import { z } from "zod";
import { withUser, parseBody, json, ApiError } from "@/lib/api";
import { duplicateConversation, exportConversation, shareConversation, revokeShare, revokeShareById, getShare, listShares, deleteMessage, EXPORT_FORMATS } from "@/lib/conversations/service";
import { LIMITS } from "@/lib/rate-limit";
import { APP_URL } from "@/lib/env";

export const dynamic = "force-dynamic";
type P = { id: string };

const schema = z.discriminatedUnion("action", [
  z.object({ action: z.literal("duplicate"), title: z.string().max(200).optional() }),
  z.object({ action: z.literal("branch"), messageId: z.string().max(64), title: z.string().max(200).optional() }),
  /** Prefer `GET /api/conversations/[id]/export?format=` for downloads; kept for existing callers. */
  z.object({ action: z.literal("export"), format: z.enum(EXPORT_FORMATS) }),
  /** `messageIds` → share only those messages (new link). Without it → the conversation's single full link (upsert). */
  z.object({ action: z.literal("share"), messageIds: z.array(z.string().max(64)).max(500).optional() }),
  /** Revoke every active link of the conversation, or one link when `shareId` is given. */
  z.object({ action: z.literal("unshare"), shareId: z.string().max(64).optional() }),
  z.object({ action: z.literal("share-status") }),
  z.object({ action: z.literal("list-shares") }),
  z.object({ action: z.literal("delete-message"), messageId: z.string().max(64) }),
]);

export const POST = withUser<P>(
  async ({ req, user }, { id }) => {
    const body = await parseBody(req, schema);
    switch (body.action) {
      case "duplicate":
        return json({ conversation: await duplicateConversation(user.id, id, { title: body.title }) }, { status: 201 });
      case "branch":
        return json({ conversation: await duplicateConversation(user.id, id, { uptoMessageId: body.messageId, title: body.title }) }, { status: 201 });
      case "export": {
        const out = await exportConversation(user.id, id, body.format, { appUrl: APP_URL });
        return new Response(out.body, { headers: { "Content-Type": out.contentType, "Content-Disposition": `attachment; filename="${out.filename}"` } });
      }
      case "share": {
        const res = await shareConversation(user.id, id, { messageIds: body.messageIds });
        return json({ ...res, path: `/share/${res.id}` }, { status: res.created ? 201 : 200 });
      }
      case "unshare":
        if (body.shareId) await revokeShareById(user.id, body.shareId);
        else await revokeShare(user.id, id);
        return json({ ok: true });
      case "share-status":
        return json({ share: await getShare(user.id, id), shares: await listShares(user.id, id) });
      case "list-shares":
        return json({ shares: await listShares(user.id, id) });
      case "delete-message":
        await deleteMessage(user.id, id, body.messageId);
        return json({ ok: true });
      default:
        throw new ApiError(400, "Unknown action");
    }
  },
  { limit: { ...LIMITS.share, key: "conv-actions" } },
);