#include "light.h"
#include "framebuffer.h"
#include "texture.h"
#include "scene.h"
#include "shader.h"
#include "shadersource.h"
#include "phongmaterial.h"
#include "mesh.h"
#include "camera.h"
#include <resource.h>
#include <glm/ext.hpp>

RESOURCE_PACK(shaders)

const char* Light::flagStr[] = {
    "AMBIENT_LIGHT",
    "DIRECTIONNAL_LIGHT",
    "POINT_LIGHT",
    "SPOT_LIGHT",
    "SHADOWMAP",
    "CASCADED"
};

const glm::mat4 Light::biasMatrix(
        0.5, 0.0, 0.0, 0.0,
        0.0, 0.5, 0.0, 0.0,
        0.0, 0.0, 0.5, 0.0,
        0.5, 0.5, 0.5, 1.0);

void AmbientLight::bindAttributes(Shader *shader, Camera *camera)
{
    shader->bindVec3(shader->getLocation("lightColor"), m_color);
}

// DIRECTIONNAL LIGHT

int DirectionnalLight::m_shaderRefCounter = 0;
Shader* DirectionnalLight::m_shaders[4] = {NULL};

DirectionnalLight::DirectionnalLight(glm::vec3 dir, glm::vec3 lightColor) :
    m_direction(dir),
    m_shadowCaster(false)
    
{
    m_color = lightColor;
    m_shadowMap = NULL;
}

void DirectionnalLight::bindAttributes(Shader *shader, Camera *camera)
{
    shader->bindVec3(shader->getLocation("lightColor"), m_color);
    glm::vec4 direction = glm::vec4(m_direction, 0.f);
    shader->bindVec3(shader->getLocation("dirLight"), glm::normalize(glm::vec3(camera->getViewMatrix()*direction)));
    if(m_shadowCaster)
    {
        switch(m_projectionMatrices.size())
        {
        case 1:
        {
            m_shadowMap->getTexture(0)->bind(7); // TODO use something else than 7
            shader->bindInteger(shader->getLocation("shadowMap"), 7);
            glm::mat4 viewToLightMatrix = Light::biasMatrix * m_projectionMatrices[0] * m_viewMatrices[0] * glm::inverse(camera->getViewMatrix());
            shader->bindMat4(shader->getLocation("viewToLightMatrix"), viewToLightMatrix);
        }
        break;
        case 3:
        {
            m_shadowMap->getTexture(0)->bind(7); // TODO use something else than 7
            shader->bindInteger(shader->getLocation("shadowMap"), 7);
            glm::mat4 lightMVP;
            lightMVP = Light::biasMatrix * m_projectionMatrices[0] * (m_viewMatrices[0] * glm::inverse(camera->getViewMatrix()));
            shader->bindMat4(shader->getLocation("frontShadowMVP"), lightMVP);
            lightMVP = Light::biasMatrix * m_projectionMatrices[1] * (m_viewMatrices[1] * glm::inverse(camera->getViewMatrix()));
            shader->bindMat4(shader->getLocation("midShadowMVP"), lightMVP);
            lightMVP = Light::biasMatrix * m_projectionMatrices[2] * (m_viewMatrices[2] * glm::inverse(camera->getViewMatrix()));
            shader->bindMat4(shader->getLocation("backShadowMVP"), lightMVP);
        }
        break;
        default:
        break;
        }
    }
}

unsigned int DirectionnalLight::getFlags()
{
    unsigned int flag = 1 << DIRECTIONNAL_FLAG;
    if(m_shadowCaster)
        flag |= 1 << SHADOWMAP_FLAG;
    if(m_projectionMatrices.size() == 3)
        flag |= 1 << CASCADED_FLAG;
    return flag;
}

void DirectionnalLight::initShadowMap(int resolution, bool isCascaded)
{
    m_shadowMapResolution = resolution;
    
    // shader compilation
    if(m_shaderRefCounter == 0)
    {
        ShaderSource source;
        Resource::ResourceMap shaderMap;
        Resource::getResourcePack_shaders(shaderMap);
        source.setSource(shaderMap["shaders/shadow.vert.glsl"], ShaderSource::VERTEX);
        source.setSource(shaderMap["shaders/shadow.frag.glsl"], ShaderSource::FRAGMENT);
        unsigned int flag = 1 << DIRECTIONNAL_FLAG;
        m_shaders[0] = source.compile(Mesh::MESH_3D, flag);
        m_shaders[1] = source.compile(Mesh::MESH_3D & Mesh::MATERIAL_ALPHA_MASK, flag);
        
        source.setSource(shaderMap["shaders/shadow.geom.glsl"], ShaderSource::GEOMETRY);
        flag |= 1 << CASCADED_FLAG;
        m_shaders[2] = source.compile(Mesh::MESH_3D, flag);
        m_shaders[3] = source.compile(Mesh::MESH_3D & Mesh::MATERIAL_ALPHA_MASK, flag);
    }
    if(!m_shadowCaster)
        ++m_shaderRefCounter;
    m_shadowCaster = true;
    
    if(isCascaded)
    {
        m_viewMatrices.resize(3);
        m_projectionMatrices.resize(3);
    }
    else
    {
        m_viewMatrices.resize(1);
        m_projectionMatrices.resize(1);
    }
    
    // Depth buffer
    Texture *tex = new Texture(GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT, resolution, resolution, GL_FLOAT, isCascaded ? GL_TEXTURE_2D_ARRAY : GL_TEXTURE_2D);
    if(isCascaded)
    {
        tex->bind();
        for(int i=0; i<3; ++i)
            glTexImage3D(GL_TEXTURE_2D_ARRAY, 0, GL_DEPTH_COMPONENT, resolution, resolution, i, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
    }
    tex->setFiltering(GL_LINEAR);
    tex->setWrap(GL_CLAMP_TO_EDGE);
    tex->setParameter(GL_TEXTURE_COMPARE_MODE, GL_COMPARE_REF_TO_TEXTURE);
    tex->setParameter(GL_TEXTURE_COMPARE_FUNC, GL_LESS);

    // framebuffer
    m_shadowCaster = true;
    m_shadowMap = new FrameBuffer();
    m_shadowMap->addTexture(tex, GL_DEPTH_ATTACHMENT);
    m_shadowMap->initColorAttachments();
}

void DirectionnalLight::destroyShadowMap()
{
    if(m_shadowCaster)
    {
        m_shadowCaster = false;
        --m_shaderRefCounter;
        if(m_shaderRefCounter == 0)
        {
            for(int i=0; i<4; ++i)
                delete m_shaders[i];
        }
        if(m_shadowMap != NULL)
            delete m_shadowMap;
    }
    m_viewMatrices.clear();
    m_projectionMatrices.clear();
    m_shadowMap = NULL;
}

void DirectionnalLight::setShadowView(glm::vec3 dim, glm::vec3 center)
{
    m_viewMatrices[0] = glm::lookAt(center, center-m_direction, glm::vec3(0, 1, 0));
    m_projectionMatrices[0] = glm::ortho(-dim.x/2, dim.x/2, -dim.y/2, dim.y/2, -dim.z/2, dim.z/2);
}

void DirectionnalLight::setCascadedShadowView(Camera *camera)
{
    // TODO find projection bounding boxes and define the 3 shadowmap views
}

void DirectionnalLight::updateShadowMap(Scene* scene)
{
    bool hasCascades = m_projectionMatrices.size() == 3;
    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
    glViewport(0, 0, m_shadowMapResolution, m_shadowMapResolution);
    m_shadowMap->bindFBO();
    glClearDepth(1.0);
    glClear(GL_DEPTH_BUFFER_BIT);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);
    for(SceneIterator<GeometryNode*>* geometryIt = scene->getGeometry();
        geometryIt->isValid(); geometryIt->next())
    {
        GeometryNode* node = geometryIt->getItem();
        if(node->mesh->getFlags() & (1 << Mesh::MESH_SHADOWED))
        {
            int shaderId = (node->mesh->getFlags() & (1 << Mesh::MATERIAL_ALPHA_MASK)) != 0;
            
            // compute matrix attributes
            if(hasCascades)
            {
                shaderId += 2;
                m_shaders[shaderId]->bind();
                glm::mat4 lightMVP;
                lightMVP = m_projectionMatrices[0] * (m_viewMatrices[0] * node->modelMatrix);
                m_shaders[shaderId]->bindMat4(m_shaders[shaderId]->getLocation("frontShadowMVP"), lightMVP);
                lightMVP = m_projectionMatrices[1] * (m_viewMatrices[1] * node->modelMatrix);
                m_shaders[shaderId]->bindMat4(m_shaders[shaderId]->getLocation("midShadowMVP"), lightMVP);
                lightMVP = m_projectionMatrices[2] * (m_viewMatrices[2] * node->modelMatrix);
                m_shaders[shaderId]->bindMat4(m_shaders[shaderId]->getLocation("backShadowMVP"), lightMVP);
                node->mesh->draw(m_shaders[shaderId], false, shaderId, false);
            }
            else
            {
                m_shaders[shaderId]->bind();
                glm::mat4 lightMVP = m_projectionMatrices[0] * (m_viewMatrices[0] * node->modelMatrix);
                m_shaders[shaderId]->bindMat4(m_shaders[shaderId]->getLocation("MVP"), lightMVP);
                node->mesh->draw(m_shaders[shaderId], false, shaderId, false);
            }
        }
    }
}

// POINT LIGHT

int PointLight::m_shaderRefCounter = 0;
Shader* PointLight::m_shaders[2] = {NULL};

PointLight::PointLight(glm::vec3 pos, float range, glm::vec3 lightColor) :
    m_position(pos),
    m_range(range),
    m_shadowCaster(false)
    
{
    m_color = lightColor;
    m_shadowMap = NULL;
}

void PointLight::bindAttributes(Shader *shader, Camera *camera)
{
    glm::vec4 posInView = camera->getViewMatrix() * glm::vec4(m_position.x, m_position.y, m_position.z, 1.f);
    shader->bindVec3(shader->getLocation("lightColor"), m_color);
    shader->bindVec3(shader->getLocation("pointLight"), glm::vec3(posInView));
    shader->bindFloat(shader->getLocation("range"), m_range);
    if(m_shadowCaster)
    {
        m_shadowMap->getTexture(0)->bind(7); // TODO use something else than 7
        shader->bindInteger(shader->getLocation("shadowMap"), 7);
        shader->bindMat3(shader->getLocation("inverseViewMatrix"), glm::inverse(glm::mat3(camera->getViewMatrix())));
    }
}

unsigned int PointLight::getFlags()
{
    unsigned int flag = 1 << POINT_FLAG;
    if(m_shadowCaster)
        flag |= 1 << SHADOWMAP_FLAG;
    return flag;
}

void PointLight::initShadowMap(int resolution)
{
    m_shadowMapResolution = resolution;
    setPos(m_position);

    // shader compilation
    if(m_shaderRefCounter == 0)
    {
        ShaderSource source;
        Resource::ResourceMap shaderMap;
        Resource::getResourcePack_shaders(shaderMap);
        source.setSource(shaderMap["shaders/shadow.vert.glsl"], ShaderSource::VERTEX);
        source.setSource(shaderMap["shaders/shadow.geom.glsl"], ShaderSource::GEOMETRY);
        source.setSource(shaderMap["shaders/shadow.frag.glsl"], ShaderSource::FRAGMENT);
        unsigned int flag = 1 << POINT_FLAG;
        m_shaders[0] = source.compile(Mesh::MESH_3D, flag);
        m_shaders[1] = source.compile(Mesh::MESH_3D & Mesh::MATERIAL_ALPHA_MASK, flag);
    }
    if(!m_shadowCaster)
        ++m_shaderRefCounter;
    m_shadowCaster = true;
    
    // Depth buffer
    Texture *tex = new Texture(GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT, resolution, resolution, GL_FLOAT, GL_TEXTURE_CUBE_MAP);
    tex->setParameter(GL_TEXTURE_COMPARE_MODE, GL_COMPARE_REF_TO_TEXTURE);
    tex->setParameter(GL_TEXTURE_COMPARE_FUNC, GL_LESS);

    // framebuffer
    m_shadowCaster = true;
    m_shadowMap = new FrameBuffer();
    m_shadowMap->addTexture(tex, GL_DEPTH_ATTACHMENT);
    m_shadowMap->initColorAttachments();
}

void PointLight::updateTransform()
{
    if(m_shadowCaster)
    {
        m_shadowTransforms.clear();
        glm::mat4 shadowProj = glm::perspective(45.0f, 1.f, 0.01f, m_range);
        m_shadowTransforms.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(1.0,0.0,0.0), glm::vec3(0.0,-1.0,0.0)));
        m_shadowTransforms.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(-1.0,0.0,0.0), glm::vec3(0.0,-1.0,0.0)));
        m_shadowTransforms.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(0.0,1.0,0.0), glm::vec3(0.0,0.0,1.0)));
        m_shadowTransforms.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(0.0,-1.0,0.0), glm::vec3(0.0,0.0,-1.0)));
        m_shadowTransforms.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(0.0,0.0,1.0), glm::vec3(0.0,-1.0,0.0)));
        m_shadowTransforms.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(0.0,0.0,-1.0), glm::vec3(0.0,-1.0,0.0)));
    }
}

void PointLight::destroyShadowMap()
{
    if(m_shadowCaster)
    {
        m_shadowCaster = false;
        --m_shaderRefCounter;
        if(m_shaderRefCounter == 0)
        {
            for(int i=0; i<2; ++i)
                delete m_shaders[i];
        }
        if(m_shadowMap != NULL)
            delete m_shadowMap;
    }
    m_shadowMap = NULL;
}

void PointLight::updateShadowMap(Scene* scene)
{
    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
    m_shadowMap->bindFBO();
    glViewport(0, 0, m_shadowMapResolution, m_shadowMapResolution);
    glClearDepth(1.0);
    glClear(GL_DEPTH_BUFFER_BIT);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);
    for(SceneIterator<GeometryNode*>* geometryIt = scene->getGeometry();
        geometryIt->isValid(); geometryIt->next())
    {
        GeometryNode* node = geometryIt->getItem();
        if(node->mesh->getFlags() & (1 << Mesh::MESH_SHADOWED))
        {
            int shaderId = (node->mesh->getFlags() & (1 << Mesh::MATERIAL_ALPHA_MASK)) != 0;
            
            m_shaders[shaderId]->bind();
            m_shaders[shaderId]->bindMat4(m_shaders[shaderId]->getLocation("modelMatrix"), node->modelMatrix);
            m_shaders[shaderId]->bindMat4Array(m_shaders[shaderId]->getLocation("layerTransform"), m_shadowTransforms.data(), m_shadowTransforms.size());
            m_shaders[shaderId]->bindFloat(m_shaders[shaderId]->getLocation("far_plane"), m_range);
            node->mesh->draw(m_shaders[shaderId], false, shaderId, false);
        }
    }
    FrameBuffer::screen->bindFBO();
}
    
// OLD IMPLEMENTATION

/*
void Light::initShadowMap(int resolution, glm::vec3 dim)
{
    m_shadowMapResolution = resolution;
    Texture* tex;

    switch(m_type)
    {
    case DIRECTIONNAL:
        // 3 orthogonal matrices (cascaded shadowmaps)
        // 3 square textures
        m_viewMatrix.push_back(glm::lookAt(m_position, m_position-m_direction, glm::vec3(0, 1, 0)));
        m_projectionMatrix = glm::ortho(-dim.x/2, dim.x/2, -dim.y/2, dim.y/2, -dim.z/2, dim.z/2);
        tex = new Texture(GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT, resolution, resolution, GL_FLOAT, GL_TEXTURE_2D);
        break;
    case POINT:
        // see http://learnopengl.com/#!Advanced-Lighting/Shadows/Point-Shadows

        // 6 projection matrices
        // 1 cubemap texture
        m_viewMatrix = glm::lookAt(m_position, m_position-glm::vec3(0, 0, 1), glm::vec3(0, 1, 0));
        m_projectionMatrix = glm::perspective(90.f, 1.f, 0.1f, 100.f);
        tex = new Texture(GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT, resolution, resolution, GL_FLOAT, GL_TEXTURE_CUBE_MAP);

        m_viewMatrices.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(1.0,0.0,0.0), glm::vec3(0.0,-1.0,0.0));
        m_viewMatrices.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(-1.0,0.0,0.0), glm::vec3(0.0,-1.0,0.0));
        m_viewMatrices.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(0.0,1.0,0.0), glm::vec3(0.0,0.0,1.0));
        m_viewMatrices.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(0.0,-1.0,0.0), glm::vec3(0.0,0.0,-1.0));
        m_viewMatrices.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(0.0,0.0,1.0), glm::vec3(0.0,-1.0,0.0));
        m_viewMatrices.push_back(shadowProj *
                         glm::lookAt(m_position, m_position + glm::vec3(0.0,0.0,-1.0), glm::vec3(0.0,-1.0,0.0));
        break;
    case SPOT:
        // 1 projection matrix
        // 1 square texture
        m_viewMatrix.push_back(glm::lookAt(m_position, m_position+m_direction, glm::vec3(0, 1, 0)));
        m_projectionMatrix = glm::perspective(m_cutOffAngle, 1.f, 0.1f, 100.f);
        tex = new Texture(GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT, resolution, resolution, GL_FLOAT, GL_TEXTURE_2D);
        break;
    case AMBIENT:
        return;
    }

    // shader compilation
    // TODO : do not compile shader for every light
    ShaderSource source;
    Resource::ResourceMap shaderMap;
    Resource::getResourcePack_shaders(shaderMap);
    source.setSource(shaderMap["shaders/shadow.vert.glsl"], ShaderSource::VERTEX);
    if(m_type == POINT)
        source.setSource(shaderMap["shaders/shadow.geom.glsl"], ShaderSource::GEOMETRY);
    source.setSource(shaderMap["shaders/shadow.frag.glsl"], ShaderSource::FRAGMENT);
    m_shaders[0] = source.compile(Mesh::MESH_3D, getFlags());
    m_shaders[1] = source.compile(Mesh::MESH_3D & Mesh::MATERIAL_ALPHA_MASK, getFlags());

    // Depth buffer
    tex->setFiltering(GL_LINEAR);
    tex->setWrap(GL_CLAMP_TO_EDGE);
    tex->setParameter(GL_TEXTURE_COMPARE_MODE, GL_COMPARE_REF_TO_TEXTURE);
    tex->setParameter(GL_TEXTURE_COMPARE_FUNC, GL_LESS);

    // framebuffer
    m_shadowCaster = true;
    m_shadowMap = new FrameBuffer();
    m_shadowMap->addTexture(tex, GL_DEPTH_ATTACHMENT);
    m_shadowMap->initColorAttachments();
}

void Light::generateShadowMap(Scene* scene)
{
    glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
    glViewport(0, 0, m_shadowMapResolution, m_shadowMapResolution);
    m_shadowMap->bindFBO();
    glClearDepth(1.0);
    glClear(GL_DEPTH_BUFFER_BIT);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);
    // glCullFace(GL_FRONT);
    for(SceneIterator<GeometryNode*>* geometryIt = scene->getGeometry();
        geometryIt->isValid(); geometryIt->next())
    {
        GeometryNode* node = geometryIt->getItem();
        if(node->mesh->getFlags() & (1 << Mesh::MESH_SHADOWED))
        {
            // compute matrix attributes
            glm::mat4 lightMVP = getProjectionMatrix() * (getViewMatrix() * node->modelMatrix);
            int hasAlpha = (node->mesh->getFlags() & (1 << Mesh::MATERIAL_ALPHA_MASK)) > 0;
            m_shaders[hasAlpha]->bind();
            m_shaders[hasAlpha]->bindMat4(m_shaders[hasAlpha]->getLocation("MVP"), lightMVP);
            node->mesh->draw(m_shaders[hasAlpha], false, hasAlpha, false);
        }
    }
    // glCullFace(GL_BACK);
}

void Light::bindShadowMap(Shader *shader)
{
    glm::mat4 lightMVP = Light::biasMatrix * m_projectionMatrix * light->getViewMatrix() * node->modelMatrix;
    shader->bindMat4(shader->getLocation("lightMVP"), lightMVP);
}

Texture* Light::getShadowMapTexture()
{
    return m_shadowMap->getTexture(0);
}

void Light::setPosition(glm::vec3 new_pos)
{
    m_position = new_pos;
    m_viewMatrix = glm::lookAt(m_position, m_position+m_direction, glm::vec3(0, 1, 0));
}

unsigned int Light::getFlags()
{
    unsigned int flags = 0;
    switch(m_type)
    {
    case AMBIENT :
        flags = 1 << AMBIENT_FLAG;
        break;
    case DIRECTIONNAL :
        flags = 1 << DIRECTIONNAL_FLAG;
        break;
    case POINT :
        flags = 1 << POINT_FLAG;
        break;
    case SPOT :
        flags = 1 << SPOT_FLAG;
        break;
    }
    if(m_shadowCaster)
        flags |= 1 << SHADOWMAP_FLAG;
    return flags;
}
*/