import type { SessionEvent } from './event-bus'

/**
 * Convert an internal session event into the SDK/control message shape that
 * bridge workers consume on both the legacy WS path and the v2 worker SSE path.
 */
export function toClientPayload(event: SessionEvent): Record<string, unknown> {
  const payload = event.payload as Record<string, unknown> | null
  const messageUuid =
    typeof payload?.uuid === 'string' && payload.uuid ? payload.uuid : event.id

  if (event.type === 'user' || event.type === 'user_message') {
    // Prefer payload.message.content (preserves image/content-block arrays from
    // the web UI) over payload.content (flattened text from normalizePayload).
    // Without this, image blocks sent by the web UI are stripped before
    // reaching the CLI bridge. Falls back to payload.content (string) and
    // finally payload.message (string) for legacy callers.
    const msgContent = (payload?.message as { content?: unknown } | undefined)
      ?.content
    const content =
      msgContent ??
      payload?.content ??
      (typeof payload?.message === 'string' ? payload.message : '')
    return {
      type: 'user',
      uuid: messageUuid,
      session_id: event.sessionId,
      ...(payload?.isSynthetic === true ? { isSynthetic: true } : {}),
      message: {
        role: 'user',
        content,
      },
    }
  }

  if (
    event.type === 'permission_response' ||
    event.type === 'control_response'
  ) {
    const approved = !!payload?.approved
    const existingResponse = payload?.response as
      | Record<string, unknown>
      | undefined
    if (existingResponse) {
      return { type: 'control_response', response: existingResponse }
    }

    const updatedInput = payload?.updated_input as
      | Record<string, unknown>
      | undefined
    const updatedPermissions = payload?.updated_permissions as
      | Record<string, unknown>[]
      | undefined
    const feedbackMessage = payload?.message as string | undefined

    return {
      type: 'control_response',
      response: {
        subtype: approved ? 'success' : 'error',
        request_id: payload?.request_id ?? '',
        ...(approved
          ? {
              response: {
                behavior: 'allow' as const,
                ...(updatedInput ? { updatedInput } : {}),
                ...(updatedPermissions ? { updatedPermissions } : {}),
              },
            }
          : {
              error: 'Permission denied by user',
              response: { behavior: 'deny' as const },
              ...(feedbackMessage ? { message: feedbackMessage } : {}),
            }),
      },
    }
  }

  if (event.type === 'interrupt') {
    return {
      type: 'control_request',
      request_id: event.id,
      request: { subtype: 'interrupt' },
    }
  }

  if (event.type === 'control_request') {
    return {
      type: 'control_request',
      request_id: payload?.request_id ?? event.id,
      request: payload?.request ?? payload,
    }
  }

  return {
    type: event.type,
    uuid: messageUuid,
    session_id: event.sessionId,
    message: payload,
  }
}