// bank_grid — pure implementation. See bank_grid.h. NO REAPER / SWELL / vendor.

#include "bank_grid.h"

namespace reasampler {

int columnsForWidth(int panelWidth, const GridSpec& spec) {
    // Layout: [gap][cell][gap][cell]...[cell][gap]. n cells occupy
    // gap + n*(cellWidth + gap). Solve for the largest n that fits panelWidth,
    // clamped to at least 1 so a too-narrow panel still shows a (clipped) column.
    const int cell = spec.cellWidth + spec.gap;
    if (cell <= 0) return 1;  // degenerate spec — one column, avoid divide-by-zero
    const int usable = panelWidth - spec.gap;
    if (usable < spec.cellWidth) return 1;
    const int cols = usable / cell;
    return cols < 1 ? 1 : cols;
}

std::vector<CellRect> computeCellRects(int itemCount,
                                       int panelWidth,
                                       const GridSpec& spec) {
    std::vector<CellRect> rects;
    if (itemCount <= 0) return rects;

    const int cols = columnsForWidth(panelWidth, spec);
    rects.reserve(static_cast<std::size_t>(itemCount));

    for (int i = 0; i < itemCount; ++i) {
        const int col = i % cols;
        const int row = i / cols;
        CellRect r;
        r.x = spec.gap + col * (spec.cellWidth + spec.gap);
        r.y = spec.gap + row * (spec.cellHeight + spec.gap);
        r.width = spec.cellWidth;
        r.height = spec.cellHeight;
        rects.push_back(r);
    }
    return rects;
}

int contentHeight(int itemCount, int panelWidth, const GridSpec& spec) {
    if (itemCount <= 0) return 0;
    const int cols = columnsForWidth(panelWidth, spec);
    // Ceil-divide item count by columns to get the row count (partial last row
    // still occupies a full row of height).
    const int rows = (itemCount + cols - 1) / cols;
    return spec.gap + rows * (spec.cellHeight + spec.gap);
}

std::string thumbnailKeyString(const ThumbnailKey& key) {
    // Length-prefix the sampleId so a delimiter byte inside an id cannot forge a
    // collision with a different (id, width, generation) triple.
    std::string s;
    s.reserve(key.sampleId.size() + 32);
    s += std::to_string(key.sampleId.size());
    s += ':';
    s += key.sampleId;
    s += '|';
    s += std::to_string(key.width);
    s += '|';
    s += std::to_string(key.generation);
    return s;
}

} // namespace reasampler