/**
 * Database connection and initialization for MosaicIQ
 */

import Database from "better-sqlite3";
import { dirname } from "node:path";
import { fileURLToPath } from "node:url";
import { existsSync, mkdirSync } from "node:fs";
import { SCHEMA_VERSION, SQL_SCHEMA, DEFAULT_PORTFOLIO_ID } from "./schema.js";

export type Db = Database.Database;

export interface DatabaseConfig {
  path?: string;
  inMemory?: boolean;
}

/**
 * Get the default data directory for the platform
 */
export function getDataDir(): string {
  const platform = process.platform;
  const base = platform === "darwin"
    ? `${process.env.HOME}/Documents/MosaicIQ`
    : platform === "win32"
    ? `${process.env.LOCALAPPDATA}\\MosaicIQ`
    : `${process.env.HOME}/.local/share/mosaiciq`;

  if (!existsSync(base)) {
    mkdirSync(base, { recursive: true });
  }

  return base;
}

/**
 * Get the default database path
 */
export function getDefaultDbPath(): string {
  return `${getDataDir()}/mosaiciq.db`;
}

/**
 * Initialize the database with schema
 */
export function initDatabase(config: DatabaseConfig = {}): Db {
  const dbPath = config.inMemory ? ":memory:" : (config.path ?? getDefaultDbPath());

  if (!config.inMemory && dbPath !== ":memory:") {
    const dbDir = dirname(dbPath);
    if (!existsSync(dbDir)) {
      mkdirSync(dbDir, { recursive: true });
    }
  }

  const db = new Database(dbPath);

  // Enable WAL mode for better concurrent access
  db.pragma("journal_mode = WAL");

  // Enable foreign keys
  db.pragma("foreign_keys = ON");

  // Check if schema exists
  const hasMeta = db.prepare("SELECT name FROM sqlite_master WHERE type = 'table' AND name = '_meta'").get();
  const version = hasMeta
    ? db.prepare("SELECT value FROM _meta WHERE key = 'schema_version'").get() as { value: string } | undefined
    : undefined;

  if (!version) {
    // Fresh database - create schema
    db.exec(SQL_SCHEMA);

    // Set schema version
    db.prepare("INSERT INTO _meta (key, value) VALUES ('schema_version', ?)").run(String(SCHEMA_VERSION));

    // Create default portfolio
    db.prepare(`
      INSERT INTO portfolios (id, name)
      VALUES (?, ?)
    `).run(DEFAULT_PORTFOLIO_ID, "Core Retail Coverage");

    console.log(`[DB] Initialized database at ${dbPath}`);
  } else {
    const currentVersion = Number(version.value);
    if (currentVersion !== SCHEMA_VERSION) {
      console.warn(`[DB] Schema version mismatch: expected ${SCHEMA_VERSION}, got ${currentVersion}`);
      // TODO: Run migrations
    }
  }

  return db;
}

/**
 * Close the database connection
 */
export function closeDatabase(db: Db): void {
  db.close();
}

/**
 * Get a database connection (singleton pattern)
 */
let dbInstance: Db | null = null;

export function getDatabase(config?: DatabaseConfig): Db {
  if (!dbInstance) {
    dbInstance = initDatabase(config);
  }
  return dbInstance;
}

export function resetDatabase(): void {
  if (dbInstance) {
    closeDatabase(dbInstance);
    dbInstance = null;
  }
}