import { NextRequest, NextResponse } from "next/server";
import { requireRequestSession } from "@/lib/boss-auth";
import { appendProjectMessage, buildCollaborationGate, readState } from "@/lib/boss-data";
import { canAccessProject } from "@/lib/boss-permissions";
import {
  queueThreadForkTask,
  ThreadConversationExecutionConflictError,
} from "@/lib/boss-master-agent";

function forbiddenResponse(message = "FORBIDDEN") {
  return NextResponse.json({ ok: false, message }, { status: 403 });
}

function normalizeReason(value: unknown) {
  const trimmed = String(value ?? "").trim();
  return trimmed ? trimmed : undefined;
}

export async function POST(
  request: NextRequest,
  context: { params: Promise<{ projectId: string }> },
) {
  const session = await requireRequestSession(request);
  if (!session) {
    return NextResponse.json({ ok: false, message: "UNAUTHORIZED" }, { status: 401 });
  }

  const { projectId } = await context.params;
  const body = (await request.json().catch(() => ({}))) as {
    reason?: unknown;
    ephemeral?: unknown;
  };
  const reason = normalizeReason(body.reason);
  const ephemeral = body.ephemeral === true;

  const state = await readState();
  const projectExists = state.projects.some((project) => project.id === projectId);
  if (!canAccessProject(state, session, projectId, "project.view")) {
    return forbiddenResponse(projectExists ? "FORBIDDEN" : "PROJECT_NOT_FOUND");
  }
  if (!canAccessProject(state, session, projectId, "master_agent.ask")) {
    return forbiddenResponse("MASTER_AGENT_FORBIDDEN");
  }

  try {
    const message = await appendProjectMessage({
      projectId,
      account: session.account,
      senderLabel: session.displayName || "你",
      body: reason || "分叉当前 Codex 线程。",
      kind: "text",
    });
    const task = await queueThreadForkTask({
      projectId,
      requestMessageId: message.id,
      ephemeral,
      reason,
      requestedBy: session.displayName || session.account,
      requestedByAccount: session.account,
    });
    const nextState = await readState();
    const project = nextState.projects.find((item) => item.id === projectId);
    return NextResponse.json({
      ok: true,
      message,
      task,
      collaborationGate: buildCollaborationGate(project),
    });
  } catch (error) {
    if (error instanceof ThreadConversationExecutionConflictError) {
      return NextResponse.json(
        {
          ok: false,
          code: error.message,
          message: "THREAD_EXECUTION_CONFLICT",
          executionConflict: error.conflict,
        },
        { status: 409 },
      );
    }
    return NextResponse.json(
      { ok: false, message: error instanceof Error ? error.message : "UNKNOWN_ERROR" },
      { status: 400 },
    );
  }
}