import { defineEventHandler, getQuery, getRouterParam, readBody, setResponseHeaders } from "h3";
import { R } from "#server/utils/response";
import { getCurrentUser, getConfigGlobal, getConfigUser } from "#server/utils/context";
import { createOpenAI } from "@ai-sdk/openai";
import { createOpenAICompatible } from "@ai-sdk/openai-compatible";
import { type LanguageModel, type ModelMessage, streamText, stepCountIs } from "ai";
import { getSessionByIdAndUser, getMessagesBySession, getMaxSortOrder, saveMessage, truncateMessagesAfter, deleteMessage, getMessageById, updateMessageContent, updateMessageParts, touchSession, countAssistantMessages } from "#server/service/agent/session";
import { getAgentToolsForChat, getAgentToolsBySlugs, executeAgentTool } from "#server/service/agent-tool";
import { getTempTokenFromCookie } from "#server/service/agent/temp-token";
import { checkRateLimit, incrementRateLimit } from "#server/service/agent/rate-limit";
import { getModelWithProviderById, getModelWithProviderByIdAny } from "#server/service/llm";
import { generateSessionTitle } from "#server/service/agent/title";
import { type StoredPart } from "./types";
import log4js from "logger";

const logger = log4js.getLogger("APP");

function resolveModel(
  provider: {
    name: string;
    apiKey: string | null;
    baseUrl: string | null;
    parseMode: string;
  },
  modelId: string,
): LanguageModel {
  const baseUrl = provider.baseUrl?.replace(/\/+$/, "") || undefined;
  if (provider.parseMode === "openai") {
    const openai = createOpenAI({
      apiKey: provider.apiKey || undefined,
      baseURL: baseUrl,
    });
    return openai(modelId) as unknown as LanguageModel;
  }
  const openaiCompatible = createOpenAICompatible({
    name: provider.name,
    apiKey: provider.apiKey || undefined,
    baseURL: baseUrl || "https://api.openai.com/v1",
  });
  return openaiCompatible(modelId) as LanguageModel;
}

function buildModelMessages(
  historyMessages: { id: string; role: string; content: string; parts: string | null }[],
  opts: {
    skipMessageId?: string;
    currentUserContent?: string;
    approvalToolResults?: Record<string, unknown>;
  },
): ModelMessage[] {
  const messages: ModelMessage[] = [];

  for (const m of historyMessages) {
    if (opts.skipMessageId && m.id === opts.skipMessageId) continue;

    if (m.role === "assistant" && m.parts) {
      let parts: StoredPart[];
      try {
        parts = JSON.parse(m.parts);
      } catch {
        parts = [];
      }

      const assistantContent: Array<Record<string, unknown>> = [];

      if (m.content) {
        assistantContent.push({ type: "text", text: m.content });
      }

      for (const p of parts) {
        if (p.type === "tool-call" && p.toolCallId && p.toolName) {
          if (p.state === "approval-requested" && p.approvalId) {
            // Tool still waiting for approval - only generate tool-approval-request
            // (SDK filters it out), do NOT generate tool-call to avoid MissingToolResultsError
            assistantContent.push({
              type: "tool-approval-request",
              approvalId: p.approvalId,
              toolCallId: p.toolCallId,
              toolName: p.toolName,
              input: p.args ?? {},
            });
          } else if (p.state === "approval-responded" && p.approvalId) {
            const hasResult = opts.approvalToolResults?.[p.toolCallId] !== undefined;
            if (p.approved === true && hasResult) {
              assistantContent.push({
                type: "tool-call",
                toolCallId: p.toolCallId,
                toolName: p.toolName,
                input: p.args ?? {},
              });
            } else {
              // Denied: generate BOTH tool-call AND tool-approval-request.
              // collectToolApprovals (SDK) scans original messages for tool-approval-response
              // and requires a matching tool-call, otherwise throws ToolCallNotFoundForApprovalError.
              // convertToLanguageModelPrompt adds toolCallId to approvedToolCallIds when
              // tool-approval-response exists, preventing MissingToolResultsError.
              assistantContent.push({
                type: "tool-call",
                toolCallId: p.toolCallId,
                toolName: p.toolName,
                input: p.args ?? {},
              });
              assistantContent.push({
                type: "tool-approval-request",
                approvalId: p.approvalId,
                toolCallId: p.toolCallId,
                toolName: p.toolName,
                input: p.args ?? {},
              });
            }
          } else {
            const toolCallPart: Record<string, unknown> = {
              type: "tool-call",
              toolCallId: p.toolCallId,
              toolName: p.toolName,
              input: p.args ?? {},
            };
            if (p.state === "result" && p.result !== undefined) {
              toolCallPart.output = p.result;
            }
            assistantContent.push(toolCallPart);
          }
        } else if (p.type === "reasoning" && p.text) {
          assistantContent.push({ type: "reasoning", text: p.text });
        } else if (p.type === "text" && p.text && !m.content) {
          assistantContent.push({ type: "text", text: p.text });
        }
      }

      if (assistantContent.length > 0) {
        messages.push({ role: "assistant", content: assistantContent } as ModelMessage);
      }

      const toolResults: Array<Record<string, unknown>> = [];
      const approvalResponses: Array<Record<string, unknown>> = [];
      for (const p of parts) {
        if (p.type === "tool-call" && p.toolCallId && p.toolName && p.state === "result" && p.result !== undefined) {
          toolResults.push({
            type: "tool-result",
            toolCallId: p.toolCallId,
            toolName: p.toolName,
            output: { type: "json" as const, value: p.result as unknown },
          });
        }
        if (p.type === "tool-call" && p.state === "approval-responded" && p.approvalId) {
          const hasResult = opts.approvalToolResults?.[p.toolCallId] !== undefined;
          if (p.approved === true && hasResult) {
            toolResults.push({
              type: "tool-result",
              toolCallId: p.toolCallId,
              toolName: p.toolName,
              output: { type: "json" as const, value: opts.approvalToolResults![p.toolCallId] as unknown },
            });
          } else {
            approvalResponses.push({
              type: "tool-approval-response",
              approvalId: p.approvalId,
              approved: p.approved ?? false,
              reason: p.approvalReason,
            });
          }
        }
      }

      if (toolResults.length > 0 || approvalResponses.length > 0) {
        messages.push({ role: "tool", content: [...toolResults, ...approvalResponses] } as ModelMessage);
      }
    } else if (m.role === "user") {
      messages.push({ role: "user", content: m.content });
    }
  }

  if (opts.currentUserContent !== undefined) {
    messages.push({ role: "user", content: opts.currentUserContent });
  }

  return messages;
}

export default defineEventHandler(async (event) => {
  const user = await getCurrentUser(event);
  const tempToken = getTempTokenFromCookie(event);

  if (!user && !tempToken) {
    throw createError({ statusCode: 401, statusMessage: "请先登录或创建临时会话" });
  }

  const body = await readBody(event);
  const { sessionId, content, editMessageId, regenerate, continueAfterApproval, approvalToolCallId, approved, approvalReason, enableThinking: bodyEnableThinking, enableTools: bodyEnableTools } = body as {
    sessionId: string;
    content: string;
    editMessageId?: string;
    regenerate?: boolean;
    continueAfterApproval?: boolean;
    approvalToolCallId?: string;
    approved?: boolean;
    approvalReason?: string;
    enableThinking?: boolean;
    enableTools?: boolean;
  };

  const isApprovalContinue = continueAfterApproval === true && approvalToolCallId;

  if (!sessionId) {
    throw createError({ statusCode: 400, statusMessage: "参数无效" });
  }

  if (!isApprovalContinue && (!content || typeof content !== "string" || content.trim().length === 0)) {
    throw createError({ statusCode: 400, statusMessage: "参数无效" });
  }

  const session = await getSessionByIdAndUser(sessionId, user?.id ?? null, tempToken);
  if (!session) {
    throw createError({ statusCode: 404, statusMessage: "会话不存在" });
  }

  const ip = getRequestIP(event, { xForwardedFor: true }) || "unknown";

  if (!user) {
    const rateLimit = checkRateLimit(sessionId, ip);
    if (rateLimit.blocked) {
      setResponseHeaders(event, {
        "X-RateLimit-Session-Remaining": String(rateLimit.sessionRemaining),
        "X-RateLimit-Ip-Remaining": String(rateLimit.ipRemaining),
      });
      throw createError({
        statusCode: 429,
        statusMessage: rateLimit.sessionRemaining === 0 ? "当前会话已达回复上限，请登录后继续" : "今日回复次数已达上限，请登录或明日再试",
      });
    }
    setResponseHeaders(event, {
      "X-RateLimit-Session-Remaining": String(rateLimit.sessionRemaining),
      "X-RateLimit-Ip-Remaining": String(rateLimit.ipRemaining),
    });
  }

  let modelRow;
  if (user) {
    const preferredModelId = await getConfigUser(event, "preferredLlmModelId");
    const targetModelId = session.modelId ?? preferredModelId;
    if (!targetModelId) {
      throw createError({ statusCode: 400, statusMessage: "未配置模型，请先在设置中选择模型" });
    }
    modelRow = await getModelWithProviderById(targetModelId, user.id);
  } else {
    if (!session.modelId) {
      throw createError({ statusCode: 400, statusMessage: "系统未配置默认模型" });
    }
    modelRow = await getModelWithProviderByIdAny(session.modelId);
  }

  if (!modelRow) {
    throw createError({ statusCode: 404, statusMessage: "模型不存在或无权访问" });
  }

  const { model, provider } = modelRow;
  if (!provider.apiKey) {
    throw createError({ statusCode: 400, statusMessage: "供应商未配置 API Key" });
  }

  const systemPrompt = await getConfigGlobal("agentSystemPrompt");
  const titleModelId = await getConfigGlobal("agentTitleModelId");

  let publicToolSlugs: string[] = [];
  if (!user) {
    const raw = await getConfigGlobal("agentPublicToolSlugs");
    if (raw && Array.isArray(raw)) {
      publicToolSlugs = raw as string[];
    }
  }

  const toolsEnabled = bodyEnableTools !== undefined ? bodyEnableTools : session.enableTools === 1;

  const { tools } = await getAgentToolsForChat({
    userId: user?.id ?? null,
    userRole: user?.role ?? null,
    enableTools: toolsEnabled,
    publicToolSlugs,
  });

  let historyMessages = await getMessagesBySession(sessionId, { limit: 100, latest: true });

  let userMessage;
  let shouldGenerateTitle = false;

  if (isApprovalContinue) {
    userMessage = historyMessages.filter((m) => m.role === "user").pop() ?? historyMessages[0];
    const assistantCount = await countAssistantMessages(sessionId);
    if (assistantCount <= 1) {
      shouldGenerateTitle = true;
    }
  } else if (editMessageId) {
    const editMsg = await getMessageById(editMessageId);
    if (!editMsg || editMsg.sessionId !== sessionId) {
      throw createError({ statusCode: 400, statusMessage: "编辑的消息不存在" });
    }
    await truncateMessagesAfter(sessionId, editMsg.sortOrder);
    await updateMessageContent(editMessageId, content.trim());
    historyMessages = await getMessagesBySession(sessionId, { limit: 100, latest: true });
    userMessage = editMsg;
  } else if (regenerate) {
    const lastAssistant = historyMessages.filter((m) => m.role === "assistant").pop();
    if (lastAssistant) {
      await deleteMessage(lastAssistant.id);
      historyMessages = await getMessagesBySession(sessionId, { limit: 100, latest: true });
    }
    const lastUser = historyMessages.filter((m) => m.role === "user").pop();
    if (lastUser) {
      await updateMessageContent(lastUser.id, content.trim());
      userMessage = lastUser;
    } else {
      const sortOrder = (await getMaxSortOrder(sessionId)) + 1;
      userMessage = await saveMessage({
        sessionId,
        role: "user",
        content: content.trim(),
        sortOrder,
      });
      shouldGenerateTitle = true;
    }
  } else {
    const sortOrder = (await getMaxSortOrder(sessionId)) + 1;
    userMessage = await saveMessage({
      sessionId,
      role: "user",
      content: content.trim(),
      sortOrder,
    });
    const assistantCount = await countAssistantMessages(sessionId);
    if (assistantCount === 0) {
      shouldGenerateTitle = true;
    }
  }

  const approvalToolResults: Record<string, unknown> = {};
  if (isApprovalContinue) {
    const pendingSlugs = new Set<string>();
    for (const m of historyMessages) {
      if (!m.parts) continue;
      let parts: StoredPart[];
      try {
        parts = JSON.parse(m.parts);
      } catch {
        continue;
      }
      for (const p of parts) {
        if (p.type !== "tool-call" || !p.toolCallId || !p.toolName) continue;
        if (p.state !== "approval-responded" || p.approved !== true) continue;
        if (approvalToolResults[p.toolCallId] !== undefined) continue;
        pendingSlugs.add(p.toolName);
      }
    }
    const toolMap = await getAgentToolsBySlugs([...pendingSlugs]);

    for (const m of historyMessages) {
      if (!m.parts) continue;
      let parts: StoredPart[];
      try {
        parts = JSON.parse(m.parts);
      } catch {
        continue;
      }
      for (const p of parts) {
        if (p.type !== "tool-call" || !p.toolCallId || !p.toolName) continue;
        if (p.state !== "approval-responded" || p.approved !== true) continue;
        if (approvalToolResults[p.toolCallId] !== undefined) continue;
        const agentTool = toolMap.get(p.toolName);
        if (!agentTool) {
          approvalToolResults[p.toolCallId] = { error: `Tool ${p.toolName} not found` };
          continue;
        }
        try {
          const result = await executeAgentTool(agentTool.id, p.args, user?.id ?? null);
          approvalToolResults[p.toolCallId] = result;
          logger.info("[%s] [APPROVAL-EXEC] tool=%s result=%s", event.context.requestId ?? "-", p.toolName, JSON.stringify(result).slice(0, 200));
        } catch (err) {
          approvalToolResults[p.toolCallId] = { error: err instanceof Error ? err.message : String(err) };
          logger.error("[%s] [APPROVAL-EXEC] tool=%s error=%s", event.context.requestId ?? "-", p.toolName, approvalToolResults[p.toolCallId]);
        }
      }
    }
  }

  const modelMessages = buildModelMessages(historyMessages, {
    skipMessageId: isApprovalContinue ? undefined : userMessage?.id,
    currentUserContent: isApprovalContinue ? undefined : content.trim(),
    approvalToolResults,
  });

  const languageModel = resolveModel(provider, model.modelId);

  const thinkingEnabled = bodyEnableThinking !== undefined ? bodyEnableThinking : session.enableThinking === 1;

  const modelSupportsTools = (model.supportsTools ?? 1) === 1;
  const effectiveTools = modelSupportsTools ? tools : {};

  logger.info(
    "[%s] [AGENT-CHAT] userId=%s sessionId=%s modelId=%d thinking=%s tools=%s supportsTools=%s edit=%s regen=%s approval=%s",
    event.context.requestId ?? "-",
    user?.id ?? "temp",
    sessionId,
    model.id,
    thinkingEnabled ? "on" : "off",
    Object.keys(effectiveTools).length > 0 ? "on" : "off",
    modelSupportsTools ? "yes" : "no",
    editMessageId ? "yes" : "no",
    regenerate ? "yes" : "no",
    isApprovalContinue ? "yes" : "no",
  );

  const result = streamText({
    model: languageModel,
    system: systemPrompt || undefined,
    messages: modelMessages,
    maxOutputTokens: model.maxTokens || undefined,
    ...(Object.keys(effectiveTools).length > 0
      ? { tools: effectiveTools, stopWhen: stepCountIs(8) }
      : {}),
    ...(thinkingEnabled
      ? {
          providerOptions: {
            openaiCompatible: { reasoningEffort: "high" },
          },
        }
      : {}),
    onError: (errorData) => {
      const errMsg = errorData?.error instanceof Error
        ? errorData.error.message
        : String(errorData?.error ?? "未知错误");
      logger.error("[%s] [AGENT-CHAT] streamText error: %s", event.context.requestId ?? "-", errMsg);
    },
    onFinish: async ({ finishReason, usage, steps, text: assistantText }) => {
      logger.info(
        "[%s] [AGENT-CHAT] finished: reason=%s steps=%d inputTokens=%d outputTokens=%d",
        event.context.requestId ?? "-",
        finishReason,
        steps.length,
        usage?.inputTokens ?? 0,
        usage?.outputTokens ?? 0,
      );

      const parts: Array<Record<string, unknown>> = [];
      for (const step of steps) {
        const toolResultMap = new Map(step.toolResults.map((tr) => [tr.toolCallId, tr.output]));
        const contentArr = step.content as Array<Record<string, unknown>>;
        const approvalToolCallIds = new Set<string>();
        for (const cp of contentArr) {
          if (cp.type === "tool-approval-request" && (cp as any).approvalId && (cp as any).toolCall) {
            approvalToolCallIds.add((cp as any).toolCall.toolCallId);
          }
        }
        for (const cp of contentArr) {
          if (cp.type === "reasoning" && (cp as any).text) {
            parts.push({ id: `p_${parts.length}`, type: "reasoning", text: (cp as any).text });
          } else if (cp.type === "text" && (cp as any).text) {
            parts.push({ id: `p_${parts.length}`, type: "text", text: (cp as any).text });
          } else if (cp.type === "tool-approval-request" && (cp as any).approvalId && (cp as any).toolCall) {
            const tc = (cp as any).toolCall;
            const toolResult = toolResultMap.get(tc.toolCallId);
            if (toolResult === undefined) {
              parts.push({
                id: `p_${parts.length}`,
                type: "tool-call",
                toolCallId: tc.toolCallId,
                toolName: tc.toolName,
                args: tc.input,
                state: "approval-requested",
                approvalId: (cp as any).approvalId,
              });
            } else {
              parts.push({
                id: `p_${parts.length}`,
                type: "tool-call",
                toolCallId: tc.toolCallId,
                toolName: tc.toolName,
                args: tc.input,
                result: toolResult,
                state: "result",
                approvalId: (cp as any).approvalId,
              });
            }
          } else if (cp.type === "tool-call") {
            const tc = cp as any;
            if (approvalToolCallIds.has(tc.toolCallId)) continue;
            const toolResult = toolResultMap.get(tc.toolCallId);
            parts.push({
              id: `p_${parts.length}`,
              type: "tool-call",
              toolCallId: tc.toolCallId,
              toolName: tc.toolName,
              args: tc.input,
              result: toolResult,
              state: "result",
            });
          }
        }
      }

      if (isApprovalContinue) {
        const lastAssistant = historyMessages.filter((m) => m.role === "assistant").pop();
        if (lastAssistant) {
          let existingParts: Array<Record<string, unknown>> = [];
          try {
            existingParts = lastAssistant.parts ? JSON.parse(lastAssistant.parts) : [];
          } catch {
            existingParts = [];
          }
          logger.info("[%s] [APPROVAL-CONTINUE] merged %d existing parts with %d new parts", event.context.requestId ?? "-", existingParts.length, parts.length);
          for (const p of existingParts) {
            if (p.type === "tool-call" && p.state === "approval-responded") {
              if (p.approved === true && approvalToolResults[p.toolCallId] !== undefined) {
                p.result = approvalToolResults[p.toolCallId];
                p.state = "result";
              } else if (p.approved === false) {
                p.result = "工具执行被拒绝";
                p.state = "result";
              }
            }
          }
          const newParts = parts.filter(
            (np) => np.type !== "tool-call" || !existingParts.some((ep) => ep.toolCallId === np.toolCallId),
          );
          const idOffset = existingParts.length;
          for (let i = 0; i < newParts.length; i++) {
            newParts[i].id = `p_${idOffset + i}`;
          }
          const mergedParts = [...existingParts, ...newParts];
          const mergedContent = (lastAssistant.content || "") + assistantText;
          await updateMessageContent(lastAssistant.id, mergedContent);
          await updateMessageParts(lastAssistant.id, JSON.stringify(mergedParts));
        }
      } else {
        const assistantSortOrder = (await getMaxSortOrder(sessionId)) + 1;
        await saveMessage({
          sessionId,
          role: "assistant",
          content: assistantText,
          parts: parts.length > 0 ? JSON.stringify(parts) : null,
          modelId: model.id,
          inputTokens: usage?.inputTokens ?? null,
          outputTokens: usage?.outputTokens ?? null,
          sortOrder: assistantSortOrder,
        });
      }

      await touchSession(sessionId);

      if (!user) {
        incrementRateLimit(sessionId, ip);
        const rateLimit = checkRateLimit(sessionId, ip);
        setResponseHeaders(event, {
          "X-RateLimit-Session-Remaining": String(rateLimit.sessionRemaining),
          "X-RateLimit-Ip-Remaining": String(rateLimit.ipRemaining),
        });
      }

      if (shouldGenerateTitle && titleModelId && assistantText.trim().length > 0) {
        generateSessionTitle(sessionId, content.trim(), assistantText, titleModelId, user?.id ?? null).catch((e) => { logger.error("[AGENT-CHAT] title gen failed: %s", e?.message ?? e); });
      }
    },
  });

  const responseHeaders: Record<string, string> = {
    "X-User-Message-Id": userMessage?.id ?? "",
  };

  const response = result.toUIMessageStreamResponse({
    sendReasoning: true,
    headers: responseHeaders,
  });

  if (continueAfterApproval && Object.keys(approvalToolResults).length > 0) {
    const originalBody = response.body;
    if (originalBody) {
      const prefixChunks = Object.entries(approvalToolResults).map(
        ([toolCallId, output]) =>
          `data: ${JSON.stringify({
            type: "tool-output-available",
            toolCallId,
            output,
          })}\n\n`,
      );
      const prefix = new TextEncoder().encode(prefixChunks.join(""));

      const transformed = new ReadableStream({
        async start(controller) {
          controller.enqueue(prefix);
          const reader = originalBody.getReader();
          try {
            while (true) {
              const { done, value } = await reader.read();
              if (done) break;
              controller.enqueue(value);
            }
          } catch (err) {
            logger.error("[%s] [AGENT-CHAT] stream read error: %s", event.context.requestId ?? "-", err instanceof Error ? err.message : String(err));
            const errorChunk = new TextEncoder().encode(
              `data: ${JSON.stringify({ type: "error", errorText: "流式响应中断" })}\n\n`,
            );
            controller.enqueue(errorChunk);
          } finally {
            controller.close();
          }
        },
      });

      return new Response(transformed, {
        status: response.status,
        statusText: response.statusText,
        headers: response.headers,
      });
    }
  }

  return response;
});