// SPDX-License-Identifier: GPL-2.0+
/*******************************************************************************
 * QtMips - MIPS 32-bit Architecture Subset Simulator
 *
 * Implemented to support following courses:
 *
 *   B35APO - Computer Architectures
 *   https://cw.fel.cvut.cz/wiki/courses/b35apo
 *
 *   B4M35PAP - Advanced Computer Architectures
 *   https://cw.fel.cvut.cz/wiki/courses/b4m35pap/start
 *
 * Copyright (c) 2017-2019 Karel Koci<cynerd@email.cz>
 * Copyright (c) 2019      Pavel Pisa <pisa@cmp.felk.cvut.cz>
 *
 * Faculty of Electrical Engineering (http://www.fel.cvut.cz)
 * Czech Technical University        (http://www.cvut.cz/)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA  02110-1301, USA.
 *
 ******************************************************************************/

#include "connection.h"
#include <qtmipsexception.h>
#include <cmath>

using namespace coreview;

Connector::Connector(enum Axis ax) {
    qx = 0;
    qy = 0;
    this->ax = ax;
}

void Connector::setPos(qreal x, qreal y) {
    qx = x;
    qy = y;
    emit updated(point());
    emit updated(vector());
}

void Connector::setPos(const QPointF &p) {
    setPos(p.x(), p.y());
}

enum Connector::Axis Connector::axis() const {
    return ax;
}

qreal Connector::x() const {
    return qx;
}

qreal Connector::y() const {
    return qy;
}

QPointF Connector::point() const {
    return QPointF(qx, qy);
}

QLineF Connector::vector() const {
    QPointF p = point();
    switch (ax) {
    case AX_X:
        return QLineF(p, p + QPointF(1, 0));
    case AX_Y:
        return QLineF(p, p + QPointF(0, 1));
    case AX_XY:
        return QLineF(p, p + QPointF(1, 1));
    case AX_MXY:
        return QLineF(p, p + QPoint(1, -1));
    }
    throw QTMIPS_EXCEPTION(Sanity, "Connection::vector() unknown axes set", QString::number(ax));
}

Connection::Connection(const Connector *a, const Connector *b) : QGraphicsObject(nullptr) {
    pen_width = 1;

    ax_start = a->vector();
    ax_end = a->vector();

    connect(a, SIGNAL(updated(QLineF)), this, SLOT(moved_start(QLineF)));
    connect(b, SIGNAL(updated(QLineF)), this, SLOT(moved_end(QLineF)));
    moved_start(a->vector());
    moved_end(b->vector());
}

void Connection::setHasText(bool has) {
    if (has && value == nullptr) {
        value = new QGraphicsSimpleTextItem(this);
        value->setText(text);
    } else if (!has && value != nullptr) {
        delete value;
    }
}

void Connection::setText(QString val) {
    text = val;
    if (value != nullptr)
        value->setText(val);
}

void Connection::setAxes(QVector<QLineF> axes) {
    break_axes = axes;
    recalc_line();
}

void Connection::moved_start(QLineF p) {
    ax_start = p;
    recalc_line();
}

void Connection::moved_end(QLineF p) {
    ax_end = p;
    recalc_line();
}

QRectF Connection::boundingRect() const {
    QRectF rect;
    for (int i = 0; i < (points.size() - 1); i++) {
        qreal x = points[i].x() > points[i+1].x() ? points[i+1].x() : points[i].x();
        qreal y = points[i].y() > points[i+1].y() ? points[i+1].y() : points[i].y();
        rect |= QRectF(x - pen_width/2.0, y - pen_width/2.0, fabs(points[i].x() - points[i+1].x()) + pen_width, fabs(points[i].y() - points[i+1].y()) + pen_width);
    }
    return rect;
}

void Connection::paint(QPainter *painter, const QStyleOptionGraphicsItem *option __attribute__((unused)), QWidget *widget __attribute__((unused))) {
    QPen pen;
    pen.setWidth(pen_width);
    pen.setColor(color);
    pen.setCapStyle(Qt::FlatCap);
    pen.setJoinStyle(Qt::BevelJoin);
    painter->setPen(pen);

    painter->drawPolyline(QPolygonF(points));
}

void Connection::recalc_line() {
    points.clear();

    points.append(ax_start.p1());

    QLineF cur_l = ax_start;
    for (int i = 0; i < break_axes.size(); i++) {
        if (recalc_line_add_point(cur_l, break_axes[i]))
            cur_l = break_axes[i];
    }
    recalc_line_add_point(cur_l, ax_end);

    points.append(ax_end.p1());
}

bool Connection::recalc_line_add_point(const QLineF &l1, const QLineF &l2) {
    QPointF intersec;
    if (l1.intersect(l2, &intersec) == QLineF::NoIntersection)
        return false;
    points.append(intersec);
    return true;
}

Bus::Bus(const Connector *start, const Connector *end, unsigned width) : Connection(start, end) {
    pen_width = width;
}

Bus::~Bus() {
    for (int i = 0; i < conns.size(); i++)
        delete conns[i].c;
}

void Bus::setAxes(QVector<QLineF> axes) {
    Connection::setAxes(axes);
    conns_update();
}

const Connector *Bus::new_connector(qreal x, qreal y, enum Connector::Axis axis) {
    Connector *c = new Connector(axis);
    conns.append({
        .c = c,
        .p = QPoint(x, y)
     });
    conns_update();
    return c;
}

const Connector *Bus::new_connector(const QPointF &p, enum Connector::Axis axis) {
    return new_connector(p.x(), p.y(), axis);
}

// Calculate closes point to given line. We do it by calculating rectangular intersection between given line and imaginary line crossing given point.
static qreal cu_closest(const QLineF &l, const QPointF &p, QPointF *intersec) {
    // Closest point is on normal vector
    QLineF normal = l.normalVector();
    // Now move normal vector to 0,0 and then to p
    QLineF nline = normal.translated(-normal.p1()).translated(p);
    // And now found intersection
    SANITY_ASSERT(l.intersect(nline, intersec) != QLineF::NoIntersection, "We are calculating intersection with normal vector and that should always have intersection");
    // Now check if that point belongs to given line
    // We know that this is intersection so just check if we are not outside of line limits
    // TODO replace intersec if it's outside of given line with one of corner points

    return (p - *intersec).manhattanLength(); // return length from each other
}

void Bus::conns_update() {
    for (int i = 0; i < conns.size(); i++) {
        QPointF closest;
        qreal closest_range = 0; // Just to suppress warning. On first check the closest is null so we set it later on

        QPointF inter;
        qreal range;
        for (int y = 0; y < (points.size() - 1); y++) {
            if (points[y] == points[y+1]) // TODO this is just workaround (for some reason we have lines with multiple points same. It should do no harm in reality but it causes this math to break so skip it here) (well reason is probably missmatch of axis, line comes from x for example but it should come from y so it creates line of zero length)
                continue;
            range = cu_closest(QLineF(points[y], points[y+1]), QPointF(conns[i].p), &inter);
            if (closest.isNull() || closest_range > range) {
                closest = inter;
                closest_range = range;
            }
        }

        conns[i].c->setPos(closest);
    }
}

Signal::Signal(const Connector *start, const Connector *end) : Connection(start, end) {
    color = QColor(0, 0, 255);
}