/**
 * Client-side rectification entry routing contracts.
 *
 * Every disposition decision comes from the server Case open API. The browser
 * never guesses "resume vs create" from session lists or message counts.
 */

export type RectificationEntrySummary = Readonly<{
  hasResumableCase: boolean;
  hasTerminalCaseWithTime: boolean;
  latestResumable: Readonly<{
    caseId: string;
    status: string;
    lastActivityAt: string;
  }> | null;
  latestTerminal: Readonly<{
    caseId: string;
    status: string;
    hasUsableTime: boolean;
  }> | null;
}>;

export type RectificationCardAction = "start" | "restart";

export const rectificationEntryLabels: Readonly<Record<RectificationCardAction, string>> = {
  start: "开始新的生时校正",
  restart: "再次校正",
};

export function resolveRectificationEntryAction(
  summary: RectificationEntrySummary,
): RectificationCardAction {
  if (summary.hasTerminalCaseWithTime) return "restart";
  return "start";
}

export type OpenRectificationDisposition = "created" | "resumed" | "readonly";

export type OpenRectificationCaseResponse = Readonly<{
  disposition: OpenRectificationDisposition;
  caseId: string;
  sessionId: string;
  status: string;
  shouldStartOpening: boolean;
  skillVersion: string;
}>;

const RESUMABLE_STATUSES = new Set([
  "draft",
  "collecting_evidence",
  "candidate_ready",
  "candidate_accepted",
  "needs_rebaseline",
  "paused",
]);

const TERMINAL_STATUSES = new Set([
  "confirmed",
  "closed",
  "abandoned",
  "superseded",
]);

export function isResumableRectificationStatus(status: string): boolean {
  return RESUMABLE_STATUSES.has(status);
}

export function isTerminalRectificationStatus(status: string): boolean {
  return TERMINAL_STATUSES.has(status);
}

/* `GET /api/rectification/cases/entry-summary` answers with the camelCase
   object `getRectificationEntrySummary` returns; only the RPC underneath speaks
   snake_case. This parser used to read the snake_case keys alone, so every real
   response parsed as "nothing on record" and the homepage never saw a resumable
   or finished case (BUG-1041). The route's camelCase shape wins; snake_case is
   still read so an RPC-shaped payload does not silently collapse either. */
function field(row: Record<string, unknown>, camel: string, snake: string): unknown {
  return camel in row ? row[camel] : row[snake];
}

function objectField(row: Record<string, unknown>, camel: string, snake: string): Record<string, unknown> | null {
  const value = field(row, camel, snake);
  return value && typeof value === "object" ? value as Record<string, unknown> : null;
}

export function entrySummaryFromResponse(value: unknown): RectificationEntrySummary {
  if (!value || typeof value !== "object") {
    return { hasResumableCase: false, hasTerminalCaseWithTime: false, latestResumable: null, latestTerminal: null };
  }
  const row = value as Record<string, unknown>;
  const latestResumable = objectField(row, "latestResumable", "latest_resumable");
  const latestTerminal = objectField(row, "latestTerminal", "latest_terminal");
  const resumableCaseId = latestResumable ? field(latestResumable, "caseId", "case_id") : null;
  const terminalCaseId = latestTerminal ? field(latestTerminal, "caseId", "case_id") : null;
  return {
    hasResumableCase: field(row, "hasResumableCase", "has_resumable_case") === true,
    hasTerminalCaseWithTime: field(row, "hasTerminalCaseWithTime", "has_terminal_case_with_time") === true,
    latestResumable: latestResumable && typeof resumableCaseId === "string"
      ? {
          caseId: resumableCaseId,
          status: String(latestResumable.status ?? ""),
          lastActivityAt: String(field(latestResumable, "lastActivityAt", "last_activity_at") ?? ""),
        }
      : null,
    latestTerminal: latestTerminal && typeof terminalCaseId === "string"
      ? {
          caseId: terminalCaseId,
          status: String(latestTerminal.status ?? ""),
          hasUsableTime: field(latestTerminal, "hasUsableTime", "has_usable_time") === true,
        }
      : null,
  };
}

export function openResponseFromPayload(value: unknown): OpenRectificationCaseResponse | null {
  if (!value || typeof value !== "object") return null;
  const row = value as Record<string, unknown>;
  const disposition = row.disposition;
  const caseId = typeof row.caseId === "string" ? row.caseId : "";
  const sessionId = typeof row.sessionId === "string" ? row.sessionId : "";
  const status = typeof row.status === "string" ? row.status : "";
  if (
    (disposition !== "created" && disposition !== "resumed" && disposition !== "readonly")
    || !caseId || !sessionId || !status
  ) {
    return null;
  }
  return {
    disposition,
    caseId,
    sessionId,
    status,
    shouldStartOpening: row.shouldStartOpening === true,
    skillVersion: typeof row.skillVersion === "string" ? row.skillVersion : "",
  };
}

export type RectificationEntryOpenIntent = "homepage" | "session" | "new";

/** Build the server open request body; the browser never adds business state. */
export function openRectificationRequestBody(
  intent: RectificationEntryOpenIntent,
  sessionId: string | null,
  sourceSessionId: string | null = null,
): { intent: RectificationEntryOpenIntent; requestId: string; sessionId?: string; sourceSessionId?: string } {
  const requestId = globalThis.crypto?.randomUUID?.() ?? fallbackUuid();
  if (intent === "session" && sessionId) {
    return { intent, requestId, sessionId };
  }
  return { intent, requestId, ...(intent === "homepage" && sourceSessionId ? { sourceSessionId } : {}) };
}

function fallbackUuid(): string {
  return "00000000-0000-4000-8000-000000000000";
}