import { inject } from '@adonisjs/core'
import { QueueService } from './queue_service.js'
import { RunDownloadJob } from '#jobs/run_download_job'
import { RunExtractPmtilesJob } from '#jobs/run_extract_pmtiles_job'
import type { RunExtractPmtilesJobParams } from '#jobs/run_extract_pmtiles_job'
import { DownloadModelJob } from '#jobs/download_model_job'
import { DownloadDrugDataJob } from '#jobs/download_drug_data_job'
import { DownloadJobWithProgress, DownloadProgressData, RunDownloadJobParams } from '../../types/downloads.js'
import type { Job, Queue } from 'bullmq'
import { normalize } from 'path'
import { deleteFileIfExists } from '../utils/fs.js'
import transmit from '@adonisjs/transmit/services/main'
import { BROADCAST_CHANNELS } from '../../constants/broadcast.js'

type FileJobState = 'waiting' | 'active' | 'delayed' | 'failed'
type TaggedJob = { job: Job; state: FileJobState }

@inject()
export class DownloadService {
  constructor(private queueService: QueueService) {}

  private parseProgress(progress: any): { percent: number; downloadedBytes?: number; totalBytes?: number; lastProgressTime?: number } {
    if (typeof progress === 'object' && progress !== null && 'percent' in progress) {
      const p = progress as DownloadProgressData
      return {
        percent: p.percent,
        downloadedBytes: p.downloadedBytes,
        totalBytes: p.totalBytes,
        lastProgressTime: p.lastProgressTime,
      }
    }
    // Backward compat: plain integer from in-flight jobs during upgrade
    return { percent: parseInt(String(progress), 10) || 0 }
  }

  /** Fetch all non-completed jobs from a queue, tagged with their current BullMQ state */
  private async fetchJobsWithStates(queueName: string): Promise<TaggedJob[]> {
    const queue = this.queueService.getQueue(queueName)
    const [waiting, active, delayed, failed] = await Promise.all([
      queue.getJobs(['waiting']),
      queue.getJobs(['active']),
      queue.getJobs(['delayed']),
      queue.getJobs(['failed']),
    ])
    return [
      ...waiting.map((j) => ({ job: j, state: 'waiting' as const })),
      ...active.map((j) => ({ job: j, state: 'active' as const })),
      ...delayed.map((j) => ({ job: j, state: 'delayed' as const })),
      ...failed.map((j) => ({ job: j, state: 'failed' as const })),
      // A job id can outlive its payload hash — BullMQ still returns an entry for
      // it, with `data` empty. One of those in the failed set used to throw on
      // every poll of this endpoint (normalize(undefined)), and because failed
      // jobs are never evicted the endpoint stayed broken until Redis was cleared
      // by hand. Drop them: with no payload there is nothing to show anyway.
    ].filter(({ job }) => job?.id != null && job.data != null)
  }

  async listDownloadJobs(filetype?: string): Promise<DownloadJobWithProgress[]> {
    const modelQueue = this.queueService.getQueue(DownloadModelJob.queue)
    const [fileTagged, extractTagged, modelJobs, drugTagged] = await Promise.all([
      this.fetchJobsWithStates(RunDownloadJob.queue),
      this.fetchJobsWithStates(RunExtractPmtilesJob.queue),
      modelQueue.getJobs(['waiting', 'active', 'delayed', 'failed']),
      this.fetchJobsWithStates(DownloadDrugDataJob.queue),
    ])

    const fileDownloads = fileTagged.map(({ job, state }) => {
      const parsed = this.parseProgress(job.progress)
      return {
        jobId: job.id!.toString(),
        url: job.data.url,
        progress: parsed.percent,
        filepath: job.data.filepath ? normalize(job.data.filepath) : '',
        filetype: job.data.filetype,
        title: job.data.title || undefined,
        downloadedBytes: parsed.downloadedBytes,
        totalBytes: parsed.totalBytes || job.data.totalBytes || undefined,
        lastProgressTime: parsed.lastProgressTime,
        status: state,
        failedReason: job.failedReason || undefined,
      }
    })

    const extractDownloads = extractTagged.map(({ job, state }) => {
      const parsed = this.parseProgress(job.progress)
      return {
        jobId: job.id!.toString(),
        url: job.data.sourceUrl,
        progress: parsed.percent,
        filepath: job.data.outputFilepath ? normalize(job.data.outputFilepath) : '',
        filetype: job.data.filetype || 'map',
        title: job.data.title || undefined,
        downloadedBytes: parsed.downloadedBytes,
        totalBytes: parsed.totalBytes || job.data.estimatedBytes || undefined,
        lastProgressTime: parsed.lastProgressTime,
        status: state,
        failedReason: job.failedReason || undefined,
      }
    })

    const modelDownloads = modelJobs.map((job) => ({
      jobId: job.id!.toString(),
      url: job.data.modelName || 'Unknown Model',
      progress: parseInt(job.progress.toString(), 10),
      filepath: job.data.modelName || 'Unknown Model',
      filetype: 'model',
      status: (job.failedReason ? 'failed' : 'active') as 'active' | 'failed',
      failedReason: job.failedReason || undefined,
    }))

    // FDA drug dataset — DOWNLOAD phase only, collapsed to ONE card. The job fans
    // the manifest's N partitions into continuations under AUTO-GENERATED jobIds
    // (only part 0 runs under the deterministic jobId), and the queue is
    // concurrency 1, so at most one part is ever in flight. Filtering to the
    // deterministic jobId would track only part 0 and then drop the card while
    // parts 2..N keep downloading. Instead represent the whole download with the
    // single in-flight job's aggregate progress (the progress emit already spans
    // all parts), and always report the deterministic jobId so the cancel/remove
    // button routes to _cancelDrugDownloadJob whichever part is active. The heavy
    // ingest is EXCLUDED here — it stays on the IngestStatus surface.
    const drugInFlight =
      drugTagged.find(({ state }) => state === 'active') ??
      drugTagged.find(({ state }) => state === 'waiting' || state === 'delayed') ??
      drugTagged.find(({ state }) => state === 'failed')
    const drugDownloads = drugInFlight
      ? [drugInFlight].map(({ job, state }) => {
          const parsed = this.parseProgress(job.progress)
          return {
            jobId: DownloadDrugDataJob.jobId,
            url: 'https://api.fda.gov/download.json',
            progress: parsed.percent,
            filepath: job.data.currentPartName || 'FDA Drug Reference',
            filetype: 'drug-data',
            title: 'FDA Drug Reference',
            downloadedBytes: parsed.downloadedBytes,
            totalBytes: parsed.totalBytes,
            lastProgressTime: parsed.lastProgressTime,
            status: state,
            failedReason: job.failedReason || undefined,
          }
        })
      : []

    const allDownloads = [...fileDownloads, ...extractDownloads, ...modelDownloads, ...drugDownloads]
    const filtered = allDownloads.filter((job) => !filetype || job.filetype === filetype)

    return filtered.sort((a, b) => {
      if (a.status === 'failed' && b.status !== 'failed') return 1
      if (a.status !== 'failed' && b.status === 'failed') return -1
      return b.progress - a.progress
    })
  }

  async removeFailedJob(jobId: string): Promise<void> {
    for (const queueName of [
      RunDownloadJob.queue,
      RunExtractPmtilesJob.queue,
      DownloadModelJob.queue,
      DownloadDrugDataJob.queue,
    ]) {
      const queue = this.queueService.getQueue(queueName)
      const job = await queue.getJob(jobId)
      if (job) {
        try {
          await job.remove()
        } catch {
          // Job may be locked by the worker after cancel. Remove the stale lock and retry.
          try {
            const client = await queue.client
            await client.del(`bull:${queueName}:${jobId}:lock`)
            await job.remove()
          } catch {
            // Last resort: already removed or truly stuck
          }
        }
        return
      }
    }
  }

  async retryFailedJob(jobId: string): Promise<{ success: boolean; message: string }> {
    // Search both the file download queue and the model download queue
    for (const queueName of [RunDownloadJob.queue, DownloadModelJob.queue]) {
      const queue = this.queueService.getQueue(queueName)
      const job = await queue.getJob(jobId)

      if (job) {
        // For Ollama model downloads, re-dispatch with the model name
        if (queueName === DownloadModelJob.queue) {
          const modelName = job.data.modelName
          if (!modelName) {
            return { success: false, message: 'Cannot retry: model name not found in job data' }
          }
          await DownloadModelJob.dispatch({ modelName })
          await job.remove().catch(() => {})
          return { success: true, message: `Retrying download for model ${modelName}` }
        }

        // For file downloads (zim, map, etc.), re-dispatch with original params
        const params = job.data as RunDownloadJobParams
        if (!params.url || !params.filepath) {
          return { success: false, message: 'Cannot retry: missing URL or filepath in job data' }
        }

        // Remove the old failed job, then dispatch a fresh one
        await job.remove().catch(() => {})
        await RunDownloadJob.dispatch(params)
        return { success: true, message: `Retrying download for ${params.url}` }
      }
    }

    return { success: false, message: 'Failed job not found. It may have already been dismissed.' }
  }

  async cancelJob(jobId: string): Promise<{ success: boolean; message: string }> {
    const queue = this.queueService.getQueue(RunDownloadJob.queue)
    const job = await queue.getJob(jobId)

    if (job) {
      return await this._cancelFileDownloadJob(jobId, job, queue)
    }

    const extractQueue = this.queueService.getQueue(RunExtractPmtilesJob.queue)
    const extractJob = await extractQueue.getJob(jobId)

    if (extractJob) {
      return await this._cancelExtractJob(jobId, extractJob, extractQueue)
    }

    const modelQueue = this.queueService.getQueue(DownloadModelJob.queue)
    const modelJob = await modelQueue.getJob(jobId)

    if (modelJob) {
      return await this._cancelModelDownloadJob(jobId, modelJob, modelQueue)
    }

    // FDA drug dataset: cancel is matched on the deterministic jobId only (the
    // single card the aggregator shows). The continuation parts run under
    // auto-generated ids, so cancelling must stop the whole CHAIN, not just the
    // current part — otherwise the next continuation fires after we remove one.
    if (jobId === DownloadDrugDataJob.jobId) {
      return await this._cancelDrugDownloadJob()
    }

    return { success: true, message: 'Job not found (may have already completed)' }
  }

  /**
   * Cancel the FDA drug-data download.
   *
   * The drug job has no Redis cancel-signal / AbortController (unlike
   * RunDownloadJob), and it self-continues into the next part under a fresh jobId.
   * So a v1 cancel that only removed the current job would leave the next
   * continuation to fire. Instead we obliterate the single-purpose drug-download
   * queue (force = removes the active/locked job too), which drops the current
   * part AND every queued continuation in one shot. Scoped to the drug-download
   * queue only — the ingest queue and everything else are untouched. The on-disk
   * parts are intentionally LEFT in place: they're resumable, and a re-trigger
   * picks up from the .tmp rather than re-downloading. (Tracked as the v1 choice
   * for cancel depth — full cross-process signal cancel is a follow-up.)
   */
  private async _cancelDrugDownloadJob(): Promise<{ success: boolean; message: string }> {
    const queue = this.queueService.getQueue(DownloadDrugDataJob.queue)
    try {
      await queue.obliterate({ force: true })
      return { success: true, message: 'Drug data download cancelled' }
    } catch (err) {
      const msg = err instanceof Error ? err.message : String(err)
      return { success: false, message: `Could not cancel drug data download: ${msg}` }
    }
  }

  private async _cancelExtractJob(
    jobId: string,
    job: Job<RunExtractPmtilesJobParams>,
    queue: Queue<RunExtractPmtilesJobParams>
  ): Promise<{ success: boolean; message: string }> {
    const outputFilepath = job.data.outputFilepath

    await RunExtractPmtilesJob.signalCancel(jobId)

    // Same-process fallback when worker and API share a process
    RunExtractPmtilesJob.childProcesses.get(jobId)?.kill('SIGTERM')
    RunExtractPmtilesJob.childProcesses.delete(jobId)

    await this._pollForTerminalState(job, jobId)
    await this._removeJobWithLockFallback(job, queue, RunExtractPmtilesJob.queue, jobId)

    if (outputFilepath) {
      try {
        await deleteFileIfExists(outputFilepath)
      } catch {
        // File may not exist yet (subprocess may not have opened it)
      }
    }

    return { success: true, message: 'Extract cancelled and partial file deleted' }
  }

  /** Cancel a content download (zim, map, pmtiles, etc.) */
  private async _cancelFileDownloadJob(
    jobId: string,
    job: any,
    queue: any
  ): Promise<{ success: boolean; message: string }> {
    const filepath = job.data.filepath

    // Signal the worker process to abort the download via Redis
    await RunDownloadJob.signalCancel(jobId)

    // Also try in-memory abort (works if worker is in same process)
    RunDownloadJob.abortControllers.get(jobId)?.abort('user-cancel')
    RunDownloadJob.abortControllers.delete(jobId)

    await this._pollForTerminalState(job, jobId)
    await this._removeJobWithLockFallback(job, queue, RunDownloadJob.queue, jobId)

    // Delete the partial file from disk
    if (filepath) {
      try {
        await deleteFileIfExists(filepath)
        // Also try .tmp in case PR #448 staging is merged
        await deleteFileIfExists(filepath + '.tmp')
      } catch {
        // File may not exist yet (waiting job)
      }
    }

    // If this was a Wikipedia download, update selection status to failed
    // (the worker's failed event may not fire if we removed the job first)
    if (job.data.filetype === 'zim' && job.data.url?.includes('wikipedia_en_')) {
      try {
        const { DockerService } = await import('#services/docker_service')
        const { ZimService } = await import('#services/zim_service')
        const dockerService = new DockerService()
        const zimService = new ZimService(dockerService)
        await zimService.onWikipediaDownloadComplete(job.data.url, false)
      } catch {
        // Best effort
      }
    }

    return { success: true, message: 'Download cancelled and partial file deleted' }
  }

  /** Cancel an Ollama model download — mirrors the file cancel pattern but skips file cleanup */
  private async _cancelModelDownloadJob(
    jobId: string,
    job: any,
    queue: any
  ): Promise<{ success: boolean; message: string }> {
    const modelName: string = job.data?.modelName ?? 'unknown'

    // Signal the worker process to abort the pull via Redis
    await DownloadModelJob.signalCancel(jobId)

    // Also try in-memory abort (works if worker is in same process)
    DownloadModelJob.abortControllers.get(jobId)?.abort('user-cancel')
    DownloadModelJob.abortControllers.delete(jobId)

    await this._pollForTerminalState(job, jobId)
    await this._removeJobWithLockFallback(job, queue, DownloadModelJob.queue, jobId)

    // Broadcast a cancelled event so the frontend hook clears the entry. We use percent: -2
    // (distinct from -1 = error) so the hook can route it to a 2s auto-clear instead of the
    // 15s error display. The frontend ALSO removes the entry optimistically from the API
    // response, so this is belt-and-suspenders for cases where the SSE arrives first.
    transmit.broadcast(BROADCAST_CHANNELS.OLLAMA_MODEL_DOWNLOAD, {
      model: modelName,
      jobId,
      percent: -2,
      status: 'cancelled',
      timestamp: new Date().toISOString(),
    })

    // Note on partial blob cleanup: Ollama manages model blobs internally at
    // /root/.ollama/models/blobs/. We deliberately do NOT call /api/delete here — Ollama's
    // expected behavior is to retain partial blobs so a re-pull resumes from where it left
    // off. If the user wants to reclaim that space, they can re-pull and let it complete,
    // or delete the partially-downloaded model from the AI Settings page.
    return { success: true, message: 'Model download cancelled' }
  }

  /** Wait up to 4s (250ms intervals) for the job to reach a terminal state */
  private async _pollForTerminalState(job: any, jobId: string): Promise<void> {
    const POLL_INTERVAL_MS = 250
    const POLL_TIMEOUT_MS = 4000
    const deadline = Date.now() + POLL_TIMEOUT_MS

    while (Date.now() < deadline) {
      await new Promise((resolve) => setTimeout(resolve, POLL_INTERVAL_MS))
      try {
        const state = await job.getState()
        if (state === 'failed' || state === 'completed' || state === 'unknown') {
          return
        }
      } catch {
        return // getState() throws if job is already gone
      }
    }

    console.warn(
      `[DownloadService] cancelJob: job ${jobId} did not reach terminal state within timeout, removing anyway`
    )
  }

  /** Remove a BullMQ job, clearing a stale worker lock if the first attempt fails */
  private async _removeJobWithLockFallback(
    job: any,
    queue: any,
    queueName: string,
    jobId: string
  ): Promise<void> {
    try {
      await job.remove()
    } catch {
      // Lock contention fallback: clear lock and retry once
      try {
        const client = await queue.client
        await client.del(`bull:${queueName}:${jobId}:lock`)
        const updatedJob = await queue.getJob(jobId)
        if (updatedJob) await updatedJob.remove()
      } catch {
        // Best effort - job will be cleaned up on next dismiss attempt
      }
    }
  }
}