import type { JobRead, SegmentationRunRead, SegmentationRunRequest, SegmentationRunResponse } from '../types'
import { jobsApi } from './api/jobs'

const ACTIVE_JOB_STATUSES = new Set(['queued', 'running'])
const TERMINAL_FAILURE_STATUSES = new Set(['failed', 'cancelled', 'partial'])

export const SEGMENTATION_JOB_POLL_INTERVAL_MS = 1_500
export const SEGMENTATION_JOB_TIMEOUT_MS = 30 * 60 * 1_000

export class SegmentationJobError extends Error {
  readonly code: string
  readonly jobId: string

  constructor(message: string, code: string, jobId: string) {
    super(message)
    this.name = 'SegmentationJobError'
    this.code = code
    this.jobId = jobId
  }
}

interface WaitForSegmentationJobOptions {
  projectId: string
  initialJob: JobRead
  signal?: AbortSignal
  intervalMs?: number
  timeoutMs?: number
  maxConsecutiveReadErrors?: number
  readJob?: (projectId: string, jobId: string) => Promise<JobRead>
  onStatus?: (job: JobRead) => void
}

function abortedError(): Error {
  const error = new Error('Het volgen van de segmentatietaak is gestopt')
  error.name = 'AbortError'
  return error
}

function wait(milliseconds: number, signal?: AbortSignal): Promise<void> {
  if (signal?.aborted) {
    return Promise.reject(abortedError())
  }
  if (milliseconds <= 0) {
    return Promise.resolve()
  }
  return new Promise((resolve, reject) => {
    const timer = window.setTimeout(() => {
      signal?.removeEventListener('abort', onAbort)
      resolve()
    }, milliseconds)
    const onAbort = () => {
      window.clearTimeout(timer)
      signal?.removeEventListener('abort', onAbort)
      reject(abortedError())
    }
    signal?.addEventListener('abort', onAbort, { once: true })
  })
}

function stringValue(record: Record<string, unknown> | null | undefined, key: string): string | null {
  const value = record?.[key]
  return typeof value === 'string' && value.trim() ? value.trim() : null
}

function numberValue(record: Record<string, unknown> | null | undefined, key: string): number | null {
  const value = record?.[key]
  return typeof value === 'number' && Number.isFinite(value) ? value : null
}

function assertSegmentationJobIdentity(projectId: string, job: JobRead): void {
  if (job.project_id !== projectId || job.job_type !== 'segmentation.run') {
    throw new SegmentationJobError(
      'De server koppelde een onverwachte taak aan deze segmentatie',
      'SEGMENTATION_JOB_IDENTITY_MISMATCH',
      job.id,
    )
  }
}

/** Follow one queued GPU segmentation until the backend marks it terminal. */
export async function waitForSegmentationJob({
  projectId,
  initialJob,
  signal,
  intervalMs = SEGMENTATION_JOB_POLL_INTERVAL_MS,
  timeoutMs = SEGMENTATION_JOB_TIMEOUT_MS,
  maxConsecutiveReadErrors = 3,
  readJob = jobsApi.get,
  onStatus,
}: WaitForSegmentationJobOptions): Promise<JobRead> {
  const startedAt = Date.now()
  let job = initialJob
  let consecutiveReadErrors = 0

  while (true) {
    if (signal?.aborted) {
      throw abortedError()
    }
    assertSegmentationJobIdentity(projectId, job)
    onStatus?.(job)

    if (job.status === 'success') {
      return job
    }
    if (TERMINAL_FAILURE_STATUSES.has(job.status)) {
      const code = stringValue(job.result_json, 'error_code') ?? `SEGMENTATION_JOB_${job.status.toUpperCase()}`
      const message = job.error_message
        ?? stringValue(job.result_json, 'message')
        ?? 'De GPU-taak is niet volledig uitgevoerd'
      throw new SegmentationJobError(message, code, job.id)
    }
    if (!ACTIVE_JOB_STATUSES.has(job.status)) {
      throw new SegmentationJobError(
        `De segmentatietaak heeft een onbekende status: ${job.status}`,
        'SEGMENTATION_JOB_STATUS_INVALID',
        job.id,
      )
    }
    if (Date.now() - startedAt >= timeoutMs) {
      throw new SegmentationJobError(
        'De segmentatietaak loopt nog op de server, maar de wachttijd in dit scherm is verstreken. Herlaad de bewaarde segmentatieruns om het resultaat later te bekijken.',
        'SEGMENTATION_JOB_POLL_TIMEOUT',
        job.id,
      )
    }

    await wait(intervalMs, signal)
    try {
      job = await readJob(projectId, job.id)
      consecutiveReadErrors = 0
    } catch (error) {
      if (signal?.aborted) {
        throw abortedError()
      }
      consecutiveReadErrors += 1
      if (consecutiveReadErrors >= maxConsecutiveReadErrors) {
        throw error
      }
    }
  }
}

/** Convert persisted server evidence into the UI summary contract. */
export function completedSegmentationResponse(
  request: SegmentationRunRequest,
  job: JobRead,
  run: SegmentationRunRead,
): SegmentationRunResponse {
  assertSegmentationJobIdentity(request.project_id, job)
  if (
    job.status !== 'success'
    || run.status !== 'success'
    || run.analysis_type !== 'segmentation'
    || run.project_id !== request.project_id
    || run.dataset_id !== request.dataset_id
    || run.job_id !== job.id
    || (run.model_name != null && run.model_name !== request.model_id)
  ) {
    throw new SegmentationJobError(
      'De bewaarde segmentatierun komt niet overeen met de voltooide GPU-taak',
      'SEGMENTATION_RUN_RESULT_MISMATCH',
      job.id,
    )
  }

  const segmentationCount = numberValue(job.result_json, 'segmentation_count')
    ?? numberValue(run.result_json, 'segmentation_count')
  if (segmentationCount === null || !Number.isInteger(segmentationCount) || segmentationCount < 0) {
    throw new SegmentationJobError(
      'De voltooide segmentatietaak bevat geen geldige, herleidbare vlakkentelling',
      'SEGMENTATION_RUN_RESULT_INCOMPLETE',
      job.id,
    )
  }

  return {
    analysis_run_id: run.id,
    job_id: job.id,
    project_id: request.project_id,
    dataset_id: request.dataset_id,
    model_id: run.model_name ?? request.model_id,
    status: 'success',
    segmentation_count: segmentationCount,
    error_code: null,
    message: segmentationCount === 0
      ? 'Segmentatie voltooid zonder vlakken boven de gekozen zekerheidsdrempel. Dit bewijst niet dat het gebied geen relevante objecten bevat.'
      : 'GPU-segmentatie voltooid; de bewaarde vlakken zijn geladen.',
  }
}

export function analysisRunIdFromSegmentationJob(job: JobRead): string | null {
  return stringValue(job.result_json, 'analysis_run_id')
}