from datetime import date, datetime, time, timedelta
from zoneinfo import ZoneInfo


OSLO_TIMEZONE = ZoneInfo("Europe/Oslo")


def get_oslo_today() -> date:
    return datetime.now(OSLO_TIMEZONE).date()


async def ensure_course_status_history_table(conn) -> None:
    await conn.execute(
        """
        CREATE TABLE IF NOT EXISTS course_status_history (
            id SERIAL PRIMARY KEY,
            course_id INTEGER NOT NULL REFERENCES courses(id) ON DELETE CASCADE,
            facility_id INTEGER NOT NULL REFERENCES facilities(id) ON DELETE CASCADE,
            old_status TEXT,
            new_status TEXT NOT NULL,
            change_source TEXT NOT NULL,
            changed_by TEXT,
            changed_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
        )
        """
    )
    await conn.execute(
        """
        CREATE INDEX IF NOT EXISTS idx_course_status_history_changed_at
        ON course_status_history (changed_at DESC)
        """
    )
    await conn.execute(
        """
        CREATE INDEX IF NOT EXISTS idx_course_status_history_course_id
        ON course_status_history (course_id, changed_at DESC)
        """
    )
    await conn.execute(
        """
        CREATE INDEX IF NOT EXISTS idx_course_status_history_facility_id
        ON course_status_history (facility_id, changed_at DESC)
        """
    )


async def log_course_status_change(
    conn,
    *,
    course_id: int,
    facility_id: int,
    old_status: str | None,
    new_status: str | None,
    change_source: str,
    changed_by: str | None = None,
) -> bool:
    normalized_old = str(old_status or "").strip().lower() or "ukjent"
    normalized_new = str(new_status or "").strip().lower() or "ukjent"
    normalized_source = str(change_source or "").strip().lower()
    normalized_changed_by = str(changed_by or "").strip() or None

    if not normalized_source:
        raise ValueError("change_source må være satt")

    if normalized_old == normalized_new:
        return False

    await conn.execute(
        """
        INSERT INTO course_status_history (
            course_id,
            facility_id,
            old_status,
            new_status,
            change_source,
            changed_by
        )
        VALUES ($1, $2, $3, $4, $5, $6)
        """,
        course_id,
        facility_id,
        normalized_old,
        normalized_new,
        normalized_source,
        normalized_changed_by,
    )
    return True


async def list_course_status_history(conn, *, changed_on: date | None = None, limit: int = 100):
    target_date = changed_on or get_oslo_today()
    start_at = datetime.combine(target_date, time.min, tzinfo=OSLO_TIMEZONE)
    end_at = start_at + timedelta(days=1)

    rows = await conn.fetch(
        """
        SELECT
            h.id,
            h.course_id,
            h.facility_id,
            h.old_status,
            h.new_status,
            h.change_source,
            h.changed_by,
            h.changed_at,
            c.name AS course_name,
            f.name AS facility_name,
            f.slug AS facility_slug
        FROM course_status_history h
        JOIN courses c ON c.id = h.course_id
        JOIN facilities f ON f.id = h.facility_id
        WHERE h.changed_at >= $1
          AND h.changed_at < $2
        ORDER BY h.changed_at DESC, h.id DESC
        LIMIT $3
        """,
        start_at,
        end_at,
        limit,
    )

    return [
        {
            "id": row["id"],
            "course_id": row["course_id"],
            "facility_id": row["facility_id"],
            "old_status": row["old_status"],
            "new_status": row["new_status"],
            "change_source": row["change_source"],
            "changed_by": row["changed_by"],
            "changed_at": row["changed_at"].isoformat() if row["changed_at"] else None,
            "course_name": row["course_name"],
            "facility_name": row["facility_name"],
            "facility_slug": row["facility_slug"],
        }
        for row in rows
    ]