"""iCalendar mapping tests (SPEC 4)."""

from __future__ import annotations

from datetime import datetime, timezone

from mdcaldav.config import Config
from mdcaldav.ical import apply_to_task, escape, fold, from_ics, to_ics, unescape
from mdcaldav.model import Status
from mdcaldav.parser import parse


def prop(text: str, name: str) -> str | None:
    from mdcaldav.ical import unfold

    for line in unfold(text):
        key = line.split(":", 1)[0].split(";", 1)[0]
        if key == name:
            return line.split(":", 1)[1]
    return None


def one(src: bytes, cfg: Config):
    return parse(src, "t.md", cfg)[0]


def test_basic_vtodo(cfg: Config):
    text = to_ics(one(b"- [ ] Water the seedlings\n", cfg))
    assert "BEGIN:VTODO" in text and "END:VTODO" in text
    assert prop(text, "SUMMARY") == "Water the seedlings"
    assert prop(text, "STATUS") == "NEEDS-ACTION"
    assert prop(text, "PRIORITY") is None
    assert text.endswith("\r\n")


def test_completed_maps_percent_and_timestamp(cfg: Config):
    when = datetime(2026, 1, 7, 15, 30, tzinfo=timezone.utc)
    text = to_ics(one(b"- [x] Rotate the compost\n", cfg), completed_at=when)
    assert prop(text, "STATUS") == "COMPLETED"
    assert prop(text, "PERCENT-COMPLETE") == "100"
    assert prop(text, "COMPLETED") == "20260107T153000Z"


def test_priority_bands(cfg: Config):
    for marker, expected in (("A", "1"), ("B", "5"), ("C", "9")):
        text = to_ics(one(f"- [ ] [#{marker}] x\n".encode(), cfg))
        assert prop(text, "PRIORITY") == expected


def test_description_and_categories(cfg: Config):
    src = b"## Garden\n\n- [ ] Prune\n  - Use the long loppers\n"
    task = parse(src, "t.md", cfg)[0]
    text = to_ics(task)
    assert prop(text, "DESCRIPTION") == "Use the long loppers"
    assert "Garden" in (prop(text, "CATEGORIES") or "")


def test_parent_relation(cfg: Config):
    tasks = parse(b"- [ ] parent\n  - [ ] child\n", "t.md", cfg)
    text = to_ics(tasks[1])
    assert f"RELATED-TO;RELTYPE=PARENT:{tasks[0].uid}" in text


def test_text_escaping_round_trip():
    raw = "Comma, semi; back\\slash\nnewline"
    assert unescape(escape(raw)) == raw


def test_special_characters_survive_serialization(cfg: Config):
    src = "- [ ] Buy: milk, eggs; and a note\\here\n".encode()
    text = to_ics(one(src, cfg))
    assert from_ics(text)["title"] == "Buy: milk, eggs; and a note\\here"


def test_folding_respects_character_boundaries():
    line = "SUMMARY:" + "é" * 100
    folded = fold(line)
    assert all(len(seg.encode()) <= 75 for seg in folded.split("\r\n "))
    from mdcaldav.ical import unfold

    assert unfold(folded)[0] == line


def test_long_summary_round_trips(cfg: Config):
    title = "Plan " + "the very long garden bed layout " * 6
    text = to_ics(one(f"- [ ] {title}\n".encode(), cfg))
    assert from_ics(text)["title"] == title.strip()


def test_from_ics_ignores_unmodelled_properties():
    text = (
        "BEGIN:VCALENDAR\r\nBEGIN:VTODO\r\nUID:abc\r\nSUMMARY:Task\r\n"
        "RRULE:FREQ=WEEKLY\r\nBEGIN:VALARM\r\nTRIGGER:-PT15M\r\n"
        "SUMMARY:Alarm text\r\nEND:VALARM\r\nSTATUS:COMPLETED\r\n"
        "END:VTODO\r\nEND:VCALENDAR\r\n"
    )
    fields = from_ics(text)
    assert fields["title"] == "Task"  # not clobbered by the VALARM's SUMMARY
    assert fields["status"] is Status.COMPLETED
    assert "rrule" not in fields


def test_percent_complete_implies_completion():
    text = (
        "BEGIN:VCALENDAR\r\nBEGIN:VTODO\r\nUID:abc\r\nSUMMARY:T\r\n"
        "PERCENT-COMPLETE:100\r\nEND:VTODO\r\nEND:VCALENDAR\r\n"
    )
    assert from_ics(text)["status"] is Status.COMPLETED


def test_apply_to_task_reports_only_real_changes(cfg: Config):
    task = one(b"- [ ] [#A] Ship it\n", cfg)
    same = from_ics(to_ics(task))
    assert apply_to_task(task, same, cfg) == {}

    changed = dict(same, status=Status.COMPLETED, title="Ship it now")
    assert apply_to_task(task, changed, cfg) == {
        "status": Status.COMPLETED,
        "title": "Ship it now",
    }


def test_priority_snaps_to_configured_bands(cfg: Config):
    task = one(b"- [ ] [#A] Ship it\n", cfg)
    # A client sending 3 stays in the "high" band → still [#A], so no change.
    assert apply_to_task(task, {"priority": 3}, cfg) == {}
    assert apply_to_task(task, {"priority": 9}, cfg) == {"priority": 9}
    assert apply_to_task(task, {"priority": 0}, cfg) == {"priority": None}