#include "filesystemmodel.hpp"

#include <qcoreapplication.h>
#include <qdatetime.h>
#include <qdir.h>
#include <qdiriterator.h>
#include <qfile.h>
#include <qfileinfo.h>
#include <qfuturewatcher.h>
#include <qimage.h>
#include <qpointer.h>
#include <qprocess.h>
#include <qregularexpression.h>
#include <qtemporarydir.h>
#include <qtconcurrentrun.h>

#include <algorithm>

namespace ZShell::models {

const QStringList kVideoExtensions = {
	"mp4",
	"mkv",
	"webm",
	"avi",
	"mov",
	"wmv",
	"flv",
	"m4v",
	"mpg",
	"mpeg",
	"3gp",
	"ogv",
	"ts",
	"vob",
};

bool hasVideoExtension(const QString& path) {
	return kVideoExtensions.contains(QFileInfo(path).suffix().toLower());
}

QString videoThumbnailPath(const QString& path) {
	const QFileInfo info(path);

	QString key = QStringLiteral("%1_%2_%3")
					  .arg(info.baseName())
					  .arg(info.size())
					  .arg(info.lastModified().toMSecsSinceEpoch() / 1000);
	key.replace(QRegularExpression("[^A-Za-z0-9._-]"), "_");

	return QDir::homePath() + "/.cache/zshell/imagecache/video-previews/" +
		   key + "_preview.jpg";
}

bool generateVideoThumbnail(const QString& src, const QString& cachePath) {
	if (QFile::exists(cachePath)) {
		return true;
	}

	const QString scale = QStringLiteral(
		"scale=1920:1080:force_original_aspect_ratio=decrease,"
		"scale=trunc(iw/2)*2:trunc(ih/2)*2");

	auto runProcess = [](const QString& program, const QStringList& args) {
		QProcess process;
		process.start(program, args);
		process.waitForFinished(15000);
		return qMakePair(process.exitCode(), process.readAllStandardOutput());
	};

	double duration = 0.0;
	const auto probe = runProcess(
		"ffprobe",
		{
			"-v",
			"error",
			"-show_entries",
			"format=duration",
			"-of",
			"default=nw=1:nk=1",
			src,
		});
	if (probe.first == 0) {
		duration = QString::fromUtf8(probe.second).trimmed().toDouble();
	}

	const int samples = duration > 0 ? std::min(10, std::max(4, int(duration)))
									 : 8;

	QTemporaryDir tmpDir;
	if (!tmpDir.isValid()) {
		return false;
	}

	int bestIndex = -1;
	double bestChroma = -1.0;
	double bestLuma = -1.0;

	for (int i = 0; i < samples; ++i) {
		const double frac = duration > 0 ? (i + 0.5) / samples : 0.0;
		const QString seek = duration > 0
								 ? QString::number(frac * duration, 'f', 3)
								 : QStringLiteral("0");

		const QString framePath =
			tmpDir.filePath(QStringLiteral("frame_%1.jpg").arg(i));

		runProcess(
			"ffmpeg",
			{
				"-hide_banner",
				"-loglevel",
				"error",
				"-ss",
				seek,
				"-i",
				src,
				"-frames:v",
				"1",
				"-vf",
				scale,
				"-pix_fmt",
				"yuvj420p",
				"-q:v",
				"2",
				"-y",
				framePath,
			});

		QImage frame(framePath);
		if (frame.isNull()) {
			continue;
		}

		frame = frame.convertToFormat(QImage::Format_RGB888);

		double chroma = 0.0;
		double luma = 0.0;
		int count = 0;
		for (int y = 0; y < frame.height(); ++y) {
			const auto* line = frame.constScanLine(y);
			for (int x = 0; x < frame.width(); ++x) {
				const int r = line[x * 3];
				const int g = line[x * 3 + 1];
				const int b = line[x * 3 + 2];
				chroma += std::max({r, g, b}) - std::min({r, g, b});
				luma += r + g + b;
				++count;
			}
		}

		const int n = std::max(1, count);
		chroma /= n;
		luma /= 3.0 * n;

		if (chroma > bestChroma + 0.5 ||
			(chroma > bestChroma - 0.5 && luma > bestLuma)) {
			bestChroma = chroma;
			bestLuma = luma;
			bestIndex = i;
		}
	}

	if (bestIndex < 0) {
		return false;
	}

	QDir().mkpath(QFileInfo(cachePath).absolutePath());
	return QFile::copy(
		tmpDir.filePath(QStringLiteral("frame_%1.jpg").arg(bestIndex)),
		cachePath);
}

FileSystemEntry::FileSystemEntry(
	const QString& path, const QString& relativePath, QObject* parent)
	: QObject(parent)
	, m_fileInfo(path)
	, m_path(path)
	, m_relativePath(relativePath)
	, m_thumbnailPath(path)
	, m_isImageInitialised(false)
	, m_mimeTypeInitialised(false) {}

QString FileSystemEntry::path() const {
	return m_path;
};

QString FileSystemEntry::relativePath() const {
	return m_relativePath;
};

QString FileSystemEntry::name() const {
	return m_fileInfo.fileName();
};

QString FileSystemEntry::baseName() const {
	return m_fileInfo.baseName();
};

QString FileSystemEntry::parentDir() const {
	return m_fileInfo.absolutePath();
};

QString FileSystemEntry::suffix() const {
	return m_fileInfo.completeSuffix();
};

qint64 FileSystemEntry::size() const {
	return m_fileInfo.size();
};

bool FileSystemEntry::isDir() const {
	return m_fileInfo.isDir();
};

bool FileSystemEntry::isImage() const {
	if (!m_isImageInitialised) {
		QImageReader reader(m_path);
		m_isImage = reader.canRead();
		m_isImageInitialised = true;
	}
	return m_isImage;
}

bool FileSystemEntry::isVideo() const {
	return hasVideoExtension(m_path);
}

QString FileSystemEntry::thumbnailPath() const {
	return m_thumbnailPath;
}

void FileSystemEntry::setThumbnailPath(const QString& path) {
	if (m_thumbnailPath == path) {
		return;
	}

	m_thumbnailPath = path;
	emit thumbnailPathChanged();
}

QString FileSystemEntry::mimeType() const {
	if (!m_mimeTypeInitialised) {
		const QMimeDatabase db;
		m_mimeType = db.mimeTypeForFile(m_path).name();
		m_mimeTypeInitialised = true;
	}
	return m_mimeType;
}

void FileSystemEntry::updateRelativePath(const QDir& dir) {
	const auto relPath = dir.relativeFilePath(m_path);
	if (m_relativePath != relPath) {
		m_relativePath = relPath;
		emit relativePathChanged();
	}
}

FileSystemModel::FileSystemModel(QObject* parent)
	: QAbstractListModel(parent)
	, m_recursive(false)
	, m_watchChanges(true)
	, m_showHidden(false)
	, m_filter(NoFilter) {
	connect(
		&m_watcher,
		&QFileSystemWatcher::directoryChanged,
		this,
		&FileSystemModel::watchDirIfRecursive);
	connect(
		&m_watcher,
		&QFileSystemWatcher::directoryChanged,
		this,
		&FileSystemModel::updateEntriesForDir);
}

int FileSystemModel::rowCount(const QModelIndex& parent) const {
	if (parent != QModelIndex()) {
		return 0;
	}
	return static_cast<int>(m_entries.size());
}

QVariant FileSystemModel::data(const QModelIndex& index, int role) const {
	if (role != Qt::UserRole || !index.isValid() ||
		index.row() >= m_entries.size()) {
		return QVariant();
	}
	return QVariant::fromValue(m_entries.at(index.row()));
}

QHash<int, QByteArray> FileSystemModel::roleNames() const {
	return {{Qt::UserRole, "modelData"}};
}

QString FileSystemModel::path() const {
	return m_path;
}

void FileSystemModel::setPath(const QString& path) {
	if (m_path == path) {
		return;
	}

	m_path = path;
	emit pathChanged();

	m_dir.setPath(m_path);

	for (const auto& entry : std::as_const(m_entries)) {
		entry->updateRelativePath(m_dir);
	}

	update();
}

bool FileSystemModel::recursive() const {
	return m_recursive;
}

void FileSystemModel::setRecursive(bool recursive) {
	if (m_recursive == recursive) {
		return;
	}

	m_recursive = recursive;
	emit recursiveChanged();

	update();
}

bool FileSystemModel::watchChanges() const {
	return m_watchChanges;
}

void FileSystemModel::setWatchChanges(bool watchChanges) {
	if (m_watchChanges == watchChanges) {
		return;
	}

	m_watchChanges = watchChanges;
	emit watchChangesChanged();

	update();
}

bool FileSystemModel::showHidden() const {
	return m_showHidden;
}

void FileSystemModel::setShowHidden(bool showHidden) {
	if (m_showHidden == showHidden) {
		return;
	}

	m_showHidden = showHidden;
	emit showHiddenChanged();

	update();
}

bool FileSystemModel::sortReverse() const {
	return m_sortReverse;
}

void FileSystemModel::setSortReverse(bool sortReverse) {
	if (m_sortReverse == sortReverse) {
		return;
	}

	m_sortReverse = sortReverse;
	emit sortReverseChanged();

	update();
}

FileSystemModel::Filter FileSystemModel::filter() const {
	return m_filter;
}

void FileSystemModel::setFilter(Filter filter) {
	if (m_filter == filter) {
		return;
	}

	m_filter = filter;
	emit filterChanged();

	update();
}

QStringList FileSystemModel::nameFilters() const {
	return m_nameFilters;
}

void FileSystemModel::setNameFilters(const QStringList& nameFilters) {
	if (m_nameFilters == nameFilters) {
		return;
	}

	m_nameFilters = nameFilters;
	emit nameFiltersChanged();

	update();
}

QQmlListProperty<FileSystemEntry> FileSystemModel::entries() {
	return QQmlListProperty<FileSystemEntry>(this, &m_entries);
}

void FileSystemModel::watchDirIfRecursive(const QString& path) {
	if (m_recursive && m_watchChanges) {
		const auto currentDir = m_dir;
		const bool showHidden = m_showHidden;
		const auto future = QtConcurrent::run([showHidden, path]() {
			QDir::Filters filters = QDir::Dirs | QDir::NoDotAndDotDot;
			if (showHidden) {
				filters |= QDir::Hidden;
			}

			QDirIterator iter(path, filters, QDirIterator::Subdirectories);
			QStringList dirs;
			while (iter.hasNext()) {
				dirs << iter.next();
			}
			return dirs;
		});
		const auto watcher = new QFutureWatcher<QStringList>(this);
		connect(
			watcher,
			&QFutureWatcher<QStringList>::finished,
			this,
			[currentDir, showHidden, watcher, this]() {
				const auto paths = watcher->result();
				if (currentDir == m_dir && showHidden == m_showHidden &&
					!paths.isEmpty()) {
					// Ignore if dir or showHidden has changed
					m_watcher.addPaths(paths);
				}
				watcher->deleteLater();
			});
		watcher->setFuture(future);
	}
	// NOLINTNEXTLINE(clang-analyzer-cplusplus.NewDeleteLeaks)
}

void FileSystemModel::update() {
	updateWatcher();
	updateEntries();
}

void FileSystemModel::updateWatcher() {
	if (!m_watcher.directories().isEmpty()) {
		m_watcher.removePaths(m_watcher.directories());
	}

	if (!m_watchChanges || m_path.isEmpty()) {
		return;
	}

	m_watcher.addPath(m_path);
	watchDirIfRecursive(m_path);
}

void FileSystemModel::updateEntries() {
	if (m_path.isEmpty()) {
		if (!m_entries.isEmpty()) {
			beginResetModel();
			qDeleteAll(m_entries);
			m_entries.clear();
			endResetModel();
			emit entriesChanged();
		}

		return;
	}

	for (auto& future : m_futures) {
		future.cancel();
	}
	m_futures.clear();

	updateEntriesForDir(m_path);
}

void FileSystemModel::updateEntriesForDir(const QString& dir) {
	const auto recursive = m_recursive;
	const auto showHidden = m_showHidden;
	const auto filter = m_filter;
	const auto nameFilters = m_nameFilters;

	QSet<QString> oldPaths;
	for (const auto& entry : std::as_const(m_entries)) {
		oldPaths << entry->path();
	}

	const auto future = QtConcurrent::run(
		[=](QPromise<QPair<QSet<QString>, QSet<QString>>>& promise) {
			const auto flags = recursive ? QDirIterator::Subdirectories
										 : QDirIterator::NoIteratorFlags;

			std::optional<QDirIterator> iter;

			if (filter == Images || filter == Videos || filter == Media) {
				QStringList extraNameFilters = nameFilters;

				if (filter == Images || filter == Media) {
					const auto formats = QImageReader::supportedImageFormats();
					for (const auto& format : formats) {
						extraNameFilters << "*." + format;
					}
				}

				if (filter == Videos || filter == Media) {
					for (const auto& ext : kVideoExtensions) {
						extraNameFilters << "*." + ext;
					}
				}

				QDir::Filters filters = QDir::Files;
				if (showHidden) {
					filters |= QDir::Hidden;
				}

				iter.emplace(dir, extraNameFilters, filters, flags);
			} else {
				QDir::Filters filters;

				if (filter == Files) {
					filters = QDir::Files;
				} else if (filter == Dirs) {
					filters = QDir::Dirs | QDir::NoDotAndDotDot;
				} else {
					filters = QDir::Dirs | QDir::Files | QDir::NoDotAndDotDot;
				}

				if (showHidden) {
					filters |= QDir::Hidden;
				}

				if (nameFilters.isEmpty()) {
					iter.emplace(dir, filters, flags);
				} else {
					iter.emplace(dir, nameFilters, filters, flags);
				}
			}

			QSet<QString> newPaths;
			while (iter->hasNext()) {
				if (promise.isCanceled()) {
					return;
				}

				QString path = iter->next();

				if (filter == Images) {
					QImageReader reader(path);
					if (!reader.canRead()) {
						continue;
					}
				} else if (filter == Media) {
					if (!hasVideoExtension(path)) {
						QImageReader reader(path);
						if (!reader.canRead()) {
							continue;
						}
					}
				}

				newPaths.insert(path);
			}

			if (promise.isCanceled() || newPaths == oldPaths) {
				return;
			}

			promise.addResult(
				qMakePair(oldPaths - newPaths, newPaths - oldPaths));
		});

	if (m_futures.contains(dir)) {
		m_futures[dir].cancel();
	}
	m_futures.insert(dir, future);

	const auto watcher =
		new QFutureWatcher<QPair<QSet<QString>, QSet<QString>>>(this);

	connect(
		watcher,
		&QFutureWatcher<QPair<QSet<QString>, QSet<QString>>>::finished,
		this,
		[dir, watcher, this]() {
			m_futures.remove(dir);

			if (!watcher->future().isResultReadyAt(0)) {
				watcher->deleteLater();
				return;
			}

			const auto result = watcher->result();
			applyChanges(result.first, result.second);

			watcher->deleteLater();
		});

	watcher->setFuture(future);
	// NOLINTNEXTLINE(clang-analyzer-cplusplus.NewDeleteLeaks)
}

void FileSystemModel::startThumbnailGeneration(FileSystemEntry* entry) {
	const QPointer<FileSystemEntry> guard(entry);
	const QString source = entry->path();
	const QString cachePath = videoThumbnailPath(source);

	const auto future = QtConcurrent::run([source, cachePath]() {
		return generateVideoThumbnail(source, cachePath);
	});

	const auto watcher = new QFutureWatcher<bool>(this);
	connect(
		watcher,
		&QFutureWatcher<bool>::finished,
		this,
		[guard, cachePath, watcher]() {
			if (guard && watcher->result()) {
				guard->setThumbnailPath(cachePath);
			}
			watcher->deleteLater();
		});
	watcher->setFuture(future);
	// NOLINTNEXTLINE(clang-analyzer-cplusplus.NewDeleteLeaks)
}

void FileSystemModel::applyChanges(
	const QSet<QString>& removedPaths, const QSet<QString>& addedPaths) {
	QList<int> removedIndices;
	for (int i = 0; i < m_entries.size(); ++i) {
		if (removedPaths.contains(m_entries[i]->path())) {
			removedIndices << i;
		}
	}
	std::sort(removedIndices.begin(), removedIndices.end(), std::greater<int>());

	// Batch remove old entries
	int start = -1;
	int end = -1;
	for (int idx : std::as_const(removedIndices)) {
		if (start == -1) {
			start = idx;
			end = idx;
		} else if (idx == end - 1) {
			end = idx;
		} else {
			beginRemoveRows(QModelIndex(), end, start);
			for (int i = start; i >= end; --i) {
				m_entries.takeAt(i)->deleteLater();
			}
			endRemoveRows();

			start = idx;
			end = idx;
		}
	}
	if (start != -1) {
		beginRemoveRows(QModelIndex(), end, start);
		for (int i = start; i >= end; --i) {
			m_entries.takeAt(i)->deleteLater();
		}
		endRemoveRows();
	}

	// Create new entries
	QList<FileSystemEntry*> newEntries;
	for (const auto& path : addedPaths) {
		auto* entry =
			new FileSystemEntry(path, m_dir.relativeFilePath(path), this);
		if (entry->isVideo()) {
			startThumbnailGeneration(entry);
		}
		newEntries << entry;
	}
	std::sort(
		newEntries.begin(),
		newEntries.end(),
		[this](const FileSystemEntry* a, const FileSystemEntry* b) {
			return compareEntries(a, b);
		});

	// Batch insert new entries
	int insertStart = -1;
	QList<FileSystemEntry*> batchItems;
	for (const auto& entry : std::as_const(newEntries)) {
		const auto it = std::lower_bound(
			m_entries.begin(),
			m_entries.end(),
			entry,
			[this](const FileSystemEntry* a, const FileSystemEntry* b) {
				return compareEntries(a, b);
			});
		const auto row = static_cast<int>(it - m_entries.begin());

		if (insertStart == -1) {
			insertStart = row;
			batchItems << entry;
		} else if (row == insertStart + batchItems.size()) {
			batchItems << entry;
		} else {
			beginInsertRows(
				QModelIndex(),
				insertStart,
				insertStart + static_cast<int>(batchItems.size()) - 1);
			for (int i = 0; i < batchItems.size(); ++i) {
				m_entries.insert(insertStart + i, batchItems[i]);
			}
			endInsertRows();

			insertStart = row;
			batchItems.clear();
			batchItems << entry;
		}
	}
	if (!batchItems.isEmpty()) {
		beginInsertRows(
			QModelIndex(),
			insertStart,
			insertStart + static_cast<int>(batchItems.size()) - 1);
		for (int i = 0; i < batchItems.size(); ++i) {
			m_entries.insert(insertStart + i, batchItems[i]);
		}
		endInsertRows();
	}

	emit entriesChanged();
}

bool FileSystemModel::compareEntries(
	const FileSystemEntry* a, const FileSystemEntry* b) const {
	if (a->isDir() != b->isDir()) {
		return m_sortReverse ^ a->isDir();
	}
	const auto cmp = a->relativePath().localeAwareCompare(b->relativePath());
	return m_sortReverse ? cmp > 0 : cmp < 0;
}

} // namespace ZShell::models