#include "pch.h"
#include "log.h"
#include "canvas.h"

ui::Canvas* ui::Canvas::I;
glm::vec3 ui::Canvas::m_plane_origin[6] = {
    { 0, 0,-1}, // front
    { 1, 0, 0}, // right
    { 0, 0, 1}, // back
    {-1, 0, 0}, // left
    { 0, 1, 0}, // top
    { 0,-1, 0}, // bottom
};
glm::vec3 ui::Canvas::m_plane_normal[6] = {
    { 0, 0, 1}, // front
    {-1, 0, 0}, // right
    { 0, 0,-1}, // back
    { 1, 0, 0}, // left
    { 0,-1, 0}, // top
    { 0, 1, 0}, // bottom
};
glm::vec3 ui::Canvas::m_plane_tangent[6] = {
    {0, 1, 0}, // front
    {0, 1, 0}, // right
    {0, 1, 0}, // back
    {0, 1, 0}, // left
    {0, 0,-1}, // top
    {0, 0, 1}, // bottom
};
glm::mat4 ui::Canvas::m_plane_transform[6] = {
    glm::lookAt(glm::vec3(), { 0, 0,-1}, {0, 1, 0}), // front
    glm::lookAt(glm::vec3(), {-1, 0, 0}, {0, 1, 0}), // right
    glm::lookAt(glm::vec3(), { 0, 0, 1}, {0, 1, 0}), // back
    glm::lookAt(glm::vec3(), { 1, 0, 0}, {0, 1, 0}), // left
    glm::lookAt(glm::vec3(), { 0, 1, 0}, {0, 0,-1}), // top
    glm::lookAt(glm::vec3(), { 0,-1, 0}, {0, 0, 1}), // bottom
};

void ui::Canvas::clear(const glm::vec4& c/*={0,0,0,1}*/)
{
    m_layers[m_current_layer_idx].clear(c);
}
void ui::Canvas::stroke_end()
{
    stroke_commit();
    m_current_stroke = nullptr;
    m_show_tmp = false;
}
void ui::Canvas::stroke_draw()
{
    if (!(m_current_stroke && m_current_stroke->has_sample()))
        return;

    m_dirty = true;

    GLint vp[4];
    GLfloat cc[4];
    glGetIntegerv(GL_VIEWPORT, vp);
    glGetFloatv(GL_COLOR_CLEAR_VALUE, cc);

    glViewport(0, 0, m_width, m_height);

    auto ortho_proj = glm::ortho(0.f, (float)m_width, 0.f, (float)m_height, -1.f, 1.f);

    auto m_brush = m_current_stroke->m_brush;
    auto samples = m_current_stroke->compute_samples();
    auto& tex = TextureManager::get(m_brush.m_tex_id);
    tex.bind();
    m_sampler.bind(0);
    m_sampler_bg.bind(1);
    m_sampler_mask.bind(2);
    
    for (int i = 0; i < 6; i++)
    {
        m_tmp[i].bindFramebuffer();
        
        glActiveTexture(GL_TEXTURE1);
        m_tex[i].bind(); // bg, copy of framebuffer (copied before drawing)
        
        if (m_use_instanced)
        {
            glEnable(GL_BLEND);
            m_mesh.shader.use();
            m_mesh.shader.u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
            m_mesh.shader.u_int(kShaderUniform::Tex, 0);
            m_mesh.draw(samples, ortho_proj);
        }
        else
        {
            glDisable(GL_BLEND);
            if (m_erase)
            {
                ShaderManager::use(ui::kShader::StrokeErase);
                //ShaderManager::u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
            }
            else if(m_layers[m_current_layer_idx].m_alpha_locked)
            {
                ShaderManager::use(kShader::StrokeLock);
                ShaderManager::u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
                ShaderManager::u_int(kShaderUniform::TexMask, 2); // alpha mask
                glActiveTexture(GL_TEXTURE2);
                m_layers[m_current_layer_idx].m_rtt[i].bindTexture();
                glActiveTexture(GL_TEXTURE1);
            }
            else
            {
                ShaderManager::use(ui::kShader::Stroke);
                ShaderManager::u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
            }
            ShaderManager::u_int(kShaderUniform::Tex, 0); // brush
            ShaderManager::u_int(kShaderUniform::TexBG, 1); // bg
            ShaderManager::u_vec2(kShaderUniform::Resolution, { m_width, m_height });
            for (const auto& s : samples)
            {
                auto unproject = [](glm::vec2 loc, glm::vec4 vp, glm::mat4 camera, glm::mat4 proj, glm::vec3& out_origin, glm::vec3& out_dir) {
                    auto clip_space = glm::vec2(loc.x, vp.w - loc.y - 1.f) / vp.zw() * 2.f - 1.f;
                    auto inv = glm::inverse(proj * camera);
                    auto wp0 = inv * glm::vec4(clip_space, 0, 1);
                    auto wp1 = inv * glm::vec4(clip_space, .5, 1);
                    out_origin = (wp0 / wp0.w).xyz();
                    out_dir = glm::normalize((wp1 / wp1.w).xyz() - out_origin);
                };
                auto intersect = [](glm::vec3 ray_origin, glm::vec3 ray_dir, glm::vec3 plane_origin, glm::vec3 plane_normal, glm::vec3 plane_tangent, glm::vec3& out_hit) {
                    float den = glm::dot(ray_dir, plane_normal);
                    if (den == 0)
                        return false;  // no intersection
                    float num = glm::dot(plane_origin - ray_origin, plane_normal);
                    float t = num / den;
                    if (t > 0)
                        out_hit = ray_origin + ray_dir * t;
                    else
                        // negative intersection
                        return false;
                    return true;
                }; 
                glm::vec3 ray_origin, ray_dir;
                unproject(s.pos, { 0, 0, m_box.zw }, m_mv, m_proj, ray_origin, ray_dir);
                glm::vec3 hit;
                glm::vec2 fb_pos;
                if (intersect(ray_origin, ray_dir, m_plane_origin[i], m_plane_normal[i], m_plane_tangent[i], hit))
                {
                    glm::mat4 plane_camera = glm::lookAt(m_plane_origin[i], m_plane_normal[i], m_plane_tangent[i]);
                    glm::vec4 plane_local = plane_camera * glm::vec4(hit, 1);
                    if (glm::abs(plane_local.x) < 1.f && glm::abs(plane_local.y) < 1.f)
                    {
                        fb_pos.x = -(plane_local.x * 0.5f - 0.5f) * m_width;
                        fb_pos.y = (plane_local.y * 0.5f + 0.5f) * m_height;
                        //LOG("draw %f %f", fb_pos.x, fb_pos.y);
                    }
                    else
                    {
                        continue;
                    }
                }
                else
                {
                    continue;
                }

                m_dirty_face[i] = true;
                
                auto mvp = ortho_proj *
                    glm::translate(glm::vec3(fb_pos, 0)) *
                    glm::scale(glm::vec3(s.size, s.size, 1)) *
                    glm::eulerAngleZ(s.angle);
                
                glm::vec4 P[4] {
                    mvp * glm::vec4(glm::vec2(-.5f, -.5f), 0, 1.f), // A - bottom-left
                    mvp * glm::vec4(glm::vec2(-.5f, +.5f), 0, 1.f), // B - top-left
                    mvp * glm::vec4(glm::vec2(+.5f, +.5f), 0, 1.f), // C - top-right
                    mvp * glm::vec4(glm::vec2(+.5f, -.5f), 0, 1.f), // D - bottom-right
                };
                
                auto mvp_inv = glm::inverse(ortho_proj);
                glm::vec4 P2[4]{
                    mvp_inv * P[0],
                    mvp_inv * P[1],
                    mvp_inv * P[2],
                    mvp_inv * P[3],
                };
                
                glm::vec2 bb_min(m_width, m_height);
                glm::vec2 bb_max(0, 0);
                for (int i = 0; i < 4; i++)
                {
                    bb_min = glm::max({ 0, 0 }, glm::min(bb_min, P2[i].xy()));
                    bb_max = glm::min({ m_width, m_height }, glm::max(bb_max, P2[i].xy()));
                }
                auto bb_sz = bb_max - bb_min;
                
                glm::vec2 pad(1);
                glm::ivec2 tex_pos = glm::clamp(glm::floor(bb_min) - pad , { 0, 0 }, { m_width, m_height });
                glm::ivec2 tex_sz  = glm::clamp(glm::ceil(bb_sz ) + pad*2.f, { 0, 0 }, (glm::vec2)(glm::ivec2(m_width, m_height) - tex_pos));
                glCopyTexSubImage2D(GL_TEXTURE_2D, 0,
                                    tex_pos.x, tex_pos.y,
                                    tex_pos.x, tex_pos.y,
                                    tex_sz.x, tex_sz.y);
                
                m_dirty_box[i].xy = glm::min(m_dirty_box[i].xy(), (glm::vec2)tex_pos);
                m_dirty_box[i].zw = glm::max(m_dirty_box[i].zw(), (glm::vec2)(tex_pos + tex_sz));
                
                ShaderManager::u_mat4(kShaderUniform::MVP, mvp);
                ShaderManager::u_float(kShaderUniform::Alpha, s.flow);
                //m_plane_brush.update_vertices(P);
                m_plane_brush.draw_fill();
            }
        }

        if (m_alpha_lock)
        {
            glActiveTexture(GL_TEXTURE2);
            m_layers[m_current_layer_idx].m_rtt[i].unbindTexture();
        }
        
        glActiveTexture(GL_TEXTURE1);
        m_tex[i].unbind();

        m_tmp[i].unbindFramebuffer();
    }
    
    glDisable(GL_BLEND);

    glActiveTexture(GL_TEXTURE0);
    m_sampler.unbind();
    m_sampler_bg.unbind();
    m_sampler_mask.unbind();
    tex.unbind();
    
    glViewport(vp[0], vp[1], vp[2], vp[3]);
    glClearColor(cc[0], cc[1], cc[2], cc[3]);

}
void ui::Canvas::stroke_commit()
{
    if (!m_dirty || m_layers.empty())
        return;
    m_dirty = false;

    // save viewport and clear color states
    GLint vp[4];
    GLfloat cc[4];
    glGetIntegerv(GL_VIEWPORT, vp);
    glGetFloatv(GL_COLOR_CLEAR_VALUE, cc);
    GLboolean blend = glIsEnabled(GL_BLEND);
    
    // allocate action to add to history
    auto action = new ActionStroke;
    
    // prepare common states
    glViewport(0, 0, m_width, m_height);
    glDisable(GL_BLEND);

    for (int i = 0; i < 6; i++)
    {
        if (!m_dirty_face[i])
            continue; // no stroke on this face, skip it

        m_layers[m_current_layer_idx].m_rtt[i].bindFramebuffer();
        
        // save image before commit
        glm::vec2 box_sz = m_dirty_box[i].zw() - m_dirty_box[i].xy();
        action->m_image[i] = std::make_unique<uint8_t[]>(box_sz.x * box_sz.y * 4);
        glReadPixels(m_dirty_box[i].x, m_dirty_box[i].y, box_sz.x, box_sz.y, GL_RGBA, GL_UNSIGNED_BYTE, action->m_image[i].get());
        
        action->m_box[i] = m_dirty_box[i];

        // copy to tmp2 for layer blending
        glActiveTexture(GL_TEXTURE0);
        m_tex2[i].bind();
        glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, m_width, m_height);
        m_tex2[i].unbind();
        
        m_tmp[i].bindTexture();
        glActiveTexture(GL_TEXTURE1);
        m_tex2[i].bind();
        m_sampler.bind(0);
        m_sampler_bg.bind(1);
        if (m_erase)
        {
            ShaderManager::use(ui::kShader::Texture);
        }
        else
        {
            ShaderManager::use(ui::kShader::StrokeLayer);
            ShaderManager::u_int(kShaderUniform::TexBG, 1);
            ShaderManager::u_float(kShaderUniform::Alpha, m_current_stroke->m_brush.m_tip_opacity);
        }
        ShaderManager::u_int(kShaderUniform::Tex, 0);
        ShaderManager::u_mat4(kShaderUniform::MVP, glm::ortho(-.5f, .5f, -.5f, .5f, -1.f, 1.f));
        m_plane.draw_fill();
        m_sampler.unbind();
        m_sampler_bg.unbind();
        m_tex2[i].unbind();
        m_tmp[i].unbindTexture();
        
        m_layers[m_current_layer_idx].m_rtt[i].unbindFramebuffer();
    }
    
    // restore viewport and clear color states
    blend ? glEnable(GL_BLEND) : glDisable(GL_BLEND);
    glViewport(vp[0], vp[1], vp[2], vp[3]);
    glClearColor(cc[0], cc[1], cc[2], cc[3]);
    glActiveTexture(GL_TEXTURE0);
    
    // save history
    action->m_layer_idx = m_current_layer_idx;
    action->m_canvas = this;
    action->m_stroke = std::move(m_current_stroke);
    ActionManager::add(action);
}
void ui::Canvas::stroke_update(glm::vec2 point, float pressure)
{
    m_current_stroke->add_point(point, pressure);
}
void ui::Canvas::stroke_start(glm::vec2 point, float pressure, const ui::Brush& brush)
{
    m_current_stroke = std::make_unique<Stroke>();
    m_current_stroke->m_camera = { m_cam_rot, m_cam_fov };
    m_current_stroke->start(brush);
    m_current_stroke->add_point(point, pressure);
    
    for (int i = 0; i < 6; i++)
    {
        m_dirty_box[i] = glm::vec4(m_width, m_height, 0, 0); // reset bounding box
        m_dirty_face[i] = false;
        
        if (m_erase)
        {
            m_layers[m_current_layer_idx].m_rtt[i].bindFramebuffer();
            m_tmp[i].bindTexture();
            glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, m_width, m_height);
            m_tmp[i].unbindTexture();
            m_layers[m_current_layer_idx].m_rtt[i].unbindFramebuffer();
        }
        else
        {
            m_tmp[i].bindFramebuffer();
            m_tmp[i].clear({ 0, 0, 0, 0 });
            m_tmp[i].unbindFramebuffer();
        }
    }
    m_show_tmp = true;
}
void ui::Canvas::layer_add(std::string name)
{
    int idx = (int)m_layers.size();
    m_layers.emplace_back();
    m_layers.back().create(m_width, m_height, name);
    m_order.push_back(idx);
}
void ui::Canvas::layer_order(int idx, int pos)
{
    std::swap(m_order[idx], m_order[pos]);
}
void ui::Canvas::resize(int width, int height)
{
    m_width = width;
    m_height = height;
    for (int i = 0; i < 6; i++)
    {
        m_tmp[i].create(width, height);
        m_tex[i].create(width, height);
        m_tex2[i].create(width, height);
    }
    for (auto& l : m_layers)
    {
        l.create(width, height, "");
    }
    m_latlong.create(width * 4, height * 2); // NOTE: w and h must be equal to make sense
}
bool ui::Canvas::create(int width, int height)
{
    m_width = width;
    m_height = height;
    for (int i = 0; i < 6; i++)
    {
        m_tmp[i].create(width, height);
        m_tex[i].create(width, height);
        m_tex2[i].create(width, height); // TODO: destroy before recreating
    }
    m_sampler.create();
    m_sampler_bg.create();
    m_sampler_mask.create();
    m_plane.create<1>(1, 1);
    m_plane_brush.create<1>(1, 1);
    m_mesh.create();
    for (auto& l : m_layers)
    {
        l.create(width, height, "");
    }
    m_latlong.create(width * 4, height * 2); // NOTE: w and h must be equal to make sense
    return true;
}

void ui::Canvas::snapshot_save(std::string data_path)
{
    LOG("SAVE SNAPSHOT");
    m_layers_snapshot.clear();
    m_layers_snapshot.resize(m_layers.size());
    for (int i = 0; i < m_layers.size(); i++)
        m_layers_snapshot[i] = m_layers[i].snapshot(data_path);
}

void ui::Canvas::snapshot_restore()
{
    LOG("RESTORE SNAPSHOT");
    for (int i = 0; i < m_layers.size(); i++)
        m_layers[i].restore(m_layers_snapshot[i]);
    m_layers_snapshot.clear();
    LOG("RESTORE SNAPSHOT complete");
}

void ui::Canvas::clear_context()
{
    LOG("Canvas CLEAR CONTEXT");
    for (auto& layer : m_layers)
        layer.destroy();
    for (int i = 0; i < 6; i++)
    {
        m_tmp[i].destroy();
        m_tex[i].destroy();
        m_tex2[i].destroy();
    }
    m_latlong.destroy();
};

void ui::Canvas::save(std::string data_path)
{
    // save viewport and clear color states
    GLint vp[4];
    GLfloat cc[4];
    glGetIntegerv(GL_VIEWPORT, vp);
    glGetFloatv(GL_COLOR_CLEAR_VALUE, cc);
    GLboolean blend = glIsEnabled(GL_BLEND);

    // prepare common states
    glViewport(0, 0, m_width, m_height);
    glDisable(GL_BLEND);

    glGenTextures(1, &cube_id);
    glBindTexture(GL_TEXTURE_CUBE_MAP, cube_id);
    for (GLuint i = 0; i < 6; i++)
        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGBA8, m_width, m_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    int faces[]{
        GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, // front
        GL_TEXTURE_CUBE_MAP_NEGATIVE_X, // right
        GL_TEXTURE_CUBE_MAP_POSITIVE_Z, // back
        GL_TEXTURE_CUBE_MAP_POSITIVE_X, // left
        GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, // top
        GL_TEXTURE_CUBE_MAP_POSITIVE_Y, // bottom
    };
    for (int i = 0; i < 6; i++)
    {
        m_tmp[i].bindFramebuffer();
        m_tmp[i].clear({ 1, 1, 1, 1 });

        for (auto layer_index : m_order)
        {
            // copy to tmp2 for layer blending
            glActiveTexture(GL_TEXTURE0); // TODO: maybe remove this line
            m_tex2[i].bind();
            glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, m_width, m_height);
            m_tex2[i].unbind();

            m_layers[layer_index].m_rtt[i].bindTexture();
            glActiveTexture(GL_TEXTURE1);
            m_tex2[i].bind();
            m_sampler.bind(0);
            m_sampler_bg.bind(1);
            ShaderManager::use(ui::kShader::StrokeLayer);
            ShaderManager::u_int(kShaderUniform::TexBG, 1);
            ShaderManager::u_float(kShaderUniform::Alpha, m_layers[layer_index].m_opacity);
            ShaderManager::u_int(kShaderUniform::Tex, 0);
            ShaderManager::u_mat4(kShaderUniform::MVP, glm::ortho(-.5f, .5f, -.5f, .5f, -1.f, 1.f));
            m_plane.draw_fill();
            m_sampler.unbind();
            m_sampler_bg.unbind();
            m_tex2[i].unbind();
            m_layers[layer_index].m_rtt[i].unbindTexture();
        }

        // copy result to cubemap
        glBindTexture(GL_TEXTURE_CUBE_MAP, cube_id);
        glCopyTexImage2D(faces[i], 0, GL_RGBA8, 0, 0, m_width, m_height, 0);
        glBindTexture(GL_TEXTURE_CUBE_MAP, 0);

        m_tmp[i].unbindFramebuffer();
    }

//     auto data = std::make_unique<uint8_t[]>(m_tmp[0].bytes());
//     for (int i = 0; i < 6; i++)
//     {
//         m_tmp[i].readTextureData(data.get());
//         static char name[128];
//         sprintf(name, "%s/Face%d.png", data_path.c_str(), i);
//         LOG("writing %s", name);
//         //int ret = stbi_write_png(name, m_tmp[i].getWidth(), m_tmp[i].getHeight(), 4, data.get(), m_tmp[i].stride());
//     }

    glViewport(0, 0, m_latlong.getWidth(), m_latlong.getHeight());
    m_latlong.bindFramebuffer();
    ui::ShaderManager::use(kShader::Equirect);
    ui::ShaderManager::u_mat4(kShaderUniform::MVP, glm::ortho(-.5f, .5f, -.5f, .5f, -1.f, 1.f));
    ui::ShaderManager::u_int(kShaderUniform::Tex, 0);
    glBindTexture(GL_TEXTURE_CUBE_MAP, cube_id);
    m_sampler.bind(0);
    m_plane.draw_fill();
    m_sampler.unbind();
    glBindTexture(GL_TEXTURE_CUBE_MAP, 0);
    m_latlong.unbindFramebuffer();
    {
        auto latlong_data = std::make_unique<uint8_t[]>(m_latlong.bytes());
        m_latlong.readTextureData(latlong_data.get());
        static char name[128];
        sprintf(name, "%s/latlong.png", data_path.c_str());
        LOG("writing %s", name);
        int ret = stbi_write_png(name, m_latlong.getWidth(), m_latlong.getHeight(), 4, latlong_data.get(), m_latlong.stride());
    }

    // restore viewport and clear color states
    blend ? glEnable(GL_BLEND) : glDisable(GL_BLEND);
    glViewport(vp[0], vp[1], vp[2], vp[3]);
    glClearColor(cc[0], cc[1], cc[2], cc[3]);
    glActiveTexture(GL_TEXTURE0);
}

void ui::Canvas::project_save(std::string data_path)
{
    static char name[128];
    sprintf(name, "%s/latlong.pano", data_path.c_str());
    FILE* fp = fopen(name, "wb");
    if (!fp)
    {
        LOG("cannot write project to %s", name);
        return;
    }

    // load thumbnail
    Image thumb = thumbnail_generate(64, 64);
    fwrite(&thumb.width, sizeof(int), 1, fp);
    fwrite(&thumb.height, sizeof(int), 1, fp);
    fwrite(&thumb.comp, sizeof(int), 1, fp);
    fwrite(thumb.data(), thumb.size(), 1, fp);

    fwrite(&m_width, sizeof(int), 1, fp);
    fwrite(&m_height, sizeof(int), 1, fp);
    
    int n_layers = (int)m_layers.size();
    fwrite(&n_layers, sizeof(int), 1, fp);
    
    for (int i  = 0; i < (int)m_layers.size(); i++)
    {
        int n_order = m_order[i];
        fwrite(&n_order, sizeof(int), 1, fp);

        int name_len = m_layers[i].m_name.size();
        fwrite(&name_len, sizeof(int), 1, fp);
        fwrite(m_layers[i].m_name.data(), name_len, 1, fp);
        
        auto snap = m_layers[i].snapshot(data_path);
        for (int plane_index = 0; plane_index < 6; plane_index++)
        {
            fwrite(snap.image[plane_index].get(), 1, m_width * m_height * 4, fp);
        }
    }
    fclose(fp);
    LOG("project saved to %s", name);
}

void ui::Canvas::project_open(std::string data_path)
{
    static char name[128];
    sprintf(name, "%s/latlong.pano", data_path.c_str());
    FILE* fp = fopen(name, "rb");
    if (!fp)
    {
        LOG("cannot write project to %s", name);
        return;
    }

    // skip thumbnail
    Image thumb;
    fread(&thumb.width, sizeof(int), 1, fp);
    fread(&thumb.height, sizeof(int), 1, fp);
    fread(&thumb.comp, sizeof(int), 1, fp);
    fseek(fp, thumb.size(), SEEK_CUR);

    fread(&m_width, sizeof(int), 1, fp);
    fread(&m_height, sizeof(int), 1, fp);
    
    int n_layers = (int)m_layers.size();
    fread(&n_layers, sizeof(int), 1, fp);
    
    const int bytes = m_width * m_height * 4;
    Layer::Snapshot snap;
    snap.create(m_width, m_height);

    m_layers.clear();
    m_order.clear();
    for (int i = 0; i < n_layers; i++)
    {
        int n_order;
        fread(&n_order, sizeof(int), 1, fp);
        m_order.push_back(n_order);

        int name_len;
        fread(&name_len, sizeof(int), 1, fp);
        std::string name(name_len, '\0');
        fread((char*)name.data(), name_len, 1, fp);
        for (int plane_index = 0; plane_index < 6; plane_index++)
        {
            fread(snap.image[plane_index].get(), 1, bytes, fp);
        }
        m_layers.emplace_back();
        m_layers.back().create(m_width, m_height, name.c_str());
        m_layers.back().restore(snap);
    }
    fclose(fp);
    LOG("project restore from %s", name);
}

ui::Image ui::Canvas::thumbnail_generate(int w, int h)
{
    // save viewport and clear color states
    GLint vp[4];
    GLfloat cc[4];
    glGetIntegerv(GL_VIEWPORT, vp);
    glGetFloatv(GL_COLOR_CLEAR_VALUE, cc);
    GLboolean blend = glIsEnabled(GL_BLEND);

    // prepare common states
    glViewport(0, 0, w, h);

    RTT fb;
    fb.create(w, h);
    fb.bindFramebuffer();
    fb.clear({ 1, 1, 1, 1 });
    ui::Plane m_face_plane;
    m_face_plane.create<1>(2, 2);

    // recalculate because of different aspect ratio than the m_proj matrix
    glm::mat4 proj = glm::perspective(glm::radians(m_cam_fov), (float)w / (float)h, 0.1f, 1000.f);

    glEnable(GL_BLEND);
    for (int plane_index = 0; plane_index < 6; plane_index++)
    {
        auto plane_mvp = proj * m_mv * m_plane_transform[plane_index] * glm::translate(glm::vec3(0, 0, -1));

        ui::ShaderManager::use(kShader::Checkerboard);
        ui::ShaderManager::u_mat4(kShaderUniform::MVP, plane_mvp);
        m_face_plane.draw_fill();

        ui::ShaderManager::use(kShader::TextureAlpha);
        ui::ShaderManager::u_int(kShaderUniform::Tex, 0);
        ui::ShaderManager::u_mat4(kShaderUniform::MVP, plane_mvp);
        for (auto layer_index : m_order)
        {
            ui::ShaderManager::u_float(kShaderUniform::Alpha, m_layers[layer_index].m_opacity);
            m_layers[layer_index].m_rtt[plane_index].bindTexture();
            m_face_plane.draw_fill();
            m_layers[layer_index].m_rtt[plane_index].unbindTexture();
        }
    }

    fb.unbindFramebuffer();

    // read the rendered image
    ui::Image image;
    image.create(w, h);
    fb.readTextureData((uint8_t*)image.data());

    fb.destroy();

    // restore viewport and clear color states
    blend ? glEnable(GL_BLEND) : glDisable(GL_BLEND);
    glViewport(vp[0], vp[1], vp[2], vp[3]);
    glClearColor(cc[0], cc[1], cc[2], cc[3]);
    glActiveTexture(GL_TEXTURE0);

    return std::move(image);
}

ui::Image ui::Canvas::thumbnail_read(std::string data_path)
{
    static char name[128];
    sprintf(name, "%s/latlong.pano", data_path.c_str());
    FILE* fp = fopen(name, "rb");
    if (!fp)
    {
        LOG("cannot read project %s", name);
        return {}; // return empty image
    }
    Image thumb;
    fread(&thumb.width, sizeof(int), 1, fp);
    fread(&thumb.height, sizeof(int), 1, fp);
    fread(&thumb.comp, sizeof(int), 1, fp);
    thumb.create();
    fread((uint8_t*)thumb.data(), thumb.size(), 1, fp);
    fclose(fp);
    LOG("project thumbnail read from %s", name);
    return std::move(thumb);
}

///////////////////////////////////////////////////////////////////////////////////////////

void ui::Layer::destroy()
{
    for (int i = 0; i < 6; i++)
        m_rtt[i].destroy();
}

void ui::Layer::restore(const Snapshot& snap)
{
    for (int i = 0; i < 6; i++)
    {
        if (!snap.image[i])
            continue;
        m_rtt[i].recreate(); // TODO: this should not be recreated here! Sorry I messed up with this, just quick fix DON'T SHIP!!
        m_rtt[i].bindTexture();
        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, m_rtt[i].getWidth(), m_rtt[i].getHeight(), GL_RGBA, GL_UNSIGNED_BYTE, snap.image[i].get());
        m_rtt[i].unbindTexture();
        LOG("restore face %d - %d bytes (%dx%d)", i, m_rtt[i].bytes(), m_rtt[i].getWidth(), m_rtt[i].getHeight());
    }
}

ui::Layer::Snapshot ui::Layer::snapshot(std::string data_path)
{
    Snapshot snap;
    static int counter = 0;
    LOG("errno = %d", errno);
    glBindTexture(GL_TEXTURE_2D, 0);
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    for (int i = 0; i < 6; i++)
    {
        snap.image[i] = std::make_unique<uint8_t[]>(m_rtt[i].bytes());
        m_rtt[i].readTextureData(snap.image[i].get());
        LOG("snapshot face %d - %d bytes (%dx%d)", i, m_rtt[i].bytes(), m_rtt[i].getWidth(), m_rtt[i].getHeight());
        static char name[128];
        sprintf(name, "%s/Layer%d-%d.png", data_path.c_str(), counter, i);
        //int ret = stbi_write_png(name, m_rtt[i].getWidth(), m_rtt[i].getHeight(), 4, snap.image[i].get(), m_rtt[i].stride());
    }
    counter++;
    return std::move(snap);
}

void ui::Layer::clear(const glm::vec4& c)
{
    // push clear color state
    GLfloat cc[4];
    glGetFloatv(GL_COLOR_CLEAR_VALUE, cc);
    glClearColor(c.r, c.g, c.b, c.a);

    for (int i = 0; i < 6; i++)
    {
        m_rtt[i].bindFramebuffer();
        glClear(GL_COLOR_BUFFER_BIT);
        m_rtt[i].unbindFramebuffer();
    }

    // restore clear color state
    glClearColor(cc[0], cc[1], cc[2], cc[3]);
}

bool ui::Layer::create(int width, int height, std::string name)
{
    m_name = name;
    for (int i = 0; i < 6; i++)
    {
        m_rtt[i].create(width, height);
        m_rtt[i].bindFramebuffer();
        m_rtt[i].clear();
        m_rtt[i].unbindFramebuffer();
    }
    return true;
}