// Placeholder substitution for skill text.
// Convention: placeholders look like {{KEY}} (uppercase + underscores).
// Inputs may be passed as either {KEY: value} or {key: value} — both resolve.

export interface SubstituteResult {
  text: string;
  bound: string[];
  unbound: string[];
}

const PLACEHOLDER_RE = /\{\{([A-Z][A-Z0-9_]*)\}\}/g;

export function substitute(text: string, inputs: Record<string, string>): string {
  return text.replace(PLACEHOLDER_RE, (match, key: string) => {
    if (inputs[key] !== undefined) return inputs[key];
    const lc = key.toLowerCase();
    if (inputs[lc] !== undefined) return inputs[lc];
    return match;
  });
}

export function substituteWithReport(
  text: string,
  inputs: Record<string, string>,
): SubstituteResult {
  const bound = new Set<string>();
  const unbound = new Set<string>();
  const out = text.replace(PLACEHOLDER_RE, (match, key: string) => {
    if (inputs[key] !== undefined) {
      bound.add(`{{${key}}}`);
      return inputs[key];
    }
    const lc = key.toLowerCase();
    if (inputs[lc] !== undefined) {
      bound.add(`{{${key}}}`);
      return inputs[lc];
    }
    unbound.add(`{{${key}}}`);
    return match;
  });
  return { text: out, bound: [...bound], unbound: [...unbound] };
}

export function findPlaceholders(text: string): string[] {
  const found = new Set<string>();
  for (const m of text.matchAll(PLACEHOLDER_RE)) {
    found.add(`{{${m[1]}}}`);
  }
  return [...found];
}