// fbgl.h - v0.1.0 - public domain Levent Kaya 2024
// FBGL - Framebuffer Graphics Library
//
// This file provides both the interface and the implementation.
// To instantiate the implementation,
//      #define FBGL_IMPLEMENTATION
// in *ONE* source file, before #including this file.
//
//
// History:
//  - 0.1.0 First public release
//
// Status:
// 24/11/2024	texture rendering implemented
//
// Contributors:
//  @lvntky
//	@dario-loi
//
// LICENSE
//
//   See end of file for license information.

#ifndef __FBGL_H__
#define __FBGL_H__

#define VERSION "0.1.0"
#define NAME "FBGL"
#define DEFAULT_FB "/dev/fb0"
#define #define FBGL_MAX_KEYS 256  // Maximum number of keys to track

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <linux/fb.h>
#include <stddef.h>
#include <stdio.h>
#include <termios.h>
#include <signal.h>
#include <stdbool.h>

#ifdef FBGL_USE_FREETYPE
#include <ft2build.h>
#include FT_FREETYPE_H
#endif //FBGL_USE_FREETYPE

/**
* Structs
*/
typedef struct fbgl {
	int width;
	int height;
	int fd;
	size_t screen_size;
	uint32_t *pixels;
	struct fb_var_screeninfo vinfo; // Variable screen information
	struct fb_fix_screeninfo finfo; // Fixed screen information
} fbgl_t;

typedef struct fbgl_window {
	int x; // Top-left x-coordinate of the window
	int y; // Top-left y-coordinate of the window
	int width; // Width of the window
	int height; // Height of the window
	fbgl_t *fb; // Pointer to the framebuffer context
} fbgl_window_t;

typedef struct fbgl_psf2_header {
	uint8_t magic[2]; // Magic number, should be {0x72, 0xB5}
	uint8_t version; // Version of PSF2 (usually 0)
	uint8_t header_size; // Size of the header (usually 32 bytes)
	uint16_t flags; // Flags (usually 0)
	uint16_t numglyphs; // Number of glyphs (characters)
	uint16_t bytes_per_glyph; // Number of bytes per glyph (depends on font size)
	uint16_t height; // Height of each character in pixels
	uint16_t width; // Width of each character in pixels
	uint8_t *glyphs; // Pointer to the glyph data
} fbgl_psf2_header_t;

typedef struct fbgl_point {
	size_t x;
	size_t y;
} fbgl_point_t;

typedef struct fbgl_tga_texture {
	uint16_t width;
	uint16_t height;
	uint32_t *data;
} fbgl_tga_texture_t;

typedef struct fbgl_keyboard {
    bool keys[FBGL_MAX_KEYS];     // Current state of each key
    bool prev_keys[FBGL_MAX_KEYS]; // Previous state of each key
    bool is_initialized;           // Track if keyboard is initialized
} fbgl_keyboard_t;


/**
 * Key state function and variables
 * 
 */
static struct termios orig_termios;
static fbgl_keyboard_t keyboard = {0};

#ifdef FBGL_HIDE_CURSOR
#include <linux/kd.h>
int fbgl_hide_cursor(int fd)
{
	int tty_fd = open("/dev/tty0", O_RDWR);
	if (tty_fd == -1) {
		perror("Error opening /dev/tty0");
		return -1;
	}

	if (ioctl(tty_fd, KDSETMODE, KD_GRAPHICS) == -1) {
		perror("Error setting graphics mode");
		close(tty_fd);
		return -1;
	}

	close(tty_fd);
	return 0;
}
#endif //FBGL_HIDE_CURSOR

#ifdef FBGL_USE_FREETYPE
FT_Library fbgl_freetype_init();
void fbgl_freetype_cleanup(FT_Library library);
FT_Face fbgl_load_font(FT_Library library, const char *font_path,
		       int font_size);
void fbgl_render_freetype_text(fbgl_t *fb, FT_Library library, FT_Face face,
			       const char *text, int x, int y);
#endif //FBGL_USE_FREETYPE

#ifdef __cplusplus
extern "C" {
#endif

/**
 * General purpose methods
 */
char const *fbgl_name_info(void);
char const *fbgl_version_info(void);
void fbgl_enable_raw_mode();
void fbgl_disable_raw_mode();
void fbgl_cleanup(int sig);
int fbgl_check_esc_key();
void fbgl_set_signal_handlers();

/*Create and destroy methods*/
int fbgl_init(const char *device, fbgl_t *fb);
void fbgl_destroy(fbgl_t *fb);

/**
* Drawing functions
*/
void fbgl_clear(uint32_t color);
void fbgl_put_pixel(int x, int y, uint32_t color, fbgl_t *fb);
void fbgl_draw_line(fbgl_point_t x, fbgl_point_t y, uint32_t color, fbgl_t *fb);
void fbgl_set_bg();

/**
* Display methods
*/
void fbgl_display();

/**
* Access framebuffer data methods
*/
uint32_t *fb_get_data(void);
int fb_get_width(void);
int fb_get_height(void);

/**
* Shapes
*/
void fbgl_draw_rectangle_outline(fbgl_point_t top_left,
				 fbgl_point_t bottom_right, uint32_t color,
				 fbgl_t *fb);
void fbgl_draw_rectangle_filled(fbgl_point_t top_left,
				fbgl_point_t bottom_right, uint32_t color,
				fbgl_t *fb);

/**
* texture
*/
fbgl_tga_texture_t *fbgl_load_tga_texture(const char *path);
void fbgl_destroy_texture(fbgl_tga_texture_t *texture);
void fbgl_draw_texture(fbgl_t *fb, fbgl_tga_texture_t *texture, int x, int y);

/**
 * Keyboard 
 */
int fbgl_keyboard_init();
void fbgl_keyboard_clean();
void fbgl_keyboard_update();
bool fbgl_key_pressed(unsigned char key);
bool fbgl_key_released(unsigned char key);
bool fbgl_key_down(unsigned char key);

#ifdef FBGL_IMPLEMENTATION

char const *fbgl_name_info(void)
{
	return NAME;
}

char const *fbgl_version_info(void)
{
	return VERSION;
}

int fbgl_init(const char *device, fbgl_t *fb)
{
	if (!fb) {
		fprintf(stderr, "Error: fbgl_t pointer is NULL.");
		return -1;
	}

	fb->fd = device == NULL ? open(DEFAULT_FB, O_RDWR) :
				  open(device, O_RDWR);
	if (fb->fd == -1) {
		perror("Error openning framebuffer device");
		return -1;
	}

	if (ioctl(fb->fd, FBIOGET_FSCREENINFO, &fb->finfo) == -1) {
		perror("Error: Reading fixed information.");
		close(fb->fd);
		return -1;
	}
	if (ioctl(fb->fd, FBIOGET_VSCREENINFO, &fb->vinfo) == -1) {
		perror("Error reading variable information");
		close(fb->fd);
		return -1;
	}

#ifdef FBGL_HIDE_CURSOR
	fbgl_hide_cursor(fb->fd);
	fbgl_set_signal_handlers();
	fbgl_enable_raw_mode();
#endif //FBGL_HIDE_CURSOR

	fb->width = fb->vinfo.xres;
	fb->height = fb->vinfo.yres;
	fb->screen_size = fb->finfo.smem_len;

	// Map framebuffer to memory
	fb->pixels = (uint32_t *)mmap(NULL, fb->screen_size,
				      PROT_READ | PROT_WRITE, MAP_SHARED,
				      fb->fd, 0);
	if (fb->pixels == MAP_FAILED) {
		perror("Error mapping framebuffer device to memory");
		close(fb->fd);
		return -1;
	}

	return 0;
}

void fbgl_destroy(fbgl_t *fb)
{
	if (!fb || fb->fd == -1) {
		fprintf(stderr,
			"Error: framebuffer not initialized or already destroyed.\n");
		return;
	}

	if (fb->pixels && fb->pixels != MAP_FAILED) {
		munmap(fb->pixels, fb->screen_size);
	}

	close(fb->fd);
	fb->fd = -1;

#ifdef FBGL_HIDE_CURSOR
	fbgl_disable_raw_mode();
#endif // FBGL_HIDE_CURSOR
}

void fbgl_set_bg(fbgl_t *fb, uint32_t color)
{
	if (!fb || fb->fd == -1) {
		fprintf(stderr, "Error: framebuffer not initialized.\n");
		return;
	}

	// Fill the entire framebuffer with the specified color
	for (size_t i = 0; i < (fb->width * fb->height); ++i) {
		fb->pixels[i] = color;
	}
}

void fbgl_put_pixel(int x, int y, uint32_t color, fbgl_t *fb)
{
	if (!fb || !fb->pixels) {
		fprintf(stderr, "Error: framebuffer not initialized.\n");
		return;
	}

	if (x < 0 || x >= fb->width || y < 0 || y >= fb->height) {
		return; // Ignore out-of-bound coordinates
	}

	size_t index = y * fb->width + x;
	fb->pixels[index] = color;
}

void fbgl_enable_raw_mode()
{
	struct termios raw;

	if (tcgetattr(STDIN_FILENO, &orig_termios) == -1) {
		perror("tcgetattr");
		exit(EXIT_FAILURE);
	}
	raw = orig_termios;
	raw.c_lflag &= ~(ECHO | ICANON);
	if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1) {
		perror("tcsetattr");
		exit(EXIT_FAILURE);
	}
}

void fbgl_disable_raw_mode()
{
	if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &orig_termios) == -1) {
		perror("tcsetattr");
	}
}

void fbgl_cleanup(int sig)
{
	fbgl_disable_raw_mode();
	printf("\033[2J\033[H"); // Clear the terminal screen and move the cursor to top-left
	exit(sig);
}

int fbgl_check_esc_key()
{
	char c;
	struct timeval tv = { 0, 0 }; // Timeout of 0, to poll immediately
	fd_set fds;
	FD_ZERO(&fds);
	FD_SET(STDIN_FILENO, &fds);

	// Check if there's input available
	if (select(STDIN_FILENO + 1, &fds, NULL, NULL, &tv) == -1) {
		perror("select");
		return 0;
	}

	if (FD_ISSET(STDIN_FILENO, &fds)) {
		if (read(STDIN_FILENO, &c, 1) == -1) {
			perror("read");
			return 0;
		}
		return c == 27; // ASCII value of the `Esc` key
	}

	return 0;
}

void fbgl_set_signal_handlers()
{
	struct sigaction sa;
	sa.sa_handler = fbgl_cleanup;
	sa.sa_flags = 0;
	sigemptyset(&sa.sa_mask);

	if (sigaction(SIGINT, &sa, NULL) == -1 ||
	    sigaction(SIGTERM, &sa, NULL) == -1) {
		perror("sigaction");
		exit(EXIT_FAILURE);
	}
}

#endif

#ifdef FBGL_USE_FREETYPE
FT_Library fbgl_freetype_init()
{
	FT_Library library;
	if (FT_Init_FreeType(&library)) {
		fprintf(stderr, "Could not init FreeType Library\n");
		return NULL;
	}
	return library;
}

void fbgl_freetype_cleanup(FT_Library library)
{
	if (library) {
		FT_Done_FreeType(library);
	}
}

FT_Face fbgl_load_font(FT_Library library, const char *font_path, int font_size)
{
	FT_Face face;
	if (FT_New_Face(library, font_path, 0, &face)) {
		fprintf(stderr, "Could not open font: %s\n", font_path);
		return NULL;
	}
	FT_Set_Pixel_Sizes(face, 0, font_size); // Set font size
	return face;
}

void fbgl_render_freetype_text(fbgl_t *fb, FT_Library library, FT_Face face,
			       const char *text, int x, int y)
{
	while (*text) {
		FT_Load_Char(face, *text, FT_LOAD_RENDER);
		FT_Bitmap bitmap = face->glyph->bitmap;

		// Draw the bitmap to framebuffer
		for (int j = 0; j < bitmap.rows; j++) {
			for (int i = 0; i < bitmap.width; i++) {
				if (bitmap.buffer[j * bitmap.width +
						  i]) { // Check pixel is not empty
					fbgl_put_pixel(x + i, y + j, 0xFF0000,
						       fb); // Draw white pixel
				}
			}
		}
		x += face->glyph->advance.x >>
		     6; // Move to the next character position
		++text;
	}
}

#endif // FBGL_USE_FREETYPE
void fbgl_draw_line(fbgl_point_t x, fbgl_point_t y, uint32_t color,
		    fbgl_t *buffer)
{
	int dx = abs(y.x - x.x);
	int dy = abs(y.y - x.y);

	int sx = (x.x < y.x) ? 1 : -1;
	int sy = (x.y < y.y) ? 1 : -1;

	int err = dx - dy;

	while (1) {
		// Set the pixel at the current position
		fbgl_put_pixel(x.x, x.y, color, buffer);

		// If we've reached the end point, break
		if (x.x == y.x && x.y == y.y)
			break;

		int e2 = 2 * err;

		if (e2 > -dy) {
			err -= dy;
			x.x += sx;
		}

		if (e2 < dx) {
			err += dx;
			x.y += sy;
		}
	}
}
void fbgl_draw_rectangle_outline(fbgl_point_t top_left,
				 fbgl_point_t bottom_right, uint32_t color,
				 fbgl_t *fb)
{
	// Top horizontal line
	for (int x = top_left.x; x < bottom_right.x; x++) {
		fbgl_put_pixel(x, top_left.y, color, fb);
	}

	// Bottom horizontal line
	for (int x = top_left.x; x < bottom_right.x; x++) {
		fbgl_put_pixel(x, bottom_right.y - 1, color, fb);
	}

	// Left vertical line
	for (int y = top_left.y; y < bottom_right.y; y++) {
		fbgl_put_pixel(top_left.x, y, color, fb);
	}

	// Right vertical line
	for (int y = top_left.y; y < bottom_right.y; y++) {
		fbgl_put_pixel(bottom_right.x - 1, y, color, fb);
	}
}

void fbgl_draw_rectangle_filled(fbgl_point_t top_left,
				fbgl_point_t bottom_right, uint32_t color,
				fbgl_t *fb)
{
	for (int y = top_left.y; y < bottom_right.y; y++) {
		// Manually set each pixel in the row
		for (int x = top_left.x; x < bottom_right.x; x++) {
			fbgl_put_pixel(x, y, color, fb);
		}
	}
}
fbgl_tga_texture_t *fbgl_load_tga_texture(const char *path)
{
	FILE *file = fopen(path, "rb");
	if (!file) {
		perror("Unable to open texture file");
		return NULL;
	}

	// TGA header structure
	uint8_t header[18];
	if (fread(header, 1, sizeof(header), file) != sizeof(header)) {
		perror("Error reading TGA header");
		fclose(file);
		return NULL;
	}

	// Allocate texture structure
	fbgl_tga_texture_t *texture =
		(fbgl_tga_texture_t *)malloc(sizeof(fbgl_tga_texture_t));
	if (!texture) {
		perror("Failed to allocate texture structure");
		fclose(file);
		return NULL;
	}

	// Extract dimensions from header
	texture->width = header[12] | (header[13] << 8);
	texture->height = header[14] | (header[15] << 8);
	uint8_t bits_per_pixel = header[16];
	uint8_t image_descriptor = header[17];

	// Verify format support
	if (bits_per_pixel != 24 && bits_per_pixel != 32) {
		fprintf(stderr,
			"Unsupported TGA bit depth: %d (only 24 and 32-bit supported)\n",
			bits_per_pixel);
		free(texture);
		fclose(file);
		return NULL;
	}

	// Skip image ID field
	if (header[0]) {
		fseek(file, header[0], SEEK_CUR);
	}

	// Allocate pixel data
	size_t pixel_count = texture->width * texture->height;
	texture->data = (uint32_t *)malloc(pixel_count * sizeof(uint32_t));
	if (!texture->data) {
		perror("Failed to allocate pixel data");
		free(texture);
		fclose(file);
		return NULL;
	}

	// Read pixel data
	uint8_t *pixel_buffer = (uint8_t *)malloc(bits_per_pixel / 8);
	if (!pixel_buffer) {
		perror("Failed to allocate pixel buffer");
		free(texture->data);
		free(texture);
		fclose(file);
		return NULL;
	}

	// Determine if image is flipped (based on image descriptor)
	bool bottom_up = !(image_descriptor & 0x20);

	for (size_t i = 0; i < pixel_count; i++) {
		size_t pixel_index =
			bottom_up ?
				(texture->height - 1 - (i / texture->width)) *
						texture->width +
					(i % texture->width) :
				i;

		if (fread(pixel_buffer, 1, bits_per_pixel / 8, file) !=
		    bits_per_pixel / 8) {
			perror("Error reading pixel data");
			free(pixel_buffer);
			free(texture->data);
			free(texture);
			fclose(file);
			return NULL;
		}

		// Convert BGR(A) to RGBA
		uint32_t pixel = 0xFF000000; // Default alpha to 255
		pixel |= pixel_buffer[2] << 16; // R
		pixel |= pixel_buffer[1] << 8; // G
		pixel |= pixel_buffer[0]; // B
		if (bits_per_pixel == 32) {
			pixel = (pixel & 0x00FFFFFF) |
				(pixel_buffer[3] << 24); // A
		}

		texture->data[pixel_index] = pixel;
	}

	free(pixel_buffer);
	fclose(file);
	return texture;
}

void fbgl_destroy_texture(fbgl_tga_texture_t *texture)
{
	if (texture) {
		free(texture->data);
		free(texture);
	}
}

void fbgl_draw_texture(fbgl_t *fb, fbgl_tga_texture_t *texture, int x, int y)
{
	if (!fb || !texture || !texture->data) {
		return;
	}

	for (int ty = 0; ty < texture->height; ty++) {
		for (int tx = 0; tx < texture->width; tx++) {
			int screen_x = x + tx;
			int screen_y = y + ty;

			// Skip if outside screen bounds
			if (screen_x < 0 || screen_x >= fb->width ||
			    screen_y < 0 || screen_y >= fb->height) {
				continue;
			}

			uint32_t pixel =
				texture->data[ty * texture->width + tx];
			// Only draw if pixel is not fully transparent
			if ((pixel & 0xFF000000) != 0) {
				fbgl_put_pixel(screen_x, screen_y, pixel, fb);
			}
		}
	}
}
#ifdef __cplusplus
} // extern "C"
#endif
#endif // __FBGL_H__

/*
------------------------------------------------------------------------------
This software is available under 2 licenses -- choose whichever you prefer.
------------------------------------------------------------------------------
ALTERNATIVE A - MIT License
Copyright (c) 2024 Levent Kaya
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.
------------------------------------------------------------------------------
ALTERNATIVE B - Public Domain (www.unlicense.org)
This is free and unencumbered software released into the public domain.
Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
software, either in source code form or as a compiled binary, for any purpose,
commercial or non-commercial, and by any means.
In jurisdictions that recognize copyright laws, the author or authors of this
software dedicate any and all copyright interest in the software to the public
domain. We make this dedication for the benefit of the public at large and to
the detriment of our heirs and successors. We intend this dedication to be an
overt act of relinquishment in perpetuity of all present and future rights to
this software under copyright law.
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 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.
------------------------------------------------------------------------------
*/