import { apiError } from "@/lib/api";
import {
  getBuilderRunEvents,
  getOrStartBuilderRun,
} from "@/lib/builder-runs";
import { encodeSse, sseResponse } from "@/lib/sse";
import { builderRequestSchema } from "@/lib/validation";

export const runtime = "nodejs";
export const maxDuration = 120;

const terminalStatuses = new Set(["complete", "stopped", "error"]);

export async function POST(request: Request) {
  try {
    const input = builderRequestSchema.parse(await request.json());
    const run = getOrStartBuilderRun(input);
    let cursor = input.afterSeq;

    const stream = new ReadableStream<Uint8Array>({
      async start(controller) {
        try {
          while (!request.signal.aborted) {
            const snapshot = getBuilderRunEvents(run.id, cursor);
            if (!snapshot) {
              controller.enqueue(
                encodeSse({ type: "error", message: "节点任务已过期" }),
              );
              controller.close();
              return;
            }

            for (const event of snapshot.events) {
              controller.enqueue(encodeSse(event));
              cursor = Math.max(cursor, event.seq ?? cursor);
            }

            if (terminalStatuses.has(snapshot.status)) {
              controller.close();
              return;
            }

            await new Promise((resolve) => setTimeout(resolve, 100));
          }
        } catch {
          try {
            controller.close();
          } catch {
            // A disconnected editor can reconnect with the last event seq.
          }
        }
      },
    });

    return sseResponse(stream);
  } catch (error) {
    return apiError(error, "无法处理 Skill 对话");
  }
}