/**
 * Write service - manages all write operations to IndexedDB
 * Routes writes through Web Worker for IndexedDB operations
 * Routes network operations through WebSocket service
 */

import type { NostrEvent } from 'nostr-tools'
import type { ObjectType } from './objectCache'

interface WriteObjectParams {
  objectType: ObjectType
  hash: string
  event: NostrEvent
  parsed: unknown
  version: number
  hidden: boolean
  index?: number
  published?: false | string[]
}

interface CreateNotificationParams {
  type: string
  objectType: string
  objectId: string
  eventId: string
  data?: Record<string, unknown>
}

interface LogPublicationParams {
  eventId: string
  relayUrl: string
  success: boolean
  error?: string
  objectType?: string
  objectId?: string
}

interface WorkerMessageEnvelope {
  type: string
  data?: unknown
}

interface WorkerErrorData {
  originalType: string | undefined
  taskId: string | undefined
  error: string | undefined
}

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null
}

function isWorkerMessageEnvelope(value: unknown): value is WorkerMessageEnvelope {
  if (!isRecord(value)) {
    return false
  }
  return typeof value.type === 'string'
}

function readString(value: unknown): string | undefined {
  return typeof value === 'string' ? value : undefined
}

function readWorkerErrorData(value: unknown): WorkerErrorData {
  if (!isRecord(value)) {
    return { originalType: undefined, taskId: undefined, error: undefined }
  }
  return {
    originalType: readString(value.originalType),
    taskId: readString(value.taskId),
    error: readString(value.error),
  }
}

function isWorkerErrorForOperation(errorData: WorkerErrorData, operation: string): boolean {
  if (errorData.originalType === operation) {
    return true
  }
  return errorData.taskId?.startsWith(operation) === true
}

class WriteService {
  private writeWorker: Worker | null = null
  private initPromise: Promise<void> | null = null

  /**
   * Initialize the write worker
   */
  private async init(): Promise<void> {
    if (this.writeWorker) {
      return
    }

    if (this.initPromise) {
      return this.initPromise
    }

    this.initPromise = this.createWorker()

    try {
      await this.initPromise
    } catch (error) {
      this.initPromise = null
      throw error
    }
  }

  private createWorker(): Promise<void> {
    return new Promise((resolve) => {
      this.createWorkerOrFallback(resolve)
    })
  }

  private createWorkerOrFallback(resolve: () => void): void {
    if (!isWebWorkerAvailable()) {
      console.warn('[WriteService] Web Workers not available, using direct writes')
      resolve()
      return
    }

    try {
      this.writeWorker = new Worker('/writeWorker.js', { type: 'classic' })
      this.registerWorkerListeners(this.writeWorker, resolve)
    } catch (error) {
      console.warn('[WriteService] Failed to create worker, using direct writes:', error)
      resolve()
    }
  }

  private registerWorkerListeners(worker: Worker, resolve: () => void): void {
    worker.addEventListener('message', (event: MessageEvent<unknown>) => {
      if (!isWorkerMessageEnvelope(event.data)) {
        console.error('[WriteService] Received invalid worker message envelope', { data: event.data })
        return
      }
      if (event.data.type === 'ERROR') {
        console.error('[WriteService] Worker error:', event.data.data)
      }
    })

    worker.addEventListener('error', (error) => {
      console.error('[WriteService] Worker error:', error)
      console.warn('[WriteService] Falling back to direct writes')
      this.writeWorker = null
      resolve()
    })

    const readyTimeout = setTimeout(() => {
      console.warn('[WriteService] Worker ready timeout, using direct writes')
      this.writeWorker?.terminate()
      this.writeWorker = null
      resolve()
    }, 2000)

    const readyHandler = (event: MessageEvent<unknown>): void => {
      if (isWorkerMessageEnvelope(event.data) && event.data.type === 'WORKER_READY') {
        clearTimeout(readyTimeout)
        this.writeWorker?.removeEventListener('message', readyHandler)
        resolve()
      }
    }
    worker.addEventListener('message', readyHandler)
  }

  /**
   * Write object to IndexedDB (via Web Worker)
   */
  async writeObject(params: WriteObjectParams): Promise<void> {
    try {
      await this.init()
      if (this.writeWorker) {
        return this.postWriteObjectToWorker(params)
      }
      await this.writeObjectDirect(params)
    } catch (error) {
      console.error('[WriteService] Error writing object:', error)
      throw error
    }
  }

  /**
   * Update published status (via Web Worker)
   */
  async updatePublished(
    objectType: ObjectType,
    id: string,
    published: false | string[]
  ): Promise<void> {
    try {
      await this.init()

      if (this.writeWorker) {
        return this.postUpdatePublishedToWorker({ objectType, id, published })
      }
      await this.updatePublishedDirect({ objectType, id, published })
    } catch (error) {
      console.error('[WriteService] Error updating published status:', error)
      throw error
    }
  }

  private postWriteObjectToWorker(params: WriteObjectParams): Promise<void> {
    const published = params.published ?? false
    return new Promise((resolve, reject) => {
      const timeout = setTimeout(() => reject(new Error('Write operation timeout')), 10000)
      const handler = (event: MessageEvent): void => {
        if (!isWorkerMessageEnvelope(event.data)) {
          return
        }
        if (event.data.type === 'WRITE_OBJECT_SUCCESS' && isRecord(event.data.data) && event.data.data.hash === params.hash) {
          clearTimeout(timeout)
          this.writeWorker?.removeEventListener('message', handler)
          resolve()
          return
        }
        if (event.data.type === 'ERROR') {
          const errorData = readWorkerErrorData(event.data.data)
          if (errorData.originalType !== 'WRITE_OBJECT') {
            return
          }
          clearTimeout(timeout)
          this.writeWorker?.removeEventListener('message', handler)
          reject(new Error(errorData.error ?? 'Write worker error'))
        }
      }
      if (this.writeWorker) {
        this.writeWorker.addEventListener('message', handler)
        this.writeWorker.postMessage({
          type: 'WRITE_OBJECT',
          data: {
            objectType: params.objectType,
            hash: params.hash,
            event: params.event,
            parsed: params.parsed,
            version: params.version,
            hidden: params.hidden,
            index: params.index,
            published,
          },
        })
      }
    })
  }

  private async writeObjectDirect(params: WriteObjectParams): Promise<void> {
    const { objectCache } = await import('./objectCache')
    await objectCache.set({
      objectType: params.objectType,
      hash: params.hash,
      event: params.event,
      parsed: params.parsed,
      version: params.version,
      hidden: params.hidden,
      ...(params.index !== undefined ? { index: params.index } : {}),
      ...(params.published !== undefined ? { published: params.published } : {}),
    })
  }

  private postUpdatePublishedToWorker(params: {
    objectType: ObjectType
    id: string
    published: false | string[]
  }): Promise<void> {
    return new Promise((resolve, reject) => {
      const timeout = setTimeout(() => reject(new Error('Update published operation timeout')), 10000)
      const handler = (event: MessageEvent): void => {
        if (!isWorkerMessageEnvelope(event.data)) {
          return
        }
        if (event.data.type === 'UPDATE_PUBLISHED_SUCCESS') {
          if (!isRecord(event.data.data) || event.data.data.id !== params.id) {
            return
          }
          clearTimeout(timeout)
          this.writeWorker?.removeEventListener('message', handler)
          resolve()
          return
        }
        if (event.data.type !== 'ERROR') {
          return
        }
        const errorData = readWorkerErrorData(event.data.data)
        if (!isWorkerErrorForOperation(errorData, 'UPDATE_PUBLISHED')) {
          return
        }
        clearTimeout(timeout)
        this.writeWorker?.removeEventListener('message', handler)
        reject(new Error(errorData.error ?? 'Write worker error'))
      }
      if (this.writeWorker) {
        this.writeWorker.addEventListener('message', handler)
        this.writeWorker.postMessage({ type: 'UPDATE_PUBLISHED', data: { ...params } })
      }
    })
  }

  private async updatePublishedDirect(params: { objectType: ObjectType; id: string; published: false | string[] }): Promise<void> {
    const { objectCache } = await import('./objectCache')
    await objectCache.updatePublished(params.objectType, params.id, params.published)
  }

  /**
   * Create notification (via Web Worker)
   */
  async createNotification(params: CreateNotificationParams): Promise<void> {
    try {
      await this.init()

      if (this.writeWorker) {
        // Send to worker
        return new Promise((resolve, reject) => {
          const timeout = setTimeout(() => {
            reject(new Error('Create notification operation timeout'))
          }, 10000)

          const handler = (event: MessageEvent): void => {
            if (!isWorkerMessageEnvelope(event.data)) {
              return
            }
            const responseType = event.data.type
            const responseData = event.data.data

            if (responseType === 'CREATE_NOTIFICATION_SUCCESS') {
              if (!isRecord(responseData) || responseData.eventId !== params.eventId) {
                return
              }
              clearTimeout(timeout)
              this.writeWorker?.removeEventListener('message', handler)
              resolve()
              return
            }

            if (responseType !== 'ERROR') {
              return
            }

            const errorData = readWorkerErrorData(responseData)
            if (!isWorkerErrorForOperation(errorData, 'CREATE_NOTIFICATION')) {
              return
            }
            clearTimeout(timeout)
            this.writeWorker?.removeEventListener('message', handler)
            reject(new Error(errorData.error ?? 'Write worker error'))
          }

          if (this.writeWorker) {
            this.writeWorker.addEventListener('message', handler)
            this.writeWorker.postMessage({
              type: 'CREATE_NOTIFICATION',
              data: {
                type: params.type,
                objectType: params.objectType,
                objectId: params.objectId,
                eventId: params.eventId,
                notificationData: params.data,
              },
            })
          }
        })
      }
        // Fallback: direct write
        const { notificationService } = await import('./notificationService')
        const notificationParams: Parameters<typeof notificationService.createNotification>[0] = {
          type: params.type as Parameters<typeof notificationService.createNotification>[0]['type'],
          objectType: params.objectType,
          objectId: params.objectId,
          eventId: params.eventId,
        }
        if (params.data !== undefined) {
          notificationParams.data = params.data
        }
        await notificationService.createNotification(notificationParams)


    } catch (error) {
      console.error('[WriteService] Error creating notification:', error)
      throw error
    }
  }

  /**
   * Log publication (via Web Worker)
   */
  async logPublication(params: LogPublicationParams): Promise<void> {
    try {
      await this.init()

      if (this.writeWorker) {
        // Send to worker
        this.writeWorker.postMessage({
          type: 'LOG_PUBLICATION',
          data: {
            eventId: params.eventId,
            relayUrl: params.relayUrl,
            success: params.success,
            error: params.error,
            objectType: params.objectType,
            objectId: params.objectId,
          },
        })
        // Don't wait for response for logs (fire and forget)
      } else {
        // Fallback: direct write
        const { publishLog } = await import('./publishLog')
        await publishLog.logPublicationDirect(params)
      }
    } catch (logError) {
      console.error('[WriteService] Error logging publication:', logError)
      // Don't throw for logs
    }
  }

  /**
   * Terminate the worker
   */
  terminate(): void {
    if (this.writeWorker) {
      this.writeWorker.terminate()
      this.writeWorker = null
      this.initPromise = null
    }
  }
}

function isWebWorkerAvailable(): boolean {
  return typeof window !== 'undefined' && Boolean(window.Worker)
}

export const writeService = new WriteService()