/**
 * 显式错误类型 — 上层调用方(B4 reviewer / B5 evolution / B6 mutator)
 * **必须**显式 catch 以下类型,不允许 generic try/catch 后默默走 NEUTRAL/0.5
 * fallback。这是反欺骗的硬约束:LLM 离线、超预算、输出违约 都必须让
 * 上层"看见",由上层 自行决定 是否走 heuristic fallback、是否登记
 * lifecycle 事件。
 *
 * 不要在调用 `llmRoleClient` 的地方写:
 *   ```ts
 *   try { ... } catch { return NEUTRAL; }   // ❌ 静默,违反反欺骗
 *   ```
 *
 * 应当写:
 *   ```ts
 *   try {
 *     const r = await llmRoleClient(...);
 *     ...
 *   } catch (e) {
 *     if (e instanceof LlmRoleDisabled) { ... 走 heuristic 并 logAlert ... }
 *     if (e instanceof LlmRoleBudgetExceeded) { ... 同上 ... }
 *     throw e; // 其他错误必须冒泡
 *   }
 *   ```
 */

abstract class LlmRoleErrorBase extends Error {
  abstract readonly status: string;
  constructor(message: string) {
    super(message);
    this.name = new.target.name;
  }
}

/** `CAPABILITY_LLM_ENABLED=false` 时所有角色调用都抛此错。 */
export class LlmRoleDisabled extends LlmRoleErrorBase {
  readonly status = "disabled";
  constructor(reason = "CAPABILITY_LLM_ENABLED is false") {
    super(reason);
  }
}

/** 该 (capability, role) 当日花销已达 / 超过 daily_limit_usd。 */
export class LlmRoleBudgetExceeded extends LlmRoleErrorBase {
  readonly status = "budget_exceeded";
  constructor(
    public readonly capabilityId: string | null,
    public readonly role: string,
    public readonly spent: number,
    public readonly limit: number,
  ) {
    super(
      `Daily LLM budget exceeded for capability=${capabilityId ?? "global"} role=${role}: spent=$${spent.toFixed(4)} limit=$${limit.toFixed(4)}`,
    );
  }
}

/** Zod validate 输出失败,1 次重试后仍失败。 */
export class LlmRoleResponseInvalid extends LlmRoleErrorBase {
  readonly status = "invalid_response";
  constructor(
    public readonly role: string,
    public readonly zodIssues: unknown,
    public readonly rawText: string,
  ) {
    super(`LLM role=${role} response did not validate after retry`);
  }
}

/** 单次调用 timeout(role-specific timeout 触发)。 */
export class LlmRoleTimeout extends LlmRoleErrorBase {
  readonly status = "timeout";
  constructor(
    public readonly role: string,
    public readonly timeoutMs: number,
  ) {
    super(`LLM role=${role} timed out after ${timeoutMs}ms`);
  }
}

/** Gateway 熔断中或没 provider — 上层应走 heuristic fallback。 */
export class LlmRoleProviderUnavailable extends LlmRoleErrorBase {
  readonly status = "provider_unavailable";
  constructor(
    public readonly role: string,
    public readonly providerErrorCode: string,
    detail = "",
  ) {
    super(
      `LLM role=${role} provider unavailable: ${providerErrorCode}${detail ? " — " + detail : ""}`,
    );
  }
}

/** 共用类型守卫 — 让上层一行判断"这是 plumbing 层抛的可处理错误"。 */
export function isLlmRoleError(err: unknown): err is LlmRoleErrorBase {
  return err instanceof LlmRoleErrorBase;
}

export type LlmRoleErrorStatus =
  | "disabled"
  | "budget_exceeded"
  | "invalid_response"
  | "timeout"
  | "provider_unavailable";