#include "game/map/paint_layer.hpp"

#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <iostream>
#include <variant>

#include "core/rendering/screen.hpp"
#include "core/rendering/surface.hpp"
#include "core/resources/resource_cache.hpp"
#include "game/map/map.hpp"
#include "game/map/tilemap.hpp"

namespace {

    // Blit d'un tile del tileset sobre un buffer ARGB de destí, respectant
    // l'índex transparent del GIF. Mateixa convenció que la versió a
    // `tilemap.cpp`: el tileset guarda índexs + paleta, i la destinació
    // és un buffer ARGB32 lineal. Duplicat intencionat per no acoblar
    // Tilemap i PaintLayer; si en el futur un tercer consumidor el vol
    // reutilitzar, es promou a un helper compartit.
    void blitTile(const Surface& tileset, int tile_size, int src_col, int src_row, std::vector<std::uint32_t>& dest, int dest_w, int dest_x, int dest_y) {
        const int SRC_X0 = src_col * tile_size;
        const int SRC_Y0 = src_row * tile_size;
        const auto TRANSPARENT = tileset.getTransparentColor();
        for (int y = 0; y < tile_size; ++y) {
            for (int x = 0; x < tile_size; ++x) {
                const auto IDX = tileset.getPixel(SRC_X0 + x, SRC_Y0 + y);
                if (IDX == TRANSPARENT) { continue; }
                const auto ARGB = tileset.getPaletteColor(IDX);
                const auto DST_OFFSET =
                    (static_cast<std::size_t>(dest_y + y) * static_cast<std::size_t>(dest_w)) + static_cast<std::size_t>(dest_x + x);
                dest[DST_OFFSET] = ARGB;
            }
        }
    }

}  // namespace

PaintLayer::PaintLayer(const Tilemap& tilemap, EventBus* bus)
    : bus_(bus),
      cols_(tilemap.getCols()),
      rows_(tilemap.getRows()),
      tile_size_(tilemap.getTileSize()),
      origin_x_(tilemap.getOriginX()),
      origin_y_(tilemap.getOriginY()),
      width_px_(tilemap.getWidth()),
      height_px_(tilemap.getHeight()),
      tileset_cols_(tilemap.getTilesetCols()),
      tileset_path_(tilemap.getTilesetPath()) {
    painted_.assign(static_cast<std::size_t>(rows_), std::vector<int>(static_cast<std::size_t>(cols_), -1));
    pixels_.assign(
        static_cast<std::size_t>(width_px_) * static_cast<std::size_t>(height_px_),
        0U);

    if (bus_ != nullptr) {
        // Subscripció a `on_tile_entered`: el Player publica aquest event
        // amb `PaintedTile{col, row, tile_index}`. Filtrem pintabilitat
        // (sòl transitable) via `Map::isPaintable` i, si aplica, marquem
        // i re-publiquem `tile_painted` amb només la posició.
        on_tile_sub_ = bus_->subscribe("on_tile_entered", [this](const Event& ev) {
            // Re-propaguem el `player_id` de qui ha trepitjat la cel·la, perquè
            // `tile_painted` (que consumeixen els sarcòfags i el HUD futur)
            // sàpiga quin jugador ha pintat.
            const auto* paint = std::get_if<PaintedTile>(&ev.payload);
            if (paint != nullptr) { tryPaint(paint->col, paint->row, paint->tile_index, ev.player_id); }
        });
    }

    std::cout << "PaintLayer: " << cols_ << "x" << rows_ << " tiles ("
              << width_px_ << "x" << height_px_ << " px), tileset "
              << tileset_path_ << '\n';
}

PaintLayer::~PaintLayer() {
    if (bus_ != nullptr && on_tile_sub_ != 0) { bus_->unsubscribe(on_tile_sub_); }
}

auto PaintLayer::isPainted(int col, int row) const -> bool {
    if (col < 0 || col >= cols_ || row < 0 || row >= rows_) { return false; }
    return painted_[static_cast<std::size_t>(row)][static_cast<std::size_t>(col)] >= 0;
}

void PaintLayer::clear() {
    // Mateixa geometria que al ctor: matriu de tiles a -1 (no pintat) i
    // buffer ARGB a zero (alpha=0 = transparent → render no escriu res).
    painted_.assign(static_cast<std::size_t>(rows_), std::vector<int>(static_cast<std::size_t>(cols_), -1));
    std::ranges::fill(pixels_, 0U);
}

auto PaintLayer::tryPaint(int col, int row, int tile_index, int player_id) -> bool {
    if (col < 0 || col >= cols_ || row < 0 || row >= rows_) { return false; }
    if (tile_index < 0) { return false; }
    if (painted_[static_cast<std::size_t>(row)][static_cast<std::size_t>(col)] >= 0) {
        // Primer que pinta guanya: no sobreescrivim.
        return false;
    }
    if (!Map::isPaintable(col, row)) { return false; }

    painted_[static_cast<std::size_t>(row)][static_cast<std::size_t>(col)] = tile_index;
    blitPaintTile(col, row, tile_index);

    if (bus_ != nullptr) {
        bus_->publish(Event{
            .name = "tile_painted",
            .payload = TilePos{.col = col, .row = row},
            .player_id = player_id,
        });
    }
    return true;
}

void PaintLayer::blitPaintTile(int col, int row, int tile_index) {
    const auto TILESET = Resource::Cache::get().getSurface(tileset_path_);
    if (TILESET == nullptr) { return; }
    const int DX = col * tile_size_;
    const int DY = row * tile_size_;
    const int SRC_COL = tile_index % tileset_cols_;
    const int SRC_ROW = tile_index / tileset_cols_;
    blitTile(*TILESET, tile_size_, SRC_COL, SRC_ROW, pixels_, width_px_, DX, DY);
}

void PaintLayer::render() const {
    // Còpia ARGB al canvas, anàloga a `Tilemap::render`. Píxels amb
    // alpha=0 (tiles no pintats) es salten per deixar visible el tilemap
    // base per sota.
    auto& screen = Screen::get();
    auto* canvas = screen.getCanvasArgb();
    const int CANVAS_W = screen.getCanvasWidth();
    const int CANVAS_H = screen.getCanvasHeight();

    const int Y_START = std::max(0, -origin_y_);
    const int Y_END = std::min(height_px_, CANVAS_H - origin_y_);
    const int X_START = std::max(0, -origin_x_);
    const int X_END = std::min(width_px_, CANVAS_W - origin_x_);

    constexpr std::uint32_t ALPHA_MASK = 0xFF000000U;
    for (int y = Y_START; y < Y_END; ++y) {
        const auto* src_row = &pixels_[static_cast<std::size_t>(y) * static_cast<std::size_t>(width_px_)];
        auto* dst_row =
            &canvas[(static_cast<std::size_t>(origin_y_ + y) * static_cast<std::size_t>(CANVAS_W)) + static_cast<std::size_t>(origin_x_)];
        for (int x = X_START; x < X_END; ++x) {
            const auto PIXEL = src_row[x];
            if ((PIXEL & ALPHA_MASK) != 0U) { dst_row[x] = PIXEL; }
        }
    }
}