import type { ChatMessage } from "../llm/types";

function sessionDir(): string {
  const profile = (Zotero as any).Profile?.dir;
  if (!profile || typeof profile !== "string") {
    throw new Error("Cannot resolve Zotero profile directory");
  }
  return PathUtils.join(profile, "chatpapers", "sessions");
}

function sessionPath(itemKey: string, attachmentKey: string): string {
  const safe = `${itemKey}-${attachmentKey || "none"}`.replace(
    /[^a-zA-Z0-9_-]/g,
    "_",
  );
  return PathUtils.join(sessionDir(), `${safe}.json`);
}

export async function loadSession(
  itemKey: string,
  attachmentKey: string,
): Promise<ChatMessage[]> {
  try {
    const path = sessionPath(itemKey, attachmentKey);
    const exists = await IOUtils.exists(path);
    if (!exists) return [];
    const raw = await IOUtils.readUTF8(path);
    const data = JSON.parse(raw) as { messages?: ChatMessage[] };
    return (data.messages || []).filter((m) => m.role !== "system");
  } catch (e) {
    ztoolkit.log("loadSession failed", e);
    return [];
  }
}

export async function saveSession(
  itemKey: string,
  attachmentKey: string,
  messages: ChatMessage[],
): Promise<void> {
  try {
    const dir = sessionDir();
    await IOUtils.makeDirectory(dir, { createAncestors: true, ignoreExisting: true });
    const path = sessionPath(itemKey, attachmentKey);
    const payload = JSON.stringify(
      {
        updatedAt: Date.now(),
        messages: messages.filter((m) => m.role !== "system").slice(-50),
      },
      null,
      2,
    );
    await IOUtils.writeUTF8(path, payload);
  } catch (e) {
    ztoolkit.log("saveSession failed", e);
  }
}

export async function clearSession(
  itemKey: string,
  attachmentKey: string,
): Promise<void> {
  try {
    const path = sessionPath(itemKey, attachmentKey);
    if (await IOUtils.exists(path)) {
      await IOUtils.remove(path);
    }
  } catch (e) {
    ztoolkit.log("clearSession failed", e);
  }
}