import { Injectable, NotFoundException, BadRequestException, UnauthorizedException } from '@nestjs/common'
import { CapturesRepository } from './captures.repository'
import { DevicesRepository } from '../devices/devices.repository'
import { RealtimeGateway } from '../../realtime/gateways/realtime.gateway'
import * as fs from 'fs'
import * as path from 'path'
import * as crypto from 'crypto'

export interface UploadedFile {
  filename: string
  originalname: string
  mimetype: string
  size: number
  path: string
}

@Injectable()
export class CapturesService {
  private readonly uploadDir: string
  private readonly uploadBaseUrl: string

  constructor(
    private readonly repo: CapturesRepository,
    private readonly deviceRepo: DevicesRepository,
    private readonly realtime: RealtimeGateway,
  ) {
    this.uploadDir = process.env['UPLOAD_DIR'] || '/uploads/captures'
    this.uploadBaseUrl = process.env['UPLOAD_BASE_URL'] || 'http://localhost:3001'
    fs.mkdirSync(this.uploadDir, { recursive: true })
  }

  private buildImageUrl(fileKey: string | null): string | null {
    if (!fileKey) return null
    return `${this.uploadBaseUrl}/uploads/captures/${fileKey}`
  }

  private async validateDeviceApiKey(deviceId: string, apiKey: string) {
    const device = await this.deviceRepo.findDeviceById(deviceId)
    if (!device) throw new NotFoundException(`Device ${deviceId} not found`)
    if (!device.apiKeyHash) throw new NotFoundException('Device not provisioned')
    const validKey = await this.deviceRepo.verifyApiKey(device.apiKeyHash, apiKey)
    if (!validKey) throw new UnauthorizedException('Invalid API key')
    if (!device.projectId || !device.orgId) throw new BadRequestException('Device not assigned to a project')
    return device as Required<Pick<typeof device, 'id' | 'projectId' | 'orgId' | 'serialNo' | 'name'>>
  }

  async handleUpload(params: {
    file: UploadedFile
    apiKey: string
    deviceId: string
    capturedAt: string
    resolution?: string
    exposureMs?: number
    iso?: number
    aperture?: string
    gpsLat?: string
    gpsLng?: string
  }) {
    const device = await this.validateDeviceApiKey(params.deviceId, params.apiKey)

    // Compute checksum
    const fileBuffer = fs.readFileSync(params.file.path)
    const checksum = crypto.createHash('sha256').update(fileBuffer).digest('hex')

    // Storage path: /uploads/captures/{projectId}/{YYYY-MM-DD}/{id}.{ext}
    const dateStr = new Date(params.capturedAt).toISOString().slice(0, 10)
    const ext = path.extname(params.file.originalname) || '.jpg'
    const id = crypto.randomUUID().slice(0, 12)
    const storagePath = path.join(this.uploadDir, device.projectId!, dateStr)
    fs.mkdirSync(storagePath, { recursive: true })

    const fileKey = `${device.projectId!}/${dateStr}/${id}${ext}`
    const destPath = path.join(this.uploadDir, fileKey)
    fs.renameSync(params.file.path, destPath)

    const capture = await this.repo.createCapture({
      projectId: device.projectId!,
      deviceId: params.deviceId,
      capturedAt: new Date(params.capturedAt),
      fileKey,
      checksum,
      resolution: params.resolution ?? undefined,
      fileSizeBytes: params.file.size,
      exposureMs: params.exposureMs ?? undefined,
      iso: params.iso ?? undefined,
      aperture: params.aperture ?? undefined,
      gpsLat: params.gpsLat ?? undefined,
      gpsLng: params.gpsLng ?? undefined,
      metadata: { originalFilename: params.file.originalname, uploadedAt: new Date().toISOString() },
    })

    this.realtime.emitCaptureUploaded(params.deviceId, device.projectId!, capture.id)

    return {
      captureId: capture.id,
      fileKey,
      checksum,
      sizeBytes: params.file.size,
      capturedAt: params.capturedAt,
    }
  }

  async registerCapture(params: {
    apiKey: string
    deviceId: string
    capturedAt: string
    fileKey: string
    checksum?: string
    resolution?: string
    fileSizeBytes?: number
    exposureMs?: number
    iso?: number
    aperture?: string
    gpsLat?: string
    gpsLng?: string
  }) {
    const device = await this.validateDeviceApiKey(params.deviceId, params.apiKey)

    const capture = await this.repo.createCapture({
      projectId: device.projectId!,
      deviceId: params.deviceId,
      capturedAt: new Date(params.capturedAt),
      fileKey: params.fileKey,
      checksum: params.checksum ?? undefined,
      resolution: params.resolution ?? undefined,
      fileSizeBytes: params.fileSizeBytes ?? undefined,
      exposureMs: params.exposureMs ?? undefined,
      iso: params.iso ?? undefined,
      aperture: params.aperture ?? undefined,
      gpsLat: params.gpsLat ?? undefined,
      gpsLng: params.gpsLng ?? undefined,
    })

    this.realtime.emitCaptureUploaded(params.deviceId, device.projectId!, capture.id)

    return { captureId: capture.id, fileKey: params.fileKey }
  }

  async getCapturesByProject(projectId: string, limit = 100) {
    const captures = await this.repo.findByProjectId(projectId, limit)
    return captures.map(c => ({ ...c, imageUrl: this.buildImageUrl(c.fileKey) }))
  }

  async getCapturesByDevice(deviceId: string, limit = 100) {
    const captures = await this.repo.findByDeviceId(deviceId, limit)
    return captures.map(c => ({ ...c, imageUrl: this.buildImageUrl(c.fileKey) }))
  }

  async getCaptureById(id: string) {
    const capture = await this.repo.findById(id)
    if (!capture) throw new NotFoundException(`Capture ${id} not found`)
    return { ...capture, imageUrl: this.buildImageUrl(capture.fileKey) }
  }

  async getCaptureStats(projectId: string) {
    const today = await this.repo.countByProjectToday(projectId)
    return { totalCaptures: today, todayCaptures: today }
  }
}