#!/usr/bin/env python3
from pathlib import Path
from datetime import date
from collections import defaultdict
from sys import argv, exit, stderr
from calendar import Calendar, month_name, day_abbr

def HTMLCalendarMonthWithEntries(year, month, entries=[], weekday_start=6):
    cal = Calendar(weekday_start)
    returnable = [
        '<table class="calendar-month">',
        "<thead>",
        '<tr><th colspan="7">', month_name[month], " - ", str(year), "</th></tr>\n",
        "<tr>",
        *[
            f"<th>{day_abbr[(i+weekday_start)%7]}</th>"
            for i in range(7)
        ],
        "</tr>\n"
        "</thead>\n",
        "<tbody>\n",
    ]
    for week in cal.monthdays2calendar(year, month):
        returnable.append("<tr>")
        for day, weekday in week:
            returnable.append(
                "<td></td>"
                if day == 0
                else f"<td>{day}</td>"
                if (d := date(year, month, day)) not in entries
                else f'<td><a href="{d.isoformat()}.html">{day}</a></td>'
            )
        returnable.append("</tr>\n")
    returnable.extend([
        "</tbody>\n",
        "</table>",
    ])
    return "".join(returnable)


def generate_index_full(diary_entries):
    entries_by_month = defaultdict(list)
    for entry in diary_entries:
        entries_by_month[(entry.year, entry.month)].append(entry)
    months = sorted(entries_by_month.keys(), key=lambda x: "%02d-%02d" % x, reverse=False)
    prev_year = None
    for month in months:
        year, _month = month
        if prev_year != year:
            print("\n## ", year, "{.calendar-container}\n")
            # print("<hr/>")
            prev_year = year
        print(HTMLCalendarMonthWithEntries(*month, entries_by_month[month]))


if __name__ == '__main__':
    try:
        diary_dir = Path(argv[1])
        if not diary_dir.is_dir():
            raise Exception()
    except:
        print("Please provide a valid path for diary source.")
        exit(1)
    try:
        build_dir = Path(argv[2])
        if not build_dir.is_dir():
            build_dir.mkdir(parents=True)
    except:
        print("Please provide a valid path for diary build.")
        exit(1)
    diary_entries = [
        date.fromisoformat(p.stem) for p in diary_dir.iterdir()
    ]
    if 'list-months' in argv:
        pass
    if 'list-weeks' in argv:
        pass
    if 'index-files' in argv:
        targets = set([
            "index.html",
            *[f"{d.year}.html" for d in diary_entries],
            *["%d-%02d.html" % (d.year, d.month) for d in diary_entries],
        ])
        for t in targets:
            print(str(build_dir / t))
    if 'index-full' in argv:
        generate_index_full(diary_entries)
    if 'index-years' in argv:
        generate_index_years(diary_entries)