from __future__ import annotations

import sqlite3
from dataclasses import dataclass
from pathlib import Path
from typing import Iterable


@dataclass(frozen=True)
class DatabaseConfig:
    db_path: Path


class DatabaseBootstrapper:
    """Creates the SQLite schema and demo data on demand."""

    def __init__(self, config: DatabaseConfig) -> None:
        self._config = config

    @property
    def path(self) -> Path:
        return self._config.db_path

    def initialize(self) -> None:
        self._ensure_parent_dir()
        with sqlite3.connect(self.path) as conn:
            conn.execute("PRAGMA foreign_keys = ON")
            self._create_tables(conn)
            self._seed_demo_data(conn)
            conn.commit()

    def _ensure_parent_dir(self) -> None:
        self.path.parent.mkdir(parents=True, exist_ok=True)

    def _create_tables(self, conn: sqlite3.Connection) -> None:
        conn.executescript(
            """
            CREATE TABLE IF NOT EXISTS modules (
                id TEXT PRIMARY KEY,
                title TEXT NOT NULL,
                credit_points INTEGER NOT NULL,
                status TEXT NOT NULL,
                progress_percent INTEGER NOT NULL
            );

            CREATE TABLE IF NOT EXISTS exams (
                id TEXT PRIMARY KEY,
                module_id TEXT NOT NULL
                    REFERENCES modules(id) ON DELETE CASCADE,
                title TEXT NOT NULL,
                exam_date TEXT NOT NULL,
                status TEXT NOT NULL
            );

            CREATE TABLE IF NOT EXISTS appointments (
                id TEXT PRIMARY KEY,
                title TEXT NOT NULL,
                start_date TEXT NOT NULL,
                description TEXT NOT NULL
            );
            """
        )

    def _seed_demo_data(self, conn: sqlite3.Connection) -> None:
        modules = [
            (
                "MAT101",
                "Analysis I",
                5,
                "In Progress",
                40,
            ),
            (
                "CS201",
                "Algorithms",
                6,
                "Planned",
                0,
            ),
            (
                "ENG150",
                "Academic Writing",
                3,
                "Completed",
                100,
            ),
        ]
        exams = [
            (
                "EXAM-MAT101",
                "MAT101",
                "Klausur Analysis I",
                "2025-12-15",
                "Scheduled",
            ),
            (
                "EXAM-CS201",
                "CS201",
                "Algorithmik Projekt",
                "2026-01-20",
                "Planned",
            ),
        ]
        appointments = [
            (
                "APPT-MENTOR",
                "Mentoring",
                "2025-12-08",
                "Mentoring call via Teams",
            ),
            (
                "APPT-STUDY",
                "Lerngruppe",
                "2025-12-10",
                "Gruppenlernen Bibliothek",
            ),
        ]

        module_sql = "INSERT OR IGNORE INTO modules " "VALUES (?, ?, ?, ?, ?)"
        exam_sql = "INSERT OR IGNORE INTO exams " "VALUES (?, ?, ?, ?, ?)"
        appointment_sql = "INSERT OR IGNORE INTO appointments " "VALUES (?, ?, ?, ?)"

        self._bulk_insert(conn, module_sql, modules)
        self._bulk_insert(conn, exam_sql, exams)
        self._bulk_insert(conn, appointment_sql, appointments)

    def _bulk_insert(
        self,
        conn: sqlite3.Connection,
        sql: str,
        rows: Iterable[tuple],
    ) -> None:
        conn.executemany(sql, rows)