/** Rough char-based token estimate. Matches OM's heuristic (≈4 chars/token). */
export function estimateStringTokens(text: string): number {
  return Math.ceil(text.length / 4);
}

export function estimateMessageTokens(message: unknown): number {
  if (!message || typeof message !== "object") return 0;
  const msg = message as { content?: unknown };
  if (typeof msg.content === "string") {
    return estimateStringTokens(msg.content);
  }
  if (Array.isArray(msg.content)) {
    let total = 0;
    for (const part of msg.content) {
      if (part && typeof part === "object") {
        if ("text" in part && typeof (part as { text?: unknown }).text === "string") {
          total += estimateStringTokens((part as { text: string }).text);
        } else if ("thinking" in part && typeof (part as { thinking?: unknown }).thinking === "string") {
          total += estimateStringTokens((part as { thinking: string }).thinking);
        }
      }
    }
    return total;
  }
  try {
    return estimateStringTokens(JSON.stringify(message));
  } catch {
    return 0;
  }
}

/**
 * Estimate the token cost of a single ledger entry. Only "source" entries
 * (message / custom_message / branch_summary) carry conversational text; every
 * other entry type (memory ledger records, compaction, etc.) contributes 0 so
 * the raw-token clocks measure only new conversation.
 */
export function estimateEntryTokens(entry: {
  type: string;
  message?: unknown;
  content?: unknown;
  summary?: unknown;
}): number {
  if (entry.type === "message" && entry.message) {
    return estimateMessageTokens(
      entry.message as Parameters<typeof estimateMessageTokens>[0],
    );
  }
  if (entry.type === "custom_message" && entry.content) {
    const content = entry.content;
    if (typeof content === "string") return estimateStringTokens(content);
    if (Array.isArray(content)) {
      let total = 0;
      for (const block of content) {
        if (block.type === "text" && block.text) {
          total += estimateStringTokens(block.text);
        }
      }
      return total;
    }
  }
  if (entry.type === "branch_summary" && typeof entry.summary === "string") {
    return estimateStringTokens(entry.summary);
  }
  return 0;
}