import type { ChatMessage } from "../llm/client.js";

/** 酒馆给示例对话消息打的 name（不是角色名）。 */
export const EXAMPLE_USER_NAME = "example_user";
export const EXAMPLE_ASSISTANT_NAME = "example_assistant";

/**
 * 把酒馆 `mes_example` 切成示例消息（对应 `openai.js` 的 `setOpenAIMessageExamples` +
 * `parseExampleIntoIndividual`）：
 * - 按 `<START>` 分块；
 * - 块内以 `用户名:` / `角色名:` 开头的行切换说话人，其余行算续行；
 * - 每条消息 role 都是 system，name 是 example_user / example_assistant，
 *   正文去掉 `名字:` 前缀。
 * 传进来的 text 应该已经展开过宏（`{{user}}` / `{{char}}`），否则名字对不上。
 */
export function parseExampleDialogue(params: {
  text: string;
  userName: string;
  charName: string;
}): ChatMessage[][] {
  const text = (params.text ?? "").replace(/\r/g, "");
  if (!text.trim()) return [];
  const userName = params.userName.trim();
  const charName = params.charName.trim();
  const blocks = text
    .split(/<START>/i)
    .map((block) => block.trim())
    .filter(Boolean);
  const source = blocks.length > 0 ? blocks : [text.trim()];

  const out: ChatMessage[][] = [];
  for (const block of source) {
    const messages: ChatMessage[] = [];
    let speaker: "user" | "assistant" | null = null;
    let lines: string[] = [];

    const flush = () => {
      const content = lines.join("\n").trim();
      if (speaker && content) {
        messages.push({
          role: "system",
          content,
          name: speaker === "user" ? EXAMPLE_USER_NAME : EXAMPLE_ASSISTANT_NAME,
        });
      }
      lines = [];
    };

    for (const rawLine of block.split("\n")) {
      const line = rawLine.replace(/\r$/, "");
      if (userName && line.startsWith(`${userName}:`)) {
        flush();
        speaker = "user";
        lines.push(line.slice(userName.length + 1));
        continue;
      }
      if (charName && line.startsWith(`${charName}:`)) {
        flush();
        speaker = "assistant";
        lines.push(line.slice(charName.length + 1));
        continue;
      }
      lines.push(line);
    }
    flush();
    if (messages.length > 0) out.push(messages);
  }
  return out;
}