#pragma once

#include <centauri/cell.h>
#include <algorithm>

class BlockRegionIterator
{
public:
    struct iterator {
        const BlockRegionIterator& base;
        Cell cell;

        iterator(const BlockRegionIterator& base, Cell cell):
            base(base), cell(cell) {}
        const iterator& operator++();
        bool operator==(const iterator& o) { return cell == o.cell; }
        bool operator!=(const iterator& o) { return cell != o.cell; }
        Cell operator*() const { return cell; }
    };

    BlockRegionIterator(BlockRegion r);

    iterator begin() const;
    iterator end() const;

    BlockRegion region() const { return _r; }

private:
    BlockRegion _r;
};

inline const BlockRegionIterator::iterator&
    BlockRegionIterator::iterator::operator++()
{
    const BlockRegion r = base.region();

    // scanline iterations
    if(cell.x == r.x2) {
        cell.x = r.x1;
        ++cell.y;
    } else {
        ++cell.x;
    }
    return *this;
}

inline BlockRegionIterator::BlockRegionIterator(BlockRegion r):
    _r(r)
{
    if(_r.x2 < _r.x1) {
        std::swap(_r.x1, _r.x2);
    }
    if(_r.y2 < _r.y1) {
        std::swap(_r.y1, _r.y2);
    }
}

inline BlockRegionIterator::iterator BlockRegionIterator::begin() const {
    return iterator(*this, _r.lower());
}

inline BlockRegionIterator::iterator BlockRegionIterator::end() const {
    return iterator(*this, Cell(_r.x1, _r.y2+1));
}