/* Freetype GL - A C OpenGL Freetype engine
 *
 * Distributed under the OSI-approved BSD 2-Clause License.  See accompanying
 * file `LICENSE` for more details.
 */
#include <stdio.h>
#include <string.h>

#include "freetype-gl.h"
#include "font-manager.h"
#include "vertex-buffer.h"
#include "text-buffer.h"
#include "markup.h"
#include "shader.h"
#include "mat4.h"
#include "screenshot-util.h"

#include <GLFW/glfw3.h>
#include <ft2build.h>
#include FT_CONFIG_OPTIONS_H


// ------------------------------------------------------- typedef & struct ---
typedef struct {
    float x, y, z;
    float r, g, b, a;
} vertex_t;


// ------------------------------------------------------- global variables ---
font_manager_t * font_manager;
text_buffer_t *text_buffer;
vertex_buffer_t *buffer;
GLuint bounds_shader;
GLuint text_shader;
mat4 model, view, projection;

void init()
{
    buffer = vertex_buffer_new( "vertex:3f,color:4f" );
    vertex_t vertices[4*2] = { { 15,  0,0, 0,0,0,1},
                               { 15,330,0, 0,0,0,1},
                               {245,  0,0, 0,0,0,1},
                               {245,330,0, 0,0,0,1} };
    GLuint indices[4*3] = { 0,1,2,3, };
    vertex_buffer_push_back( buffer, vertices, 4, indices, 4 );

    text_shader = shader_load( "shaders/text.vert",
                               "shaders/text.frag" );

    font_manager = font_manager_new( 512, 512, LCD_FILTERING_ON );
    text_buffer = text_buffer_new( );
    vec4 black  = {{0.0, 0.0, 0.0, 1.0}};
    text_buffer->base_color = black;

    vec4 none   = {{1.0, 1.0, 1.0, 0.0}};
    markup_t markup;
    markup.family  = "fonts/Vera.ttf";
    markup.size    = 9.0;
    markup.bold    = 0;
    markup.italic  = 0;
    markup.spacing = 0.0;
    markup.gamma   = 1.0;
    markup.foreground_color    = black;
    markup.background_color    = none;
    markup.underline           = 0;
    markup.underline_color     = black;
    markup.overline            = 0;
    markup.overline_color      = black;
    markup.strikethrough       = 0;
    markup.strikethrough_color = black;
    markup.font = 0;

    markup.font = font_manager_get_from_markup( font_manager, &markup );

    size_t i;
    vec2 pen = {{20, 320}};
    char *text = "| A Quick Brown Fox Jumps Over The Lazy Dog\n";
    for( i=0; i < 30; ++i)
    {
        text_buffer_add_text( text_buffer, &pen, &markup, text, 0 );
        pen.x += i*0.1;
    }

    glGenTextures( 1, &font_manager->atlas->id );
    glBindTexture( GL_TEXTURE_2D, font_manager->atlas->id );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGB, font_manager->atlas->width,
        font_manager->atlas->height, 0, GL_RGB, GL_UNSIGNED_BYTE,
        font_manager->atlas->data );

    bounds_shader = shader_load( "shaders/v3f-c4f.vert",
                                 "shaders/v3f-c4f.frag" );
    mat4_set_identity( &projection );
    mat4_set_identity( &model );
    mat4_set_identity( &view );
}


// ---------------------------------------------------------------- display ---
void display( GLFWwindow* window )
{
    glClearColor( 1.0, 1.0, 1.0, 1.0 );
    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

    glUseProgram( text_shader );
    {
        glUniformMatrix4fv( glGetUniformLocation( text_shader, "model" ),
                            1, 0, model.data);
        glUniformMatrix4fv( glGetUniformLocation( text_shader, "view" ),
                            1, 0, view.data);
        glUniformMatrix4fv( glGetUniformLocation( text_shader, "projection" ),
                            1, 0, projection.data);
        glUniform1i( glGetUniformLocation( text_shader, "tex" ), 0 );
        glUniform3f( glGetUniformLocation( text_shader, "pixel" ),
                     1.0f/font_manager->atlas->width,
                     1.0f/font_manager->atlas->height,
                     (float)font_manager->atlas->depth );

        glEnable( GL_BLEND );

        glActiveTexture( GL_TEXTURE0 );
        glBindTexture( GL_TEXTURE_2D, font_manager->atlas->id );

        glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
        glBlendColor( 1, 1, 1, 1 );

        vertex_buffer_render( text_buffer->buffer, GL_TRIANGLES );
        glBindTexture( GL_TEXTURE_2D, 0 );
        glBlendColor( 0, 0, 0, 0 );
        glUseProgram( 0 );
    }
    glBlendFunc( GL_ONE, GL_ONE_MINUS_SRC_ALPHA );
    glBlendColor( 1.0, 1.0, 1.0, 1.0 );
    glUseProgram( bounds_shader );
    {
        glUniformMatrix4fv( glGetUniformLocation( bounds_shader, "model" ),
                            1, 0, model.data);
        glUniformMatrix4fv( glGetUniformLocation( bounds_shader, "view" ),
                            1, 0, view.data);
        glUniformMatrix4fv( glGetUniformLocation( bounds_shader, "projection" ),
                            1, 0, projection.data);
        vertex_buffer_render( buffer, GL_LINES );
    }

    glfwSwapBuffers( window );
}


// ---------------------------------------------------------------- reshape ---
void reshape( GLFWwindow* window, int width, int height )
{
    glViewport(0, 0, width, height);
    mat4_set_orthographic( &projection, 0, width, 0, height, -1, 1);
}


// --------------------------------------------------------------- keyboard ---
void keyboard( GLFWwindow* window, int key, int scancode, int action, int mods )
{
    if ( key == GLFW_KEY_ESCAPE && action == GLFW_PRESS )
    {
        glfwSetWindowShouldClose( window, GL_TRUE );
    }
}


// --------------------------------------------------------- error-callback ---
void error_callback( int error, const char* description )
{
    fputs( description, stderr );
}


// ------------------------------------------------------------------- main ---
int main( int argc, char **argv )
{
    GLFWwindow* window;
    char* screenshot_path = NULL;

    if (argc > 1)
    {
        if (argc == 3 && 0 == strcmp( "--screenshot", argv[1] ))
            screenshot_path = argv[2];
        else
        {
            fprintf( stderr, "Unknown or incomplete parameters given\n" );
            exit( EXIT_FAILURE );
        }
    }

#ifndef FT_CONFIG_OPTION_SUBPIXEL_RENDERING
    fprintf(stderr,
            "This demo requires freetype to be compiled "
            "with subpixel rendering.\n");
    exit( EXIT_FAILURE) ;
#endif

    glfwSetErrorCallback( error_callback );

    if (!glfwInit( ))
    {
        exit( EXIT_FAILURE );
    }

    glfwWindowHint( GLFW_VISIBLE, GL_FALSE );
    glfwWindowHint( GLFW_RESIZABLE, GL_FALSE );

    window = glfwCreateWindow( 260, 330, argv[0], NULL, NULL );

    if (!window)
    {
        glfwTerminate( );
        exit( EXIT_FAILURE );
    }

    glfwMakeContextCurrent( window );
    glfwSwapInterval( 1 );

    glfwSetFramebufferSizeCallback( window, reshape );
    glfwSetWindowRefreshCallback( window, display );
    glfwSetKeyCallback( window, keyboard );

#ifndef __APPLE__
    glewExperimental = GL_TRUE;
    GLenum err = glewInit();
    if (GLEW_OK != err)
    {
        /* Problem: glewInit failed, something is seriously wrong. */
        fprintf( stderr, "Error: %s\n", glewGetErrorString(err) );
        exit( EXIT_FAILURE );
    }
    fprintf( stderr, "Using GLEW %s\n", glewGetString(GLEW_VERSION) );
#endif

    init();

    glfwShowWindow( window );
    reshape( window, 260, 330 );

    while (!glfwWindowShouldClose( window ))
    {
        display( window );
        glfwPollEvents( );

        if (screenshot_path)
        {
            screenshot( window, screenshot_path );
            glfwSetWindowShouldClose( window, 1 );
        }
    }

    glDeleteProgram( bounds_shader );
    glDeleteProgram( text_shader );
    glDeleteTextures( 1, &font_manager->atlas->id );
    font_manager->atlas->id = 0;
    text_buffer_delete( text_buffer );
    font_manager_delete( font_manager );

    glfwDestroyWindow( window );
    glfwTerminate( );

    return EXIT_SUCCESS;
}