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

void ui::Canvas::clear()
{
    m_fb.bindFramebuffer();

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

    glClearColor(1, 1, 1, 0);
    glClear(GL_COLOR_BUFFER_BIT);
    glViewport(0, 0, m_width, m_height);

    //

    glViewport(vp[0], vp[1], vp[2], vp[3]);
    glClearColor(cc[0], cc[1], cc[2], cc[3]);

    m_fb.unbindFramebuffer();
}
void ui::Canvas::stroke_end()
{
    m_current_stroke = nullptr;
    stroke_commit();
    m_show_tmp = false;
}
void ui::Canvas::stroke_draw()
{
    if (!(m_current_stroke && m_current_stroke->has_sample()))
        return;

    m_tmp.bindFramebuffer();

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

    glViewport(0, 0, m_width, m_height);

    auto 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);
    glActiveTexture(GL_TEXTURE1);
    m_tex.bind();
    m_sampler_bg.bind(1);

    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, proj);
    }
    else
    {
        glDisable(GL_BLEND);
        ShaderManager::use(ui::kShader::Stroke);
        ShaderManager::u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
        ShaderManager::u_int(kShaderUniform::Tex, 0);
        ShaderManager::u_int(kShaderUniform::TexBG, 1);
        ShaderManager::u_vec2(kShaderUniform::Resolution, { m_width, m_height });
        for (const auto& s : samples)
        {
            auto mvp = proj *
                glm::translate(glm::vec3(s.pos, 0)) *
                glm::scale(glm::vec3(s.size, s.size, 1)) *
                glm::eulerAngleZ(s.angle);

            //ShaderManager::u_mat4(kShaderUniform::MVP, mvp);
            //ShaderManager::u_float(kShaderUniform::Alpha, s.flow);
            //m_plane.draw_fill();

            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(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 }, { m_width, m_height });
            glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 
                tex_pos.x, tex_pos.y,
                tex_pos.x, tex_pos.y,
                tex_sz.x, tex_sz.y);
//             glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 10, 10, 10, 10, 200, 200);

            ShaderManager::u_mat4(kShaderUniform::MVP, mvp);
            ShaderManager::u_float(kShaderUniform::Alpha, s.flow);
            //m_plane.update_vertices(P);
            m_plane.draw_fill();
        }
    }

    m_tex.unbind();
    glActiveTexture(GL_TEXTURE0);
    m_sampler.unbind();
    m_sampler_bg.unbind();
    tex.unbind();

    glDisable(GL_BLEND);

    glViewport(vp[0], vp[1], vp[2], vp[3]);
    glClearColor(cc[0], cc[1], cc[2], cc[3]);

    m_tmp.unbindFramebuffer();
}
void ui::Canvas::stroke_commit()
{
    m_fb.bindFramebuffer();

    // copy to tmp2 for layer blending
    m_tex2.bind();
    glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, m_width, m_height);
    m_tex2.unbind();

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

    glViewport(0, 0, m_width, m_height);
    GLboolean blend = glIsEnabled(GL_BLEND);
    glDisable(GL_BLEND);

    m_tmp.bindTexture();
    glActiveTexture(GL_TEXTURE1);
    m_tex2.bind();
    m_sampler.bind(0);
    m_sampler_bg.bind(1);
    ShaderManager::use(ui::kShader::StrokeLayer);
    ShaderManager::u_int(kShaderUniform::Tex, 0);
    ShaderManager::u_int(kShaderUniform::TexBG, 1);
    //ShaderManager::u_float(kShaderUniform::Alpha, 1); // TODO: if using opacity in commit, update blending to match the preview when rendering m_tmp in NodeCanvas
    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.unbind();
    glActiveTexture(GL_TEXTURE0);
    m_tmp.unbindTexture();

    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]);

    m_fb.unbindFramebuffer();
}
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_strokes.emplace_back();
    m_strokes.back().start(brush);
    m_strokes.back().add_point(point, pressure);
    m_current_stroke = &m_strokes.back();
    
    m_tmp.bindFramebuffer();
    m_tmp.clear({ 0, 0, 0, 0 });
    m_tmp.unbindFramebuffer();
    m_show_tmp = true;
}
void ui::Canvas::layer_add(std::string name)
{
    m_layers.emplace_back();
    m_layers.back().create(m_width, m_height, name);
}
void ui::Canvas::resize(int width, int height)
{
    m_width = width;
    m_height = height;
    m_tmp.create(width, height);
    m_fb.create(width, height);
    m_tex.create(width, height);
    m_tex2.create(width, height);
}
bool ui::Canvas::create(int width, int height)
{
    m_width = width;
    m_height = height;
    m_tmp.create(width, height);
    m_fb.create(width, height);
    m_tex.create(width, height);
    m_tex2.create(width, height); // TODO: destroy before recreating
    m_sampler.create(GL_LINEAR, GL_CLAMP_TO_EDGE);
    m_sampler_bg.create(GL_NEAREST, GL_CLAMP_TO_EDGE);
    m_plane.create<1>(1, 1);
    m_mesh.create();
    return true;
}