"""
Database layer for TalkToDoc.
Local development and testing use SQLite (no setup needed). When deployed,
DATABASE_URL is set by Render and the app uses Postgres instead, since
Render's free tier wipes local files like a SQLite database on every
restart.

Queries are written once using SQLite-style '?' placeholders and adapted
automatically for Postgres, so there's a single query per function rather
than two versions of everything.
"""

import os
from pathlib import Path

import sqlite3

DB_PATH = Path(__file__).parent / "talktodoc.db"
SCHEMA_PATH = Path(__file__).parent / "schema.sql"
SCHEMA_PATH_POSTGRES = Path(__file__).parent / "schema_postgres.sql"

DATABASE_URL = os.environ.get("DATABASE_URL")

if DATABASE_URL:
    import psycopg2
    import psycopg2.extras


def get_connection():
    if DATABASE_URL:
        return psycopg2.connect(DATABASE_URL, cursor_factory=psycopg2.extras.RealDictCursor)
    connection = sqlite3.connect(DB_PATH)
    connection.row_factory = sqlite3.Row
    connection.execute("PRAGMA foreign_keys = ON")
    return connection


def _run(connection, query, params=()):
    if DATABASE_URL:
        query = query.replace("?", "%s")
    cursor = connection.cursor()
    cursor.execute(query, params)
    return cursor


def _insert_and_get_id(connection, query, params):
    if DATABASE_URL:
        cursor = _run(connection, query + " RETURNING id", params)
        return cursor.fetchone()["id"]
    cursor = _run(connection, query, params)
    return cursor.lastrowid


def init_db():
    schema_path = SCHEMA_PATH_POSTGRES if DATABASE_URL else SCHEMA_PATH
    schema_sql = schema_path.read_text()
    with get_connection() as connection:
        if DATABASE_URL:
            connection.cursor().execute(schema_sql)
        else:
            connection.executescript(schema_sql)


def add_user(name, preferred_language, role):
    with get_connection() as connection:
        return _insert_and_get_id(
            connection,
            "INSERT INTO app_user (name, preferred_language, role) VALUES (?, ?, ?)",
            (name, preferred_language, role),
        )


def add_session(user_id, start_time):
    with get_connection() as connection:
        return _insert_and_get_id(
            connection,
            "INSERT INTO session (user_id, start_time) VALUES (?, ?)",
            (user_id, start_time),
        )


def end_session(session_id, end_time):
    with get_connection() as connection:
        _run(connection, "UPDATE session SET end_time = ? WHERE id = ?", (end_time, session_id))


def add_interaction(user_id, input_text, detected_language, translated_text, nlu_summary, timestamp):
    with get_connection() as connection:
        return _insert_and_get_id(
            connection,
            """INSERT INTO interaction
               (user_id, input_text, detected_language, translated_text, nlu_summary, timestamp)
               VALUES (?, ?, ?, ?, ?, ?)""",
            (user_id, input_text, detected_language, translated_text, nlu_summary, timestamp),
        )


def get_interactions_for_user(user_id):
    with get_connection() as connection:
        cursor = _run(
            connection,
            "SELECT * FROM interaction WHERE user_id = ? ORDER BY timestamp",
            (user_id,),
        )
        return [dict(row) for row in cursor.fetchall()]


def get_pending_interactions():
    with get_connection() as connection:
        cursor = _run(
            connection,
            "SELECT * FROM interaction WHERE provider_response IS NULL ORDER BY timestamp",
        )
        return [dict(row) for row in cursor.fetchall()]


def get_completed_interactions():
    with get_connection() as connection:
        cursor = _run(
            connection,
            "SELECT * FROM interaction WHERE provider_response IS NOT NULL ORDER BY timestamp DESC",
        )
        return [dict(row) for row in cursor.fetchall()]


def get_interaction(interaction_id):
    with get_connection() as connection:
        cursor = _run(connection, "SELECT * FROM interaction WHERE id = ?", (interaction_id,))
        row = cursor.fetchone()
        return dict(row) if row else None


def update_interaction_response(interaction_id, provider_response, translated_response):
    with get_connection() as connection:
        _run(
            connection,
            "UPDATE interaction SET provider_response = ?, translated_response = ? WHERE id = ?",
            (provider_response, translated_response, interaction_id),
        )


if __name__ == "__main__":
    init_db()
    if DATABASE_URL:
        print("Database initialized (Postgres)")
    else:
        print("Database created at:", DB_PATH)