export interface InterpolationSegment {
  expression: string;
  start: number;
  end: number;
}

/** Extract top-level `{...}` expressions while preserving nested object/array literals. */
export function extractInterpolations(value: string): InterpolationSegment[] {
  const segments: InterpolationSegment[] = [];
  let index = 0;
  while (index < value.length) {
    if (value[index] !== "{") {
      index++;
      continue;
    }
    const start = index++;
    let depth = 1;
    let quote: string | null = null;
    while (index < value.length && depth > 0) {
      const char = value[index]!;
      if (quote) {
        if (char === "\\" && index + 1 < value.length) index += 2;
        else {
          if (char === quote) quote = null;
          index++;
        }
        continue;
      }
      if (char === '"' || char === "'" || char === "`") quote = char;
      else if (char === "{") depth++;
      else if (char === "}") depth--;
      index++;
    }
    if (depth === 0) {
      segments.push({ expression: value.slice(start + 1, index - 1).trim(), start, end: index });
    }
  }
  return segments;
}