#include "grid_model.h"

namespace roro {

void GridModel::setCount(int count) {
    count_ = count < 0 ? 0 : count;
    if (count_ == 0) {
        selected_ = -1;
        first_ = 0;
        return;
    }
    select(selected_ < 0 ? 0 : selected_);
}

void GridModel::select(int index) {
    if (count_ == 0) return;
    selected_ = index < 0 ? 0 : index >= count_ ? count_ - 1 : index;
    int row = selected_ / cols_;
    if (row < first_) first_ = row;
    if (row >= first_ + rows_) first_ = row - rows_ + 1;
    int maxFirst = rows() > rows_ ? rows() - rows_ : 0;
    if (first_ > maxFirst) first_ = maxFirst;
}

void GridModel::left() {
    if (count_) select(selected_ == 0 ? count_ - 1 : selected_ - 1);
}

void GridModel::right() {
    if (count_) select(selected_ == count_ - 1 ? 0 : selected_ + 1);
}

void GridModel::up() {
    if (!count_) return;
    int col = selected_ % cols_, row = selected_ / cols_;
    row = row == 0 ? rows() - 1 : row - 1;
    select(row * cols_ + col);  // past the end of a short last row: the last item
}

void GridModel::down() {
    if (!count_) return;
    int col = selected_ % cols_, row = selected_ / cols_;
    row = row == rows() - 1 ? 0 : row + 1;
    select(row * cols_ + col);
}

}  // namespace roro