import re
import sqlite3
import logging
from contextlib import contextmanager
from core.config import DB_PATH

logger = logging.getLogger("omnivoice.db")

_IDENT_RE = re.compile(r"^[A-Za-z_][A-Za-z0-9_]*$")
_TYPE_RE = re.compile(r"^[A-Za-z0-9_ '\"\(\)\-\.]+$")


def get_db():
    conn = sqlite3.connect(DB_PATH)
    conn.row_factory = sqlite3.Row
    conn.execute("PRAGMA journal_mode=WAL")
    conn.execute("PRAGMA foreign_keys=ON")
    return conn


@contextmanager
def db_conn():
    """Context-managed SQLite connection that commits on clean exit and always closes."""
    conn = get_db()
    try:
        yield conn
        conn.commit()
    except Exception:
        try:
            conn.rollback()
        except Exception:
            pass
        raise
    finally:
        conn.close()


_BASE_SCHEMA = """
    CREATE TABLE IF NOT EXISTS voice_profiles (
        id TEXT PRIMARY KEY,
        name TEXT NOT NULL,
        ref_audio_path TEXT,
        ref_text TEXT DEFAULT '',
        instruct TEXT DEFAULT '',
        language TEXT DEFAULT 'Auto',
        locked_audio_path TEXT DEFAULT '',
        seed INTEGER DEFAULT NULL,
        is_locked INTEGER DEFAULT 0,
        personality TEXT DEFAULT '',
        created_at REAL
    );
    CREATE TABLE IF NOT EXISTS generation_history (
        id TEXT PRIMARY KEY,
        text TEXT,
        mode TEXT,
        language TEXT,
        instruct TEXT,
        profile_id TEXT,
        audio_path TEXT,
        duration_seconds REAL,
        generation_time REAL,
        seed INTEGER DEFAULT NULL,
        created_at REAL,
        FOREIGN KEY (profile_id) REFERENCES voice_profiles(id)
    );
    CREATE TABLE IF NOT EXISTS dub_history (
        id TEXT PRIMARY KEY,
        filename TEXT,
        duration REAL,
        segments_count INTEGER,
        language TEXT,
        language_code TEXT,
        tracks TEXT DEFAULT '[]',
        job_data TEXT,
        content_hash TEXT DEFAULT '',
        created_at REAL
    );
    CREATE TABLE IF NOT EXISTS studio_projects (
        id TEXT PRIMARY KEY,
        name TEXT NOT NULL,
        video_path TEXT,
        audio_path TEXT,
        duration REAL,
        state_json TEXT,
        created_at REAL,
        updated_at REAL
    );
    CREATE TABLE IF NOT EXISTS export_history (
        id TEXT PRIMARY KEY,
        filename TEXT,
        destination_path TEXT,
        mode TEXT,
        created_at REAL
    );
    CREATE TABLE IF NOT EXISTS glossary_terms (
        id TEXT PRIMARY KEY,
        project_id TEXT NOT NULL,
        source TEXT NOT NULL,
        target TEXT NOT NULL,
        note TEXT DEFAULT '',
        auto INTEGER DEFAULT 0,
        created_at REAL
    );
    CREATE INDEX IF NOT EXISTS idx_glossary_project ON glossary_terms(project_id);

    CREATE TABLE IF NOT EXISTS jobs (
        id TEXT PRIMARY KEY,
        type TEXT NOT NULL,
        project_id TEXT,
        status TEXT NOT NULL,
        created_at REAL NOT NULL,
        updated_at REAL NOT NULL,
        finished_at REAL,
        error TEXT,
        meta_json TEXT DEFAULT '{}'
    );
    CREATE INDEX IF NOT EXISTS idx_jobs_status ON jobs(status);
    CREATE INDEX IF NOT EXISTS idx_jobs_project ON jobs(project_id);
    CREATE INDEX IF NOT EXISTS idx_jobs_created ON jobs(created_at);

    CREATE TABLE IF NOT EXISTS job_events (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        job_id TEXT NOT NULL,
        seq INTEGER NOT NULL,
        created_at REAL NOT NULL,
        payload TEXT NOT NULL
    );
    CREATE INDEX IF NOT EXISTS idx_job_events_job_seq ON job_events(job_id, seq);

    -- Phase 1 AUTH-02: encrypted per-install key/value store. Used today
    -- for the HF token row + the per-install Fernet salt. Both fresh
    -- installs (this CREATE) and v0.2.7 upgrades (alembic
    -- 0001_phase1_settings) converge on the same schema.
    CREATE TABLE IF NOT EXISTS settings (
        key TEXT PRIMARY KEY,
        value TEXT NOT NULL,
        updated_at REAL NOT NULL
    );
"""

# Only tables/columns this module is allowed to ALTER. Prevents SQL injection via
# the f-string ALTER below if these helpers ever get exposed to user input.
_ALLOWED_MIGRATIONS = {
    ("voice_profiles", "locked_audio_path"),
    ("voice_profiles", "seed"),
    ("voice_profiles", "is_locked"),
    ("voice_profiles", "personality"),
    ("generation_history", "seed"),
    ("dub_history", "content_hash"),
}


def _add_column_if_missing(conn, table: str, column: str, typedef: str):
    if (table, column) not in _ALLOWED_MIGRATIONS:
        raise ValueError(f"Migration not allowed: {table}.{column}")
    if not _IDENT_RE.match(table) or not _IDENT_RE.match(column):
        raise ValueError(f"Invalid identifier: {table}.{column}")
    if not _TYPE_RE.match(typedef):
        raise ValueError(f"Invalid typedef: {typedef!r}")
    try:
        conn.execute(f"ALTER TABLE {table} ADD COLUMN {column} {typedef}")
    except sqlite3.OperationalError as e:
        if "duplicate column" not in str(e).lower():
            logger.warning("ALTER %s.%s failed: %s", table, column, e)


def _migrate(conn, current: int) -> int:
    """Apply migrations sequentially. Return new version."""
    if current < 1:
        _add_column_if_missing(conn, "voice_profiles", "locked_audio_path", "TEXT DEFAULT ''")
        _add_column_if_missing(conn, "voice_profiles", "seed", "INTEGER DEFAULT NULL")
        _add_column_if_missing(conn, "voice_profiles", "is_locked", "INTEGER DEFAULT 0")
        _add_column_if_missing(conn, "generation_history", "seed", "INTEGER DEFAULT NULL")
        current = 1
    if current < 2:
        _add_column_if_missing(conn, "dub_history", "content_hash", "TEXT DEFAULT ''")
        current = 2
    # v3: glossary_terms table lives in _BASE_SCHEMA (IF NOT EXISTS), so an old
    # DB simply picks it up on the next init — no ALTER needed.
    if current < 3:
        current = 3
    if current < 4:
        _add_column_if_missing(conn, "voice_profiles", "personality", "TEXT DEFAULT ''")
        current = 4
    return current


def init_db():
    conn = get_db()
    try:
        conn.executescript(_BASE_SCHEMA)
        version = conn.execute("PRAGMA user_version").fetchone()[0]
        new_version = _migrate(conn, version)
        if new_version != version:
            conn.execute(f"PRAGMA user_version = {new_version}")
        conn.commit()
    finally:
        conn.close()
    # Phase 1: also run any pending alembic migrations. Fresh installs land
    # the schema via _BASE_SCHEMA above; v0.2.7 → v0.3.0 upgrades pick up
    # the same end-state via the alembic versions/ chain. Both paths
    # converge because every migration uses `CREATE TABLE IF NOT EXISTS`
    # or explicit existence checks.
    _run_alembic_upgrade()


def _run_alembic_upgrade() -> None:
    """Best-effort `alembic upgrade head` on startup. Non-fatal: if alembic
    isn't reachable (e.g. user running a stripped-down install or migrations
    were already applied out-of-band), log a warning and move on. The
    _BASE_SCHEMA CREATE TABLE IF NOT EXISTS above guarantees the runtime
    schema is correct regardless."""
    try:
        import os
        from alembic import command
        from alembic.config import Config

        # Walk up from backend/core/db.py to find the alembic.ini at the
        # project root.
        here = os.path.dirname(os.path.abspath(__file__))
        root = os.path.dirname(os.path.dirname(here))
        ini = os.path.join(root, "alembic.ini")
        if not os.path.isfile(ini):
            logger.debug("alembic.ini not found at %s; skipping migrations", ini)
            return
        cfg = Config(ini)
        cfg.set_main_option("sqlalchemy.url", f"sqlite:///{DB_PATH}")
        command.upgrade(cfg, "head")
    except Exception as exc:
        # Don't block startup on a migration tooling problem. The runtime
        # schema is already correct via _BASE_SCHEMA.
        logger.warning("alembic upgrade head skipped: %s", exc)