// Parse the JSON a CLI printed on stdout, scanning lines LAST-TO-FIRST.
//
// Lifted from checkAvailability.ts (where it read yt-dlp --dump-json) because
// the digest registry needs exactly the same tolerance for `claude -p
// --output-format json`: both tools may print warnings, deprecation notices, or
// progress to stdout BEFORE the payload, so the JSON is the last parseable line,
// not the first. Reading forward finds the warning; reading backward finds the
// answer.
export function parseStdoutJson(stdout: string): unknown | null {
  const lines = stdout
    .split("\n")
    .map((l) => l.trim())
    .filter(Boolean);
  for (let i = lines.length - 1; i >= 0; i--) {
    try {
      return JSON.parse(lines[i]);
    } catch {
      continue;
    }
  }
  // Fall back to the whole buffer: `--output-format json` pretty-prints across
  // several lines, so no single line parses on its own.
  try {
    return JSON.parse(stdout);
  } catch {
    return null;
  }
}

// Pull a JSON object out of model prose. A CLI lane has no constrained decoding,
// so the body may arrive fenced (```json … ```) or with a sentence in front of
// it. Tries the whole string, then the fenced block, then the outermost braces.
export function extractJsonObject(text: string): unknown | null {
  const trimmed = text.trim();
  try {
    return JSON.parse(trimmed);
  } catch {
    // fall through
  }
  const fence = trimmed.match(/```(?:json)?\s*([\s\S]*?)```/);
  if (fence) {
    try {
      return JSON.parse(fence[1].trim());
    } catch {
      // fall through
    }
  }
  const first = trimmed.indexOf("{");
  const last = trimmed.lastIndexOf("}");
  if (first >= 0 && last > first) {
    try {
      return JSON.parse(trimmed.slice(first, last + 1));
    } catch {
      return null;
    }
  }
  return null;
}