const PREVIEW_KEYS = [
  "command",
  "cmd",
  "path",
  "file_path",
  "filePath",
  "pattern",
  "query",
  "url",
] as const;

const MAX_PREVIEW_LENGTH = 160;
const MAX_DETAIL_LENGTH = 6000;

/** Single-line summary of tool call arguments, e.g. the bash command or file path. */
export function toolArgsPreview(args: unknown): string | undefined {
  if (!args || typeof args !== "object" || Array.isArray(args)) {
    return undefined;
  }

  const record = args as Record<string, unknown>;
  let preview: string | undefined;

  for (const key of PREVIEW_KEYS) {
    const value = record[key];
    if (typeof value === "string" && value.trim()) {
      preview = value.trim();
      break;
    }
  }

  if (!preview) {
    const entries = Object.entries(record).filter(([, value]) => value !== undefined);
    if (entries.length === 0) {
      return undefined;
    }
    preview = entries
      .map(([key, value]) => `${key}: ${typeof value === "string" ? value : safeStringify(value)}`)
      .join(", ");
  }

  const lines = preview.split("\n");
  let line = lines[0].trim();
  if (lines.length > 1) {
    line += " …";
  }
  return line.length > MAX_PREVIEW_LENGTH ? `${line.slice(0, MAX_PREVIEW_LENGTH)}…` : line;
}

/** Pulls readable text out of a tool result / partial result of unknown shape. */
export function extractResultText(result: unknown): string {
  if (result == null) {
    return "";
  }

  if (typeof result === "string") {
    return result;
  }

  if (Array.isArray(result)) {
    return result.map(blockText).join("");
  }

  if (typeof result === "object") {
    const record = result as Record<string, unknown>;
    if (Array.isArray(record.content)) {
      return record.content.map(blockText).join("");
    }
    if (typeof record.output === "string") {
      return record.output;
    }
    if (typeof record.text === "string") {
      return record.text;
    }
    return safeStringify(record);
  }

  return String(result);
}

/** Caps tool output length so a huge result doesn't bloat list state. */
export function truncateDetail(text: string): string {
  const trimmed = text.trim();
  if (trimmed.length <= MAX_DETAIL_LENGTH) {
    return trimmed;
  }
  return `${trimmed.slice(0, MAX_DETAIL_LENGTH)}\n… (output truncated)`;
}

function blockText(block: unknown): string {
  if (typeof block === "string") {
    return block;
  }
  if (typeof block === "object" && block && "text" in block) {
    return String((block as { text?: string }).text ?? "");
  }
  return "";
}

function safeStringify(value: unknown): string {
  try {
    return JSON.stringify(value) ?? "";
  } catch {
    return "";
  }
}