#include "pch.h"
#include "canvas.h"
#include "app.h"
#include "legacy_canvas_stroke_composite_services.h"
#include "legacy_ui_gl_dispatch.h"
#include "renderer_gl/opengl_capabilities.h"
#include "util.h"

#include <array>
#include <cstdint>
#include <vector>

namespace {

GLenum blend_state()
{
    return static_cast<GLenum>(pp::renderer::gl::blend_state());
}

void set_active_texture_unit(std::uint32_t unit_index)
{
    pp::legacy::ui_gl::activate_texture_unit(unit_index, "Canvas");
}

void apply_canvas_viewport(std::int32_t x, std::int32_t y, std::int32_t width, std::int32_t height)
{
    pp::legacy::ui_gl::apply_viewport(x, y, width, height, "Canvas");
}

void apply_canvas_capability(std::uint32_t state, bool enabled)
{
    pp::legacy::ui_gl::set_capability(state, enabled, "Canvas");
}

} // namespace

void Canvas::layer_merge(int source_idx, int dest_idx) // m_layer index
{
    m_dirty = false;

    App::I->render_task([&]
    {
        apply_canvas_viewport(0, 0, m_width, m_height);
        apply_canvas_capability(blend_state(), false);

        for (int i = 0; i < 6; i++)
        {
            if (!m_layers[source_idx]->face(i))
                continue;

            m_layers[dest_idx]->rtt(i).bindFramebuffer();

            auto& lbox = m_layers[dest_idx]->box(i);
            lbox = glm::vec4(
                glm::min(xy(m_layers[source_idx]->box(i)), xy(lbox)),
                glm::max(zw(m_layers[source_idx]->box(i)), zw(lbox))
            );
            m_layers[dest_idx]->face(i) = true;

            set_active_texture_unit(0);
            m_tex2[i].bind();
            copy_framebuffer_to_texture_2d(0, 0, 0, 0, m_width, m_height);
            m_tex2[i].unbind();

            m_sampler.bind(0);
            m_sampler_nearest.bind(1);
            {
                pp::panopainter::setup_legacy_stroke_composite_shader(
                    pp::panopainter::LegacyStrokeCompositeUniforms {
                        .resolution = m_size,
                        .mvp = glm::ortho(-.5f, .5f, -.5f, .5f, -1.f, 1.f),
                        .layer_alpha = m_layers[source_idx]->m_opacity,
                        .alpha_lock = false,
                        .mask_enabled = false,
                        .use_fragcoord = false,
                        .blend_mode = m_layers[source_idx]->m_blend_mode,
                        .use_dual = false,
                        .dual_alpha = 0.0f,
                        .use_pattern = false,
                    });

                set_active_texture_unit(0);
                m_tex2[i].bind();
                set_active_texture_unit(1);
                m_layers[source_idx]->rtt(i).bindTexture();
                m_plane.draw_fill();
                m_layers[source_idx]->rtt(i).unbindTexture();
                set_active_texture_unit(0);
                m_tex2[i].unbind();
            }

            m_layers[dest_idx]->rtt(i).unbindFramebuffer();
        }
    });
}

void Canvas::flood_fill(int layer, int plane, std::vector<glm::ivec2> pos, FloodData& plane_data,
    float threshold, glm::vec4 dest_color, std::unique_ptr<glm::vec4>& source_color)
{
    struct adj_t
    {
        int plane;
        bool flipx;
        bool flipy;
        bool flipcoord;
        adj_t(int plane, bool flipx, bool flipy, int flipcoord) :
            plane(plane), flipx(flipx), flipy(flipy), flipcoord(flipcoord) { }
        glm::ivec2 compute(glm::ivec2 p, glm::ivec2 sz) const
        {
            glm::ivec2 ret;
            ret[flipcoord] = flipx ? sz.x - p.x : p.x;
            ret[1 - flipcoord] = flipy ? sz.y - p.y : p.y;
            return ret;
        }
    };

    LOG("flood_fill plane %d", plane);

    auto& rtt = m_layers[layer]->rtt(plane);
    auto sz = rtt.getSize();

    if (!plane_data.mask[plane])
    {
        plane_data.mask[plane] = std::make_unique<bool[]>((size_t)sz.x * sz.y);
        plane_data.rgb[plane] = std::unique_ptr<glm::u8vec4[]>(
            reinterpret_cast<glm::u8vec4*>(m_layers[layer]->rtt(plane).readTextureData()));
        plane_data.bb[plane] = { sz.x, sz.y, 0, 0 };
        plane_data.dirty[plane] = false;
        plane_data.layer = m_layers[layer];
    }
    auto& mask = plane_data.mask[plane];
    auto& rgb = plane_data.rgb[plane];

    if (!source_color)
        source_color = std::make_unique<glm::vec4>(rgb[pos.back().y * sz.x + pos.back().x]);
    const glm::vec4 c = *source_color;

    std::array<std::vector<glm::ivec2>, 4> edges;
    static const std::array<adj_t, 4> adj[6] = {
        {
            adj_t(3, 1, 0, 0),
            adj_t(4, 1, 1, 0),
            adj_t(1, 0, 0, 0),
            adj_t(5, 1, 0, 0),
        },
        {
            adj_t(0, 1, 0, 0),
            adj_t(4, 1, 0, 1),
            adj_t(2, 0, 0, 0),
            adj_t(5, 0, 0, 1),
        },
        {
            adj_t(1, 1, 0, 0),
            adj_t(4, 0, 0, 0),
            adj_t(3, 0, 0, 0),
            adj_t(5, 0, 1, 0),
        },
        {
            adj_t(2, 1, 0, 0),
            adj_t(4, 0, 1, 1),
            adj_t(0, 0, 0, 0),
            adj_t(5, 1, 1, 1),
        },
        {
            adj_t(1, 1, 1, 1),
            adj_t(0, 1, 1, 0),
            adj_t(3, 1, 0, 1),
            adj_t(2, 0, 1, 0),
        },
        {
            adj_t(1, 0, 0, 1),
            adj_t(2, 0, 0, 0),
            adj_t(3, 0, 1, 1),
            adj_t(0, 1, 0, 0),
        },
    };

    auto test = [&](glm::ivec2 p, bool set_color) -> bool
    {
        int i = p.y * sz.x + p.x;
        if (p.x < 0)
        {
            edges[0].push_back(adj[plane][0].compute({ -p.x, p.y }, sz));
            return false;
        }
        else if (p.x >= sz.x)
        {
            edges[2].push_back(adj[plane][2].compute({ sz.x - p.x + 1, p.y }, sz));
            return false;
        }
        else if (p.y < 0)
        {
            edges[3].push_back(adj[plane][3].compute({ p.x, -p.y }, sz));
            return false;
        }
        else if (p.y >= sz.y)
        {
            edges[1].push_back(adj[plane][1].compute({ p.x, sz.y - p.y + 1 }, sz));
            return false;
        }
        if (!mask[i])
        {
            if (c.a == 0 && glm::abs(rgb[i].a - c.a) < threshold ||
                c.a > 0 && rgb[i].a > 0 && glm::distance(glm::vec3(c), glm::vec3(rgb[i])) < threshold)
            {
                if (set_color)
                {
                    mask[i] = true;
                    rgb[i] = dest_color * 255.f;
                    plane_data.dirty[plane] = true;
                    glm::vec2 bb_min = glm::min((glm::vec2)p, xy(plane_data.bb[plane]));
                    glm::vec2 bb_max = glm::max((glm::vec2)p + glm::vec2(1), zw(plane_data.bb[plane]));
                    plane_data.bb[plane] = { bb_min, bb_max };
                }
                pos.push_back(p);
            }
            return true;
        }
        return false;
    };

    while (!pos.empty())
    {
        auto p = pos.back();
        pos.pop_back();
        if (!test(p + glm::ivec2(0, 0), true))
            continue;
        test(p + glm::ivec2(-1, 0), false);
        test(p + glm::ivec2(1, 0), false);
        test(p + glm::ivec2(0, 1), false);
        test(p + glm::ivec2(0, -1), false);
    }

    for (int i = 0; i < 4; i++)
    {
        if (!edges[i].empty())
        {
            flood_fill(layer, adj[plane][i].plane, edges[i], plane_data, threshold, dest_color, source_color);
        }
    }
}

void Canvas::FloodData::apply()
{
    for (int plane = 0; plane < 6; plane++)
    {
        if (!dirty[plane])
            continue;
        auto& rtt = layer->rtt(plane);
        App::I->render_task([&]
        {
            rtt.updateRgba8(0, 0, rtt.getWidth(), rtt.getHeight(), rgb[plane].get());
        });
        layer->face(plane) = true;
        layer->box(plane) = box_union(layer->box(plane), bb[plane]);
    }
    Canvas::I->m_unsaved = true;
}