# -*- coding: utf-8 -*-
# This file is part of beets.
# Copyright 2016, Adrian Sampson.
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

"""Shows file metadata.
"""

from __future__ import division, absolute_import, print_function

import os
import re

from beets.plugins import BeetsPlugin
from beets import ui
import mediafile
from beets.library import Album, Item
from beets.util import displayable_path, normpath, syspath


def tag_data(lib, args):
    query = []
    for arg in args:
        path = normpath(arg)
        if os.path.isfile(syspath(path)):
            yield tag_data_emitter(path)
        else:
            query.append(arg)

    if query:
        for item in lib.items(query):
            yield tag_data_emitter(item.path)


def tag_data_emitter(path):
    def emitter(included_keys):
        mf = mediafile.MediaFile(syspath(path))
        tags = {}
        for field in included_keys:
            value = getattr(mf, field)
            if field == 'art':
                tags['art'] = bool(value)
            elif value:
                tags[field] = value
        # create a temporary Item to take advantage of __format__
        item = Item.from_path(syspath(path))

        return tags, item
    return emitter


def library_data(lib, args):
    for item in lib.items(args):
        yield library_data_emitter(item)


def library_data_emitter(item):
    def emitter(included_keys):
        data = {}
        for field in included_keys:
            if field in item:
                data[field] = item[field]

        return data, item
    return emitter


def all_tag_fields():
    fields = list(mediafile.MediaFile.readable_fields())
    fields.remove('images')
    return fields

def all_library_fields():
    return Item.all_keys() + Album.all_keys()


def expand_key_list(keys, all_fields):
    """Process '*' glob patterns in a list of library key names."""

    # By default, if no field inclusions are specified, include everything.
    if not keys:
        return all_fields

    matchers = []
    for key in keys:
        pattern = re.escape(key).replace(r'\*', '.*') + '$'
        matchers.append(re.compile(pattern))
        keys.remove(key)

    def filter_(fields):
        for field in fields:
            if field in keys:
                yield field
            if any([m.match(field) for m in matchers]):
                yield field

    return list(filter_(all_fields))


def update_summary(summary, tags):
    for key, value in tags.items():
        if key not in summary:
            summary[key] = value
        elif summary[key] != value:
            summary[key] = '[various]'
    return summary


def print_data(data, item=None, fmt=None):
    """Print, with optional formatting, the fields of a single element.

    If no format string `fmt` is passed, the entries on `data` are printed one
    in each line, with the format 'field: value'. If `fmt` is not `None`, the
    `item` is printed according to `fmt`, using the `Item.__format__`
    machinery.
    """
    if fmt:
        # use fmt specified by the user
        ui.print_(format(item, fmt))
        return

    path = displayable_path(item.path) if item else None
    formatted = {}
    for key, value in data.items():
        if isinstance(value, list):
            formatted[key] = u'; '.join(value)
        if value is not None:
            formatted[key] = value

    if len(formatted) == 0:
        return

    maxwidth = max(len(key) for key in formatted)
    lineformat = u'{{0:>{0}}}: {{1}}'.format(maxwidth)

    if path:
        ui.print_(displayable_path(path))

    for field in sorted(formatted):
        value = formatted[field]
        if isinstance(value, list):
            value = u'; '.join(value)
        ui.print_(lineformat.format(field, value))


def print_data_keys(data, item=None):
    """Print only the keys (field names) for an item.
    """
    path = displayable_path(item.path) if item else None
    formatted = []
    for key, value in data.items():
        formatted.append(key)

    if len(formatted) == 0:
        return

    line_format = u'{0}{{0}}'.format(u' ' * 4)
    if path:
        ui.print_(displayable_path(path))

    for field in sorted(formatted):
        ui.print_(line_format.format(field))


class InfoPlugin(BeetsPlugin):

    def commands(self):
        cmd = ui.Subcommand('info', help=u'show file metadata')
        cmd.func = self.run
        cmd.parser.add_option(
            u'-l', u'--library', action='store_true',
            help=u'show library fields instead of tags',
        )
        cmd.parser.add_option(
            u'-s', u'--summarize', action='store_true',
            help=u'summarize the tags of all files',
        )
        cmd.parser.add_option(
            u'-i', u'--include-keys', default=[],
            action='append', dest='included_keys',
            help=u'comma separated list of keys to show',
        )
        cmd.parser.add_option(
            u'-k', u'--keys-only', action='store_true',
            help=u'show only the keys',
        )
        cmd.parser.add_format_option(target='item')
        return [cmd]

    def run(self, lib, opts, args):
        """Print tag info or library data for each file referenced by args.

        Main entry point for the `beet info ARGS...` command.

        If an argument is a path pointing to an existing file, then the tags
        of that file are printed. All other arguments are considered
        queries, and for each item matching all those queries the tags from
        the file are printed.

        If `opts.summarize` is true, the function merges all tags into one
        dictionary and only prints that. If two files have different values
        for the same tag, the value is set to '[various]'
        """
        if opts.library:
            data_collector = library_data
        else:
            data_collector = tag_data

        all_fields = all_library_fields() if opts.library else all_tag_fields()
        included_keys = []
        for keys in opts.included_keys:
            included_keys.extend(keys.split(','))
        included_keys = expand_key_list(included_keys, all_fields)
        # Drop path even if user provides it multiple times
        included_keys = [k for k in included_keys if k != 'path']

        first = True
        summary = {}
        for data_emitter in data_collector(lib, ui.decargs(args)):
            try:
                data, item = data_emitter(included_keys)
            except (mediafile.UnreadableFileError, IOError) as ex:
                self._log.error(u'cannot read file: {0}', ex)
                continue

            if opts.summarize:
                update_summary(summary, data)
            else:
                if not first:
                    ui.print_()
                if opts.keys_only:
                    print_data_keys(data, item)
                else:
                    fmt = ui.decargs([opts.format])[0] if opts.format else None
                    print_data(data, item, fmt)
                first = False

        if opts.summarize:
            print_data(summary)