/**
 * ai-client.ts
 * Client untuk berkomunikasi dengan AI melalui OpenRouter API.
 * Menggunakan SDK OpenAI karena OpenRouter API-nya OpenAI-compatible.
 */

import OpenAI from 'openai';
import type { ChatCompletionMessageParam, ChatCompletionTool } from 'openai/resources/chat/completions';

// Inisialisasi client OpenAI dengan baseURL OpenRouter
// Lazy initialization client OpenAI menggunakan konfigurasi dari .env
let openai: OpenAI | null = null;

function getOpenAI(): OpenAI {
  if (openai) return openai;

  const aiBaseUrl = process.env.AI_BASE_URL;
  const aiApiKey = process.env.AI_API_KEY;
  const aiModel = process.env.AI_MODEL;

  if (!aiApiKey || !aiBaseUrl || !aiModel) {
    throw new Error('Konfigurasi AI tidak lengkap di file .env (Pastikan AI_BASE_URL, AI_API_KEY, dan AI_MODEL terisi).');
  }

  openai = new OpenAI({
    baseURL: aiBaseUrl,
    apiKey: aiApiKey,
  });

  return openai;
}

export interface PesanChat {
  role: 'system' | 'user' | 'assistant' | 'tool';
  content: string;
  tool_call_id?: string;
  tool_calls?: any[];
}

export interface HasilAI {
  balasan: string | null;
  tool_calls: ToolCall[] | null;
  usage?: {
    prompt_tokens: number;
    completion_tokens: number;
    total_tokens: number;
  };
}

export interface ToolCall {
  id: string;
  nama: string;
  argumen: Record<string, any>;
}

/**
 * Kirim pesan ke AI dan dapatkan response.
 * Support function calling / tool use.
 */
export async function chatCompletion(
  messages: PesanChat[],
  tools?: ChatCompletionTool[]
): Promise<HasilAI> {
  const model = process.env.AI_MODEL!;
  const maxTokens = Number(process.env.AI_MAX_TOKENS) || 2000;

  const requestMessages: ChatCompletionMessageParam[] = messages.map((m) => {
    if (m.role === 'tool') {
      return {
        role: 'tool' as const,
        content: m.content,
        tool_call_id: m.tool_call_id || '',
      };
    }
    if (m.role === 'assistant' && m.tool_calls) {
      return {
        role: 'assistant' as const,
        content: m.content || null,
        tool_calls: m.tool_calls,
      };
    }
    return {
      role: m.role as 'system' | 'user' | 'assistant',
      content: m.content,
    };
  });

  const params: any = {
    model,
    messages: requestMessages,
    max_tokens: maxTokens,
    temperature: 0.7,
  };

  // Hanya tambahkan tools jika ada
  if (tools && tools.length > 0) {
    params.tools = tools;
    params.tool_choice = 'auto';
  }

  console.log('[AI Client] Params:', JSON.stringify(params, null, 2));
  const response = await getOpenAI().chat.completions.create(params);
  console.log('[AI Client] Raw Response Choices:', JSON.stringify(response.choices, null, 2));

  const choice = response.choices[0];

  // Parse tool calls jika ada secara native
  let toolCalls: ToolCall[] | null = null;
  if (choice.message.tool_calls && choice.message.tool_calls.length > 0) {
    toolCalls = choice.message.tool_calls.map((tc) => ({
      id: tc.id,
      nama: (tc as any).function.name,
      argumen: JSON.parse((tc as any).function.arguments || '{}'),
    }));
  }

  let balasan = choice.message.content || null;

  // Fallback parser jika AI menulis tag DSML secara literal di teks (karena limitasi API/model gratis)
  if (!toolCalls && balasan) {
    const dsmlCalls = parseDsmlToolCalls(balasan);
    if (dsmlCalls) {
      toolCalls = dsmlCalls;
      // Bersihkan teks tag XML/DSML dari balasan agar bubble chat rapi
      balasan = balasan
        .replace(/<\s*\|?\s*\|?\s*DSML[\s\S]*?<\s*\/\s*\|?\s*\|?\s*DSML\s*\|?\s*\|?\s*tool_calls\s*>/g, '')
        // Hapus juga tag invoke/tool_calls sisa jika terpisah
        .replace(/<\s*\|?\s*\|?\s*DSML[\s\S]*?>/g, '')
        .replace(/<\s*\/\s*\|?\s*\|?\s*DSML[\s\S]*?>/g, '')
        .trim();
    }
  }

  return {
    balasan,
    tool_calls: toolCalls,
    usage: response.usage
      ? {
          prompt_tokens: response.usage.prompt_tokens,
          completion_tokens: response.usage.completion_tokens,
          total_tokens: response.usage.total_tokens,
        }
      : undefined,
  };
}

/**
 * Parser penanganan tag DSML/XML tool calls yang dikirim literal oleh model AI
 */
function parseDsmlToolCalls(text: string): ToolCall[] | null {
  if (!text.includes('tool_calls') && !text.includes('DSML')) return null;

  try {
    const toolCalls: ToolCall[] = [];
    
    // Regex fleksibel mencocokkan invoke block: < | | DSML | | invoke name="NAMA"> ... </ | | DSML | | invoke>
    const invokeRegex = /<\s*\|?\s*\|?\s*DSML\s*\|?\s*\|?\s*invoke\s+name="([^"]+)"\s*>([\s\S]*?)<\s*\/\s*\|?\s*\|?\s*DSML\s*\|?\s*\|?\s*invoke\s*>/g;
    
    let match;
    let idx = 0;
    while ((match = invokeRegex.exec(text)) !== null) {
      const toolName = match[1];
      const innerContent = match[2];
      const args: Record<string, any> = {};

      // Regex mencocokkan argument: <arg name="NAMA">NILAI</arg>
      const argRegex = /<\s*(?:arg|parameter)\s+name="([^"]+)"\s*>([\s\S]*?)<\s*\/\s*(?:arg|parameter)\s*>/g;
      let argMatch;
      while ((argMatch = argRegex.exec(innerContent)) !== null) {
        const argName = argMatch[1];
        const argValue = argMatch[2].trim();
        
        if (/^-?\d+$/.test(argValue)) {
          args[argName] = parseInt(argValue, 10);
        } else if (/^-?\d+\.\d+$/.test(argValue)) {
          args[argName] = parseFloat(argValue);
        } else {
          args[argName] = argValue;
        }
      }

      toolCalls.push({
        id: `dsml_${Date.now()}_${idx++}`,
        nama: toolName,
        argumen: args,
      });
    }

    return toolCalls.length > 0 ? toolCalls : null;
  } catch (err) {
    console.error('Gagal parsing DSML tool calls:', err);
    return null;
  }
}

/**
 * Kirim pesan sederhana tanpa tools (untuk format ulang jawaban dll).
 */
export async function chatSederhana(systemPrompt: string, userMessage: string): Promise<string> {
  const hasil = await chatCompletion([
    { role: 'system', content: systemPrompt },
    { role: 'user', content: userMessage },
  ]);
  return hasil.balasan || '';
}