import SQLiteESMFactory from '@journeyapps/wa-sqlite/dist/wa-sqlite.mjs'
import * as SQLite from '@journeyapps/wa-sqlite'
import { SCHEMA_SQL } from './schema.js'

let db = null
let sqlite3 = null
const tableListeners = new Map()

let initPromise = null

export function initDatabase() {
  if (initPromise) return initPromise
  initPromise = _init()
  return initPromise
}

async function _init() {
  const module = await SQLiteESMFactory()
  sqlite3 = SQLite.Factory(module)
  db = await sqlite3.open_v2(':memory:')

  for (const sql of SCHEMA_SQL.split(';').filter(s => s.trim())) {
    await sqlite3.exec(db, sql)
  }
  return db
}

export function notifyTableChanged(table) {
  tableListeners.get(table)?.forEach(cb => cb())
}

export function onTableChange(table, cb) {
  if (!tableListeners.has(table)) tableListeners.set(table, new Set())
  tableListeners.get(table).add(cb)
  return () => tableListeners.get(table).delete(cb)
}

export async function execSQL(sql, params = []) {
  if (!db) throw new Error('DB not initialized')
  const results = []

  if (params.length === 0) {
    await sqlite3.exec(db, sql, (row, cols) => {
      results.push(Object.fromEntries(cols.map((c, i) => [c, row[i]])))
    })
  } else {
    for await (const stmt of sqlite3.statements(db, sql)) {
      sqlite3.bind_collection(stmt, params)
      const cols = sqlite3.column_names(stmt)
      while ((await sqlite3.step(stmt)) === SQLite.SQLITE_ROW) {
        results.push(Object.fromEntries(cols.map((c, i) => [c, sqlite3.column(stmt, i)])))
      }
    }
  }

  return results
}