/*
    KindlePDFViewer: Picture viewer abstraction for Lua
    Copyright (C) 2012 Tigran Aivazian <tigran@bibles.org.uk>

    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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <setjmp.h>
#include <math.h>

#include "jpeglib.h"
#include "blitbuffer.h"
#include "drawcontext.h"
#include "pic.h"

#define MIN(a, b)      ((a) < (b) ? (a) : (b))
#define MAX(a, b)      ((a) > (b) ? (a) : (b))

typedef struct PicDocument {
	int width;
	int height;
	int components;
	uint8_t *image;
} PicDocument;

typedef struct PicPage {
	int width, height;
	PicDocument *doc;
} PicPage;

struct my_error_mgr {
	struct jpeg_error_mgr pub;
	jmp_buf setjmp_buffer;
};

typedef struct my_error_mgr *my_error_ptr;

METHODDEF(void) my_error_exit(j_common_ptr cinfo)
{
	my_error_ptr myerr = (my_error_ptr) cinfo->err;
	(*cinfo->err->output_message) (cinfo);
	longjmp(myerr->setjmp_buffer, 1);
}

uint8_t *readJPEG(const char *fname, int *width, int *height, int *components)
{
	struct jpeg_decompress_struct cinfo;
	struct my_error_mgr jerr;
	FILE *infile;
	JSAMPARRAY buffer;
	int row_stride;
	long cont;
	JSAMPLE *image_buffer;

	if ((infile = fopen(fname, "r")) == NULL) return NULL;
	cinfo.err = jpeg_std_error(&jerr.pub);
	jerr.pub.error_exit = my_error_exit;
	if (setjmp(jerr.setjmp_buffer)) {
		jpeg_destroy_decompress(&cinfo);
		fclose(infile);
		return NULL;
	}
	jpeg_create_decompress(&cinfo);
	jpeg_stdio_src(&cinfo, infile);
	(void) jpeg_read_header(&cinfo, TRUE);
	(void) jpeg_start_decompress(&cinfo);
	row_stride = cinfo.output_width * cinfo.output_components;
	buffer = (*cinfo.mem->alloc_sarray)
		((j_common_ptr) & cinfo, JPOOL_IMAGE, row_stride, 1);

	image_buffer = (JSAMPLE *) malloc(cinfo.image_width*cinfo.image_height*cinfo.output_components);
	if (image_buffer == NULL) return NULL;
	*width = cinfo.image_width;
	*height = cinfo.image_height;

	//cont = cinfo.output_height - 1;
	cont = 0;
	while (cinfo.output_scanline < cinfo.output_height) {
		(void) jpeg_read_scanlines(&cinfo, buffer, 1);
		memcpy(image_buffer + cinfo.image_width * cinfo.output_components * cont, buffer[0], row_stride);
		cont++;
	}

	(void) jpeg_finish_decompress(&cinfo);
	jpeg_destroy_decompress(&cinfo);
	fclose(infile);
	*components = cinfo.output_components;
	return (uint8_t *)image_buffer;
}

static int openDocument(lua_State *L) {
	int width, height, components;
	const char *filename = luaL_checkstring(L, 1);

	PicDocument *doc = (PicDocument*) lua_newuserdata(L, sizeof(PicDocument));
	luaL_getmetatable(L, "picdocument");
	lua_setmetatable(L, -2);

	unsigned char *image = readJPEG(filename, &width, &height, &components);
	if (!image)
		return luaL_error(L, "cannot open jpeg file");

	doc->image = image;
	doc->width = width;
	doc->height = height;
	doc->components = components;
	//printf("openDocument(%s) decoded image: %dx%dx%d\n", filename, width, height, components);
	return 1;
}

static int openPage(lua_State *L) {
	PicDocument *doc = (PicDocument*) luaL_checkudata(L, 1, "picdocument");
	int pageno = luaL_checkint(L, 2);

	PicPage *page = (PicPage*) lua_newuserdata(L, sizeof(PicPage));
	luaL_getmetatable(L, "picpage");
	lua_setmetatable(L, -2);
	page->width = doc->width;
	page->height = doc->height;
	page->doc = doc;

	return 1;
}

static int getNumberOfPages(lua_State *L) {
	lua_pushinteger(L, 1);
	return 1;
}

static int getOriginalPageSize(lua_State *L) {
	PicDocument *doc = (PicDocument*) luaL_checkudata(L, 1, "picdocument");
	lua_pushnumber(L, doc->width);
	lua_pushnumber(L, doc->height);
	return 2;
}

static int closeDocument(lua_State *L) {
	PicDocument *doc = (PicDocument*) luaL_checkudata(L, 1, "picdocument");
	if (doc->image != NULL)
		free(doc->image);
	return 0;
}

static void scaleImage(uint8_t *result, uint8_t *image, int width, int height, int components, int new_width, int new_height)
{
	int x, y;

	for (x = 0; x<new_width; x++)
		for (y=0; y<new_height; y++)
			result[x+y*new_width] = image[(x*width/new_width) + (y*height/new_height)*width];
}

static int drawPage(lua_State *L) {
	PicPage *page = (PicPage*) luaL_checkudata(L, 1, "picpage");
	DrawContext *dc = (DrawContext*) luaL_checkudata(L, 2, "drawcontext");
	BlitBuffer *bb = (BlitBuffer*) luaL_checkudata(L, 3, "blitbuffer");
	int x_offset = MAX(0, dc->offset_x);
	int y_offset = MAX(0, dc->offset_y);
	int x, y;
	int img_width = page->doc->width;
	int img_height = page->doc->height;
	int img_components = page->doc->components;
	int img_new_width = bb->w;
	int img_new_height = bb->h;
	unsigned char adjusted_low[16], adjusted_high[16];
	int i, adjust_pixels = 0;

	/* prepare the tables for adjusting the intensity of pixels */
	if (dc->gamma != -1.0) {
		for (i=0; i<16; i++) {
			adjusted_low[i] = MIN(15, (unsigned char)floorf(dc->gamma * (float)i));
			adjusted_high[i] = adjusted_low[i] << 4;
		}
		adjust_pixels = 1;
	}

	uint8_t *scaled_image = malloc(img_new_width*img_new_height+1);
	if (!scaled_image)
		return 0;

	scaleImage(scaled_image, page->doc->image, img_width, img_height, img_components, img_new_width, img_new_height);

	uint8_t *bbptr = bb->data;
	uint8_t *pmptr = scaled_image;
	bbptr += bb->pitch * y_offset;
	for(y = y_offset; y < img_new_height; y++) {
		for(x = x_offset/2; x < (img_new_width / 2); x++) {
			int p = x*2 - x_offset;
			unsigned char low, high;
			if (img_components == 1) {
				low = 15 - (pmptr[p + 1] >> 4);
				high = 15 - (pmptr[p] >> 4);
			} else if (img_components == 3) {
				low = 15 - (pmptr[p + 3] >> 4);
				high = 15 - (pmptr[p] >> 4);
			} else {
				fprintf(stderr, "pic.c:drawPage(): unsupported image format\n");
				return 0;
			}
			if (adjust_pixels)
				bbptr[x] = adjusted_high[high] | adjusted_low[low];
			else
				bbptr[x] = (high << 4) | low;
		}
		if (img_new_width & 1)
			bbptr[x] = 255 - (pmptr[x*2] & 0xF0);
		bbptr += bb->pitch;
		pmptr += img_new_width;
	}

	free(scaled_image);
	return 0;
}

static int getCacheSize(lua_State *L) {
	PicDocument *doc = (PicDocument*) luaL_checkudata(L, 1, "picdocument");
	lua_pushnumber(L, doc->width * doc->height * doc->components);
	return 1;
}

static int cleanCache(lua_State *L) {
	return 0;
}

static int getPageSize(lua_State *L) {
	PicPage *page = (PicPage*) luaL_checkudata(L, 1, "picpage");
	DrawContext *dc = (DrawContext*) luaL_checkudata(L, 2, "drawcontext");
	
	lua_pushnumber(L, dc->zoom * page->width);
	lua_pushnumber(L, dc->zoom * page->height);

	return 2;
}


static int closePage(lua_State *L) {
	PicPage *page = (PicPage*) luaL_checkudata(L, 1, "picpage");
	return 0;
}

/* unsupported so fake it */
static int getUsedBBox(lua_State *L) {
	lua_pushnumber(L, (double)0.01);
	lua_pushnumber(L, (double)0.01);
	lua_pushnumber(L, (double)-0.01);
	lua_pushnumber(L, (double)-0.01);
	return 4;
}

static int getTableOfContent(lua_State *L) {
	lua_newtable(L);
	return 1;
}

static const struct luaL_Reg pic_func[] = {
	{"openDocument", openDocument},
	{NULL, NULL}
};

static const struct luaL_Reg picdocument_meth[] = {
	{"openPage", openPage},
	{"getPages", getNumberOfPages},
	{"getToc", getTableOfContent},
	{"getOriginalPageSize", getOriginalPageSize},
	{"getCacheSize", getCacheSize},
	{"close", closeDocument},
	{"cleanCache", cleanCache},
	{"__gc", closeDocument},
	{NULL, NULL}
};


static const struct luaL_Reg picpage_meth[] = {
	{"getSize", getPageSize},
	{"getUsedBBox", getUsedBBox},
	{"close", closePage},
	{"__gc", closePage},
	{"draw", drawPage},
	{NULL, NULL}
};


int luaopen_pic(lua_State *L) {
	luaL_newmetatable(L, "picdocument");
	lua_pushstring(L, "__index");
	lua_pushvalue(L, -2);
	lua_settable(L, -3);
	luaL_register(L, NULL, picdocument_meth);
	lua_pop(L, 1);

	luaL_newmetatable(L, "picpage");
	lua_pushstring(L, "__index");
	lua_pushvalue(L, -2);
	lua_settable(L, -3);
	luaL_register(L, NULL, picpage_meth);
	lua_pop(L, 1);

	luaL_register(L, "pic", pic_func);
	return 1;
}