/*
 * demoscene-eo, an ASCII art demoscene written as a gift for Emmanuel Otton retirement 
 * Copyright (C) 2019  Ludovic Pouzenc <ludovic@pouzenc.fr>
 *  
 * This file is part of demoscene-eo.
 *
 *  demoscene-eo 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.
 *
 *  demoscene-eo 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 demoscene-eo.  If not, see <http://www.gnu.org/licenses/>
 */
#include "main.h"
#include "scene00.h"
#include "scene01.h"
#include "scene02.h"

#include <stdlib.h>    // calloc()
#include <strings.h>   // bzero()
#include <sys/mman.h>  // mmap()
#include <semaphore.h> // sem_t, sem_init(), Link with -pthread
#include <unistd.h>    // fork()
#include <sys/wait.h>  // wait()
#include <errno.h>     // errno
#include <stdint.h>    // uint32_t
#include <stdio.h>     // printf()
#include <signal.h>    // sigaction()

#ifdef DEBUG_SEM
#define TRACE_SEM(sem,op,hint) printf("%s(): %s(%s) %s\n", __func__, op, #sem, hint)
#else
#define TRACE_SEM(sem,op,hint)
#endif

#define SCENE_COUNT 3
#define SCENE_NEXT do { shm->scene = (shm->scene+1)%SCENE_COUNT; } while(0)

#define SEM_POST(sem,errcode) \
	do { \
		TRACE_SEM(sem,"sem_post",""); \
		if (sem_post(sem) == -1) { return errcode; } \
	} while(0)

#define SEM_WAIT(sem,errcode) \
	do { \
		TRACE_SEM(sem,"sem_wait","call"); \
		while (sem_wait(sem) == -1) { \
			switch(errno) { \
				case EINTR: \
				case EAGAIN: \
					break; \
				default: \
					return errcode; \
			} \
		} \
		TRACE_SEM(sem,"sem_wait","done"); \
	} while(0)

typedef struct {
	sem_t worker_gl_can_render, worker_sdl_can_render, parent_can_read_result;
	int scene, paused, done;
	graphical_env_t ge;
	scene00_env_t s00e;
	scene01_env_t s01e;
	scene02_env_t s02e;
} shm_t;

int do_fork1();
int do_fork2();
int parent();
int worker_sdl();
int worker_gl();

static int skip = 0;
shm_t *shm;

int main() {
	TRACE("call");
	shm = mmap(NULL, sizeof(shm_t), PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, 0, 0);
	if (shm == NULL) return 1;
	bzero(shm, sizeof(shm_t));

	if (sem_init(&shm->worker_gl_can_render, 1, 0) < 0) return 2;
	if (sem_init(&shm->worker_sdl_can_render, 1, 0) < 0) return 3;
	if (sem_init(&shm->parent_can_read_result, 1, 0) < 0) return 4;

	return do_fork1();
}

int do_fork1() {
	TRACE("call");
	fflush(stdout);
	switch (fork()) {
		case -1: return 4; break;
		case 0:  return worker_sdl(); break;
		default: return do_fork2(); break;
	}
}

int do_fork2() {
	TRACE("call");
	fflush(stdout);
	switch (fork()) {
		case -1: return 5; break;
		case 0:  return worker_gl(); break;
		default: return parent(); break;
	}
}

int parent() {
	int lastscene=-1, res, child_status;
	caca_event_t caca_ev;

	TRACE("call");

	// Initialize libcaca (http://caca.zoy.org/doxygen/libcaca/caca_8h.html)
	shm->ge.dp = caca_create_display(NULL);
	if(!shm->ge.dp) return 1;
	caca_set_display_title(shm->ge.dp, "demoscene-eo");
	caca_set_display_time(shm->ge.dp, 41666); // 1e6µs/24 = 41666.66... It is ~24 fps
	shm->ge.cv = caca_get_canvas(shm->ge.dp);

	shm->ge.d = caca_create_dither(32, FBUF_W, FBUF_H, FBUF_W*4, 0x00ff0000, 0x0000ff00, 0x000000ff, 0);
	if (!shm->ge.d) return 2;
	caca_set_dither_color(shm->ge.d, "16");

	// Main libcaca loop for caca window
	shm->ge.framecount=0;
	do {

		// Check canvas size at every frame because of unreliable CACA_EVENT_RESIZE
		shm->ge.w = caca_get_canvas_width(shm->ge.cv);
		shm->ge.h = caca_get_canvas_height(shm->ge.cv);
		if ( EXPR_MIN_SIZE ) {
			caca_set_color_ansi(shm->ge.cv, CACA_BLACK, CACA_WHITE);
			caca_put_str(shm->ge.cv, 0, 0, "Need a minimum of " TEXT_MIN_SIZE " terminal");
		} else if (!shm->paused) {
			// init / free if scene transition
			if (lastscene != shm->scene) {
				switch(lastscene) {
					case 0: scene00_free_caca(&shm->ge, &shm->s00e); break;
					case 1: scene01_free_caca(&shm->ge, &shm->s01e); break;
					case 2: scene02_free_caca(&shm->ge, &shm->s02e); break;
				}
			}
			while (lastscene != shm->scene) {
				shm->ge.sdl_ticks = SDL_GetTicks();
				shm->ge.sc_framecount = 0;
				switch(shm->scene) {
					case 0: res = scene00_init_caca(&shm->ge, &shm->s00e); break;
					case 1: res = scene01_init_caca(&shm->ge, &shm->s01e); break;
					case 2: res = scene02_init_caca(&shm->ge, &shm->s02e); break;
				}
				// If scene init fail, skip to the next one
				if (res) { printf("scene%02i_init_caca() returned %i\n", shm->scene, res); SCENE_NEXT; } else lastscene = shm->scene;
			}
			shm->ge.sdl_ticks = SDL_GetTicks(); // This value wraps if the program runs for more than ~49 days

			SEM_POST(&shm->worker_gl_can_render,30);
			SEM_WAIT(&shm->parent_can_read_result,31);

			SEM_POST(&shm->worker_sdl_can_render,32);
			SEM_WAIT(&shm->parent_can_read_result,33);

			// Compute current scene frame (caca part)
			switch(shm->scene) {
				case 0: res = scene00_next_caca(&shm->ge, &shm->s00e); break;
				case 1: res = scene01_next_caca(&shm->ge, &shm->s01e); break;
				case 2: res = scene02_next_caca(&shm->ge, &shm->s02e); break;
			}
			if (res) SCENE_NEXT;
			shm->ge.framecount++;
			shm->ge.sc_framecount++;
		}
		// Display it
		caca_refresh_display(shm->ge.dp); // Auto framerate limiting (see caca_set_display_time())

		// Event handling for the libcaca "window" (depending on CACA_DRIVER env variable)
		if (caca_get_event(shm->ge.dp, CACA_EVENT_KEY_PRESS|CACA_EVENT_RESIZE|CACA_EVENT_QUIT, &caca_ev, 0)) {
			switch(caca_get_event_type(&caca_ev)) {
					case CACA_EVENT_QUIT:
						shm->done = 1;
						break;
					case CACA_EVENT_KEY_PRESS:
						switch(caca_get_event_key_ch(&caca_ev)) {
							case 'q': shm->done = 1; break;
							case 'p': shm->paused = !shm->paused; break;
							case CACA_KEY_ESCAPE: SCENE_NEXT; break;
						}
						break;
						/* On Debian 10, no CACA_EVENT_RESIZE fired when using x11 CACA_DRIVER
					case CACA_EVENT_RESIZE:
						w = caca_get_event_resize_width(&caca_ev);
						h = caca_get_event_resize_height(&caca_ev);
						small = EXPR_MIN_SIZE;
						break;
						*/
					default:
						break;
			}
		}
	} while(!shm->done);

	caca_free_dither(shm->ge.d);
	caca_free_display(shm->ge.dp);
	shm->ge.cv=NULL;

	// reap forked processes (order doesn't matter)
	if (wait(&child_status) != -1) {
		if (child_status > 0) return child_status;
	}
	if (wait(&child_status) != -1) {
		if (child_status > 0) return child_status;
	}
	return 0;
}

static void worker_sdl_sighandler(int sig) {
	TRACE("call");
	if ( sig == SIGALRM ) {
		skip = 1;
		sem_post(&shm->worker_sdl_can_render);
	}
}

int worker_sdl() {
	int lastscene=-1, res;
	struct sigaction sa;
#ifdef DEBUG
	Uint32 sdl_win_flags = 0; //XXX for final version, consider adding SDL_WINDOW_HIDDEN
	SDL_Event sdl_ev;
#else
	Uint32 sdl_win_flags = SDL_WINDOW_HIDDEN;
#endif
	SDL_RendererInfo renderer_info;

	TRACE("call");

	sa.sa_handler = worker_sdl_sighandler;
	sigemptyset(&sa.sa_mask);
	sa.sa_flags = 0;
	if (sigaction(SIGALRM, &sa, NULL) == -1) return 2;

	// Initialize SDL (http://wiki.libsdl.org/SDL_CreateWindowAndRenderer)
	// Useful snippet : https://gist.github.com/koute/7391344
	res = SDL_Init(SDL_INIT_VIDEO);
	if (res == -1) return 3;
	atexit(SDL_Quit);

	res = SDL_CreateWindowAndRenderer(FBUF_W, FBUF_H, sdl_win_flags, &shm->ge.sdl_win, &shm->ge.sdl_rndr);
	if (res == -1) return 4;
	SDL_SetWindowTitle(shm->ge.sdl_win, "SDL debug");
	res = SDL_GetRendererInfo(shm->ge.sdl_rndr, &renderer_info);
	if (res < 0) return 5;
	if (!(renderer_info.flags & SDL_RENDERER_ACCELERATED)) return 6;
	if (!(renderer_info.flags & SDL_RENDERER_TARGETTEXTURE)) return 7;
	shm->ge.sdl_target = SDL_CreateTexture(shm->ge.sdl_rndr, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_TARGET, FBUF_W, FBUF_H);
	if (shm->ge.sdl_target == NULL) return 9;


	while (!shm->done) {
		alarm(1);
		SEM_WAIT(&shm->worker_sdl_can_render,20);
		alarm(0);

		if (!shm->paused && !skip) {
			// init / free if scene transition
			if (lastscene != shm->scene) {
				switch(lastscene) {
					case 0: scene00_free_sdl(&shm->ge, &shm->s00e); break;
					case 1: scene01_free_sdl(&shm->ge, &shm->s01e); break;
					case 2: scene02_free_sdl(&shm->ge, &shm->s02e); break;
				}
			}
			while (lastscene != shm->scene ) {
				shm->ge.sdl_ticks = SDL_GetTicks();
				shm->ge.sc_framecount = 0;
				switch(shm->scene) {
					case 0: res = scene00_init_sdl(&shm->ge, &shm->s00e); break;
					case 1: res = scene01_init_sdl(&shm->ge, &shm->s01e); break;
					case 2: res = scene02_init_sdl(&shm->ge, &shm->s02e); break;
				}
				// If scene init fail, skip to the next one
				if (res) { printf("scene%02i_init_sdl() returned %i\n", shm->scene, res); SCENE_NEXT; } else lastscene = shm->scene;
			}
			// Compute current scene frame (sdl part)
			switch(shm->scene) {
				case 0: res = scene00_next_sdl(&shm->ge, &shm->s00e); break;
				case 1: res = scene01_next_sdl(&shm->ge, &shm->s01e); break;
				case 2: res = scene02_next_sdl(&shm->ge, &shm->s02e); break;
			}
			if (res) SCENE_NEXT;
		}
		if (skip) skip = 0;

#ifdef DEBUG
		// Event handling for the SDL window (debug purposes)
		while(SDL_PollEvent(&sdl_ev)) {
			switch(sdl_ev.type) {
				case SDL_QUIT:
					shm->done = 1;
					break;
				case SDL_KEYDOWN:
					switch(sdl_ev.key.keysym.sym) {
						case SDLK_q: shm->done = 1; break;
						case SDLK_p: shm->paused = !shm->paused; break;
						case SDLK_ESCAPE: SCENE_NEXT; break;
					}
					break;
				default:
					break;
			}
		}
#endif
		SEM_POST(&shm->parent_can_read_result, 21);
	}

	SDL_DestroyRenderer(shm->ge.sdl_rndr);
	SDL_DestroyTexture(shm->ge.sdl_target);
	SDL_DestroyWindow(shm->ge.sdl_win);

	return 0;
}

static void worker_gl_sighandler(int sig) {
	TRACE("call");
	if ( sig == SIGALRM ) {
		skip = 1;
		sem_post(&shm->worker_gl_can_render);
	}
}

int worker_gl() {
	int lastscene=-1, res;
	struct sigaction sa;
#ifdef DEBUG
	Uint32 sdl_win_flags = SDL_WINDOW_OPENGL;
	SDL_Event gl_ev;
#else
	Uint32 sdl_win_flags = SDL_WINDOW_OPENGL | SDL_WINDOW_HIDDEN;
#endif
	SDL_RendererInfo renderer_info;

	TRACE("call");

	sa.sa_handler = worker_gl_sighandler;
	sigemptyset(&sa.sa_mask);
	sa.sa_flags = 0;
	if (sigaction(SIGALRM, &sa, NULL) == -1) return 2;

	// Initialize SDL for GL. Useful snippet : https://gist.github.com/koute/7391344
	res = SDL_Init(SDL_INIT_VIDEO);
	if (res == -1) return 3;
	atexit(SDL_Quit);

	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
	SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL, 1);
	SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
	SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
	SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
	SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);

	// Initialize OpenGL
	//shm->ge.gl_win = SDL_CreateWindow("GL Debug", SDL_WINDOWPOS_CENTERED, 0, FBUF_W, FBUF_H, sdl_win_flags);

	res = SDL_CreateWindowAndRenderer(FBUF_W, FBUF_H, sdl_win_flags, &shm->ge.gl_win, &shm->ge.gl_rndr);
	if (res == -1) return 4;
	SDL_SetWindowTitle(shm->ge.gl_win, "GL debug");
	res = SDL_GetRendererInfo(shm->ge.gl_rndr, &renderer_info);
	if (res < 0) return 5;
	if (!(renderer_info.flags & SDL_RENDERER_ACCELERATED)) return 6;
	if (!(renderer_info.flags & SDL_RENDERER_TARGETTEXTURE)) return 7;
	shm->ge.gl_target = SDL_CreateTexture(shm->ge.gl_rndr, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_TARGET, FBUF_W, FBUF_H);
	if (shm->ge.gl_target == NULL) return 9;
	shm->ge.gl_ctx = SDL_GL_CreateContext(shm->ge.gl_win);
	if (shm->ge.gl_ctx == NULL) return 11;
/*
	glBindFramebuffer(GL_FRAMEBUFFER,0);
	glClearColor(0,0,0,1);
	glClear(GL_COLOR_BUFFER_BIT);
	SDL_GL_SwapWindow(shm->ge.gl_win);
*/
	while (!shm->done) {
		alarm(1);
		SEM_WAIT(&shm->worker_gl_can_render,10);
		alarm(0);

		if (!shm->paused && !skip) {
			// init / free if scene transition
			if (lastscene != shm->scene) {
				switch(lastscene) {
					case 0: scene00_free_gl(&shm->ge, &shm->s00e); break;
					case 1: scene01_free_gl(&shm->ge, &shm->s01e); break;
					case 2: scene02_free_gl(&shm->ge, &shm->s02e); break;
				}
			}
			while (lastscene != shm->scene) {
				shm->ge.sdl_ticks = SDL_GetTicks();
				shm->ge.sc_framecount = 0;
				switch(shm->scene) {
					case 0: res = scene00_init_gl(&shm->ge, &shm->s00e); break;
					case 1: res = scene01_init_gl(&shm->ge, &shm->s01e); break;
					case 2: res = scene02_init_gl(&shm->ge, &shm->s02e); break;
				}
				// If scene init fail, skip to the next one
				if (res) { printf("scene%02i_init_gl() returned %i\n", shm->scene, res); SCENE_NEXT; } else lastscene = shm->scene;
			}

			// Compute current scene frame (gl part)
			switch(shm->scene) {
				case 0: res = scene00_next_gl(&shm->ge, &shm->s00e); break;
				case 1: res = scene01_next_gl(&shm->ge, &shm->s01e); break;
				case 2: res = scene02_next_gl(&shm->ge, &shm->s02e); break;
			}
			if (res) SCENE_NEXT;
		}
		if (skip) skip = 0;

#ifdef DEBUG
		// Event handling for the GL window (debug purposes)
		while(SDL_PollEvent(&gl_ev)) {
			switch(gl_ev.type) {
				case SDL_QUIT:
					shm->done = 1;
					break;
				case SDL_KEYDOWN:
					switch(gl_ev.key.keysym.sym) {
						case SDLK_q: shm->done = 1; break;
						case SDLK_p: shm->paused = !shm->paused; break;
						case SDLK_ESCAPE: SCENE_NEXT; break;
					}
					break;
				default:
					break;
			}
		}
#endif
		SEM_POST(&shm->parent_can_read_result, 11);
	}

	SDL_DestroyTexture(shm->ge.gl_target);
	SDL_GL_DeleteContext(shm->ge.gl_ctx);
	SDL_DestroyWindow(shm->ge.gl_win);

	return 0;
}