'use client'

/**
 * useStickerCache — cache de figurinhas em IndexedDB.
 *
 * Chave de cache: sha256 hex do arquivo (conteúdo permanente — nunca muda).
 * Sem TTL: stickers são imutáveis, então o cache é eterno.
 * O único motivo para uma entrada sumir é o usuário limpar dados do navegador.
 *
 * Armazenamento: dataURL base64 do WebP (compatível com <img src>).
 */

const DB_NAME    = 'nw-stickers'
const STORE_NAME = 'blobs'
const DB_VERSION = 1

interface CacheEntry {
  sha256:  string
  dataUrl: string
}

let dbPromise: Promise<IDBDatabase> | null = null

function openDB(): Promise<IDBDatabase> {
  if (dbPromise) return dbPromise
  dbPromise = new Promise((resolve, reject) => {
    const req = indexedDB.open(DB_NAME, DB_VERSION)
    req.onupgradeneeded = () => {
      const db = req.result
      if (!db.objectStoreNames.contains(STORE_NAME)) {
        db.createObjectStore(STORE_NAME, { keyPath: 'sha256' })
      }
    }
    req.onsuccess = () => resolve(req.result)
    req.onerror   = () => { dbPromise = null; reject(req.error) }
  })
  return dbPromise
}

export async function getStickerFromCache(sha256: string): Promise<string | null> {
  if (typeof window === 'undefined') return null
  try {
    const db = await openDB()
    return new Promise((resolve) => {
      const tx  = db.transaction(STORE_NAME, 'readonly')
      const req = tx.objectStore(STORE_NAME).get(sha256)
      req.onsuccess = () => resolve((req.result as CacheEntry | undefined)?.dataUrl ?? null)
      req.onerror   = () => resolve(null)
    })
  } catch {
    return null
  }
}

export async function setStickerInCache(sha256: string, dataUrl: string): Promise<void> {
  if (typeof window === 'undefined') return
  try {
    const db = await openDB()
    await new Promise<void>((resolve, reject) => {
      const tx    = db.transaction(STORE_NAME, 'readwrite')
      const entry: CacheEntry = { sha256, dataUrl }
      const req   = tx.objectStore(STORE_NAME).put(entry)
      req.onsuccess = () => resolve()
      req.onerror   = () => reject(req.error)
    })
  } catch { /* quota exceeded — ignora */ }
}

export async function hasStickerInCache(sha256: string): Promise<boolean> {
  if (typeof window === 'undefined') return false
  try {
    const db = await openDB()
    return new Promise((resolve) => {
      const tx  = db.transaction(STORE_NAME, 'readonly')
      const req = tx.objectStore(STORE_NAME).count(sha256)
      req.onsuccess = () => resolve(req.result > 0)
      req.onerror   = () => resolve(false)
    })
  } catch {
    return false
  }
}