<?php

namespace OCA\Notes\Service;

use OCP\Files\FileInfo;
use OCP\IL10N;
use OCP\Files\IRootFolder;
use OCP\Files\Folder;
use OCP\ILogger;
use OCP\Encryption\Exceptions\GenericEncryptionException;
use OCA\Notes\Db\Note;
use OCA\Notes\Service\SettingsService;
use OCP\IConfig;
use OCP\IUserSession;

/**
 * Class NotesService
 *
 * @package OCA\Notes\Service
 */
class NotesService {

	private $l10n;
	private $root;
	private $logger;
	private $config;
	private $settings;
	private $appName;

	/**
	 * @param IRootFolder $root
	 * @param IL10N $l10n
	 * @param ILogger $logger
	 * @param IConfig $config
	 * @param \OCA\Notes\Service\SettingsService $settings
	 * @param String $appName
	 */
	public function __construct(IRootFolder $root, IL10N $l10n, ILogger $logger, IConfig $config, SettingsService $settings, $appName) {
		$this->root = $root;
		$this->l10n = $l10n;
		$this->logger = $logger;
		$this->config = $config;
		$this->settings = $settings;
		$this->appName = $appName;
	}


	/**
	 * @param string $userId
	 * @return array with all notes in the current directory
	 */
	public function getAll($userId, $onlyMeta = false) {
		$notesFolder = $this->getFolderForUser($userId);
		$notes = $this->gatherNoteFiles($notesFolder);
		$filesById = [];
		foreach ($notes as $note) {
			$filesById[$note->getId()] = $note;
		}
		$tagger = \OC::$server->getTagManager()->load('files');
		if ($tagger===null) {
			$tags = [];
		} else {
			$tags = $tagger->getTagsForObjects(array_keys($filesById));
		}

		$notes = [];
		foreach ($filesById as $id => $file) {
			$notes[] = $this->getNote($file, $notesFolder, array_key_exists($id, $tags) ? $tags[$id] : [], $onlyMeta);
		}

		return $notes;
	}


	/**
	 * Used to get a single note by id
	 * @param int $id the id of the note to get
	 * @param string $userId
	 * @throws NoteDoesNotExistException if note does not exist
	 * @return Note
	 */
	public function get($id, $userId) {
		$folder = $this->getFolderForUser($userId);
		return $this->getNote($this->getFileById($folder, $id), $folder, $this->getTags($id));
	}

	private function getTags($id) {
		$tagger = \OC::$server->getTagManager()->load('files');
		if ($tagger===null) {
			$tags = [];
		} else {
			$tags = $tagger->getTagsForObjects([$id]);
		}
		return array_key_exists($id, $tags) ? $tags[$id] : [];
	}

	private function getNote($file, $notesFolder, $tags = [], $onlyMeta = false) {
		$id = $file->getId();
		try {
			$note = Note::fromFile($file, $notesFolder, $tags, $onlyMeta);
		} catch (GenericEncryptionException $e) {
			$note = Note::fromException($this->l10n->t('Encryption Error').': ('.$file->getName().') '.$e->getMessage(), $file, $notesFolder, array_key_exists($id, $tags) ? $tags[$id] : []);
		} catch (\Exception $e) {
			$note = Note::fromException($this->l10n->t('Error').': ('.$file->getName().') '.$e->getMessage(), $file, $notesFolder, array_key_exists($id, $tags) ? $tags[$id] : []);
		}
		return $note;
	}


	/**
	 * Creates a note and returns the empty note
	 * @param string $userId
	 * @see update for setting note content
	 * @return Note the newly created note
	 */
	public function create($userId) {
		$title = $this->l10n->t('New note');
		$folder = $this->getFolderForUser($userId);

		// check new note exists already and we need to number it
		// pass -1 because no file has id -1 and that will ensure
		// to only return filenames that dont yet exist
		$path = $this->generateFileName($folder, $title, $this->settings->get($userId, 'fileSuffix'), -1);
		$file = $folder->newFile($path);

		// If server-side encryption is activated, the server creates an empty file without signature
		// which leads to an GenericEncryptionException('Missing Signature') afterwards.
		// Saving a space-char (and removing it later) is a working work-around.
		$file->putContent(' ');

		return $this->getNote($file, $folder);
	}


	/**
	 * Updates a note. Be sure to check the returned note since the title is
	 * dynamically generated and filename conflicts are resolved
	 * @param int $id the id of the note used to update
	 * @param string|null $content the content which will be written into the note
	 * the title is generated from the first line of the content
	 * @param string|null $category the category in which the note should be saved
	 * @param int $mtime time of the note modification (optional)
	 * @throws NoteDoesNotExistException if note does not exist
	 * @return \OCA\Notes\Db\Note the updated note
	 */
	public function update($id, $content, $userId, $category = null, $mtime = 0) {
		$notesFolder = $this->getFolderForUser($userId);
		$file = $this->getFileById($notesFolder, $id);
		$title = $this->getSafeTitleFromContent($content===null ? $file->getContent() : $content);


		// rename/move file with respect to title/category
		// this can fail if access rights are not sufficient or category name is illegal
		try {
			$currentFilePath = $this->root->getFullPath($file->getPath());
			$currentBasePath = pathinfo($currentFilePath, PATHINFO_DIRNAME);
			$fileSuffix = '.' . pathinfo($file->getName(), PATHINFO_EXTENSION);

			// detect (new) folder path based on category name
			if ($category===null) {
				$basePath = $currentBasePath;
			} else {
				$basePath = $notesFolder->getPath();
				if (!empty($category)) {
					// sanitise path
					$cats = explode('/', $category);
					$cats = array_map([$this, 'sanitisePath'], $cats);
					$cats = array_filter($cats, function ($str) {
						return !empty($str);
					});
					$basePath .= '/'.implode('/', $cats);
				}
			}
			$folder = $this->getOrCreateFolder($basePath);

			// assemble new file path
			$newFilePath = $basePath . '/' . $this->generateFileName($folder, $title, $fileSuffix, $id);

			// if the current path is not the new path, the file has to be renamed
			if ($currentFilePath !== $newFilePath) {
				$file->move($newFilePath);
			}
			if ($currentBasePath !== $basePath) {
				$this->deleteEmptyFolder($notesFolder, $this->root->get($currentBasePath));
			}
		} catch (\OCP\Files\NotPermittedException $e) {
			$this->logger->error('Moving note '.$id.' ('.$title.') to the desired target is not allowed. Please check the note\'s target category ('.$category.').', ['app' => $this->appName]);
		} catch (\Exception $e) {
			$this->logger->error('Moving note '.$id.' ('.$title.') to the desired target has failed with a '.get_class($e).': '.$e->getMessage(), ['app' => $this->appName]);
		}

		if ($content !== null) {
			$file->putContent($content);
		}

		if ($mtime) {
			$file->touch($mtime);
		}

		return $this->getNote($file, $notesFolder, $this->getTags($id));
	}

	/**
	 * Set or unset a note as favorite.
	 * @param int $id the id of the note used to update
	 * @param boolean $favorite whether the note should be a favorite or not
	 * @throws NoteDoesNotExistException if note does not exist
	 * @return boolean the new favorite state of the note
	 */
	public function favorite($id, $favorite, $userId) {
		$folder = $this->getFolderForUser($userId);
		$file = $this->getFileById($folder, $id);
		if (!$this->isNote($file)) {
			throw new NoteDoesNotExistException();
		}
		$tagger = \OC::$server->getTagManager()->load('files');
		if ($favorite) {
			$tagger->addToFavorites($id);
		} else {
			$tagger->removeFromFavorites($id);
		}

		$tags = $tagger->getTagsForObjects([$id]);
		return array_key_exists($id, $tags) && in_array(\OC\Tags::TAG_FAVORITE, $tags[$id]);
	}


	/**
	 * Deletes a note
	 * @param int $id the id of the note which should be deleted
	 * @param string $userId
	 * @throws NoteDoesNotExistException if note does not
	 * exist
	 */
	public function delete($id, $userId) {
		$notesFolder = $this->getFolderForUser($userId);
		$file = $this->getFileById($notesFolder, $id);
		$parent = $file->getParent();
		$file->delete();
		$this->deleteEmptyFolder($notesFolder, $parent);
	}

	// removes characters that are illegal in a file or folder name on some operating systems
	private function sanitisePath($str) {
		// remove characters which are illegal on Windows (includes illegal characters on Unix/Linux)
		// prevents also directory traversal by eliminiating slashes
		// see also \OC\Files\Storage\Common::verifyPosixPath(...)
		$str = str_replace(['*', '|', '/', '\\', ':', '"', '<', '>', '?'], '', $str);

		// if mysql doesn't support 4byte UTF-8, then remove those characters
		// see \OC\Files\Storage\Common::verifyPath(...)
		if (!\OC::$server->getDatabaseConnection()->supports4ByteText()) {
			$str = preg_replace('%(?:
                \xF0[\x90-\xBF][\x80-\xBF]{2}      # planes 1-3
              | [\xF1-\xF3][\x80-\xBF]{3}          # planes 4-15
              | \xF4[\x80-\x8F][\x80-\xBF]{2}      # plane 16
              )%xs', '', $str);
		}

		// prevent file to be hidden
		$str = preg_replace("/^[\. ]+/mu", "", $str);
		return trim($str);
	}

	private function getSafeTitleFromContent($content) {
		// prepare content: remove markdown characters and empty spaces
		$content = preg_replace("/^\s*[*+-]\s+/mu", "", $content); // list item
		$content = preg_replace("/^#+\s+(.*?)\s*#*$/mu", "$1", $content); // headline
		$content = preg_replace("/^(=+|-+)$/mu", "", $content); // separate line for headline
		$content = preg_replace("/(\*+|_+)(.*?)\\1/mu", "$2", $content); // emphasis

		// sanitize: prevent directory traversal, illegal characters and unintended file names
		$content = $this->sanitisePath($content);

		// generate title from the first line of the content
		$splitContent = preg_split("/\R/u", $content, 2);
		$title = trim($splitContent[0]);

		// ensure that title is not empty
		if (empty($title)) {
			$title = $this->l10n->t('New note');
		}

		// using a maximum of 100 chars should be enough
		$title = mb_substr($title, 0, 100, "UTF-8");

		return $title;
	}

	/**
	 * @param Folder $folder
	 * @param int $id
	 * @throws NoteDoesNotExistException
	 * @return \OCP\Files\File
	 */
	private function getFileById($folder, $id) {
		$file = $folder->getById($id);

		if (count($file) <= 0 || !$this->isNote($file[0])) {
			throw new NoteDoesNotExistException();
		}
		return $file[0];
	}

	/**
	 * @param string $userId the user id
	 * @return boolean true if folder is accessible, or Exception otherwise
	 */
	public function checkNotesFolder($userId) {
		$this->getFolderForUser($userId);
		return true;
	}

	/**
	 * @param string $userId the user id
	 * @return Folder
	 */
	private function getFolderForUser($userId) {
		$path = '/' . $userId . '/files/' . $this->settings->get($userId, 'notesPath');
		try {
			$folder = $this->getOrCreateFolder($path);
		} catch (\Exception $e) {
			throw new NotesFolderException($path);
		}
		return $folder;
	}


	/**
	 * Finds a folder and creates it if non-existent
	 * @param string $path path to the folder
	 * @return Folder
	 */
	private function getOrCreateFolder($path) {
		if ($this->root->nodeExists($path)) {
			$folder = $this->root->get($path);
		} else {
			$folder = $this->root->newFolder($path);
		}
		return $folder;
	}

	/*
	 * Delete a folder and it's parent(s) if it's/they're empty
	 * @param Folder root folder for notes
	 * @param Folder folder to delete
	 */
	private function deleteEmptyFolder(Folder $notesFolder, Folder $folder) {
		$content = $folder->getDirectoryListing();
		$isEmpty = !count($content);
		$isNotesFolder = $folder->getPath()===$notesFolder->getPath();
		if ($isEmpty && !$isNotesFolder) {
			$this->logger->info('Deleting empty category folder '.$folder->getPath(), ['app' => $this->appName]);
			$parent = $folder->getParent();
			$folder->delete();
			$this->deleteEmptyFolder($notesFolder, $parent);
		}
	}

	/**
	 * get path of file and the title.txt and check if they are the same
	 * file. If not the title needs to be renamed
	 *
	 * @param Folder $folder a folder to the notes directory
	 * @param string $title the filename which should be used
	 * @param string $suffix the suffix (incl. dot) which should be used
	 * @param int $id the id of the note for which the title should be generated
	 * used to see if the file itself has the title and not a different file for
	 * checking for filename collisions
	 * @return string the resolved filename to prevent overwriting different
	 * files with the same title
	 */
	private function generateFileName(Folder $folder, $title, $suffix, $id) {
		$path = $title . $suffix;

		// if file does not exist, that name has not been taken. Similar we don't
		// need to handle file collisions if it is the filename did not change
		if (!$folder->nodeExists($path) || $folder->get($path)->getId() === $id) {
			return $path;
		} else {
			// increments name (2) to name (3)
			$match = preg_match('/\((?P<id>\d+)\)$/u', $title, $matches);
			if ($match) {
				$newId = ((int) $matches['id']) + 1;
				$newTitle = preg_replace(
					'/(.*)\s\((\d+)\)$/u',
					'$1 (' . $newId . ')',
					$title
				);
			} else {
				$newTitle = $title . ' (2)';
			}
			return $this->generateFileName($folder, $newTitle, $suffix, $id);
		}
	}

	/**
	 * gather note files in given directory and all subdirectories
	 * @param Folder $folder
	 * @return array
	 */
	private function gatherNoteFiles($folder) {
		$notes = [];
		$nodes = $folder->getDirectoryListing();
		foreach ($nodes as $node) {
			if ($node->getType() === FileInfo::TYPE_FOLDER) {
				$notes = array_merge($notes, $this->gatherNoteFiles($node));
				continue;
			}
			if ($this->isNote($node)) {
				$notes[] = $node;
			}
		}
		return $notes;
	}


	/**
	 * test if file is a note
	 *
	 * @param \OCP\Files\File $file
	 * @return bool
	 */
	private function isNote($file) {
		$allowedExtensions = ['txt', 'org', 'markdown', 'md', 'note'];

		if ($file->getType() !== 'file') {
			return false;
		}

		$ext = pathinfo($file->getName(), PATHINFO_EXTENSION);
		$iext = strtolower($ext);
		if (!in_array($iext, $allowedExtensions)) {
			return false;
		}
		return true;
	}
}
