from __future__ import annotations

from .shared import (
    Any,
    BACKUP_RESTORE_POLICY,
    CASHFLOW_KIND_SQL,
    DEFAULT_LEDGER_BACKUP_DIR,
    KST,
    Path,
    current_kst_month,
    datetime,
    db,
    read_db,
    read_operation,
    fail,
    hashlib,
    init_db,
    ok,
    resolve_db_path,
    row_to_dict,
    sqlite3,
    timedelta,
)
from .shared import _current_kst_datetime, _month_range

def health_check(db_path: str | None = None) -> dict[str, Any]:
    path = init_db(db_path)
    with db(path) as conn:
        schema_version = conn.execute("SELECT value FROM schema_meta WHERE key='schema_version'").fetchone()[0]
        tx_count = conn.execute("SELECT COUNT(*) FROM transactions WHERE status='active'").fetchone()[0]
    return ok(server="jarca-ledger-mcp", db_path=path, schema_version=schema_version, active_transactions=tx_count)


@read_operation
def health_check_readonly(db_path: str | None = None) -> dict[str, Any]:
    path = resolve_db_path(db_path)
    with read_db(str(path)) as conn:
        schema_version = conn.execute("SELECT value FROM schema_meta WHERE key='schema_version'").fetchone()[0]
        tx_count = conn.execute("SELECT COUNT(*) FROM transactions WHERE status='active'").fetchone()[0]
    return ok(server="jarca-ledger-mcp", db_path=path, schema_version=schema_version, active_transactions=tx_count)


def _sha256_file(path: Path) -> str:
    digest = hashlib.sha256()
    with path.open("rb") as f:
        for chunk in iter(lambda: f.read(1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def _file_metadata(path: Path, include_hash: bool = True) -> dict[str, Any]:
    stat = path.stat()
    metadata: dict[str, Any] = {
        "path": str(path.resolve()),
        "size_bytes": stat.st_size,
        "mtime": datetime.fromtimestamp(stat.st_mtime).replace(microsecond=0).isoformat(),
    }
    if include_hash:
        metadata["sha256"] = _sha256_file(path)
    return metadata


def _readonly_sqlite_connection(path: Path) -> sqlite3.Connection:
    conn = sqlite3.connect(f"file:{path}?mode=ro", uri=True)
    conn.row_factory = sqlite3.Row
    return conn


def _safe_table_counts(conn: sqlite3.Connection) -> dict[str, int]:
    counts: dict[str, int] = {}
    for table in ("accounts", "transactions", "budgets", "import_batches", "category_rules", "ledger_categories", "manual_assets", "asset_snapshots", "review_decisions", "reconciliation_sessions"):
        exists = conn.execute("SELECT 1 FROM sqlite_master WHERE type='table' AND name=?", (table,)).fetchone()
        if exists:
            counts[table] = int(conn.execute(f"SELECT COUNT(*) FROM {table}").fetchone()[0])
    return counts


def _safe_monthly_aggregates(conn: sqlite3.Connection) -> dict[str, Any]:
    current_month = current_kst_month()
    start, next_month = _month_range(current_month)
    rows = conn.execute(
        f"""SELECT {CASHFLOW_KIND_SQL} AS cashflow_kind, SUM(t.amount) AS total, COUNT(*) AS count
              FROM transactions t
              LEFT JOIN ledger_categories lc ON lc.active=1 AND t.category=lc.category AND t.subcategory=lc.subcategory
             WHERE t.status='active' AND t.transaction_date>=? AND t.transaction_date<?
             GROUP BY {CASHFLOW_KIND_SQL}""",
        (start, next_month),
    ).fetchall()
    return {
        "month": current_month,
        "by_cashflow_kind": {
            str(row["cashflow_kind"]): {"amount": int(row["total"] or 0), "count": int(row["count"] or 0)}
            for row in rows
        },
    }


def _ledger_db_status_for_path(path: Path, include_hash: bool = True, include_integrity: bool = True) -> dict[str, Any]:
    status: dict[str, Any] = {"db_path": str(path.resolve()), "exists": path.exists()}
    if not path.exists():
        return status
    status.update(_file_metadata(path, include_hash=include_hash))
    try:
        with _readonly_sqlite_connection(path) as conn:
            if include_integrity:
                status["integrity_check"] = str(conn.execute("PRAGMA integrity_check").fetchone()[0])
            status["table_counts"] = _safe_table_counts(conn)
            status["aggregate_totals"] = _safe_monthly_aggregates(conn)
    except Exception as e:
        status["integrity_check"] = "error"
        status["error"] = str(e)
    return status


def get_ledger_db_status(db_path: str | None = None, include_hash: bool = True, include_integrity: bool = True) -> dict[str, Any]:
    """Return non-sensitive metadata evidence for the selected ledger DB."""
    path = resolve_db_path(db_path)
    if not path.exists():
        return fail("not_found", f"ledger DB not found: {path}", db_path=str(path), exists=False)
    return ok(**_ledger_db_status_for_path(path, include_hash=include_hash, include_integrity=include_integrity))


def _resolve_backup_dir(backup_dir: str | None = None) -> Path:
    return Path(backup_dir).expanduser().resolve() if backup_dir else DEFAULT_LEDGER_BACKUP_DIR.resolve()


def _backup_file_metadata(path: Path, include_hash: bool = False) -> dict[str, Any]:
    metadata = _file_metadata(path, include_hash=include_hash)
    metadata["name"] = path.name
    metadata["restore_policy"] = BACKUP_RESTORE_POLICY
    return metadata


def _apply_backup_retention(backup_dir: Path, retention_days: int = 30, retention_count: int = 20) -> list[str]:
    backups = sorted(backup_dir.glob("*.sqlite3"), key=lambda p: p.stat().st_mtime, reverse=True)
    keep_count = max(1, int(retention_count))
    # Retention comparison needs sub-second precision for retention_days=0:
    # the timestamp used for backup names is second-truncated, but filesystem mtimes
    # can identify files created just before retention runs as older than "now".
    cutoff = datetime.now(KST) - timedelta(days=max(0, int(retention_days)))
    pruned: list[str] = []
    for idx, path in enumerate(backups):
        mtime = datetime.fromtimestamp(path.stat().st_mtime, tz=KST)
        should_keep = idx < keep_count or mtime >= cutoff
        if should_keep:
            continue
        path.unlink()
        pruned.append(str(path.resolve()))
    return pruned


def create_ledger_backup(db_path: str | None = None, backup_dir: str | None = None, retention_days: int = 30, retention_count: int = 20) -> dict[str, Any]:
    """Create a timestamped SQLite backup and return metadata-only evidence."""
    source_path = resolve_db_path(db_path)
    if not source_path.exists():
        return fail("not_found", f"ledger DB not found: {source_path}", db_path=str(source_path), exists=False)
    backup_root = _resolve_backup_dir(backup_dir)
    backup_root.mkdir(parents=True, exist_ok=True)
    timestamp = _current_kst_datetime().strftime("%Y%m%d%H%M%S%f")
    backup_path = backup_root / f"ledger_{timestamp}.sqlite3"
    try:
        # Use SQLite's online backup API so WAL-mode databases are copied consistently.
        with sqlite3.connect(f"file:{source_path}?mode=ro", uri=True) as source_conn:
            with sqlite3.connect(backup_path) as backup_conn:
                source_conn.backup(backup_conn)
    except Exception:
        if backup_path.exists():
            backup_path.unlink()
        raise
    source_status = _ledger_db_status_for_path(source_path, include_hash=True, include_integrity=True)
    backup_status = _ledger_db_status_for_path(backup_path, include_hash=True, include_integrity=True)
    pruned_paths = _apply_backup_retention(backup_root, retention_days=retention_days, retention_count=retention_count)
    return ok(
        source_db=source_status,
        backup=backup_status,
        backup_dir=str(backup_root),
        retention={"retention_days": int(retention_days), "retention_count": int(retention_count), "pruned_paths": pruned_paths},
        restore_policy=BACKUP_RESTORE_POLICY,
    )


def list_ledger_backups(backup_dir: str | None = None, include_hash: bool = False, limit: int = 50) -> dict[str, Any]:
    backup_root = _resolve_backup_dir(backup_dir)
    if not backup_root.exists():
        return ok(backup_dir=str(backup_root), backups=[], count=0, restore_policy=BACKUP_RESTORE_POLICY)
    max_items = max(1, min(int(limit), 500))
    files = sorted(backup_root.glob("*.sqlite3"), key=lambda p: p.stat().st_mtime, reverse=True)[:max_items]
    backups = [_backup_file_metadata(path, include_hash=include_hash) for path in files]
    return ok(backup_dir=str(backup_root), backups=backups, count=len(backups), restore_policy=BACKUP_RESTORE_POLICY)


def get_ledger_backup_status(file_path: str, include_hash: bool = True, include_integrity: bool = True) -> dict[str, Any]:
    path = Path(file_path).expanduser().resolve()
    if not path.exists():
        return fail("not_found", f"backup file not found: {path}", path=str(path), exists=False)
    return ok(backup=_ledger_db_status_for_path(path, include_hash=include_hash, include_integrity=include_integrity), restore_policy=BACKUP_RESTORE_POLICY)

from .accounts_write_services import create_ledger_account as create_ledger_account

@read_operation
def list_ledger_accounts(active_only: bool = True, db_path: str | None = None) -> dict[str, Any]:
    sql = "SELECT * FROM accounts" + (" WHERE active=1" if active_only else "") + " ORDER BY name"
    with read_db(db_path) as conn:
        rows = conn.execute(sql).fetchall()
    return ok(accounts=[row_to_dict(r) for r in rows], count=len(rows))