#!/usr/bin/env python3
'''
Extracts a section of the changelog and converts it from Markdown to Steam's
BBCode implementation.

Copyright (C) 2018 by Iris Morelle <shadowm@wesnoth.org>
Part of the Battle for Wesnoth Project <https://www.wesnoth.org/>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, see <http://www.gnu.org/licenses/>.
'''

import argparse
import re

import io, os, sys


LIST_ITEM_BASE_INDENT = 3
LIST_ITEM_NESTED_INDENT = 2


def warn(line, msg):
    sys.stderr.write("Line {}: {}\n".format(line, msg))

def list_items_to_bbcode(list_items):
    current_depth = 1
    lines = []
    lines.append('[list]')
    for depth, item in list_items:
        if depth > current_depth:
            lines[-1] += '[list]'
        elif depth < current_depth:
            lines.append('[/list]')
        current_depth = depth
        lines.append('[*]{}'.format(item))
    for i in range(current_depth):
        lines.append('[/list]')
    return lines

def process_changelog(file_handle, version_heading):
    version_rx = re.compile(r'^\s*##\s*Version\s+(.*)\s*:?\s*$')
    category_rx = re.compile(r'^\s*###\s*(.*)\s*:?\s*$')
    list_item_start_rx = re.compile(r'^(\s+)\*\s*(.*)\s*:?\s*$')
    list_item_cont_rx = re.compile(r'^(\s+)([^*].*)\s*$')

    lines = []
    list_items = []
    lno = 0
    in_section = False
    in_list_item = 0

    for line in file_handle:
        lno += 1
        if not in_section:
            match = version_rx.search(line)
            if match:
                found_ver = match.group(1)
                if found_ver == version_heading:
                    in_section = True
            continue
        elif len(line.strip()) == 0:
            # Empty line.
            continue
        else:
            end_of_section = False
            if version_rx.search(line):
                # New section, we're done here.
                end_of_section = True

            # Entry category heading.
            category = category_rx.search(line)

            # New category or end of the section, we write the list into the
            # output set.
            if (category and list_items) or end_of_section:
                # New section, spurt list
                lines += list_items_to_bbcode(list_items)
                in_list_item = 0
                list_items = []

            if category:
                lines.append('[h1]{0}[/h1]'.format(category.group(1)))
                continue

            if end_of_section:
                break

            # Entry start.
            list_item = list_item_start_rx.search(line)
            if list_item:
                indent = len(list_item.group(1))
                if indent < LIST_ITEM_BASE_INDENT:
                    warn(lno, "Bad base indent for list item (expected {}, got {}), list may be corrupted".format(indent, LIST_ITEM_BASE_INDENT))
                depth = int((indent - LIST_ITEM_BASE_INDENT) / LIST_ITEM_NESTED_INDENT + 1)
                if depth < in_list_item:
                    # Stop current list, write it
                    lines += list_items_to_bbcode(list_items)
                    list_items = []
                list_items.append([depth, list_item.group(2)])
                in_list_item = depth
                continue

            # Entry continuation.
            list_item = list_item_cont_rx.search(line)
            if list_item:
                if not in_list_item or not list_items:
                    warn(lno, "Orphaned line is not part of a list item")
                    continue
                indent = len(list_item.group(1))
                if indent < LIST_ITEM_BASE_INDENT + LIST_ITEM_NESTED_INDENT:
                    warn(lno, "Bad base indent for list item continuation (expected {}, got {}), list may be corrupted".format(indent, LIST_ITEM_BASE_INDENT + LIST_ITEM_NESTED_INDENT))
                depth = int((indent - LIST_ITEM_BASE_INDENT) / LIST_ITEM_NESTED_INDENT)
                if depth != in_list_item:
                    warn(lno, "Weird indent for list item continuation (expected {}, got {}), list may be corrupted".format(in_list_item, depth))
                list_items[-1][1] += ' ' + list_item.group(2)
                continue

            warn(lno, "wut")

    return lines


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('input_file', metavar='CHANGELOG_FILE')
    parser.add_argument('version_heading', metavar='RELEASE_VERSION')

    args = parser.parse_args()
    input_file = args.input_file
    version_heading = args.version_heading

    try:
        lines = ()
        with open(input_file, 'r', encoding='utf-8') as changelog:
            lines = process_changelog(changelog, version_heading.strip())
        if not lines:
            sys.exit("Could not find a changelog section for version {0}.".format(version_heading))
        for line in lines:
            sys.stdout.write(line + "\n")
    except FileNotFoundError as err:
        sys.exit("Could not open {0}, aborting.\n".format(err.filename))

# kate: indent-mode normal; encoding utf-8; space-indent on;