#include "shaders.h"

char * load_file(char *path, int *out_len)
{
    FILE *file = NULL;
    if((file = fopen(path, "r")) != NULL)
    {
        fseek(file, 0, SEEK_END);
        int length = ftell(file);
        fseek(file, 0, SEEK_SET);
        
        char *content = malloc(length+1);
        fread(content, 1, length, file);
        
        if(out_len != NULL)
        {
            *out_len = length;
        }
        return content;
    }
    
    return NULL;
}

tc_shader_program_s tc_make_shader_program(char *vertex_path, char *fragment_path)
{
    int         vertex_shader       = glCreateShader(GL_VERTEX_SHADER);
    int         fragment_shader     = glCreateShader(GL_FRAGMENT_SHADER);
    
    int         len_vertex_source   = 0;
    const char *vertex_source       = load_file(vertex_path, &len_vertex_source);
    const char *const *vsource      = &vertex_source;
    
    int         len_fragment_source = 0;
    const char *fragment_source     = load_file(fragment_path, &len_fragment_source);
    const char *const *fsource      = &fragment_source;
    
    glShaderSource(vertex_shader, 1, vsource, &len_vertex_source);
    glShaderSource(fragment_shader, 1, fsource, &len_fragment_source);
    
    glCompileShader(vertex_shader);
    glCompileShader(fragment_shader);
    
    int         vertex_compile_status = 0;
    glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &vertex_compile_status);
    
    if(vertex_compile_status != GL_TRUE)
    {
        int         log_length  = 0;
        glGetShaderiv(vertex_shader, GL_INFO_LOG_LENGTH, &log_length);
        
        char       *info_log    = malloc(log_length+1);
        
        glGetShaderInfoLog(vertex_shader, log_length, &log_length, info_log);
        
        printf("VERTEX SHADER FAILED COMPILING! ERROR: %s\n", info_log);
        
        tc_shader_program_s invalid_program;
        invalid_program.program_id      = 0;
        
        return invalid_program;
    }
    
    int         fragment_compile_status = 0;
    glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &fragment_compile_status);
    
    if(fragment_compile_status != GL_TRUE)
    {
        int         log_length  = 0;
        glGetShaderiv(fragment_shader, GL_INFO_LOG_LENGTH, &log_length);
        
        char       *info_log    = malloc(log_length+1);
        
        glGetShaderInfoLog(fragment_shader, log_length, &log_length, info_log);
        
        printf("FRAGMENT SHADER FAILED COMPILING! ERROR: %s\n", info_log);
        
        tc_shader_program_s invalid_program;
        invalid_program.program_id      = 0;
        
        return invalid_program;
    }
    
    int         program             = glCreateProgram();
    glAttachShader(program, vertex_shader);
    glAttachShader(program, fragment_shader);
    glLinkProgram(program);
    
    tc_shader_program_s shader_program;
    shader_program.program_id = program;
    
    return shader_program;
}