#include "LayoutBuilder.h"
#include "KeyGeometry.h"

#include <QSet>

#include <algorithm>

namespace {

// Letters without a Unicode decomposition, and the key they belong under.
const QHash<QString, QString> &baseOverrides()
{
    static const QHash<QString, QString> bases = {
        {QStringLiteral("ß"), QStringLiteral("s")}, {QStringLiteral("ł"), QStringLiteral("l")},
        {QStringLiteral("ø"), QStringLiteral("o")}, {QStringLiteral("æ"), QStringLiteral("a")},
        {QStringLiteral("œ"), QStringLiteral("o")}, {QStringLiteral("đ"), QStringLiteral("d")},
        {QStringLiteral("ð"), QStringLiteral("d")}, {QStringLiteral("þ"), QStringLiteral("t")},
        {QStringLiteral("ħ"), QStringLiteral("h")}, {QStringLiteral("ı"), QStringLiteral("i")},
    };
    return bases;
}

// "š" → "s": the letter an accented letter is a variant of.
QString baseLetter(const QString &letter)
{
    if (const auto it = baseOverrides().constFind(letter); it != baseOverrides().cend())
        return *it;
    return letter.normalized(QString::NormalizationForm_D).left(1);
}

// Long-press choices per key letter: the keymap's extras first (they're what
// this language types), then the template's, minus letters that have a key.
QHash<QString, QStringList> alternatesByLetter(const Layout &tmpl, const KeymapLetters &letters)
{
    QSet<QString> onKeys;
    for (const auto &row : letters.rows) {
        for (const Letter &letter : row)
            onKeys.insert(letter.lower);
    }

    QHash<QString, QStringList> result;
    const auto add = [&](const QString &base, const QString &choice) {
        QStringList &list = result[base];
        if (!onKeys.contains(choice) && !list.contains(choice))
            list.append(choice);
    };
    for (const Letter &extra : letters.extras)
        add(baseLetter(extra.lower), extra.lower);
    for (auto it = tmpl.alternates.cbegin(); it != tmpl.alternates.cend(); ++it) {
        for (const QString &choice : *it)
            add(it.key(), choice);
    }
    return result;
}

Row expandLetters(const Row &row, const KeymapLetters &letters, const QHash<QString, QStringList> &alternates)
{
    Row result;
    for (const KeyDef &key : row) {
        if (key.type != KeyType::Letters) {
            result.append(key);
            continue;
        }
        const QList<Letter> source = letters.rows.value(key.lettersRow);
        for (qsizetype i = 0; i < source.size(); ++i) {
            KeyDef letter;
            letter.label = source[i].lower;
            letter.shifted = source[i].upper;
            letter.flick = key.flicks.value(i);
            letter.alternates = alternates.value(source[i].lower);
            result.append(letter);
        }
    }
    return result;
}

void stretchRows(Layer &layer)
{
    qreal widest = 0;
    for (const Row &row : layer.rows)
        widest = std::max(widest, rowUnits(row));

    for (Row &row : layer.rows) {
        const auto stretchy = std::ranges::count_if(row, &KeyDef::stretch);
        if (stretchy == 0)
            continue;
        const qreal extra = (widest - rowUnits(row)) / qreal(stretchy);
        for (KeyDef &key : row) {
            if (key.stretch)
                key.width += extra;
        }
    }
}

} // namespace

Layout buildLayout(const Layout &tmpl, const KeymapLetters &letters)
{
    Layout layout = tmpl;
    layout.name = letters.name.isEmpty() ? tmpl.name : letters.name;
    layout.alternates.clear();

    const QHash<QString, QStringList> alternates = alternatesByLetter(tmpl, letters);
    for (Layer &layer : layout.layers) {
        for (Row &row : layer.rows)
            row = expandLetters(row, letters, alternates);
        stretchRows(layer);
    }
    return layout;
}