// SPDX-FileCopyrightText: 2021 Nheko Contributors
// SPDX-FileCopyrightText: 2022 Nheko Contributors
//
// SPDX-License-Identifier: GPL-3.0-or-later

#include "CompletionProxyModel.h"

#include <QRegularExpression>
#include <QTextBoundaryFinder>

#include "CompletionModelRoles.h"
#include "Logging.h"
#include "Utils.h"

CompletionProxyModel::CompletionProxyModel(QAbstractItemModel *model,
                                           int max_mistakes,
                                           size_t max_completions,
                                           QObject *parent)
  : QAbstractProxyModel(parent)
  , maxMistakes_(max_mistakes)
  , max_completions_(max_completions)
{
    setSourceModel(model);

    auto insertParts = [this](const QString &str, int id) {
        QTextBoundaryFinder finder(QTextBoundaryFinder::BoundaryType::Word, str);
        finder.toStart();
        do {
            auto start = finder.position();
            finder.toNextBoundary();
            auto end = finder.position();

            auto ref = str.midRef(start, end - start).trimmed();
            if (!ref.isEmpty())
                trie_.insert<ElementRank::second>(ref.toUcs4(), id);
        } while (finder.position() < str.size());
    };

    const auto start_at = std::chrono::steady_clock::now();

    // insert full texts and partial matches
    for (int i = 0; i < sourceModel()->rowCount(); i++) {
        // full texts are ranked first and partial matches second
        // that way when searching full texts will be first in result list

        auto string1 = sourceModel()
                         ->data(sourceModel()->index(i, 0), CompletionModel::SearchRole)
                         .toString()
                         .toLower();
        if (!string1.isEmpty()) {
            trie_.insert<ElementRank::first>(string1.toUcs4(), i);
            insertParts(string1, i);
        }

        auto string2 = sourceModel()
                         ->data(sourceModel()->index(i, 0), CompletionModel::SearchRole2)
                         .toString()
                         .toLower();
        if (!string2.isEmpty()) {
            trie_.insert<ElementRank::first>(string2.toUcs4(), i);
            insertParts(string2, i);
        }
    }

    const auto end_at     = std::chrono::steady_clock::now();
    const auto build_time = std::chrono::duration<double, std::milli>(end_at - start_at);
    nhlog::ui()->debug("CompletionProxyModel: build trie: {} ms", build_time.count());

    // initialize default mapping
    mapping.resize(std::min(max_completions_, static_cast<size_t>(model->rowCount())));
    std::iota(mapping.begin(), mapping.end(), 0);

    connect(
      this,
      &CompletionProxyModel::newSearchString,
      this,
      [this](const QString &s) {
          searchString_ = s.toLower();
          invalidate();
      },
      Qt::QueuedConnection);
}

void
CompletionProxyModel::invalidate()
{
    auto key = searchString_.toUcs4();
    beginResetModel();
    if (!key.empty()) // return default model data, if no search string
        mapping = trie_.search(key, max_completions_, maxMistakes_);
    endResetModel();
}

QHash<int, QByteArray>
CompletionProxyModel::roleNames() const
{
    return this->sourceModel()->roleNames();
}

int
CompletionProxyModel::rowCount(const QModelIndex &) const
{
    if (searchString_.isEmpty())
        return std::min(
          static_cast<int>(std::min<size_t>(max_completions_, std::numeric_limits<int>::max())),
          sourceModel()->rowCount());
    else
        return (int)mapping.size();
}

QModelIndex
CompletionProxyModel::mapFromSource(const QModelIndex &sourceIndex) const
{
    // return default model data, if no search string
    if (searchString_.isEmpty()) {
        return index(sourceIndex.row(), 0);
    }

    for (int i = 0; i < (int)mapping.size(); i++) {
        if (mapping[i] == sourceIndex.row()) {
            return index(i, 0);
        }
    }
    return QModelIndex();
}

QModelIndex
CompletionProxyModel::mapToSource(const QModelIndex &proxyIndex) const
{
    auto row = proxyIndex.row();

    // return default model data, if no search string
    if (searchString_.isEmpty()) {
        return index(row, 0);
    }

    if (row < 0 || row >= (int)mapping.size())
        return QModelIndex();

    return sourceModel()->index(mapping[row], 0);
}

QModelIndex
CompletionProxyModel::index(int row, int column, const QModelIndex &) const
{
    return createIndex(row, column);
}

QModelIndex
CompletionProxyModel::parent(const QModelIndex &) const
{
    return QModelIndex{};
}
int
CompletionProxyModel::columnCount(const QModelIndex &) const
{
    return sourceModel()->columnCount();
}

QVariant
CompletionProxyModel::completionAt(int i) const
{
    if (i >= 0 && i < rowCount())
        return data(index(i, 0), CompletionModel::CompletionRole);
    else
        return {};
}

void
CompletionProxyModel::setSearchString(const QString &s)
{
    emit newSearchString(s);
}