#include "shader.h"

#include <iostream>
#include <fstream>
#include <sstream>

#include <spdlog/spdlog.h>
#include <glad/glad.h>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>


Shader::Shader(const char* vertexPath, const char* fragmentPath)
{
    std::string vertexCode;
    std::string fragmentCode;
    std::ifstream vShaderFile;
    std::ifstream fShaderFile;
    // ensure ifstream objects can throw exceptions:
    vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
    fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
    try
    {
        // open files
        vShaderFile.open(vertexPath);
        fShaderFile.open(fragmentPath);
        std::stringstream vShaderStream, fShaderStream;
        // read file's buffer contents into streams
        vShaderStream << vShaderFile.rdbuf();
        fShaderStream << fShaderFile.rdbuf();
        // close file handlers
        vShaderFile.close();
        fShaderFile.close();
        // convert stream into string
        vertexCode = vShaderStream.str();
        fragmentCode = fShaderStream.str();
    }
    catch (std::ifstream::failure e)
    {
        spdlog::error("SHADER::FILE_NOT_SUCCESFULLY_READ");
        return;
    }
    
    const char* vShaderCode = vertexCode.c_str();
    const char* fShaderCode = fragmentCode.c_str();

    unsigned int vertex, fragment;
    int success;
    char infoLog[512];

    // vertex Shader
    vertex = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex, 1, &vShaderCode, NULL);
    glCompileShader(vertex);
    // print compile errors if any
    glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(vertex, 512, NULL, infoLog);
        spdlog::error("SHADER::VERTEX::COMPILATION_FAILED {}", infoLog);
        return;
    };

    // similiar for Fragment Shader
    fragment = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment, 1, &fShaderCode, NULL);
    glCompileShader(fragment);
    // print compile errors if any
    glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(vertex, 512, NULL, infoLog);
        spdlog::error("SHADER::FRAGMENT::COMPILATION_FAILED {}", infoLog);
        return;
    };

    // shader Program
    ID = glCreateProgram();
    glAttachShader(ID, vertex);
    glAttachShader(ID, fragment);
    glLinkProgram(ID);
    // print linking errors if any
    glGetProgramiv(ID, GL_LINK_STATUS, &success);
    if (!success)
    {
        glGetProgramInfoLog(ID, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
        return;
    }

    // delete the shaders as they're linked into our program now and no longer necessary
    glDeleteShader(vertex);
    glDeleteShader(fragment);

    compiled = true;
}

void Shader::use()
{
    if (!compiled) {
        spdlog::error("Shader not compiler. Exiting");
        return;
    }
    glUseProgram(ID);
}


void Shader::set4f(const std::string& uniform, float val1, float val2, float val3, float val4) {
    glUniform4f(glGetUniformLocation(ID, uniform.c_str()), val1, val2, val3, val4);
}

void Shader::setFloat(const char* name, float value, bool useShader)
{
    if (useShader)
        this->use();
    glUniform1f(glGetUniformLocation(this->ID, name), value);
}
void Shader::setInteger(const char* name, int value, bool useShader)
{
    if (useShader)
        this->use();
    glUniform1i(glGetUniformLocation(this->ID, name), value);
}
void Shader::setVector2f(const char* name, float x, float y, bool useShader)
{
    if (useShader)
        this->use();
    glUniform2f(glGetUniformLocation(this->ID, name), x, y);
}
void Shader::setVector2f(const char* name, const glm::vec2& value, bool useShader)
{
    if (useShader)
        this->use();
    glUniform2f(glGetUniformLocation(this->ID, name), value.x, value.y);
}
void Shader::setVector3f(const char* name, float x, float y, float z, bool useShader)
{
    if (useShader)
        this->use();
    glUniform3f(glGetUniformLocation(this->ID, name), x, y, z);
}
void Shader::setVector3f(const char* name, const glm::vec3& value, bool useShader)
{
    if (useShader)
        this->use();
    glUniform3f(glGetUniformLocation(this->ID, name), value.x, value.y, value.z);
}
void Shader::setVector4f(const char* name, float x, float y, float z, float w, bool useShader)
{
    if (useShader)
        this->use();
    glUniform4f(glGetUniformLocation(this->ID, name), x, y, z, w);
}
void Shader::setVector4f(const char* name, const glm::vec4& value, bool useShader)
{
    if (useShader)
        this->use();
    glUniform4f(glGetUniformLocation(this->ID, name), value.x, value.y, value.z, value.w);
}
void Shader::setMatrix4(const char* name, const glm::mat4& matrix, bool useShader)
{
    if (useShader)
        this->use();
    glUniformMatrix4fv(glGetUniformLocation(this->ID, name), 1, false, glm::value_ptr(matrix));
}