export interface CommitCompletionResponse {
  content: unknown;
  stopReason: string;
  errorMessage?: string;
}

export interface CommitResponseContext {
  modelLabel: string;
  maxOutputTokens: number;
}

const MAX_ERROR_DETAIL_LENGTH = 600;

/** 将未知错误转换为经过脱敏和截断的安全诊断文本。 */
export function formatSafeErrorDetail(error: unknown): string {
  const raw = error instanceof Error ? error.message : String(error);
  const redacted = raw
    .replace(/\bauthorization\s*[:=]\s*(?:bearer\s+)?[^\s,;]+/giu, "Authorization: [REDACTED]")
    .replace(/\bbearer\s+[^\s,;]+/giu, "Bearer [REDACTED]")
    .replace(/\b(api[-_ ]?key|access[-_ ]?token)\s*[:=]\s*[^\s,;]+/giu, "$1: [REDACTED]")
    .replace(/([?&](?:key|token|api_key)=)[^&\s]+/giu, "$1[REDACTED]");

  if (redacted.length <= MAX_ERROR_DETAIL_LENGTH) {
    return redacted;
  }
  return `${redacted.slice(0, MAX_ERROR_DETAIL_LENGTH)}…`;
}

/** 汇总模型响应中的内容块类型，但不暴露具体内容。 */
function describeContentTypes(content: unknown): string {
  if (!Array.isArray(content) || content.length === 0) {
    return "none";
  }

  const types = content.map((part) => {
    if (
      typeof part === "object" &&
      part !== null &&
      "type" in part &&
      typeof part.type === "string"
    ) {
      return part.type;
    }
    return typeof part;
  });
  return [...new Set(types)].join(", ");
}

/** 从模型响应内容中提取所有文本块。 */
function extractTextContent(content: unknown): string {
  if (!Array.isArray(content)) {
    return "";
  }

  return content
    .filter(
      (part): part is { type: "text"; text: string } =>
        typeof part === "object" &&
        part !== null &&
        "type" in part &&
        part.type === "text" &&
        "text" in part &&
        typeof part.text === "string",
    )
    .map((part) => part.text)
    .join("\n")
    .trim();
}

/** 清理常见包装，同时保留合法的多行提交正文。 */
function normalizeCommitMessage(raw: string): string {
  let message = raw.replaceAll("\r\n", "\n").trim();
  const fenced = message.match(/^```(?:[\w-]+)?\s*\n([\s\S]*?)\n```$/);
  if (fenced?.[1] !== undefined) {
    message = fenced[1].trim();
  }

  message = message.replace(
    /^(?:commit message|git commit message|提交信息|提交消息)\s*[:：]\s*/i,
    "",
  );
  return message;
}

/** 根据停止原因和内容类型提取消息，失败时返回可执行的配置诊断。 */
export function parseCommitCompletionResponse(
  response: CommitCompletionResponse,
  context: CommitResponseContext,
): string {
  const contentTypes = describeContentTypes(response.content);
  const responseSummary = `stop reason: ${response.stopReason}; content types: ${contentTypes}`;

  if (response.stopReason === "aborted") {
    throw new Error("Commit message generation was cancelled.");
  }
  if (response.stopReason === "error") {
    const detail = response.errorMessage
      ? formatSafeErrorDetail(response.errorMessage)
      : "The provider returned an error without details.";
    throw new Error(
      `Model request failed for ${context.modelLabel}: ${detail} Check the provider, model ID, credentials, base URL, and network connection.`,
    );
  }
  if (response.stopReason === "length") {
    throw new Error(
      `Model ${context.modelLabel} reached the output limit of ${context.maxOutputTokens} tokens before completing a commit message (${responseSummary}). Increase maxOutputTokens in ai-git-commit.json, up to 4096, or use a model with a smaller reasoning budget.`,
    );
  }
  if (response.stopReason === "toolUse") {
    throw new Error(
      `Model ${context.modelLabel} attempted a tool call instead of returning a commit message (${responseSummary}). Check provider/model compatibility and use a text-generation model.`,
    );
  }

  const raw = extractTextContent(response.content);
  if (!raw) {
    throw new Error(
      `Model ${context.modelLabel} returned no text content (${responseSummary}). If the response is thinking-only, increase maxOutputTokens in ai-git-commit.json; otherwise check provider/model compatibility.`,
    );
  }

  const message = normalizeCommitMessage(raw);
  if (!message) {
    throw new Error(
      `Model ${context.modelLabel} returned text, but no usable commit message remained after removing common wrappers (${responseSummary}). Adjust prompt or choose another model.`,
    );
  }
  if (message.includes("\0")) {
    throw new Error(
      `Model ${context.modelLabel} returned a commit message containing an invalid NUL character. Adjust prompt or choose another model.`,
    );
  }
  return message;
}