#!/usr/bin/env python

# parse.py - converts telegram json to jekyll md.
# Copyright (c) 2020, Lev Brekalov

# TODO summary:
# - replies
# - single/muliple tags
# - forwarded posts
# - custom post header
# - multiple photos in one post

import os
import argparse
import json
from datetime import datetime


def print_default_post_header(post_title, post_date, post_tag):

    '''
    returns default post header
    '''

    # TODO: handle post tag/tags
    # TODO: support for custom header
    post_header = '---\n'\
        'title: {title}\n'\
        'date: {date}\n'\
        'tags: {tag}\n'\
        'layout: post\n'\
        '---\n'.format(title=post_title, date=post_date, tag=post_tag)

    return post_header


def print_custom_post_header(post_header_file, *args):

    '''
    now unusable (i dunno how it may work)
    '''

    with post_header_file as f:
        post_header_content = read(post_header_file)
    for arg in args:
        pass
    return post_header_content


def parse_post_photo(post, photo_dir):

    '''
    converts photo tag to markdown image link
    '''

    post_photo_src = os.path.basename(post['photo'])
    post_photo_src = os.path.join(photo_dir, post_photo_src)
    post_photo = '![image]({src})\n\n'.format(src=post_photo_src)

    return post_photo


def parse_post_photo_as_file(post, media_dir):

    '''
    converts file tag with thumbnail to image and a link
    '''

    # links to files are currently broken, because these files are
    # going to `files` directory, not `photos`.
    # need to track down any files with thumbnails and then to move them
    # to a photos directory.
    post_photo_file_src = os.path.basename(post['file'])
    post_photo_file_src = os.path.join(media_dir, post_photo_file_src)
    post_photo_thumbnail_src = os.path.basename(post['thumbnail'])
    post_photo_thumbnail_src = os.path.join(media_dir,
                                            post_photo_thumbnail_src)

    post_photo_as_file = '![image]({thumb})\n[full size]({file})\n\n'\
        .format(thumb=post_photo_thumbnail_src, file=post_photo_file_src)

    return post_photo_as_file


def text_format(string, fmt):

    '''
    wraps string in markdown-styled formatting
    '''

    if fmt in ('*', '**', '***', '`', '```'):
        output = '{fmt}{txt}{fmt}'
    elif fmt == '```':
        output = '{fmt}\n{txt}\n{fmt}'
    else:
        output = '<{fmt}>{txt}</{fmt}>'

    output = output.format(fmt=fmt, txt=string.strip())
    output += '\n' * string.split('\n').count('') * string.endswith('\n')
    return output


def text_link_format(text, link):

    '''
    formats links
    '''

    # convert telegram links to anchors
    # this implies that telegram links are pointing to the same channel
    if link.startswith('https://t.me/c/'):
        link = '#' + link.split('/')[-1]
    link_fmt = '[{text}]({href})'
    link_fmt = link_fmt.format(text=text.strip(), href=link)
    link_fmt += '\n' * text.count('\n') * text.endswith('\n')
    return link_fmt


def parse_text_object(obj):

    '''
    detects type of text object and wraps it in corresponding formatting
    '''

    obj_type = obj['type']
    obj_text = obj['text']

    if obj_type == 'hashtag':
        post_tag = obj_text
        return post_tag

    elif obj_type == 'text_link':
        return text_link_format(obj_text, obj['href'])

    elif obj_type == 'link' or obj_type == 'email':
        link = obj_text.strip()
        link = 'https://' * (obj_type == 'link') * \
            (1 - link.startswith('https://')) + link
        post_link = '<{href}>'.format(href=link)
        return post_link

    elif obj_type == 'phone':
        return obj_text

    elif obj_type == 'italic':
        return text_format(obj_text, '*')

    elif obj_type == 'bold':
        return text_format(obj_text, '**')

    elif obj_type == 'code':
        return text_format(obj_text, '`')

    elif obj_type == 'pre':
        return text_format(obj_text, '```')

    elif obj_type == 'underline':
        return text_format(obj_text, 'u')

    elif obj_type == 'strikethrough':
        return text_format(obj_text, 's')


def parse_post_text(post):
    # TODO: handle reply-to
    post_raw_text = post['text']
    post_parsed_text = ''

    if type(post_raw_text) == str:
        return str(post_raw_text)

    else:
        for obj in post_raw_text:
            if type(obj) == str:
                post_parsed_text += obj
            else:
                post_parsed_text += str(parse_text_object(obj))

        return post_parsed_text


def parse_post_media(post, media_dir):

    '''
    wraps media files into html tags
    '''

    post_media_file = os.path.basename(post['file'])
    post_media_ext = post_media_file.split(".")[-1]
    post_media_src = os.path.join(media_dir, post_media_file)

    # audiofiles can be presented as audioplayers and other media types
    # could be left as just links to them
    # ???
    post_media = '\n<audio controls>\n\
            <source src="{src}" type="{mime_type}">\n\
            </audio>'.format(src=post_media_src, mime_type=post['mime_type'])

    return post_media


def parse_post_file(post, media_dir):

    '''
    wrap files into link tags
    '''

    post_file_src = os.path.basename(post['file'])
    post_file_ext = post_file_src.split('.')[-1]
    post_file_name = post_file_src.removesuffix('.' + post_file_ext)

    post_file = f'\n\n[{post_file_name}]({post_file_src})\n\n'

    return post_file

def parse_post(post, photo_dir, media_dir):

    '''
    converts post object to formatted text
    '''

    post_output = ''

    # optional image
    # TODO: handle multiple photos in one post (maybe by comparing timestamps)
    if 'photo' in post:
        post_output += str(parse_post_photo(post, photo_dir))

    if all(['file' in post, 'thumbnail' in post]):
        post_output += str(parse_post_photo_as_file(post, media_dir))

    # post text
    post_output += str(parse_post_text(post))

    # optional media
    if 'media_type' in post:
        post_output += str(parse_post_media(post, media_dir))
    elif 'file' in post and not 'thumbnail' in post:
        post_output += str(parse_post_file(post, media_dir))

    return post_output


def main():

    parser = argparse.ArgumentParser(
            usage='%(prog)s [options] json_file',
            description='Convert exported Telegram channel data json to \
                    bunch of markdown posts ready to use with jekyll')
    parser.add_argument(
            'json', metavar='json_file',
            help='result.json file from telegram export')
    parser.add_argument(
            '-o', '--out-dir', metavar='out_dir',
            nargs='?', default='formatted_posts',
            help='output directory for markdown files\
                    (default: formatted_posts)')
    parser.add_argument(
            '-p', '--photo-dir', metavar='photo_dir',
            nargs='?', default='photos',
            help='location of image files. this changes only links\
                    to photos in markdown text, so specify your\
                    desired location (default: photos)')
    parser.add_argument(
            '-m', '--media-dir', metavar='media_dir',
            nargs='?', default='files',
            help='location of media files. this changes only links\
                    to files in markdown text, so specify your \
                    desired location (default: files)')
    args_wip = parser.add_argument_group('work in progress')
    args_wip.add_argument(
            '-H', '--post-header', metavar='post_header',
            nargs='?',
            help='yaml front matter for your posts \
                    (now doesn\'t work)')

    args = parser.parse_args()

    try:
        os.mkdir(args.out_dir)
    except FileExistsError:
        pass

    # load json file
    try:
        with open(args.json, 'r', encoding='utf-8') as f:
            data = json.load(f)
    except FileNotFoundError:
        sys.exit('result.json not found.\nPlease, specify right file')

    # load only messages
    raw_posts = data['messages']

    for post in raw_posts:
        # TODO: handle forwarded posts
        if post['type'] == 'message' and 'forwarded_from' not in post:

            post_date = datetime.fromisoformat(post['date'])
            post_id = post['id']
            post_filename = str(post_date.date()) + '-' + str(post_id) + '.md'
            post_path = os.path.join(args.out_dir, post_filename)

            with open(post_path, 'w', encoding='utf-8') as f:
                print(print_default_post_header(post_id, post_date, None),
                      file=f)
                print(parse_post(post, args.photo_dir, args.media_dir), file=f)


if __name__ == '__main__':
    main()