"""Migration 010's downgrade: reconstruct `is_pinned`/`planned_day_exclusion`
from `day_assertion` instead of losing them.

The naive downgrade — `ADD COLUMN is_pinned ... DEFAULT 0` plus a bare
`CREATE TABLE planned_day_exclusion` — silently unpins every previously
pinned day and drops every exclusion, then a further `downgrade` to 008
deletes `day_assertion` itself, at which point the facts are gone for good.
This proves the fixed downgrade instead reconstructs both shapes from
`day_assertion` (still present at the moment 010's `downgrade()` runs) for a
full `upgrade head` -> `downgrade 008` round trip, and pins down exactly the
two cases that are honestly NOT round-trippable (see 010's docstring):

- a concrete assertion whose `wish_id IS NULL`-driven mirrored row was never
  pinned still comes back with `is_pinned = 1` (over-restored, not
  under-restored — `day_assertion` never recorded *why* a row was asserted).
- a pinned row that collided with an exclusion at the same key loses its
  `is_pinned` fact at 009's *upgrade* already (`INSERT OR REPLACE`, exclusion
  wins), long before 010's downgrade runs, so there is nothing left to
  recover it from.
"""

from __future__ import annotations

import sqlite3
import uuid
from datetime import date, datetime
from pathlib import Path

from alembic import command
from alembic.config import Config


def _alembic_config(db_path: Path) -> Config:
    cfg = Config("alembic.ini")
    cfg.set_main_option("sqlalchemy.url", f"sqlite:///{db_path}")
    return cfg


def _seed_workspace_and_child(conn: sqlite3.Connection, now: str) -> tuple[str, str]:
    ws_id = str(uuid.uuid4())
    child_id = str(uuid.uuid4())
    conn.execute(
        "INSERT INTO workspace (id, name, created_at) VALUES (?, ?, ?)", (ws_id, "WS", now)
    )
    conn.execute(
        "INSERT INTO child (id, workspace_id, name, birth_date, "
        "preschool_start_date, preschool_planning_days_per_year, created_at) "
        "VALUES (?, ?, ?, ?, NULL, 0, ?)",
        (child_id, ws_id, "Barn", date(2026, 5, 1).isoformat(), now),
    )
    return ws_id, child_id


def _insert_planned_leave_day(
    conn: sqlite3.Connection,
    *,
    workspace_id: str,
    child_id: str,
    parent_id: str,
    day: date,
    day_type: str,
    is_pinned: bool,
    wish_id: str | None,
    now: str,
) -> str:
    row_id = str(uuid.uuid4())
    conn.execute(
        "INSERT INTO planned_leave_day "
        "(id, workspace_id, child_id, parent_personal_data_uuid, date, day_type, "
        " is_dubbeldag, wish_id, is_pinned, created_at, updated_at) "
        "VALUES (?, ?, ?, ?, ?, ?, 0, ?, ?, ?, ?)",
        (
            row_id,
            workspace_id,
            child_id,
            parent_id,
            day.isoformat(),
            day_type,
            wish_id,
            int(is_pinned),
            now,
            now,
        ),
    )
    return row_id


def _insert_exclusion(
    conn: sqlite3.Connection,
    *,
    workspace_id: str,
    child_id: str,
    parent_id: str,
    day: date,
    now: str,
) -> None:
    conn.execute(
        "INSERT INTO planned_day_exclusion "
        "(id, workspace_id, child_id, parent_personal_data_uuid, date, created_at, updated_at) "
        "VALUES (?, ?, ?, ?, ?, ?, ?)",
        (str(uuid.uuid4()), workspace_id, child_id, parent_id, day.isoformat(), now, now),
    )


def _planned_day(db_path: Path, row_id: str) -> sqlite3.Row:
    conn = sqlite3.connect(db_path)
    conn.row_factory = sqlite3.Row
    try:
        row = conn.execute("SELECT * FROM planned_leave_day WHERE id = ?", (row_id,)).fetchone()
        assert row is not None
        return row
    finally:
        conn.close()


def _exclusion_exists(
    db_path: Path, *, workspace_id: str, child_id: str, parent_id: str, day: date
) -> bool:
    conn = sqlite3.connect(db_path)
    try:
        row = conn.execute(
            "SELECT 1 FROM planned_day_exclusion "
            "WHERE workspace_id = ? AND child_id = ? AND parent_personal_data_uuid = ? "
            "AND date = ?",
            (workspace_id, child_id, parent_id, day.isoformat()),
        ).fetchone()
        return row is not None
    finally:
        conn.close()


def test_full_round_trip_reconstructs_pins_and_exclusions(tmp_path: Path) -> None:
    db = tmp_path / "roundtrip.db"
    command.upgrade(_alembic_config(db), "008")
    now = datetime(2026, 1, 1, 12, 0, 0).isoformat()

    conn = sqlite3.connect(db)
    ws_id, child_id = _seed_workspace_and_child(conn, now)
    parent_id = str(uuid.uuid4())
    wish_id = str(uuid.uuid4())

    pinned_day = date(2027, 1, 10)
    pinned_id = _insert_planned_leave_day(
        conn,
        workspace_id=ws_id,
        child_id=child_id,
        parent_id=parent_id,
        day=pinned_day,
        day_type="lagsta",
        is_pinned=True,
        wish_id=wish_id,
        now=now,
    )

    adhoc_day = date(2027, 1, 11)
    adhoc_id = _insert_planned_leave_day(
        conn,
        workspace_id=ws_id,
        child_id=child_id,
        parent_id=parent_id,
        day=adhoc_day,
        day_type="vacation",
        is_pinned=False,
        wish_id=None,
        now=now,
    )

    pinned_and_adhoc_day = date(2027, 1, 12)
    pinned_and_adhoc_id = _insert_planned_leave_day(
        conn,
        workspace_id=ws_id,
        child_id=child_id,
        parent_id=parent_id,
        day=pinned_and_adhoc_day,
        day_type="sjukpenning",
        is_pinned=True,
        wish_id=None,
        now=now,
    )

    derived_day = date(2027, 1, 13)
    derived_id = _insert_planned_leave_day(
        conn,
        workspace_id=ws_id,
        child_id=child_id,
        parent_id=parent_id,
        day=derived_day,
        day_type="sjukpenning",
        is_pinned=False,
        wish_id=wish_id,
        now=now,
    )

    plain_exclusion_day = date(2027, 1, 14)
    _insert_exclusion(
        conn,
        workspace_id=ws_id,
        child_id=child_id,
        parent_id=parent_id,
        day=plain_exclusion_day,
        now=now,
    )

    # A pinned row and a colliding exclusion at the same key (a historical
    # anomaly the runtime never creates going forward, but old data might
    # still hold) — 009's upgrade resolves this "exclusion wins".
    collision_day = date(2027, 1, 15)
    collision_id = _insert_planned_leave_day(
        conn,
        workspace_id=ws_id,
        child_id=child_id,
        parent_id=parent_id,
        day=collision_day,
        day_type="sjukpenning",
        is_pinned=True,
        wish_id=None,
        now=now,
    )
    _insert_exclusion(
        conn,
        workspace_id=ws_id,
        child_id=child_id,
        parent_id=parent_id,
        day=collision_day,
        now=now,
    )

    conn.commit()
    conn.close()

    command.upgrade(_alembic_config(db), "head")
    command.downgrade(_alembic_config(db), "008")

    # -- pinned row: round-trips exactly ------------------------------------
    pinned_row = _planned_day(db, pinned_id)
    assert bool(pinned_row["is_pinned"]) is True
    assert pinned_row["day_type"] == "lagsta"
    assert pinned_row["wish_id"] == wish_id

    # -- ad-hoc, never-pinned row: over-restored, documented and expected --
    # `day_assertion` never recorded whether a concrete assertion came from
    # `is_pinned=1` or from `wish_id IS NULL` (009's own upgrade backfill
    # already conflates them: `WHERE is_pinned = 1 OR wish_id IS NULL`), so
    # this row comes back pinned even though it started unpinned. It is
    # still exempt from the allocator via `wish_id IS NULL`, unaffected by
    # this bit either way.
    adhoc_row = _planned_day(db, adhoc_id)
    assert bool(adhoc_row["is_pinned"]) is True
    assert adhoc_row["wish_id"] is None

    # -- pinned AND ad-hoc: round-trips exactly (was already pinned) -------
    both_row = _planned_day(db, pinned_and_adhoc_id)
    assert bool(both_row["is_pinned"]) is True

    # -- ordinary planner-derived row: never asserted, stays unpinned -------
    derived_row = _planned_day(db, derived_id)
    assert bool(derived_row["is_pinned"]) is False
    assert derived_row["wish_id"] == wish_id

    # -- plain exclusion: round-trips exactly --------------------------------
    assert _exclusion_exists(
        db, workspace_id=ws_id, child_id=child_id, parent_id=parent_id, day=plain_exclusion_day
    )

    # -- collision: exclusion wins, is_pinned is a KNOWN, documented loss ---
    # 009's upgrade already discarded the pinned assertion at this key via
    # `INSERT OR REPLACE` (exclusion wins) before 010 ever runs, so there is
    # no assertion left for 010's downgrade to recover `is_pinned` from.
    # This is not a bug in the downgrade under test — it is a fact already
    # lost one migration earlier, and the exclusion itself is what survives.
    collision_row = _planned_day(db, collision_id)
    assert bool(collision_row["is_pinned"]) is False
    assert _exclusion_exists(
        db, workspace_id=ws_id, child_id=child_id, parent_id=parent_id, day=collision_day
    )


def test_concrete_assertion_with_no_mirrored_row_does_not_error(tmp_path: Path) -> None:
    """An assertion can outlive its `planned_leave_day` mirror (e.g. a later

    plan sync re-derives the day away). Reconstruction must not crash on it
    — there is simply nothing to set `is_pinned` on.
    """
    db = tmp_path / "orphan.db"
    command.upgrade(_alembic_config(db), "008")
    now = datetime(2026, 1, 1, 12, 0, 0).isoformat()

    conn = sqlite3.connect(db)
    ws_id, child_id = _seed_workspace_and_child(conn, now)
    parent_id = str(uuid.uuid4())
    day = date(2027, 2, 1)
    row_id = _insert_planned_leave_day(
        conn,
        workspace_id=ws_id,
        child_id=child_id,
        parent_id=parent_id,
        day=day,
        day_type="vacation",
        is_pinned=True,
        wish_id=None,
        now=now,
    )
    conn.commit()
    conn.close()

    command.upgrade(_alembic_config(db), "head")

    # Delete the mirrored row after the assertion was backfilled, simulating
    # a later re-derivation that removed it — the assertion survives.
    conn = sqlite3.connect(db)
    conn.execute("DELETE FROM planned_leave_day WHERE id = ?", (row_id,))
    conn.commit()
    conn.close()

    # Must downgrade cleanly, not raise.
    command.downgrade(_alembic_config(db), "008")

    conn = sqlite3.connect(db)
    try:
        remaining = conn.execute(
            "SELECT COUNT(*) FROM planned_leave_day WHERE workspace_id = ?", (ws_id,)
        ).fetchone()[0]
    finally:
        conn.close()
    assert remaining == 0