import { apiError } from "@/lib/api";
import { startChatRun } from "@/lib/chat-runs";
import {
  createChatRunWithMessages,
  getActiveChatRun,
  getConversation,
  getConversationContinuation,
  getDefaultConversation,
  getSkill,
  listMessages,
} from "@/lib/db";
import { hasDeepSeekApiKey } from "@/lib/deepseek";
import {
  pinSkillsToSnapshots,
  snapshotsForSkills,
} from "@/lib/skill-snapshots";
import { classifyContinuationReply } from "@/lib/skill-continuation";
import type { ChatMessage, Skill } from "@/lib/types";
import { createId } from "@/lib/utils";
import { chatRequestSchema } from "@/lib/validation";

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

export async function GET() {
  try {
    const conversation = getDefaultConversation();
    const continuation = getConversationContinuation(conversation.id);
    return Response.json({
      conversation,
      messages: listMessages(conversation.id),
      activeRun: getActiveChatRun(conversation.id),
      retainedSkillIds: continuation.skillIds,
      continuation,
      apiConfigured: hasDeepSeekApiKey(),
    });
  } catch (error) {
    return apiError(error, "无法读取聊天记录");
  }
}

export async function POST(request: Request) {
  try {
    const input = chatRequestSchema.parse(await request.json());
    if (!getConversation(input.conversationId)) {
      return Response.json({ error: "会话不存在" }, { status: 404 });
    }
    const existingMessages = listMessages(input.conversationId);
    const continuation = getConversationContinuation(
      input.conversationId,
    );
    const currentSelectedSkills = [...new Set(input.selectedSkillIds)]
      .map((id) => getSkill(id))
      .filter(
        (skill): skill is Skill => skill?.status === "active",
      );
    const replyKind = classifyContinuationReply(input.message);
    const continuesExistingTask =
      !["complete", "abandoned"].includes(continuation.state) &&
      replyKind !== "new_topic" &&
      replyKind !== "decline";
    const retainedSnapshots = continuesExistingTask
      ? continuation.skillSnapshots
      : [];
    const selectedSkills = pinSkillsToSnapshots(
      currentSelectedSkills,
      retainedSnapshots,
    );
    const skillSnapshots = snapshotsForSkills(
      selectedSkills,
      retainedSnapshots,
    );

    const userMessageId = createId("message");
    const assistantMessageId = createId("message");
    const runId = createId("run");
    const now = new Date().toISOString();

    const creation = createChatRunWithMessages({
      conversationId: input.conversationId,
      userMessage: {
        id: userMessageId,
        role: "user",
        content: input.message,
        selectedSkillIds: selectedSkills.map((skill) => skill.id),
        usedSkillIds: [],
        skillSnapshots,
        skillExecutions: [],
        status: "complete",
        createdAt: now,
      },
      assistantMessage: {
        id: assistantMessageId,
        role: "assistant",
        content: "",
        selectedSkillIds: selectedSkills.map((skill) => skill.id),
        usedSkillIds: [],
        skillSnapshots,
        skillExecutions: [],
        status: "streaming",
        createdAt: new Date(Date.now() + 1).toISOString(),
      },
      run: {
        id: runId,
        clientRequestId: input.clientRequestId,
        userMessageId,
        assistantMessageId,
      },
    });
    if (creation.outcome === "existing") {
      return Response.json({ run: creation.run });
    }
    if (creation.outcome === "active_conflict") {
      return Response.json(
        { error: "当前已有一轮回答正在进行", run: creation.run },
        { status: 409 },
      );
    }
    const run = creation.run;

    const history = existingMessages
      .filter((message) => message.status !== "error")
      .slice(-20)
      .map((message) => ({
        role: message.role,
        content: message.content,
      })) satisfies Array<{
      role: ChatMessage["role"];
      content: string;
    }>;

    startChatRun({
      runId,
      conversationId: input.conversationId,
      userMessage: input.message,
      selectedSkills,
      skillSnapshots,
      continuation,
      history,
    });

    return Response.json({ run }, { status: 202 });
  } catch (error) {
    return apiError(error, "无法发送消息");
  }
}