#include "bcm_host.h"
#include "GLES/gl.h"
#include "EGL/egl.h"
#include "EGL/eglext.h"
#include "GLES2/gl2.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <memory.h>

static uint32_t frame_width = 0;
static uint32_t frame_height = 0;


#define	SHOW_ERROR		gles_show_error();

static void SetOrtho(GLfloat m[4][4], GLfloat left, GLfloat right, GLfloat bottom, GLfloat top, GLfloat near, GLfloat far, GLfloat scale_x, GLfloat scale_y);

static const char* vertex_shader =
	"uniform mat4 u_vp_matrix;								\n"
	"attribute vec4 a_position;								\n"
	"attribute vec2 a_texcoord;								\n"
	"varying mediump vec2 v_texcoord;						\n"
	"void main()											\n"
	"{														\n"
	"	v_texcoord = a_texcoord;							\n"
	"	gl_Position = u_vp_matrix * a_position;				\n"
	"}														\n";

static const char* fragment_shader =
	"varying mediump vec2 v_texcoord;						\n"
	"uniform sampler2D u_texture;							\n"
	"void main()											\n"
	"{														\n"
	"	gl_FragColor = texture2D(u_texture, v_texcoord);	\n"
	"}														\n";

static const GLfloat vertices[] =
{
	-0.5f, -0.5f, 0.0f,
	+0.5f, -0.5f, 0.0f,
	+0.5f, +0.5f, 0.0f,
	-0.5f, +0.5f, 0.0f,
};

#define	TEX_WIDTH	1024
#define	TEX_HEIGHT	512

static const GLfloat uvs[8];

static const GLushort indices[] =
{
	0, 1, 2,
	0, 2, 3,
};

static const int kVertexCount = 4;
static const int kIndexCount = 6;


void Create_uvs(GLfloat * matrix, GLfloat max_u, GLfloat max_v) {
    memset(matrix,0,sizeof(GLfloat)*8);
    matrix[3]=max_v;
    matrix[4]=max_u;
    matrix[5]=max_v;
    matrix[6]=max_u;

}

void gles_show_error()
{
	GLenum error = GL_NO_ERROR;
    error = glGetError();
    if (GL_NO_ERROR != error)
        printf("GL Error %x encountered!\n", error);
}

static GLuint CreateShader(GLenum type, const char *shader_src)
{
	GLuint shader = glCreateShader(type);
	if(!shader)
		return 0;

	// Load and compile the shader source
	glShaderSource(shader, 1, &shader_src, NULL);
	glCompileShader(shader);

	// Check the compile status
	GLint compiled = 0;
	glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
	if(!compiled)
	{
		GLint info_len = 0;
		glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &info_len);
		if(info_len > 1)
		{
			char* info_log = (char *)malloc(sizeof(char) * info_len);
			glGetShaderInfoLog(shader, info_len, NULL, info_log);
			// TODO(dspringer): We could really use a logging API.
			printf("Error compiling shader:\n%s\n", info_log);
			free(info_log);
		}
		glDeleteShader(shader);
		return 0;
	}
	return shader;
}

static GLuint CreateProgram(const char *vertex_shader_src, const char *fragment_shader_src)
{
	GLuint vertex_shader = CreateShader(GL_VERTEX_SHADER, vertex_shader_src);
	if(!vertex_shader)
		return 0;
	GLuint fragment_shader = CreateShader(GL_FRAGMENT_SHADER, fragment_shader_src);
	if(!fragment_shader)
	{
		glDeleteShader(vertex_shader);
		return 0;
	}

	GLuint program_object = glCreateProgram();
	if(!program_object)
		return 0;
	glAttachShader(program_object, vertex_shader);
	glAttachShader(program_object, fragment_shader);

	// Link the program
	glLinkProgram(program_object);

	// Check the link status
	GLint linked = 0;
	glGetProgramiv(program_object, GL_LINK_STATUS, &linked);
	if(!linked)
	{
		GLint info_len = 0;
		glGetProgramiv(program_object, GL_INFO_LOG_LENGTH, &info_len);
		if(info_len > 1)
		{
			char* info_log = (char *)malloc(info_len);
			glGetProgramInfoLog(program_object, info_len, NULL, info_log);
			// TODO(dspringer): We could really use a logging API.
			printf("Error linking program:\n%s\n", info_log);
			free(info_log);
		}
		glDeleteProgram(program_object);
		return 0;
	}
	// Delete these here because they are attached to the program object.
	glDeleteShader(vertex_shader);
	glDeleteShader(fragment_shader);
	return program_object;
}

typedef	struct ShaderInfo {
		GLuint program;
		GLint a_position;
		GLint a_texcoord;
		GLint u_vp_matrix;
		GLint u_texture;
} ShaderInfo;

static ShaderInfo shader;
static ShaderInfo shader_filtering;
static GLuint buffers[3];
static GLuint textures[2];


static void gles2_create()
{
	memset(&shader, 0, sizeof(ShaderInfo));
	shader.program = CreateProgram(vertex_shader, fragment_shader);
	if(shader.program)
	{
		shader.a_position	= glGetAttribLocation(shader.program,	"a_position");
		shader.a_texcoord	= glGetAttribLocation(shader.program,	"a_texcoord");
		shader.u_vp_matrix	= glGetUniformLocation(shader.program,	"u_vp_matrix");
		shader.u_texture	= glGetUniformLocation(shader.program,	"u_texture");
	}
	glGenTextures(1, textures);
	glBindTexture(GL_TEXTURE_2D, textures[0]);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, TEX_WIDTH, TEX_HEIGHT, 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, NULL);

	Create_uvs(uvs, (float)frame_width/TEX_WIDTH, (float)frame_height/TEX_HEIGHT);

	glGenBuffers(3, buffers);
	glBindBuffer(GL_ARRAY_BUFFER, buffers[0]);
	glBufferData(GL_ARRAY_BUFFER, kVertexCount * sizeof(GLfloat) * 3, vertices, GL_STATIC_DRAW);
	glBindBuffer(GL_ARRAY_BUFFER, buffers[1]);
	glBufferData(GL_ARRAY_BUFFER, kVertexCount * sizeof(GLfloat) * 2, uvs, GL_STATIC_DRAW);
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffers[2]);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, kIndexCount * sizeof(GL_UNSIGNED_SHORT), indices, GL_STATIC_DRAW);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
	glDisable(GL_DEPTH_TEST);
	glDisable(GL_BLEND);
	glDisable(GL_DITHER);
}

static uint32_t screen_width = 0;
static uint32_t screen_height = 0;

static EGLDisplay display = NULL;
static EGLSurface surface = NULL;
static EGLContext context = NULL;
static EGL_DISPMANX_WINDOW_T nativewindow;

static GLfloat proj[4][4];
static GLint filter_min;
static GLint filter_mag;

void video_init(uint32_t _width, uint32_t _height, uint32_t filter)
{
	if ((_width==0)||(_height==0))
		return;

	frame_width = _width;
	frame_height = _height;
	
	bcm_host_init();

	// get an EGL display connection
	display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
	assert(display != EGL_NO_DISPLAY);

	// initialize the EGL display connection
	EGLBoolean result = eglInitialize(display, NULL, NULL);
	assert(EGL_FALSE != result);

	// get an appropriate EGL frame buffer configuration
	EGLint num_config;
	EGLConfig config;
	static const EGLint attribute_list[] =
	{
		EGL_RED_SIZE, 8,
		EGL_GREEN_SIZE, 8,
		EGL_BLUE_SIZE, 8,
		EGL_ALPHA_SIZE, 8,
		EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
		EGL_NONE
	};
	result = eglChooseConfig(display, attribute_list, &config, 1, &num_config);
	assert(EGL_FALSE != result);

	result = eglBindAPI(EGL_OPENGL_ES_API);
	assert(EGL_FALSE != result);

	// create an EGL rendering context
	static const EGLint context_attributes[] =
	{
		EGL_CONTEXT_CLIENT_VERSION, 2,
		EGL_NONE
	};
	context = eglCreateContext(display, config, EGL_NO_CONTEXT, context_attributes);
	assert(context != EGL_NO_CONTEXT);

	// create an EGL window surface
	int32_t success = graphics_get_display_size(0, &screen_width, &screen_height);
	assert(success >= 0);

	VC_RECT_T dst_rect;
	dst_rect.x = 0;
	dst_rect.y = 0;
	dst_rect.width = screen_width;
	dst_rect.height = screen_height;

	VC_RECT_T src_rect;
	src_rect.x = 0;
	src_rect.y = 0;
	src_rect.width = screen_width << 16;
	src_rect.height = screen_height << 16;

	DISPMANX_DISPLAY_HANDLE_T dispman_display = vc_dispmanx_display_open(0);
	DISPMANX_UPDATE_HANDLE_T dispman_update = vc_dispmanx_update_start(0);
	DISPMANX_ELEMENT_HANDLE_T dispman_element = vc_dispmanx_element_add(dispman_update, dispman_display,
	  0, &dst_rect, 0, &src_rect, DISPMANX_PROTECTION_NONE, NULL, NULL, DISPMANX_NO_ROTATE);

	nativewindow.element = dispman_element;
	nativewindow.width = screen_width;
	nativewindow.height = screen_height;
	vc_dispmanx_update_submit_sync(dispman_update);

	surface = eglCreateWindowSurface(display, config, &nativewindow, NULL);
	assert(surface != EGL_NO_SURFACE);

	// connect the context to the surface
	result = eglMakeCurrent(display, surface, surface, context);
	assert(EGL_FALSE != result);

	gles2_create();

	int r=(screen_height*10/frame_height);
	int h = (frame_height*r)/10;
	int w = (frame_width*r)/10;

	glViewport((screen_width-w)/2, (screen_height-h)/2, w, h);
	SetOrtho(proj, -0.5f, +0.5f, +0.5f, -0.5f, -1.0f, 1.0f, 1.0f ,1.0f );
	if (filter==0) {
	    filter_min = GL_NEAREST;
	    filter_mag = GL_NEAREST;
	} else if (filter==1) {
	    filter_min = GL_LINEAR_MIPMAP_LINEAR;
	    filter_mag = GL_LINEAR;
	} else if (filter==2) {
	    filter_min = GL_LINEAR_MIPMAP_NEAREST;
	    filter_mag = GL_LINEAR;

	}

}

static void gles2_destroy()
{
	if(!shader.program)
		return;
	glDeleteBuffers(3, buffers); SHOW_ERROR
	glDeleteProgram(shader.program); SHOW_ERROR
}

static void SetOrtho(GLfloat m[4][4], GLfloat left, GLfloat right, GLfloat bottom, GLfloat top, GLfloat near, GLfloat far, GLfloat scale_x, GLfloat scale_y)
{
	memset(m, 0, 4*4*sizeof(GLfloat));
	m[0][0] = 2.0f/(right - left)*scale_x;
	m[1][1] = 2.0f/(top - bottom)*scale_y;
	m[2][2] = -2.0f/(far - near);
	m[3][0] = -(right + left)/(right - left);
	m[3][1] = -(top + bottom)/(top - bottom);
	m[3][2] = -(far + near)/(far - near);
	m[3][3] = 1;
}
#define RGB15(r, g, b)  (((r) << (5+6)) | ((g) << 6) | (b))

static void gles2_Draw( uint16_t *pixels)
{
	if(!shader.program)
		return;

	glClear(GL_COLOR_BUFFER_BIT);

	glUseProgram(shader.program);

        glBindTexture(GL_TEXTURE_2D, textures[0]);
	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, frame_width, frame_height, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, pixels);
	glActiveTexture(GL_TEXTURE0);
	glUniform1i(shader.u_texture, 0);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filter_min);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filter_mag);
	glGenerateMipmap(GL_TEXTURE_2D);

	glBindBuffer(GL_ARRAY_BUFFER, buffers[0]);
	glVertexAttribPointer(shader.a_position, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), NULL);
	glEnableVertexAttribArray(shader.a_position);

	glBindBuffer(GL_ARRAY_BUFFER, buffers[1]);
	glVertexAttribPointer(shader.a_texcoord, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(GLfloat), NULL);
	glEnableVertexAttribArray(shader.a_texcoord);

	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffers[2]);
	glUniformMatrix4fv(shader.u_vp_matrix, 1, GL_FALSE, (const GLfloat * )&proj);
	glDrawElements(GL_TRIANGLES, kIndexCount, GL_UNSIGNED_SHORT, 0);

	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
	//glFlush();
}

void video_close()
{
	gles2_destroy();
	// Release OpenGL resources
	eglMakeCurrent( display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT );
	eglDestroySurface( display, surface );
	eglDestroyContext( display, context );
	eglTerminate( display );
}

void video_draw(uint16_t *pixels)
{
	gles2_Draw (pixels);
	eglSwapBuffers(display, surface);
}