// server/cloudflare-worker/src/push-drain.ts
// Cloudflare Cron-triggered drain for the Supabase push outbox.
//
// Supabase owns the durable outbox and the send-push Edge Function; nothing in
// the repository scheduled the drain, so transactionally enqueued notifications
// (team invites, transcription completion, billing) never left the queue. This
// worker drains them on a cron schedule.

export interface PushDrainEnv {
  SUPABASE_URL?: string
  SUPABASE_SERVICE_ROLE_KEY?: string
  PUSH_DRAIN_BATCH_LIMIT?: string
}

export interface PushDrainResult {
  ok: boolean
  status: number
  claimed?: number
  completed?: number
  pending?: number
  error?: string
}

const DEFAULT_BATCH_LIMIT = 20
const MAX_BATCH_LIMIT = 100
const REQUEST_TIMEOUT_MS = 30_000

export function resolveBatchLimit(raw: string | undefined): number {
  const parsed = Number(raw ?? DEFAULT_BATCH_LIMIT)
  if (!Number.isSafeInteger(parsed) || parsed < 1) return DEFAULT_BATCH_LIMIT
  return Math.min(parsed, MAX_BATCH_LIMIT)
}

export async function drainPushDispatches(
  env: PushDrainEnv,
  fetchImpl: typeof fetch = fetch,
): Promise<PushDrainResult> {
  const baseUrl = env.SUPABASE_URL?.trim().replace(/\/+$/, '') ?? ''
  const serviceRoleKey = env.SUPABASE_SERVICE_ROLE_KEY?.trim() ?? ''
  if (!baseUrl || serviceRoleKey.length < 20) {
    return { ok: false, status: 503, error: 'push_drain_not_configured' }
  }

  const limit = resolveBatchLimit(env.PUSH_DRAIN_BATCH_LIMIT)
  let response: Response
  try {
    response = await fetchImpl(
      `${baseUrl}/functions/v1/send-push?mode=drain&limit=${limit}`,
      {
        method: 'POST',
        headers: {
          Authorization: `Bearer ${serviceRoleKey}`,
          'Content-Type': 'application/json',
        },
        body: '{}',
        signal: AbortSignal.timeout(REQUEST_TIMEOUT_MS),
      },
    )
  } catch {
    return { ok: false, status: 502, error: 'push_drain_unreachable' }
  }

  if (!response.ok) {
    return { ok: false, status: response.status, error: `push_drain_http_${response.status}` }
  }

  let body: Record<string, unknown> = {}
  try {
    const parsed = await response.json()
    if (parsed !== null && typeof parsed === 'object' && !Array.isArray(parsed)) {
      body = parsed as Record<string, unknown>
    }
  } catch {
    body = {}
  }

  return {
    ok: true,
    status: response.status,
    claimed: typeof body.claimed === 'number' ? body.claimed : undefined,
    completed: typeof body.completed === 'number' ? body.completed : undefined,
    pending: typeof body.pending === 'number' ? body.pending : undefined,
  }
}