import type {
  IssueComment,
  IssueQueuedCommentProtocol,
  IssueQueuedCommentQueue,
  IssueQueuedCommentQueueState,
  IssueQueuedCommentSteeringDisposition,
} from "@paperclipai/shared";

function record(value: unknown): Record<string, unknown> | null {
  return typeof value === "object" && value !== null && !Array.isArray(value)
    ? (value as Record<string, unknown>)
    : null;
}

const STEERING_DISPOSITIONS = new Set<IssueQueuedCommentSteeringDisposition>([
  "available",
  "unsupported",
  "temporarily_unavailable",
]);
const QUEUE_STATES = new Set<IssueQueuedCommentQueueState>([
  "deferred",
  "queued",
]);

/** Defensive boundary shared by IssueDetail and Storybook queue fixtures. */
export function normalizeIssueQueuedCommentQueue(
  value: unknown,
  fallbackIssueId: string,
): IssueQueuedCommentQueue {
  const source = record(value);
  const seen = new Set<string>();
  const entries = (Array.isArray(source?.entries) ? source.entries : [])
    .flatMap((candidate, sourcePosition) => {
      const entry = record(candidate);
      const comment = record(entry?.comment);
      const id = typeof comment?.id === "string" ? comment.id : "";
      const body = typeof comment?.body === "string" ? comment.body : null;
      if (!id || body === null || seen.has(id)) return [];
      seen.add(id);
      const position =
        typeof entry?.position === "number" && Number.isFinite(entry.position)
          ? entry.position
          : sourcePosition;
      return [
        {
          comment: comment as unknown as IssueComment,
          position,
          canEdit: entry?.canEdit === true,
          canDiscard: entry?.canDiscard === true,
        },
      ];
    })
    .sort((left, right) => left.position - right.position)
    .map((entry, position) => ({ ...entry, position }));
  const disposition = source?.steeringDisposition;
  const state = source?.state;

  return {
    issueId:
      typeof source?.issueId === "string" ? source.issueId : fallbackIssueId,
    queueId: typeof source?.queueId === "string" ? source.queueId : null,
    state:
      typeof state === "string" &&
      QUEUE_STATES.has(state as IssueQueuedCommentQueueState)
        ? (state as IssueQueuedCommentQueueState)
        : null,
    targetRunId:
      typeof source?.targetRunId === "string" ? source.targetRunId : null,
    revision:
      typeof source?.revision === "string" ? source.revision : "unavailable",
    protocol:
      source?.protocol === "paperclip_runner_v1"
        ? "paperclip_runner_v1"
        : "legacy",
    steeringDisposition:
      typeof disposition === "string" &&
      STEERING_DISPOSITIONS.has(
        disposition as IssueQueuedCommentSteeringDisposition,
      )
        ? (disposition as IssueQueuedCommentSteeringDisposition)
        : "unsupported",
    entries,
  };
}

export interface PendingIssueQueuedComment {
  comment: IssueComment;
  targetRunId: string | null;
}

/**
 * Keeps a just-submitted follow-up in the composer queue while the comment and
 * queue endpoints acknowledge it independently. If the server has not yet
 * included every local entry, queue mutations are withheld by clearing the
 * queue id; local discard remains available through the optimistic comment
 * cancellation path.
 */
export function mergePendingIssueQueuedComments(params: {
  issueId: string;
  authoritativeQueue: IssueQueuedCommentQueue | null | undefined;
  pendingComments: PendingIssueQueuedComment[];
  fallbackProtocol: IssueQueuedCommentProtocol;
}): IssueQueuedCommentQueue | null {
  const authoritativeEntries = params.authoritativeQueue?.entries ?? [];
  const authoritativeIds = new Set(
    authoritativeEntries.map((entry) => entry.comment.id),
  );
  const pendingEntries = params.pendingComments
    .filter(({ comment }) => !authoritativeIds.has(comment.id))
    .map(({ comment }, position) => ({
      comment,
      position: authoritativeEntries.length + position,
      canEdit: false,
      canDiscard: true,
    }));
  const entries = [...authoritativeEntries, ...pendingEntries].map(
    (entry, position) => ({ ...entry, position }),
  );
  if (entries.length === 0) return null;

  const queueAcknowledged = pendingEntries.length === 0;
  const authoritativeOwnsQueue = Boolean(params.authoritativeQueue?.queueId);
  const fallbackTargetRunId =
    params.pendingComments.find((entry) => entry.targetRunId)?.targetRunId ??
    null;
  const protocol =
    params.authoritativeQueue?.protocol ?? params.fallbackProtocol;
  const targetRunId = authoritativeOwnsQueue
    ? (params.authoritativeQueue?.targetRunId ?? null)
    : fallbackTargetRunId;

  return {
    issueId: params.authoritativeQueue?.issueId ?? params.issueId,
    queueId: queueAcknowledged
      ? (params.authoritativeQueue?.queueId ?? null)
      : null,
    state:
      params.authoritativeQueue?.state ?? (targetRunId ? "deferred" : null),
    targetRunId,
    revision: params.authoritativeQueue?.revision ?? "awaiting-server",
    protocol,
    steeringDisposition:
      params.authoritativeQueue?.steeringDisposition ??
      (protocol === "paperclip_runner_v1" && targetRunId
        ? "temporarily_unavailable"
        : "unsupported"),
    entries,
  };
}