/**
 * Is a work/ file a real solution or just a scaffolded stub?
 *
 * `bun run pick` writes a statement header plus an empty function body, so
 * file existence alone means nothing: close-solved.ts must not close an issue
 * on a stub, and work.ts must not ask for the spaced-repetition re-solve of a
 * problem that was never solved in the first place.
 *
 * sync.ts keeps its own copy of the header split — it runs its whole pipeline
 * on import, so it cannot be imported from. Don't "deduplicate" that one.
 *
 * Library: side-effect-free on import.
 */

/** Placeholder bodies that leetcode-cli / a human leaves behind. */
const PLACEHOLDERS: Record<string, true> = { pass: true, "...": true, TODO: true };

/**
 * Decide whether a work/ file contains an implementation.
 *
 * The header comment is dropped the same way sync.ts splitSource() does it.
 * Comments must go before any brace analysis: the scaffold's JSDoc carries
 * `@param {number[]}`, whose braces would otherwise read as a body.
 *
 * A brace-language file counts as implemented when at least one *innermost*
 * brace pair holds real content. That distinguishes a bare stub
 * (`function(nums) {}`) and a class-shaped design stub (every method body
 * empty) from any genuine solution, whose innermost block always has code.
 * Every non-Python language the campaign has ever used is brace-shaped, so
 * "not .py" is the only branch that matters.
 */
export function isImplemented(src: string, lang: "js" | "py"): boolean {
  if (lang === "py") {
    const open = src.indexOf('"""');
    const close = src.indexOf('"""', open + 3);
    const code = open === -1 || close === -1 ? src : src.slice(close + 3);
    for (const raw of code.split("\n")) {
      const line = raw.replace(/#.*$/, "").trim();
      if (!line || PLACEHOLDERS[line]) continue;
      if (/^(?:@|def\s|class\s)/.test(line)) continue;
      return true; // a statement inside some def body
    }
    return false;
  }

  const headerEnd = src.indexOf("*/");
  const body = headerEnd === -1 ? src : src.slice(headerEnd + 2);
  const code = body.replace(/\/\*[\s\S]*?\*\//g, " ").replace(/\/\/.*$/gm, " ");

  let innermost = -1;
  for (let i = 0; i < code.length; i++) {
    if (code[i] === "{") {
      innermost = i;
    } else if (code[i] === "}" && innermost !== -1) {
      const inner = code.slice(innermost + 1, i).replace(/[\s;]/g, "");
      if (inner && !PLACEHOLDERS[inner]) return true;
      innermost = -1; // measured; the enclosing pair is not innermost
    }
  }
  return false;
}