#include "shader.h"

#include <fstream>
#include <sstream>
#include <vector>

#include "../lib/glew/GL/glew.h"
#include "../lib/glfw/glfw3.h"

#include "logger.h"
#include "vertex.h"

Shader::Shader(const std::string& vertexPath, const std::string& fragmentPath)
{
	const uint32_t vshader = compile_shader(GL_VERTEX_SHADER, vertexPath);
	const uint32_t fshader =
	    compile_shader(GL_FRAGMENT_SHADER, fragmentPath);

	if (vshader == 0 || fshader == 0) {
		program_id_ = 0;
		return;
	}

	program_id_ = glCreateProgram();
	glAttachShader(program_id_, vshader);
	glAttachShader(program_id_, fshader);
	glLinkProgram(program_id_);

	// Error handling
	int ret;
	glGetProgramiv(program_id_, GL_LINK_STATUS, &ret);
	if (ret == GL_FALSE) {
		char buffer[1024];
		glGetProgramInfoLog(program_id_, sizeof(buffer), nullptr,
				    buffer);
		error_ = buffer;
		glDeleteProgram(program_id_);
		program_id_ = 0;
	}

	glDeleteShader(vshader);
	glDeleteShader(fshader);
}

void Shader::use() const
{
	if (program_id_ != 0)
		glUseProgram(program_id_);
}

void Shader::setup_attribs() const
{
	int loc = glGetAttribLocation(program_id_, "vpos");
	if (loc != -1) {
		glEnableVertexAttribArray(loc);
		glVertexAttribPointer(
		    loc, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex),
		    reinterpret_cast<const void*>(offsetof(Vertex, position)));
	}

	loc = glGetAttribLocation(program_id_, "vcolor");
	if (loc != -1) {
		glEnableVertexAttribArray(loc);
		glVertexAttribPointer(
		    loc, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex),
		    reinterpret_cast<const void*>(offsetof(Vertex, color)));
	}
}

int Shader::uniform_location(const char* key) const
{
	return glGetUniformLocation(program_id_, key);
}

void Shader::set_int(int loc, int value)
{
	if (loc != -1)
		glUniform1i(loc, value);
}

void Shader::set_float(int loc, float value)
{
	if (loc != -1)
		glUniform1f(loc, value);
}

void Shader::set_vec3(int loc, const glm::vec3& value)
{
	if (loc != -1)
		glUniform3fv(loc, 1, &value[0]);
}

void Shader::set_vec4(int loc, const glm::vec4& value)
{
	if (loc != -1)
		glUniform4fv(loc, 1, &value[0]);
}

void Shader::set_mat4(int loc, const glm::mat4& value)
{
	if (loc != -1)
		glUniformMatrix4fv(loc, 1, GL_FALSE, &value[0][0]);
}

std::string Shader::read_shader_file(const std::string& filename)
{
	std::ifstream file(filename);
	if (!file) {
		error_ = "Failed to open shader file: " + filename;
		Logger::error(sstr("Failed to open shader file: ", filename));
		return std::string{0};
	}

	std::stringstream buffer;
	buffer << file.rdbuf();
	return buffer.str();
}

uint32_t Shader::compile_shader(uint32_t type, const std::string& source_path)
{
	const char* shader_type_name =
	    (type == GL_VERTEX_SHADER) ? "vertex" : "fragment";

	std::string source = read_shader_file(source_path);
	if (source.empty())
		return 0;

	Logger::info(
	    sstr("Compiling ", shader_type_name, " shader: ", source_path));

	const uint32_t shader	   = glCreateShader(type);
	const char*    shader_code = source.c_str();

	glShaderSource(shader, 1, &shader_code, nullptr);
	glCompileShader(shader);

	// Error handling
	int ret;
	glGetShaderiv(shader, GL_COMPILE_STATUS, &ret);
	if (ret == GL_FALSE) {
		char buffer[1024];
		glGetShaderInfoLog(shader, sizeof(buffer), nullptr, buffer);
		error_ = buffer;
		Logger::error(
		    sstr("Shader compilation failed (", shader_type_name, "): ",
			 buffer));
		glDeleteShader(shader);
		return 0;
	}

	Logger::info(sstr(shader_type_name, " shader compiled successfully"));
	return shader;
}