lotag, hitag, extra;
} walltype;

typedef struct
{
    int32_t x, y, z;
    int16_t cstat, picnum;
    int8_t shade;
    uint8_t pal, clipdist, filler;
    uint8_t xrepeat, yrepeat;
    int8_t xoffset, yoffset;
    const int16_t sectnum, statnum;
    int16_t ang, owner, xvel, yvel, zvel;
    int16_t lotag, hitag, extra;
} spritetype;

typedef struct {
    const uint32_t mdanimtims;
    const int16_t mdanimcur;
    int16_t angoff, pitch, roll;
    int32_t xoff, yoff, zoff;
    uint8_t flags;
    uint8_t xpanning, ypanning;
    const uint8_t filler;
    float alpha;
    const int32_t _do_not_use1;
    const int32_t _do_not_use2;
} spriteext_t;
#pragma pack(pop)
]]

-- game structs
ffi.cdef[[
#pragma pack(push,1)
// ACTOR_T, might still need to make some fields read-only
typedef struct
{
    const int32_t t_data[10];  // 40b sometimes used to hold offsets to con code
    int16_t picnum,ang,extra,owner; //8b
    int16_t movflag,tempang,timetosleep; //6b

    int32_t flags, bposx,bposy,bposz; //16b
    int32_t floorz,ceilingz,lastvx,lastvy; //16b
    int32_t lasttransport; //4b

    const int16_t lightId, lightcount, lightmaxrange, cgg; //8b
    int16_t actorstayput, dispicnum, shootzvel; // 6b

    const int8_t _do_not_use[24];
} actor_t;
#pragma pack(pop)

int32_t engine_main_arrays_are_static;
]]

if (ffi.C.engine_main_arrays_are_static) then
    ffi.cdef[[
sectortype sector[];
walltype wall[];
spritetype sprite[];
spriteext_t spriteext[];
]]
else
    ffi.cdef[[
sectortype *sector;
walltype *wall;
spritetype *sprite;
spriteext_t *spriteext;
]]
end

ffi.cdef[[
const int16_t numsectors, numwalls;

const int16_t headspritesect[16384+1], headspritestat[1024+1];
const int16_t prevspritesect[16384], prevspritestat[16384];
const int16_t nextspritesect[16384], nextspritestat[16384];
]]

ffi.cdef[[
actor_t actor[16384];
]]

---- _G tweaks -- pull in only 'safe' stuff ----

local G_ = {}  -- our soon-to-be global environment
local oG = _G

G_.coroutine = coroutine
G_.assert = assert
G_.tostring = tostring
G_.tonumber = tonumber
--rawget
G_.xpcall = xpcall
G_.ipairs = ipairs
G_.print = print
G_.pcall = pcall
--gcinfo --DEPRECATED
--module
--setfenv
--require
--rawset
--jit
G_.bit = bit
--package
G_.error = error
--debug
--loadfile
--rawequal
--load
G_.unpack = unpack
G_.pairs = pairs
G_.table = table
G_._VERSION = _VERSION
--newproxy --NOT STD?
--collectgarbage
--dofile
G_.next = next
G_.math = math
--loadstring
--_G
G_.select = select
G_.string = string
G_.type = type
--getmetatable
--getfenv
--setmetatable

G_._G = G_

-- REMOVE this for release
DBG_ = {}
DBG_.loadstring = oG.loadstring

---- Set up restricted access to ffi.C from lunatic. ----
local ffiC = ffi.C

-- TODO: error(...) --> error(..., 2) to blame the caller?

local det = {}  -- dummy empty table
local tmpmt = {
    __index = function() error('dummy variable: read access forbidden') end,
    __newindex = function() error('dummy variable: write access forbidden') end,
    __metatable = true  -- forbid setting the metatable
}
oG.setmetatable(det, tmpmt)

-- GLOBAL gv: provides access to C global *scalars*
gv = {
    -- all non-scalars need to be explicitly listed
    -- and access to them is redirected to the dummy
    -- empty table... this is somewhat ugly
    sector = det,
    wall = det,
    sprite = det,
    spriteext = det,

    headspritesect = det, headspritestat = det,
    prevspritesect = det, prevspritestat = det,
    nextspritesect = det, nextspritestat = det,

    actor = det,
}
local tmpmt = {
    __index = ffiC,
    __newindex = function() error("cannot create new or write into existing fields of 'gv'") end,
    __metatable = true,
}
oG.setmetatable(gv, tmpmt)

---- indirect C array access ----
sector = {}
local tmpmt = {
    __index = function(tab, key)
                  if (key >= 0 and key < ffiC.numsectors) then return ffiC.sector[key] end
                  error('out-of-bounds sector[] read access')
              end,

    __newindex = function(tab, key, val) error('cannot write directly to sector[] struct') end,
    __metatable = true,
}
oG.setmetatable(sector, tmpmt)

wall = {}
local tmpmt = {
    __index = function(tab, key)
                  if (key >= 0 and key < ffiC.numwalls) then return ffiC.wall[key] end
                  error('out-of-bounds wall[] read access')
              end,

    __newindex = function(tab, key, val) error('cannot write directly to wall[] struct') end,
    __metatable = true,
}
oG.setmetatable(wall, tmpmt)

-- create a safe indirection for a ffi.C array
local function creategtab(ctab, maxidx, name)
    local tab = {}
    local tmpmt = {
        __index = function(tab, key)
                      if (key>=0 and key < maxidx) then
                          return ctab[key]
                      end
                      error('out-of-bounds '..name..' read access')
                  end,
        __newindex = function(tab, key, val)
                         error('cannot write directly to '..name)
                     end,
        __metatable = true,
    }
    oG.setmetatable(tab, tmpmt)
    return tab
end

sprite = creategtab(ffiC.sprite, 16384, 'sprite[] struct')
spriteext = creategtab(ffiC.spriteext, 16384, 'spriteext[] struct')
headspritesect = creategtab(ffiC.headspritesect, 16384, 'headspritesect[]')
headspritestat = creategtab(ffiC.headspritestat, 1024, 'headspritestat[]')
nextspritesect = creategtab(ffiC.nextspritesect, 16384, 'nextspritesect[]')
nextspritestat = creategtab(ffiC.nextspritestat, 16384, 'nextspritestat[]')
prevspritesect = creategtab(ffiC.prevspritesect, 16384, 'prevspritesect[]')
prevspritestat = creategtab(ffiC.prevspritestat, 16384, 'prevspritestat[]')

actor = creategtab(ffiC.actor, 16384, 'actor[]')

---- per-sector/per-statnum sprite iterators ----
local function iter_spritesofsect(sect, i)
    if (i < 0) then
        i = ffiC.headspritesect[sect]
    else
        i = ffiC.nextspritesect[i]
    end

    if (i >= 0) then return i, i end
end

function spritesofsect(sect)
    assert(sect >= 0 and sect < ffiC.numsectors, "passed invalid sectnum to spritesofsect iterator")

    return iter_spritesofsect, sect, -1
end

local function iter_spritesofstat(stat, i)
    if (i < 0) then
        i = ffiC.headspritestat[stat]
    else
        i = ffiC.nextspritestat[i]
    end

    if (i >= 0) then return i, i end
end

function spritesofstat(stat)
    assert(stat >= 0 and stat < 1024, "passed invalid statnum to spritesofstat iterator")

    return iter_spritesofstat , stat, -1
end


-- add new variables/functions living in the global environment
G_.DBG_ = DBG_  -- REMOVE this for release
G_.gv = gv
G_.sector = sector
G_.wall = wall
G_.sprite = sprite
G_.spriteext = spriteext
G_.headspritesect = headspritesect
G_.headspritestat = headspritestat
G_.nextspritesect = nextspritesect
G_.nextspritestat = nextspritestat
G_.prevspritesect = prevspritesect
G_.prevspritestat = prevspritestat

G_.actor = actor

G_.spritesofsect = spritesofsect
G_.spritesofstat = spritesofstat

-- 'simple' code for prohibiting initial assignments to create new variables,
-- from 14.2 of PiL
function gamevar(name, initval)  -- aka 'declare'
    rawset(G_, name, initval or false)
end

setmetatable(
    G_, {
        __newindex = function (_, n)
            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 to the table G_
setfenv(0, G_)