// server/supabase/functions/send-push/dispatch-response.ts
// Pure presenter: turns a processed push dispatch into the HTTP body/status.
//
// Provider transport codes (webpush_send_timeout, fcm_send_failed, …) and
// their distinct HTTP statuses describe what happened on the function's own
// network. Echoing them to an end-user caller turns the dispatch endpoint into
// a reachability oracle, so user callers only ever see one generic failure.
// Trusted system callers (service role, drain worker) keep the detailed code
// for operations.

export type DispatchAudience = 'user' | 'system'

export interface DispatchOutcome {
  status: 'pending' | 'processing' | 'succeeded' | 'partial' | 'failed'
  complete: boolean
  attempted: number
  delivered: number
  stale: number
  retryableFailed: number
  permanentFailed: number
  nextRetryAt: string | null
  transientError: string | null
  transientStatus: number | null
}

export interface DispatchResponse {
  body: Record<string, unknown>
  status: number
}

export const DELIVERY_FAILURE_CODE = 'push_delivery_failed'
const DELIVERY_FAILURE_STATUS = 502

export function presentDispatchOutcome(
  audience: DispatchAudience,
  eventType: string,
  resourceId: string,
  outcome: DispatchOutcome,
): DispatchResponse {
  const body: Record<string, unknown> = {
    event_type: eventType,
    resource_id: resourceId,
    duplicate: false,
    status: outcome.status,
    complete: outcome.complete,
    attempted: outcome.attempted,
    sent: outcome.delivered,
    stale_removed: outcome.stale,
    retryable_failed: outcome.retryableFailed,
    permanent_failed: outcome.permanentFailed,
    next_retry_at: outcome.nextRetryAt,
  }
  const failed = outcome.status === 'partial' || outcome.status === 'failed'

  if (outcome.transientError) {
    if (audience === 'user') {
      return {
        body: { error: DELIVERY_FAILURE_CODE, ...body },
        status: DELIVERY_FAILURE_STATUS,
      }
    }
    return {
      body: { error: outcome.transientError, ...body },
      status: outcome.transientStatus ?? DELIVERY_FAILURE_STATUS,
    }
  }
  if (failed) {
    return {
      body: { error: DELIVERY_FAILURE_CODE, ...body },
      status: DELIVERY_FAILURE_STATUS,
    }
  }
  return { body, status: outcome.complete ? 200 : 202 }
}