/*
 *  db.ts
 *  Zyquo Cloud Web
 *
 *  Author: Simon-Pierre Boucher
 *  Mail: contact@spboucher.ai
 *
 *  Tiny promise wrapper around IndexedDB — no external dependency (every
 *  dependency is key-theft surface). One database, versioned schema.
 */

const DB_NAME = 'zyquo.cloud.web'
const DB_VERSION = 1
export const STORE_CONVERSATIONS = 'conversations'

let dbPromise: Promise<IDBDatabase> | null = null

export function openDB(): Promise<IDBDatabase> {
  if (dbPromise) return dbPromise
  dbPromise = new Promise((resolve, reject) => {
    const request = indexedDB.open(DB_NAME, DB_VERSION)
    request.onupgradeneeded = () => {
      const db = request.result
      // v1: conversations store keyed by id, indexed by updatedAt for sorting.
      if (!db.objectStoreNames.contains(STORE_CONVERSATIONS)) {
        const store = db.createObjectStore(STORE_CONVERSATIONS, { keyPath: 'id' })
        store.createIndex('updatedAt', 'updatedAt')
      }
    }
    request.onsuccess = () => {
      request.result.onversionchange = () => request.result.close()
      resolve(request.result)
    }
    request.onerror = () => reject(request.error ?? new Error('IndexedDB open failed'))
    request.onblocked = () => reject(new Error('IndexedDB open blocked'))
  })
  return dbPromise
}

function requestToPromise<T>(request: IDBRequest<T>): Promise<T> {
  return new Promise((resolve, reject) => {
    request.onsuccess = () => resolve(request.result)
    request.onerror = () => reject(request.error ?? new Error('IndexedDB request failed'))
  })
}

export async function dbGet<T>(store: string, key: string): Promise<T | undefined> {
  const db = await openDB()
  const tx = db.transaction(store, 'readonly')
  return requestToPromise(tx.objectStore(store).get(key) as IDBRequest<T | undefined>)
}

export async function dbGetAll<T>(store: string): Promise<T[]> {
  const db = await openDB()
  const tx = db.transaction(store, 'readonly')
  return requestToPromise(tx.objectStore(store).getAll() as IDBRequest<T[]>)
}

export async function dbPut(store: string, value: unknown): Promise<void> {
  const db = await openDB()
  const tx = db.transaction(store, 'readwrite')
  await requestToPromise(tx.objectStore(store).put(value))
}

export async function dbDelete(store: string, key: string): Promise<void> {
  const db = await openDB()
  const tx = db.transaction(store, 'readwrite')
  await requestToPromise(tx.objectStore(store).delete(key))
}

export async function dbClear(store: string): Promise<void> {
  const db = await openDB()
  const tx = db.transaction(store, 'readwrite')
  await requestToPromise(tx.objectStore(store).clear())
}