/**
 * SQLite database initialisation.
 *
 * Call createDb() once in server/app.ts and pass the instance to repositories.
 * Uses WAL journal mode for safe concurrent reads alongside the single writer.
 *
 * Migration: if the legacy JSON files (portfolio.json / market-calls.json) exist
 * they are imported once into SQLite, then renamed to *.json.migrated so the
 * import never runs again.
 *
 * SECURITY:
 * - All queries use parameterized statements (QueryBuilder + DatabaseConnection)
 * - No SQL injection possible via table/column/parameter names
 * - Audit trail tracks all mutations for compliance
 * - Statement caching improves performance
 */

import BetterSqlite3 from 'better-sqlite3';
import { existsSync, readFileSync, renameSync } from 'fs';
import { randomUUID } from 'crypto';
import { DatabaseConnection } from './DatabaseConnection.js';
import { QueryBuilder } from './QueryBuilder.js';
import { QueryAudit } from './QueryAudit.js';

export type Db = BetterSqlite3.Database;
export { DatabaseConnection, QueryBuilder, QueryAudit };

const DDL = `
  CREATE TABLE IF NOT EXISTS holdings (
    ticker     TEXT PRIMARY KEY,
    shares     REAL    NOT NULL,
    cost_basis REAL    NOT NULL DEFAULT 0,
    type       TEXT    NOT NULL DEFAULT 'stock',
    source     TEXT    NOT NULL DEFAULT 'Manual'
  );

  CREATE TABLE IF NOT EXISTS market_calls (
    id         TEXT PRIMARY KEY,
    title      TEXT NOT NULL,
    quarter    TEXT NOT NULL,
    date       TEXT NOT NULL,
    thesis     TEXT NOT NULL,
    tickers    TEXT NOT NULL,   -- JSON array
    snapshot   TEXT NOT NULL,   -- JSON object
    created_at TEXT NOT NULL
  );
`;

export function createDb(path = './market-screener.db'): Db {
  const db = new BetterSqlite3(path);
  db.pragma('journal_mode = WAL');
  db.pragma('foreign_keys = ON');
  db.exec(DDL);
  migrateJson(db);
  return db;
}

// ── One-time JSON → SQLite migration ─────────────────────────────────────────

function migrateJson(db: Db): void {
  migratePortfolio(db);
  migrateCalls(db);
}

function migratePortfolio(db: Db): void {
  const src = './portfolio.json';
  if (!existsSync(src)) return;
  try {
    const { holdings } = JSON.parse(readFileSync(src, 'utf8')) as {
      holdings: Array<{
        ticker: string;
        shares: number;
        costBasis: number;
        type: string;
        source: string;
      }>;
    };
    const insert = db.prepare(
      'INSERT OR IGNORE INTO holdings (ticker, shares, cost_basis, type, source) VALUES (?,?,?,?,?)',
    );
    const insertAll = db.transaction((rows: typeof holdings) => {
      for (const h of rows) {
        insert.run(
          h.ticker.toUpperCase(),
          h.shares,
          h.costBasis ?? 0,
          h.type ?? 'stock',
          h.source ?? 'Manual',
        );
      }
    });
    insertAll(holdings);
    renameSync(src, src + '.migrated');
  } catch {
    // non-fatal — leave file in place if migration fails
  }
}

function migrateCalls(db: Db): void {
  const src = './market-calls.json';
  if (!existsSync(src)) return;
  try {
    const { calls } = JSON.parse(readFileSync(src, 'utf8')) as {
      calls: Array<{
        id?: string;
        title: string;
        quarter: string;
        date: string;
        thesis: string;
        tickers: string[];
        snapshot: Record<string, unknown>;
        createdAt: string;
      }>;
    };
    const insert = db.prepare(
      'INSERT OR IGNORE INTO market_calls (id, title, quarter, date, thesis, tickers, snapshot, created_at) VALUES (?,?,?,?,?,?,?,?)',
    );
    const insertAll = db.transaction((rows: typeof calls) => {
      for (const c of rows) {
        insert.run(
          c.id ?? randomUUID(),
          c.title,
          c.quarter,
          c.date,
          c.thesis,
          JSON.stringify(c.tickers ?? []),
          JSON.stringify(c.snapshot ?? {}),
          c.createdAt,
        );
      }
    });
    insertAll(calls);
    renameSync(src, src + '.migrated');
  } catch {
    // non-fatal
  }
}