/**
 * @file WF.cpp
 * @brief implementation of waterfall spectrum display
 */

#include "WF.h"
#include "qt_helpers.h"
#include "ui_wf_palette_design_dialog.h"

#include <QAction>
#include <QBrush>
#include <QColor>
#include <QColorDialog>
#include <QDialog>
#include <QFile>
#include <QFileDialog>
#include <QLoggingCategory>
#include <QMenu>
#include <QMetaType>
#include <QObject>
#include <QPoint>
#include <QPushButton>
#include <QStandardPaths>
#include <QString>
#include <QTableWidget>
#include <QTableWidgetItem>
#include <QTextStream>

#include <memory>

/******************************************************************************/
// Private Implementation
/******************************************************************************/

namespace {
int constexpr points{256};

using Colours = WF::Palette::Colours;

// ensure that palette colours are useable for interpolation
Colours make_valid(Colours colours) {
    if (colours.size() < 2) {
        // allow single element by starting at black
        colours.prepend(QColor{0, 0, 0});
    }

    if (1 == colours.size()) {
        // allow empty list by using black to white
        colours.append(QColor{255, 255, 255});
    }

    if (colours.size() > points) {
        throw_qstring(QObject::tr("Too many colours in palette."));
    }

    return colours;
}

// load palette colours from a file
Colours load_palette(QString const &file_name) {
    Colours colours;
    QFile file{file_name};
    if (file.open(QIODevice::ReadOnly)) {
        unsigned count{0};
        QTextStream in(&file);
        int line_counter{0};
        while (!in.atEnd()) {
            auto line = in.readLine();
            ++line_counter;

            if (++count >= points) {
                throw_qstring(QObject::tr("Error reading waterfall palette "
                                          "file \"%1:%2\" too many colors.")
                                  .arg(file.fileName())
                                  .arg(line_counter));
            }
            auto items = line.split(';');
            if (items.size() != 3) {
                throw_qstring(QObject::tr("Error reading waterfall palette "
                                          "file \"%1:%2\" invalid triplet.")
                                  .arg(file.fileName())
                                  .arg(line_counter));
            }
            bool r_ok, g_ok, b_ok;
            auto r = items[0].toInt(&r_ok);
            auto g = items[1].toInt(&g_ok);
            auto b = items[2].toInt(&b_ok);
            if (!r_ok || !g_ok || !b_ok || r < 0 || r > 255 || g < 0 ||
                g > 255 || b < 0 || b > 255) {
                throw_qstring(QObject::tr("Error reading waterfall palette "
                                          "file \"%1:%2\" invalid color.")
                                  .arg(file.fileName())
                                  .arg(line_counter));
            }
            colours.append(QColor{r, g, b});
        }
    } else {
        throw_qstring(
            QObject::tr("Error opening waterfall palette file \"%1\": %2.")
                .arg(file.fileName())
                .arg(file.errorString()));
    }

    return colours;
}

// GUI to design and manage waterfall palettes
class Designer : public QDialog {
    Q_OBJECT;

  public:
    explicit Designer(Colours const &current, QWidget *parent = nullptr)
        : QDialog{parent}, colours_{current} {
        ui_.setupUi(this);

        // context menu actions
        auto import_button = ui_.button_box->addButton(
            "&Import...", QDialogButtonBox::ActionRole);
        connect(import_button, &QPushButton::clicked, this,
                &Designer::import_palette);

        auto export_button = ui_.button_box->addButton(
            "&Export...", QDialogButtonBox::ActionRole);
        connect(export_button, &QPushButton::clicked, this,
                &Designer::export_palette);

        // hookup the context menu handler
        connect(ui_.colour_table_widget, &QWidget::customContextMenuRequested,
                this, &Designer::context_menu);

        load_table();
    }

    void load_table() {
        // load the table items
        ui_.colour_table_widget->clear();
        ui_.colour_table_widget->setRowCount(colours_.size());
        for (int i{0}; i < colours_.size(); ++i) {
            insert_item(i);
        }
    }

    Colours colours() const { return colours_; }

    // invoke the colour editor
    Q_SLOT void
    on_colour_table_widget_itemDoubleClicked(QTableWidgetItem *item) {
        auto new_colour =
            QColorDialog::getColor(item->background().color(), this);
        if (new_colour.isValid()) {
            item->setBackground(QBrush{new_colour});
            colours_[item->row()] = new_colour;
        }
    }

  private:
    void insert_item(int row) {
        std::unique_ptr<QTableWidgetItem> item{new QTableWidgetItem{""}};
        item->setBackground(QBrush{colours_[row]});
        item->setFlags(Qt::ItemIsEnabled);
        ui_.colour_table_widget->setItem(row, 0, item.release());
    }

    void insert_new_item(int row, QColor const &default_colour) {
        // use the prior row colour as default if available
        auto new_colour = QColorDialog::getColor(
            row > 0 ? colours_[row - 1] : default_colour, this);
        if (new_colour.isValid()) {
            ui_.colour_table_widget->insertRow(row);
            colours_.insert(row, new_colour);
            insert_item(row);
        }
    }

    void context_menu(QPoint const &p) {
        context_menu_.clear();
        if (ui_.colour_table_widget->itemAt(p)) {
            auto delete_action = context_menu_.addAction(tr("&Delete"));
            connect(delete_action, &QAction::triggered, [this]() {
                auto row = ui_.colour_table_widget->currentRow();
                ui_.colour_table_widget->removeRow(row);
                colours_.removeAt(row);
            });
        }

        auto insert_action = context_menu_.addAction(tr("&Insert ..."));
        connect(insert_action, &QAction::triggered, [this]() {
            auto item = ui_.colour_table_widget->itemAt(menu_pos_);
            int row = item ? item->row() : colours_.size();
            insert_new_item(row, QColor{0, 0, 0});
        });

        auto insert_after_action =
            context_menu_.addAction(tr("Insert &after ..."));
        connect(insert_after_action, &QAction::triggered, [this]() {
            auto item = ui_.colour_table_widget->itemAt(menu_pos_);
            int row = item ? item->row() + 1 : colours_.size();
            insert_new_item(row, QColor{255, 255, 255});
        });

        menu_pos_ = p; // save for context menu action handlers
        context_menu_.popup(ui_.colour_table_widget->mapToGlobal(p));
    }

    void import_palette() {
        auto docs =
            QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
        auto file_name = QFileDialog::getOpenFileName(
            this, tr("Import Palette"), docs, tr("Palettes (*.pal)"));
        if (!file_name.isEmpty()) {
            colours_ = load_palette(file_name);
            load_table();
        }
    }

    void export_palette() {
        auto docs =
            QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
        auto file_name = QFileDialog::getSaveFileName(
            this, tr("Export Palette"), docs, tr("Palettes (*.pal)"));
        if (!file_name.isEmpty()) {
            if (!QFile::exists(file_name) && !file_name.contains('.')) {
                file_name += ".pal";
            }
            QFile file{file_name};
            if (file.open(QFile::WriteOnly | QFile::Truncate | QFile::Text)) {
                QTextStream stream{&file};
                Q_FOREACH (auto colour, colours_) {
                    stream << colour.red() << ';' << colour.green() << ';'
                           << colour.blue() << Qt::endl;
                }
            } else {
                throw_qstring(
                    QObject::tr(
                        "Error writing waterfall palette file \"%1\": %2.")
                        .arg(file.fileName())
                        .arg(file.errorString()));
            }
        }
    }

    Ui::wf_palette_design_dialog ui_;
    Colours colours_;
    QMenu context_menu_;
    QPoint menu_pos_;
};
} // namespace

#include "WF.moc"

Q_DECLARE_LOGGING_CATEGORY(wf_js8)

/******************************************************************************/
// Public Implementation
/******************************************************************************/

namespace WF {
Palette::Palette(QString const &file_path)
    : colours_{load_palette(file_path)} {}

Palette::Palette(Colours const &colour_list) : colours_{colour_list} {}

// generate an array of colours suitable for the waterfall plotter
QVector<QColor> Palette::interpolate() const {
    Colours colours{make_valid(colours_)};
    QVector<QColor> result;
    result.reserve(points);

    // do a linear-ish gradient between each supplied colour point
    auto interval = qreal(points) / (colours.size() - 1);

    for (int i{0}; i < points; ++i) {
        int prior = i / interval;

        if (prior >= (colours.size() - 1)) {
            --prior;
        }
        auto next = prior + 1;
        if (next >= colours.size()) {
            --next;
        }

        // qCDebug (wf_js8) << "Palette::interpolate: prior:" << prior <<
        // "total:" << colours.size ();

        auto increment = i - qreal(interval) * prior;
        qreal r{colours[prior].redF() +
                (increment * (colours[next].redF() - colours[prior].redF())) /
                    interval};
        qreal g{
            colours[prior].greenF() +
            (increment * (colours[next].greenF() - colours[prior].greenF())) /
                interval};
        qreal b{colours[prior].blueF() +
                (increment * (colours[next].blueF() - colours[prior].blueF())) /
                    interval};
        result.append(QColor::fromRgbF(r, g, b));

        // qCDebug (wf_js8) << "Palette colour[" << (result.size () - 1) << "]
        // =" << result[result.size () - 1] << "from: r:" << r << "g:" << g <<
        // "b:" << b;
    }

    return result;
}

// invoke the palette designer
bool Palette::design() {
    if (auto designer = Designer{colours_};
        designer.exec() == QDialog::Accepted) {
        colours_ = designer.colours();
        return true;
    }
    return false;
}
} // namespace WF

/******************************************************************************/

Q_LOGGING_CATEGORY(wf_js8, "wf.js8", QtWarningMsg)