// mandel.cpp

#include "colors.h"
#include "mandel.h"

MandelResultCell::MandelResultCell() {}

MandelResultCell::MandelResultCell(size_t iter, QPointF rpos)
:   iter(iter), rpos(rpos) {}

static inline void incrpos(QPoint &pos, const int width) {
    pos.setX(pos.x() + 1);
    if (pos.x() == width) {
        pos.setX(0);
        pos.setY(pos.y() + 1);
    }
}

MandelMeta::MandelMeta(size_t max_iter, const QSize size)
:   max_iter(max_iter),
    img(size, QImage::Format_RGB888),
    cells(size.width() * size.height(), MandelCell(this)),
    center_f(qreal(-3) / 4, 0),
    one(1),
    four(4),
    scale(std::max(qreal(3) / size.width(), qreal(3) / size.height()))
{
    QVector<MandelCell>::iterator i;
    QPointF c(size.width() / 2., size.height() / 2.);
    QPoint pos;

    for (i = cells.begin(); i != cells.end(); incrpos(pos, size.width()), i++) {
        i->set_meta(this);
        i->set_pos(pos);
    }
}

void MandelMeta::zoom2x(QPoint pos) {
    QVector<MandelCell>::iterator i;
    center_f = cells[img.width() * pos.y() + pos.x()].get_rpos0();
    scale /= 2;
    img.fill(Qt::GlobalColor::black);
    for (i = cells.begin(); i != cells.end(); i++)
        i->reset_iter_and_rpos();
}

void MandelMeta::finished_cell(int num, const MandelResultCell &cell) {
    img.setPixelColor(
        cells[num].update_result(cell.iter, cell.rpos),
        cell.iter < max_iter
        ? colors[cell.iter % colors.size()]
        : Qt::GlobalColor::black
    );
}

MandelResultCell MandelMeta::iterate(const MandelCell &cell) {
    return cell.iterate();
}

void MandelCell::reset_rpos0() {
    QPointF center_f = meta->get_center_f();
    rpos0 = QPointF(
        center_f.x() + (pos.x() - meta->get_width() / 2.) * meta->get_scale(),
        center_f.y() + (pos.y() - meta->get_height() / 2.) * meta->get_scale()
    );
}

MandelCell::MandelCell(MandelMeta *meta) : meta(meta), iter(0) {}

MandelCell::MandelCell(const MandelCell &cell)
:   meta(cell.meta), pos(cell.pos), iter(cell.iter),
    rpos(cell.rpos), rpos0(cell.rpos0) {}

QPoint MandelCell::update_result(size_t iter, const QPointF &rpos) {
    this->iter = iter;
    this->rpos = rpos;
    return pos;
}

void MandelCell::reset_iter_and_rpos() {
    iter = 0;
    rpos = QPointF();
    reset_rpos0();
}

void MandelCell::set_meta(MandelMeta *meta) {
    this->meta = meta;
}

void MandelCell::set_pos(QPoint pos) {
    this->pos = pos;
    reset_rpos0();
}

MandelResultCell MandelCell::iterate() const {
    size_t iter = this->iter;
    QPointF rpos = this->rpos, sq;
    for (; iter < this->meta->get_max_iter(); iter++) {
        sq = QPointF(rpos.x() * rpos.x(), rpos.y() * rpos.y());
        if (sq.x() + sq.y() > meta->get_four())
            break;
        rpos = QPointF(
            sq.x() - sq.y() + rpos0.x(),
            2 * rpos.x() * rpos.y() + rpos0.y()
        );
    }
    return MandelResultCell(iter, rpos);
}