"""Populate an item's `added` and `mtime` fields by using the file
modification time (mtime) of the item's source file before import.

Reimported albums and items are skipped.
"""

import os

from beets import util
from beets import importer
from beets.plugins import BeetsPlugin


class ImportAddedPlugin(BeetsPlugin):
    def __init__(self):
        super().__init__()
        self.config.add({
            'preserve_mtimes': False,
            'preserve_write_mtimes': False,
        })

        # item.id for new items that were reimported
        self.reimported_item_ids = None
        # album.path for old albums that were replaced by a reimported album
        self.replaced_album_paths = None
        # item path in the library to the mtime of the source file
        self.item_mtime = {}

        register = self.register_listener
        register('import_task_created', self.check_config)
        register('import_task_created', self.record_if_inplace)
        register('import_task_files', self.record_reimported)
        register('before_item_moved', self.record_import_mtime)
        register('item_copied', self.record_import_mtime)
        register('item_linked', self.record_import_mtime)
        register('item_hardlinked', self.record_import_mtime)
        register('album_imported', self.update_album_times)
        register('item_imported', self.update_item_times)
        register('after_write', self.update_after_write_time)

    def check_config(self, task, session):
        self.config['preserve_mtimes'].get(bool)

    def reimported_item(self, item):
        return item.id in self.reimported_item_ids

    def reimported_album(self, album):
        return album.path in self.replaced_album_paths

    def record_if_inplace(self, task, session):
        if not (session.config['copy'] or session.config['move'] or
                session.config['link'] or session.config['hardlink']):
            self._log.debug("In place import detected, recording mtimes from "
                            "source paths")
            items = [task.item] \
                if isinstance(task, importer.SingletonImportTask) \
                else task.items
            for item in items:
                self.record_import_mtime(item, item.path, item.path)

    def record_reimported(self, task, session):
        self.reimported_item_ids = {item.id for item, replaced_items
                                    in task.replaced_items.items()
                                    if replaced_items}
        self.replaced_album_paths = set(task.replaced_albums.keys())

    def write_file_mtime(self, path, mtime):
        """Write the given mtime to the destination path.
        """
        stat = os.stat(util.syspath(path))
        os.utime(util.syspath(path), (stat.st_atime, mtime))

    def write_item_mtime(self, item, mtime):
        """Write the given mtime to an item's `mtime` field and to the mtime
        of the item's file.
        """
        # The file's mtime on disk must be in sync with the item's mtime
        self.write_file_mtime(util.syspath(item.path), mtime)
        item.mtime = mtime

    def record_import_mtime(self, item, source, destination):
        """Record the file mtime of an item's path before its import.
        """
        mtime = os.stat(util.syspath(source)).st_mtime
        self.item_mtime[destination] = mtime
        self._log.debug("Recorded mtime {0} for item '{1}' imported from "
                        "'{2}'", mtime, util.displayable_path(destination),
                        util.displayable_path(source))

    def update_album_times(self, lib, album):
        if self.reimported_album(album):
            self._log.debug("Album '{0}' is reimported, skipping import of "
                            "added dates for the album and its items.",
                            util.displayable_path(album.path))
            return

        album_mtimes = []
        for item in album.items():
            mtime = self.item_mtime.pop(item.path, None)
            if mtime:
                album_mtimes.append(mtime)
                if self.config['preserve_mtimes'].get(bool):
                    self.write_item_mtime(item, mtime)
                    item.store()
        album.added = min(album_mtimes)
        self._log.debug("Import of album '{0}', selected album.added={1} "
                        "from item file mtimes.", album.album, album.added)
        album.store()

    def update_item_times(self, lib, item):
        if self.reimported_item(item):
            self._log.debug("Item '{0}' is reimported, skipping import of "
                            "added date.", util.displayable_path(item.path))
            return
        mtime = self.item_mtime.pop(item.path, None)
        if mtime:
            item.added = mtime
            if self.config['preserve_mtimes'].get(bool):
                self.write_item_mtime(item, mtime)
            self._log.debug("Import of item '{0}', selected item.added={1}",
                            util.displayable_path(item.path), item.added)
            item.store()

    def update_after_write_time(self, item, path):
        """Update the mtime of the item's file with the item.added value
        after each write of the item if `preserve_write_mtimes` is enabled.
        """
        if item.added:
            if self.config['preserve_write_mtimes'].get(bool):
                self.write_item_mtime(item, item.added)
            self._log.debug("Write of item '{0}', selected item.added={1}",
                            util.displayable_path(item.path), item.added)