"""Identity, generation and sync-token tests (SPEC 12, tests 4-7/11)."""

from __future__ import annotations

from pathlib import Path

import pytest

from mdcaldav.config import Config
from mdcaldav.index import Index
from mdcaldav.model import Status


@pytest.fixture
def index(vault: Path, tmp_path: Path) -> Index:
    cfg = Config()
    cfg.vault.path = vault
    cfg.index.db = tmp_path / "index.db"
    idx = Index(cfg)
    idx.rescan()
    yield idx
    idx.close()


def uid_of(index: Index, title: str, rel: str | None = None) -> str:
    matches = [
        t
        for t in index.tasks.values()
        if t.title == title and (rel is None or t.source.rel_path == rel)
    ]
    assert len(matches) == 1, f"{title!r} matched {len(matches)} tasks"
    return matches[0].uid


def write(vault: Path, rel: str, text: str) -> None:
    (vault / rel).write_text(text, encoding="utf-8")


def test_uids_are_stable_across_an_unchanged_rescan(index: Index):
    before = {t.uid: t.title for t in index.tasks.values()}
    index.rescan()
    after = {t.uid: t.title for t in index.tasks.values()}
    assert before == after


def test_status_change_preserves_uid(index: Index, vault: Path):
    uid = uid_of(index, "Water the seedlings", "daily/2026-01-07.md")
    rel = "daily/2026-01-07.md"
    text = (vault / rel).read_text()
    write(vault, rel, text.replace("- [ ] Water the seedlings", "- [x] Water the seedlings"))
    index.rescan()

    assert index.tasks[uid].status is Status.COMPLETED
    assert uid_of(index, "Water the seedlings", rel) == uid


def test_reorder_preserves_uid(index: Index, vault: Path):
    rel = "daily/2026-01-07.md"
    uid = uid_of(index, "Call the arborist", rel)
    text = (vault / rel).read_text()
    lines = text.splitlines(keepends=True)
    lines[8], lines[9] = lines[9], lines[8]  # swap two task lines
    write(vault, rel, "".join(lines))
    index.rescan()

    assert uid_of(index, "Call the arborist", rel) == uid


def test_retitle_in_place_preserves_uid(index: Index, vault: Path):
    rel = "daily/2026-01-07.md"
    uid = uid_of(index, "Tidy the potting bench", rel)
    text = (vault / rel).read_text()
    write(vault, rel, text.replace("Tidy the potting bench", "Tidy the potting bench properly"))
    index.rescan()

    assert uid_of(index, "Tidy the potting bench properly", rel) == uid


def test_carry_forward_duplicates_stay_distinct(index: Index):
    """SPEC 6.3: the same title in three daily notes is three tasks, not one."""
    uids = {
        rel: uid_of(index, "Water the seedlings", rel)
        for rel in (
            "daily/2026-01-05.md",
            "daily/2026-01-06.md",
            "daily/2026-01-07.md",
        )
    }
    assert len(set(uids.values())) == 3


def test_completing_one_carry_forward_copy_does_not_affect_others(
    index: Index, vault: Path
):
    monday = uid_of(index, "Water the seedlings", "daily/2026-01-05.md")
    wednesday = uid_of(index, "Water the seedlings", "daily/2026-01-07.md")

    rel = "daily/2026-01-07.md"
    text = (vault / rel).read_text()
    write(vault, rel, text.replace("- [ ] Water the seedlings", "- [x] Water the seedlings"))
    index.rescan()

    assert index.tasks[wednesday].status is Status.COMPLETED
    assert index.tasks[monday].status is Status.NEEDS_ACTION


def test_true_cross_file_move_preserves_uid(index: Index, vault: Path):
    """A task that disappears from A and appears in B keeps its UID."""
    uid = uid_of(index, "Book the soil test", "daily/2026-01-07.md")

    src = "daily/2026-01-07.md"
    text = (vault / src).read_text()
    write(vault, src, text.replace("- [ ] [#A] Book the soil test\n", ""))
    dest = "daily/2026-01-06.md"
    write(vault, dest, (vault / dest).read_text() + "\n- [ ] [#A] Book the soil test\n")
    index.rescan()

    assert uid_of(index, "Book the soil test", dest) == uid


def test_deleted_task_is_tombstoned(index: Index, vault: Path):
    rel = "daily/2026-01-07.md"
    uid = uid_of(index, "Call the arborist", rel)
    text = (vault / rel).read_text()
    write(vault, rel, text.replace("- [ ] [#B] Call the arborist\n", ""))
    index.rescan()

    assert uid not in index.tasks
    row = index.db.execute(
        "SELECT deleted_gen FROM tasks WHERE uid = ?", (uid,)
    ).fetchone()
    assert row["deleted_gen"] is not None


def test_uids_survive_a_restart(vault: Path, tmp_path: Path):
    cfg = Config()
    cfg.vault.path = vault
    cfg.index.db = tmp_path / "index.db"

    first = Index(cfg)
    first.rescan()
    before = {t.uid for t in first.tasks.values()}
    first.close()

    second = Index(cfg)
    second.rescan()
    assert {t.uid for t in second.tasks.values()} == before
    second.close()


def test_completed_timestamp_recorded_on_transition(index: Index, vault: Path):
    rel = "daily/2026-01-07.md"
    uid = uid_of(index, "Water the seedlings", rel)
    assert index.completed_at(uid) is None

    text = (vault / rel).read_text()
    write(vault, rel, text.replace("- [ ] Water the seedlings", "- [x] Water the seedlings"))
    index.rescan()
    assert index.completed_at(uid) is not None


def test_collections_follow_directories(index: Index):
    assert set(index.collections()) == {"daily", "projects"}


def test_sync_returns_only_changed(index: Index, vault: Path):
    token, hrefs = index.sync("daily")
    assert hrefs  # initial sync returns everything

    rel = "daily/2026-01-07.md"
    uid = uid_of(index, "Water the seedlings", rel)
    text = (vault / rel).read_text()
    write(vault, rel, text.replace("- [ ] Water the seedlings", "- [x] Water the seedlings"))
    index.rescan()

    _, changed = index.sync("daily", token)
    assert changed == [f"{uid}.ics"]


def test_sync_rejects_stale_token(index: Index):
    index.cfg.index.tombstone_retention = 1
    for _ in range(4):
        index.rescan()
    with pytest.raises(ValueError):
        index.sync("daily", "http://mdcaldav.local/ns/sync/0")


def test_sync_rejects_malformed_token(index: Index):
    with pytest.raises(ValueError):
        index.sync("daily", "not-a-token")