#pragma once

#include "Gedeng/Mesh.h"
#include "Gedeng/Shader.h"
#include <glm/glm.hpp>

namespace Gedeng {

class DirectionalLight {
  public:
    glm::vec3 direction;

    explicit DirectionalLight(glm::vec3 direction)
        // TODO: Avoid all this duplication
        : direction(direction), shadow_shader(Gedeng::Shader("Shader/shadow.vs", "Shader/shadow.fs")) {
        // Configure depth map
        glGenFramebuffers(1, &depth_map_fbo);

        // Create depth texture
        glGenTextures(1, &depth_map);
        glBindTexture(GL_TEXTURE_2D, depth_map);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, SHADOW_WIDTH, SHADOW_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_FLOAT,
                     NULL);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

        // Attach depth texture as FBO's depth buffer
        glBindFramebuffer(GL_FRAMEBUFFER, depth_map_fbo);
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depth_map, 0);
        glDrawBuffer(GL_NONE);
        glReadBuffer(GL_NONE);
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
    }

    void set_in_shader(Shader &shader) {
        shader.setVec3("light_direction", direction);
        shader.setMat4("light_space_matrix", get_light_space_matrix());
    }

    void render_shadow(Mesh &mesh) {
        shadow_shader.use();

        shadow_shader.setMat4("lightSpaceMatrix", get_light_space_matrix());

        glViewport(0, 0, SHADOW_WIDTH, SHADOW_HEIGHT);
        glBindFramebuffer(GL_FRAMEBUFFER, depth_map_fbo);

        mesh.render(shadow_shader);

        glBindFramebuffer(GL_FRAMEBUFFER, 0);
    }

    glm::mat4 get_light_space_matrix() {
        // TODO: Make the values here configurable
        float near_plane = 1.0f, far_plane = 100.0f;
        glm::mat4 lightProjection = glm::ortho(-20.0f, 20.0f, -20.0f, 20.0f, near_plane, far_plane);
        glm::mat4 lightView = glm::lookAt(-direction * 10.0f, direction, glm::vec3(0.0, 1.0, 0.0));
        return lightProjection * lightView;
    }

    void clear_shadows() {
        shadow_shader.use();
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    }

    void bind_depth_map_to(int unit) {
        glActiveTexture(GL_TEXTURE0 + unit);
        glBindTexture(GL_TEXTURE_2D, depth_map);
    }

  private:
    unsigned int depth_map;
    unsigned int depth_map_fbo;

    const unsigned int SHADOW_WIDTH = 2048;
    const unsigned int SHADOW_HEIGHT = 2048;

    Gedeng::Shader shadow_shader;
};

} // namespace Gedeng