from __future__ import annotations

import os
import sqlite3
from contextlib import contextmanager
from pathlib import Path
from typing import Iterator
from urllib.parse import quote

DEFAULT_DB_PATH = Path.home() / ".local" / "share" / "jarca" / "ledger.sqlite3"


class DatabaseNotInitializedError(RuntimeError):
    """Raised when a read is requested before the ledger exists."""


def resolve_db_path(db_path: str | None = None) -> Path:
    raw = db_path or os.getenv("JARCA_LEDGER_DB_PATH") or str(DEFAULT_DB_PATH)
    return Path(raw).expanduser().resolve()


def connect(db_path: str | None = None) -> sqlite3.Connection:
    path = resolve_db_path(db_path)
    path.parent.mkdir(parents=True, exist_ok=True)
    conn = sqlite3.connect(path)
    conn.row_factory = sqlite3.Row
    conn.execute("PRAGMA foreign_keys=ON")
    return conn


def connect_readonly(db_path: str | None = None) -> sqlite3.Connection:
    """Open an existing ledger in SQLite URI read-only mode."""
    path = resolve_db_path(db_path)
    if not path.is_file():
        raise DatabaseNotInitializedError("ledger database is not initialized")
    uri = f"file:{quote(str(path), safe='/')}?mode=ro"
    try:
        conn = sqlite3.connect(uri, uri=True)
    except sqlite3.Error as exc:
        raise DatabaseNotInitializedError("ledger database is not initialized") from exc
    conn.row_factory = sqlite3.Row
    conn.execute("PRAGMA foreign_keys=ON")
    return conn


@contextmanager
def read_db(db_path: str | None = None) -> Iterator[sqlite3.Connection]:
    """Open an existing ledger without filesystem or transaction writes."""
    conn = connect_readonly(db_path)
    try:
        yield conn
    finally:
        conn.close()


@contextmanager
def db(db_path: str | None = None) -> Iterator[sqlite3.Connection]:
    from .migrations import init_db

    init_db(db_path)
    conn = connect(db_path)
    try:
        yield conn
        conn.commit()
    except Exception:
        conn.rollback()
        raise
    finally:
        conn.close()