const JS_RESERVED = new Set([
  "abstract",
  "arguments",
  "await",
  "boolean",
  "break",
  "byte",
  "case",
  "catch",
  "char",
  "class",
  "const",
  "continue",
  "debugger",
  "default",
  "delete",
  "do",
  "double",
  "else",
  "enum",
  "eval",
  "export",
  "extends",
  "false",
  "final",
  "finally",
  "float",
  "for",
  "function",
  "goto",
  "if",
  "implements",
  "import",
  "in",
  "instanceof",
  "int",
  "interface",
  "let",
  "long",
  "native",
  "new",
  "null",
  "package",
  "private",
  "protected",
  "public",
  "return",
  "short",
  "static",
  "super",
  "switch",
  "synchronized",
  "this",
  "throw",
  "throws",
  "transient",
  "true",
  "try",
  "typeof",
  "undefined",
  "var",
  "void",
  "volatile",
  "while",
  "with",
  "yield"
]);

/**
 * Sanitize a tool name into a valid JavaScript identifier.
 * Replaces hyphens, dots, and spaces with `_`, strips other invalid chars,
 * prefixes digit-leading names with `_`, and appends `_` to JS reserved words.
 */
export function sanitizeToolName(name: string): string {
  if (!name) return "_";

  // Replace common separators with underscores
  let sanitized = name.replace(/[-.\s]/g, "_");

  // Strip any remaining non-identifier characters
  sanitized = sanitized.replace(/[^a-zA-Z0-9_$]/g, "");

  if (!sanitized) return "_";

  // Prefix with _ if starts with a digit
  if (/^[0-9]/.test(sanitized)) {
    sanitized = "_" + sanitized;
  }

  // Append _ to reserved words
  if (JS_RESERVED.has(sanitized)) {
    sanitized = sanitized + "_";
  }

  return sanitized;
}

export function toPascalCase(str: string) {
  return str
    .replace(/_([a-z])/g, (_, letter) => letter.toUpperCase())
    .replace(/^[a-z]/, (letter) => letter.toUpperCase());
}

/**
 * Escape a character as a unicode escape sequence if it is a control character.
 */
function escapeControlChar(ch: string): string {
  const code = ch.charCodeAt(0);
  if (code <= 0x1f || code === 0x7f) {
    return "\\u" + code.toString(16).padStart(4, "0");
  }
  return ch;
}

/**
 * Quote a property name if needed.
 * Escapes backslashes, quotes, and control characters.
 */
export function quoteProp(name: string): string {
  if (!/^[a-zA-Z_$][a-zA-Z0-9_$]*$/.test(name)) {
    let escaped = "";
    for (const ch of name) {
      if (ch === "\\") escaped += "\\\\";
      else if (ch === '"') escaped += '\\"';
      else if (ch === "\n") escaped += "\\n";
      else if (ch === "\r") escaped += "\\r";
      else if (ch === "\t") escaped += "\\t";
      else if (ch === "\u2028") escaped += "\\u2028";
      else if (ch === "\u2029") escaped += "\\u2029";
      else escaped += escapeControlChar(ch);
    }
    return `"${escaped}"`;
  }
  return name;
}

/**
 * Escape a string for use inside a double-quoted TypeScript string literal.
 */
export function escapeStringLiteral(s: string): string {
  let out = "";
  for (const ch of s) {
    if (ch === "\\") out += "\\\\";
    else if (ch === '"') out += '\\"';
    else if (ch === "\n") out += "\\n";
    else if (ch === "\r") out += "\\r";
    else if (ch === "\t") out += "\\t";
    else if (ch === "\u2028") out += "\\u2028";
    else if (ch === "\u2029") out += "\\u2029";
    else out += escapeControlChar(ch);
  }
  return out;
}

/**
 * Escape a string for use inside a JSDoc comment.
 * Prevents premature comment closure from star-slash sequences.
 */
export function escapeJsDoc(text: string): string {
  return text.replace(/\*\//g, "*\\/");
}