/*
 * Copyright (C) 2008 - 2016 The Geeqie Team
 *
 * Author: Klaus Ethgen
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define _XOPEN_SOURCE

#include "glua.h"

#include <unistd.h>

#include <cstring>
#include <ctime>
#include <memory>
#include <utility>

#include <glib.h>
#include <lua.hpp>

#include "debug.h"
#include "exif.h"
#include "filedata.h"
#include "main.h"
#include "ui-fileops.h"

struct ExifData;

/**
 * @file
 * User API consists of the following namespaces:
 *
 * @link image_methods Image:@endlink basic image information
 *
 * <b>Collection</b>: not implemented
 *
 * @link exif_methods <exif-structure>:get_datum() @endlink get single exif parameter
 *
 */

static lua_State *L; /** The LUA object needed for all operations (NOTE: That is
		       * a upper-case variable to match the documentation!) */

/* Taking that definition from lua 5.1 source */
#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM >= 502
int luaL_typerror(lua_State *L, int narg, const char *tname)
{
	const char *msg = lua_pushfstring(L, "%s expected, got %s", tname, luaL_typename(L, narg));
	return luaL_argerror(L, narg, msg);
}

# define LUA_register_meta(L, meta) luaL_setfuncs(L, meta, 0);
# define LUA_register_global(L, string, func) \
	lua_newtable(L); \
	luaL_setfuncs(L, func, 0); \
	lua_pushvalue(L, -1); \
	lua_setglobal(L, string)
#else
# define LUA_register_meta(L, meta) luaL_register(L, NULL, meta)
# define LUA_register_global(L, string, func) luaL_register(L, string, func)
#endif

static FileData *lua_check_image(lua_State *L, int index)
{
	FileData **fd;
	luaL_checktype(L, index, LUA_TUSERDATA);
	fd = static_cast<FileData **>(luaL_checkudata(L, index, "Image"));
	if (fd == nullptr) luaL_typerror(L, index, "Image");
	return *fd;
}

/**
 * @brief Get exif structure of selected image
 * @param L
 * @returns An #ExifData data structure containing the entire exif data
 *
 * To be used in conjunction with @link lua_exif_get_datum <exif-structure>:get_datum() @endlink
 */
static int lua_image_get_exif(lua_State *L)
{
	FileData *fd;
	ExifData *exif;
	ExifData **exif_data;

	fd = lua_check_image(L, 1);
	exif = exif_read_fd(fd);

	exif_data = static_cast<ExifData **>(lua_newuserdata(L, sizeof(ExifData *)));
	luaL_getmetatable(L, "Exif");
	lua_setmetatable(L, -2);

	*exif_data = exif;

	return 1;
}

/**
 * @brief Get full path of selected image
 * @param L
 * @returns char The full path of the file, including filename and extension
 *
 *
 */
static int lua_image_get_path(lua_State *L)
{
	FileData *fd;

	fd = lua_check_image(L, 1);
	lua_pushstring(L, fd->path);
	return 1;
}

/**
 * @brief Get full filename of selected image
 * @param L
 * @returns char The full filename including extension
 *
 *
 */
static int lua_image_get_name(lua_State *L)
{
	FileData *fd;

	fd = lua_check_image(L, 1);
	lua_pushstring(L, fd->name);
	return 1;
}

/**
 * @brief Get file extension of selected image
 * @param L
 * @returns char The file extension including preceding dot
 *
 *
 */
static int lua_image_get_extension(lua_State *L)
{
	FileData *fd;

	fd = lua_check_image(L, 1);
	lua_pushstring(L, fd->extension);
	return 1;
}

/**
 * @brief Get file date of selected image
 * @param L
 * @returns time_t The file date in Unix timestamp format.
 *
 * time_t - signed integer which represents the number of seconds since
 * the start of the Unix epoch: midnight UTC of January 1, 1970
 */
static int lua_image_get_date(lua_State *L)
{
	FileData *fd;

	fd = lua_check_image(L, 1);
	lua_pushnumber(L, fd->date);
	return 1;
}

/**
 * @brief Get file size of selected image
 * @param L
 * @returns integer The file size in bytes
 *
 *
 */
static int lua_image_get_size(lua_State *L)
{
	FileData *fd;

	fd = lua_check_image(L, 1);
	lua_pushnumber(L, fd->size);
	return 1;
}

/**
 * @brief Get marks of selected image
 * @param L
 * @returns unsigned integer Bit map of marks set
 *
 * Bit 0 == Mark 1 etc.
 *
 *
 */
static int lua_image_get_marks(lua_State *L)
{
	FileData *fd;

	fd = lua_check_image(L, 1);
	lua_pushnumber(L, fd->marks);
	return 1;
}

static ExifData *lua_check_exif(lua_State *L, int index)
{
	ExifData **exif;
	luaL_checktype(L, index, LUA_TUSERDATA);
	exif = static_cast<ExifData **>(luaL_checkudata(L, index, "Exif"));
	if (exif == nullptr) luaL_typerror(L, index, "Exif");
	return *exif;
}

/**
 * @brief Interface for EXIF data
 * @param L
 * @returns <i>return</i> A single exif tag extracted from a structure output by the @link lua_image_get_exif Image:get_exif() @endlink command
 *
 * e.g. \n
 * exif_structure = Image:get_exif(); \n
 * DateTimeDigitized = exif_structure:get_datum("Exif.Photo.DateTimeDigitized");
 *
 * Where <i>return</i> is: \n
 * Exif.Photo.DateTimeOriginal = signed integer time_t \n
 * Exif.Photo.DateTimeDigitized = signed integer time_t \n
 * otherwise char
 *
 */
static int lua_exif_get_datum(lua_State *L)
{
	const gchar *key;
	gchar *value = nullptr;
	ExifData *exif;
	struct tm tm;
	time_t datetime;

	exif = lua_check_exif(L, 1);
	key = luaL_checkstring(L, 2);
	if (key == nullptr || key[0] == '\0')
		{
		lua_pushnil(L);
		return 1;
		}
	if (!exif)
		{
		lua_pushnil(L);
		return 1;
		}
	value = exif_get_data_as_text(exif, key);
	if (strcmp(key, "Exif.Photo.DateTimeOriginal") == 0)
		{
		memset(&tm, 0, sizeof(tm));
		if (value && strptime(value, "%Y:%m:%d %H:%M:%S", &tm))
			{
			datetime = mktime(&tm);
			lua_pushnumber(L, datetime);
			return 1;
			}

		lua_pushnil(L);
		return 1;
		}

	if (strcmp(key, "Exif.Photo.DateTimeDigitized") == 0)
		{
		memset(&tm, 0, sizeof(tm));
		if (value && strptime(value, "%Y:%m:%d %H:%M:%S", &tm))
			{
			datetime = mktime(&tm);
			lua_pushnumber(L, datetime);
			return 1;
			}

		lua_pushnil(L);
		return 1;
		}
	lua_pushstring(L, value);
	return 1;
}

/**
 * @brief  <b>Image:</b> metatable and methods \n
 * Call by e.g. \n
 * path_name = @link lua_image_get_path Image:getpath() @endlink \n
 * where the keyword <b>Image</b> represents the currently selected image
 */
static const luaL_Reg image_methods[] = {
		{"get_path", lua_image_get_path},
		{"get_name", lua_image_get_name},
		{"get_extension", lua_image_get_extension},
		{"get_date", lua_image_get_date},
		{"get_size", lua_image_get_size},
		{"get_exif", lua_image_get_exif},
		{"get_marks", lua_image_get_marks},
		{nullptr, nullptr}
};

/**
 * @brief  <b>exif:</b> table and methods \n
 * Call by e.g. \n
 * @link lua_exif_get_datum <exif-structure>:get_datum() @endlink \n
 * where <exif-structure> is the output of @link lua_image_get_exif Image:get_exif() @endlink
 *
 * exif_structure = Image:get_exif(); \n
 * DateTimeDigitized = exif_structure:get_datum("Exif.Photo.DateTimeDigitized");
 */
static const luaL_Reg exif_methods[] = {
		{"get_datum", lua_exif_get_datum},
		{nullptr, nullptr}
};

/**
 * @brief Initialize the lua interpreter.
 */
void lua_init()
{
	L = luaL_newstate();
	luaL_openlibs(L); /* Open all libraries for lua programs */

	/* Now create custom methodes to do something */
	static const luaL_Reg meta_methods[] = {
			{nullptr, nullptr}
	};

	LUA_register_global(L, "Image", image_methods);
	luaL_newmetatable(L, "Image");
	LUA_register_meta(L, meta_methods);
	lua_pushliteral(L, "__index");
	lua_pushvalue(L, -3);
	lua_settable(L, -3);
	lua_pushliteral(L, "__metatable");
	lua_pushvalue(L, -3);
	lua_settable(L, -3);
	lua_pop(L, 1);
	lua_pop(L, 1);

	LUA_register_global(L, "Exif", exif_methods);
	luaL_newmetatable(L, "Exif");
	LUA_register_meta(L, meta_methods);
	lua_pushliteral(L, "__index");
	lua_pushvalue(L, -3);
	lua_settable(L, -3);
	lua_pushliteral(L, "__metatable");
	lua_pushvalue(L, -3);
	lua_settable(L, -3);
	lua_pop(L, 1);
	lua_pop(L, 1);
}

/**
 * @brief Call a lua function to get a single value.
 */
gchar *lua_callvalue(FileData *fd, const gchar *file, const gchar *function)
{
	std::unique_ptr<gchar, decltype(&g_free)> path{g_build_filename(get_rc_dir(), "lua", file, NULL), g_free};
	if (access(path.get(), R_OK) == -1)
		{
		path.reset(g_build_filename(gq_bindir, file, NULL));
		if (access(path.get(), R_OK) == -1)
			{
			return g_strdup("");
			}
		}

	/* Collection Table (Dummy at the moment) */
	lua_newtable(L);
	lua_setglobal(L, "Collection");

	/* Current Image */
	auto image_data = static_cast<FileData **>(lua_newuserdata(L, sizeof(FileData *)));
	luaL_getmetatable(L, "Image");
	lua_setmetatable(L, -2);
	lua_setglobal(L, "Image");

	*image_data = fd;

	gint result;
	if (file[0] == '\0')
		{
		result = luaL_dostring(L, function);
		}
	else
		{
		result = luaL_dofile(L, path.get());
		}

	if (result)
		{
		return g_strdup_printf("Error running lua script: %s", lua_tostring(L, -1));
		}

	gchar *data = g_strdup(lua_tostring(L, -1));
	GError *error = nullptr;
	gchar *tmp = g_locale_to_utf8(data, strlen(data), nullptr, nullptr, &error);
	if (error)
		{
		log_printf("Error converting lua output from locale to UTF-8: %s\n", error->message);
		g_error_free(error);
		}
	else
		{
		std::swap(data, tmp);
		} // if (error) { ... } else
	g_free(tmp);
	return data;
}

/* vim: set shiftwidth=8 softtabstop=0 cindent cinoptions={1s: */
