const ANSI_ESCAPE_PATTERN = String.raw`\u001B\[[0-?]*[ -/]*[@-~]`;
const ANSI_ESCAPE_REGEXP = new RegExp(ANSI_ESCAPE_PATTERN, "g");
const LEADING_ANSI_ESCAPE_REGEXP = new RegExp(`^(?:${ANSI_ESCAPE_PATTERN})+`);
const TRAILING_ANSI_ESCAPE_REGEXP = new RegExp(`(?:${ANSI_ESCAPE_PATTERN})+$`);
const DIAGNOSTIC_MAX_LENGTH = 500;

function replaceControlCharacters(value: string): string {
  let result = "";
  for (const char of value) {
    const code = char.charCodeAt(0);
    result += code <= 31 || (code >= 127 && code <= 159) ? " " : char;
  }
  return result;
}

export function stripAnsi(value: string): string {
  return value.replace(ANSI_ESCAPE_REGEXP, "");
}

export function visibleWidth(value: string): number {
  return stripAnsi(value).length;
}

function leadingAnsi(value: string): string {
  return value.match(LEADING_ANSI_ESCAPE_REGEXP)?.[0] ?? "";
}

function trailingAnsi(value: string): string {
  return value.match(TRAILING_ANSI_ESCAPE_REGEXP)?.[0] ?? "";
}

export function truncateToWidth(value: string, width: number, ellipsis = "..."): string {
  if (visibleWidth(value) <= width) return value;
  if (width <= 0) return "";
  const plain = stripAnsi(value);
  if (width <= ellipsis.length) return ellipsis.slice(0, width);
  return `${leadingAnsi(value)}${plain.slice(0, Math.max(0, width - ellipsis.length))}${ellipsis}${trailingAnsi(value)}`;
}

export function formatTokens(count: number): string {
  if (count < 1000) return count.toString();
  if (count < 10000) return `${(count / 1000).toFixed(1)}k`;
  if (count < 1000000) return `${Math.round(count / 1000)}k`;
  if (count < 10000000) return `${(count / 1000000).toFixed(1)}M`;
  return `${Math.round(count / 1000000)}M`;
}

export function sanitizeStatusText(text: string): string {
  return text
    .replace(/[\r\n\t]/g, " ")
    .replace(/ +/g, " ")
    .trim();
}

export function maskIdentifier(value: string | undefined): string | undefined {
  const trimmed = value?.trim();
  if (!trimmed) return undefined;
  if (trimmed.length <= 8) return "found";
  return `${trimmed.slice(0, 4)}...${trimmed.slice(-4)}`;
}

export function sanitizeDiagnosticError(
  message: string,
  maxLength = DIAGNOSTIC_MAX_LENGTH,
): string {
  const redactedSecrets = stripAnsi(message)
    .replace(/\bBearer\s+[A-Za-z0-9._~+/=-]+/gi, "Bearer [REDACTED]")
    .replace(/\bsk-[A-Za-z0-9_-]{8,}\b/g, "sk-[REDACTED]")
    .replace(/\bacct_[A-Za-z0-9_-]{6,}\b/g, "acct_[REDACTED]")
    .replace(
      /(["']?(?:access|access_token|token|api[_-]?key|authorization|accountId|account_id)["']?\s*[:=]\s*["']?)([^"',\s}\]]+)/gi,
      "$1[REDACTED]",
    )
    .replace(/\[REDACTED\](?:\])+/g, "[REDACTED]");
  const redacted = replaceControlCharacters(redactedSecrets).replace(/ +/g, " ").trim();
  const sanitized = redacted || "Unknown error.";
  if (sanitized.length <= maxLength) return sanitized;
  return `${sanitized.slice(0, Math.max(0, maxLength - 1)).trimEnd()}…`;
}