/*
Copyright (c) 2012 codingow.com

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

// Adapted from https://github.com/cloudwu/lua-snapshot

#include "./luvi.h"

#if defined(_MSC_VER) && _MSC_VER < 1900

#define snprintf c99_snprintf
#define vsnprintf c99_vsnprintf

static int c99_vsnprintf(char *outBuf, size_t size, const char *format, va_list ap)
{
    int count = -1;

    if (size != 0)
        count = _vsnprintf_s(outBuf, size, _TRUNCATE, format, ap);
    if (count == -1)
        count = _vscprintf(format, ap);

    return count;
}

static int c99_snprintf(char *outBuf, size_t size, const char *format, ...)
{
    int count;
    va_list ap;

    va_start(ap, format);
    count = c99_vsnprintf(outBuf, size, format, ap);
    va_end(ap);

    return count;
}

#endif

static void mark_object(lua_State *L, lua_State *dL, const void * parent, const char * desc);

#if LUA_VERSION_NUM == 501

static void
luaL_checkversion(lua_State *L) {
	if (lua_pushthread(L) == 0) {
		luaL_error(L, "Must require in main thread");
	}
	lua_setfield(L, LUA_REGISTRYINDEX, "mainthread");
}

static void
lua_rawsetp(lua_State *L, int idx, const void *p) {
	if (idx < 0) {
		idx += lua_gettop(L) + 1;
	}
	lua_pushlightuserdata(L, (void *)p);
	lua_insert(L, -2);
	lua_rawset(L, idx);
}

static void
lua_rawgetp(lua_State *L, int idx, const void *p) {
	if (idx < 0) {
		idx += lua_gettop(L) + 1;
	}
	lua_pushlightuserdata(L, (void *)p);
	lua_rawget(L, idx);
}

static void
mark_function_env(lua_State *L, lua_State *dL, const void * t) {
	lua_getfenv(L,-1);
	if (lua_istable(L,-1)) {
		mark_object(L, dL, t, "[environment]");
	} else {
		lua_pop(L,1);
	}
}

#else

#define mark_function_env(L,dL,t)

#endif

#include <stdbool.h>
#include <stdio.h>
#include <string.h>

#define TABLE 1
#define FUNCTION 2
#define SOURCE 3
#define THREAD 4
#define USERDATA 5
#define MARK 6

static bool
ismarked(lua_State *dL, const void *p) {
	lua_rawgetp(dL, MARK, p);
	if (lua_isnil(dL,-1)) {
		lua_pop(dL,1);
		lua_pushboolean(dL,1);
		lua_rawsetp(dL, MARK, p);
		return false;
	}
	lua_pop(dL,1);
	return true;
}

static const void *
readobject(lua_State *L, lua_State *dL, const void *parent, const char *desc) {
	int t = lua_type(L, -1);
	int tidx = 0;
	switch (t) {
	case LUA_TTABLE:
		tidx = TABLE;
		break;
	case LUA_TFUNCTION:
		tidx = FUNCTION;
		break;
	case LUA_TTHREAD:
		tidx = THREAD;
		break;
	case LUA_TUSERDATA:
		tidx = USERDATA;
		break;
	default:
		return NULL;
	}

	const void * p = lua_topointer(L, -1);
	if (ismarked(dL, p)) {
		lua_rawgetp(dL, tidx, p);
		if (!lua_isnil(dL,-1)) {
			lua_pushstring(dL,desc);
			lua_rawsetp(dL, -2, parent);
		}
		lua_pop(dL,1);
		lua_pop(L,1);
		return NULL;
	}

	lua_newtable(dL);
	lua_pushstring(dL,desc);
	lua_rawsetp(dL, -2, parent);
	lua_rawsetp(dL, tidx, p);

	return p;
}

static const char *
keystring(lua_State *L, int index, char * buffer) {
	int t = lua_type(L,index);
	switch (t) {
	case LUA_TSTRING:
		return lua_tostring(L,index);
	case LUA_TNUMBER:
		sprintf(buffer,"[%lg]",lua_tonumber(L,index));
		break;
	case LUA_TBOOLEAN:
		sprintf(buffer,"[%s]",lua_toboolean(L,index) ? "true" : "false");
		break;
	case LUA_TNIL:
		sprintf(buffer,"[nil]");
		break;
	default:
		sprintf(buffer,"[%s:%p]",lua_typename(L,t),lua_topointer(L,index));
		break;
	}
	return buffer;
}

static void
mark_table(lua_State *L, lua_State *dL, const void * parent, const char * desc) {
	const void * t = readobject(L, dL, parent, desc);
	if (t == NULL)
		return;

	bool weakk = false;
	bool weakv = false;
	if (lua_getmetatable(L, -1)) {
		lua_pushliteral(L, "__mode");
		lua_rawget(L, -2);
		if (lua_isstring(L,-1)) {
			const char *mode = lua_tostring(L, -1);
			if (strchr(mode, 'k')) {
				weakk = true;
			}
			if (strchr(mode, 'v')) {
				weakv = true;
			}
		}
		lua_pop(L,1);

		luaL_checkstack(L, LUA_MINSTACK, NULL);
		mark_table(L, dL, t, "[metatable]");
	}

	lua_pushnil(L);
	while (lua_next(L, -2) != 0) {
		if (weakv) {
			lua_pop(L,1);
		} else {
			char temp[32];
			const char * desc = keystring(L, -2, temp);
			mark_object(L, dL, t , desc);
		}
		if (!weakk) {
			lua_pushvalue(L,-1);
			mark_object(L, dL, t , "[key]");
		}
	}

	lua_pop(L,1);
}

static void
mark_userdata(lua_State *L, lua_State *dL, const void * parent, const char *desc) {
	const void * t = readobject(L, dL, parent, desc);
	if (t == NULL)
		return;
	if (lua_getmetatable(L, -1)) {
		mark_table(L, dL, t, "[metatable]");
	}

	lua_getfenv(L,-1);
	if (lua_isnil(L,-1)) {
		lua_pop(L,2);
	} else {
		mark_table(L, dL, t, "[uservalue]");
		lua_pop(L,1);
	}
}

static void
mark_function(lua_State *L, lua_State *dL, const void * parent, const char *desc) {
	const void * t = readobject(L, dL, parent, desc);
	if (t == NULL)
		return;

	mark_function_env(L,dL,t);
	int i;
	for (i=1;;i++) {
		const char *name = lua_getupvalue(L,-1,i);
		if (name == NULL)
			break;
		mark_object(L, dL, t, name[0] ? name : "[upvalue]");
	}
	if (lua_iscfunction(L,-1)) {
		if (i==1) {
			// light c function
			lua_pushnil(dL);
			lua_rawsetp(dL, FUNCTION, t);
		}
		lua_pop(L,1);
	} else {
		lua_Debug ar;
		lua_getinfo(L, ">S", &ar);
		luaL_Buffer b;
		luaL_buffinit(dL, &b);
		luaL_addstring(&b, ar.short_src);
		char tmp[16];
		sprintf(tmp,":%d",ar.linedefined);
		luaL_addstring(&b, tmp);
		luaL_pushresult(&b);
		lua_rawsetp(dL, SOURCE, t);
	}
}

static void
mark_thread(lua_State *L, lua_State *dL, const void * parent, const char *desc) {
	const void * t = readobject(L, dL, parent, desc);
	if (t == NULL)
		return;
	int level = 0;
	lua_State *cL = lua_tothread(L,-1);
	if (cL == L) {
		level = 1;
	}
	lua_Debug ar;
	luaL_Buffer b;
	luaL_buffinit(dL, &b);
	while (lua_getstack(cL, level, &ar)) {
		char tmp[128];
		lua_getinfo(cL, "Sl", &ar);
		luaL_addstring(&b, ar.short_src);
		if (ar.currentline >=0) {
			char tmp[16];
			sprintf(tmp,":%d ",ar.currentline);
			luaL_addstring(&b, tmp);
		}

		int i,j;
		for (j=1;j>-1;j-=2) {
			for (i=j;;i+=j) {
				const char * name = lua_getlocal(cL, &ar, i);
				if (name == NULL)
					break;
				snprintf(tmp, sizeof(tmp), "%s : %s:%d",name,ar.short_src,ar.currentline);
				mark_object(cL, dL, t, tmp);
			}
		}

		++level;
	}
	luaL_pushresult(&b);
	lua_rawsetp(dL, SOURCE, t);
	lua_pop(L,1);
}

static void
mark_object(lua_State *L, lua_State *dL, const void * parent, const char *desc) {
	luaL_checkstack(L, LUA_MINSTACK, NULL);
	int t = lua_type(L, -1);
	switch (t) {
	case LUA_TTABLE:
		mark_table(L, dL, parent, desc);
		break;
	case LUA_TUSERDATA:
		mark_userdata(L, dL, parent, desc);
		break;
	case LUA_TFUNCTION:
		mark_function(L, dL, parent, desc);
		break;
	case LUA_TTHREAD:
		mark_thread(L, dL, parent, desc);
		break;
	default:
		lua_pop(L,1);
		break;
	}
}

static int
count_table(lua_State *L, int idx) {
	int n = 0;
	lua_pushnil(L);
	while (lua_next(L, idx) != 0) {
		++n;
		lua_pop(L,1);
	}
	return n;
}

static void
gen_table_desc(lua_State *dL, luaL_Buffer *b, const void * parent, const char *desc) {
	char tmp[32];
	size_t l = sprintf(tmp,"%p : ",parent);
	luaL_addlstring(b, tmp, l);
	luaL_addstring(b, desc);
	luaL_addchar(b, '\n');
}

static void
pdesc(lua_State *L, lua_State *dL, int idx, const char * typename) {
	lua_pushnil(dL);
	while (lua_next(dL, idx) != 0) {
		luaL_Buffer b;
		luaL_buffinit(L, &b);
		const void * key = lua_touserdata(dL, -2);
		if (idx == FUNCTION) {
			lua_rawgetp(dL, SOURCE, key);
			if (lua_isnil(dL, -1)) {
				luaL_addstring(&b,"cfunction\n");
			} else {
				size_t l = 0;
				const char * s = lua_tolstring(dL, -1, &l);
				luaL_addlstring(&b,s,l);
				luaL_addchar(&b,'\n');
			}
			lua_pop(dL, 1);
		} else if (idx == THREAD) {
			lua_rawgetp(dL, SOURCE, key);
			size_t l = 0;
			const char * s = lua_tolstring(dL, -1, &l);
			luaL_addlstring(&b,s,l);
			luaL_addchar(&b,'\n');
			lua_pop(dL, 1);
		} else {
			luaL_addstring(&b, typename);
			luaL_addchar(&b,'\n');
		}
		lua_pushnil(dL);
		while (lua_next(dL, -2) != 0) {
			const void * parent = lua_touserdata(dL,-2);
			const char * desc = luaL_checkstring(dL,-1);
			gen_table_desc(dL, &b, parent, desc);
			lua_pop(dL,1);
		}
		luaL_pushresult(&b);
		lua_rawsetp(L, -2, key);
		lua_pop(dL,1);
	}
}

static void
gen_result(lua_State *L, lua_State *dL) {
	int count = 0;
	count += count_table(dL, TABLE);
	count += count_table(dL, FUNCTION);
	count += count_table(dL, USERDATA);
	count += count_table(dL, THREAD);
	lua_createtable(L, 0, count);
	pdesc(L, dL, TABLE, "table");
	pdesc(L, dL, USERDATA, "userdata");
	pdesc(L, dL, FUNCTION, "function");
	pdesc(L, dL, THREAD, "thread");
}

static int
snapshot(lua_State *L) {
	int i;
	lua_State *dL = luaL_newstate();
	for (i=0;i<MARK;i++) {
		lua_newtable(dL);
	}
	lua_pushvalue(L, LUA_REGISTRYINDEX);
	mark_table(L, dL, NULL, "[registry]");
	gen_result(L, dL);
	lua_close(dL);
	return 1;
}

LUALIB_API int luaopen_snapshot(lua_State *L) {
	luaL_checkversion(L);
	lua_pushcfunction(L, snapshot);
	return 1;
}