/**
 * DeepSeek Provider Adapter
 *
 * 基于 OpenAI 兼容 API 的 DeepSeek 适配器。
 * 支持 Tool Calling、Thinking 模式、流式输出、JSON 结构化输出。
 *
 * 完整实现 DeepSeek API 文档中所有参数：
 * - model, messages, thinking, reasoning_effort
 * - stream, stream_options
 * - tools, tool_choice
 * - response_format (JSON)
 * - stop, max_tokens, temperature, top_p
 * - logprobs, top_logprobs
 * - prompt_cache_hit/miss_tokens, reasoning_tokens
 * - GET /models, GET /user/balance
 *
 * @see apis/deepseek-api-docs-20260518.html
 */

import { BaseAdapter } from './base-adapter';
import { nanoid } from 'nanoid';
import type { MetonaRequest, MetonaResponse, MetonaStreamEvent } from '../types';
import { MetonaFinishReason, MetonaStreamEventType, MetonaErrorCode } from '../types';

export class DeepSeekAdapter extends BaseAdapter {
  override readonly provider: string = 'deepseek';
  readonly supportedModels = ['deepseek-v4-pro', 'deepseek-v4-flash'];
  readonly supportsToolCalling = true;
  readonly supportsThinking = true;

  async chat(request: MetonaRequest): Promise<MetonaResponse> {
    const nativeRequest = this.toNativeRequest(request);

    const response = await fetch(`${this.config.baseURL}/chat/completions`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        Authorization: `Bearer ${this.config.apiKey}`,
        ...this.config.headers,
      },
      body: JSON.stringify(nativeRequest),
      signal: AbortSignal.timeout(this.config.timeoutMs ?? 120_000),
    });

    if (!response.ok) {
      const errorBody = await response.text().catch(() => '');
      throw new Error(`DeepSeek API error: ${response.status} ${response.statusText} - ${errorBody}`);
    }

    const data = await response.json();
    return this.toMetonaResponse(data, request.meta.requestId);
  }

  async *chatStream(request: MetonaRequest): AsyncIterable<MetonaStreamEvent> {
    const nativeRequest = { ...this.toNativeRequest(request), stream: true, stream_options: { include_usage: true } };

    const response = await fetch(`${this.config.baseURL}/chat/completions`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        Authorization: `Bearer ${this.config.apiKey}`,
        ...this.config.headers,
      },
      body: JSON.stringify(nativeRequest),
    });

    if (!response.ok || !response.body) {
      throw new Error(`DeepSeek stream error: ${response.status}`);
    }

    const reader = response.body.getReader();
    const decoder = new TextDecoder();
    let seq = 0;
    let buffer = '';

    // 工具调用缓冲区：index → { name, argsBuffer }
    const toolCallsBuffer = new Map<number, { name: string; argsBuffer: string }>();

    while (true) {
      const { done, value } = await reader.read();
      if (done) break;

      buffer += decoder.decode(value, { stream: true });
      const lines = buffer.split('\n');
      buffer = lines.pop() ?? '';

      for (const line of lines) {
        const trimmed = line.trim();
        if (!trimmed || !trimmed.startsWith('data: ')) continue;
        const data = trimmed.slice(6);
        if (data === '[DONE]') {
          // 流结束前，将缓冲区中的工具调用转为 TOOL_CALL_COMPLETE
          for (const [index, buf] of toolCallsBuffer) {
            try {
              yield {
                type: MetonaStreamEventType.TOOL_CALL_COMPLETE,
                requestId: request.meta.requestId,
                sessionId: request.meta.sessionId,
                iteration: request.meta.iteration,
                seq: seq++,
                timestamp: Date.now(),
                toolCall: {
                  id: `tc_${nanoid(8)}`,
                  name: buf.name,
                  args: buf.argsBuffer ? JSON.parse(buf.argsBuffer) : {},
                  iteration: request.meta.iteration,
                  timestamp: Date.now(),
                },
              };
            } catch {
              // JSON 解析失败，跳过
            }
          }
          toolCallsBuffer.clear();

          yield {
            type: MetonaStreamEventType.DONE,
            requestId: request.meta.requestId,
            sessionId: request.meta.sessionId,
            iteration: request.meta.iteration,
            seq: seq++,
            timestamp: Date.now(),
          };
          return;
        }

        try {
          const chunk = JSON.parse(data);
          const delta = chunk.choices?.[0]?.delta;

          // 文本内容增量
          if (delta?.content) {
            yield {
              type: MetonaStreamEventType.TEXT_DELTA,
              requestId: request.meta.requestId,
              sessionId: request.meta.sessionId,
              iteration: request.meta.iteration,
              seq: seq++,
              timestamp: Date.now(),
              delta: delta.content,
            };
          }

          // 推理内容增量（Thinking 模式）
          if (delta?.reasoning_content) {
            yield {
              type: MetonaStreamEventType.REASONING_DELTA,
              requestId: request.meta.requestId,
              sessionId: request.meta.sessionId,
              iteration: request.meta.iteration,
              seq: seq++,
              timestamp: Date.now(),
              delta: delta.reasoning_content,
            };
          }

          // 工具调用增量 — 缓冲拼接
          if (delta?.tool_calls) {
            for (const tc of delta.tool_calls) {
              const idx = tc.index ?? 0;
              if (!toolCallsBuffer.has(idx)) {
                toolCallsBuffer.set(idx, { name: tc.function?.name ?? '', argsBuffer: '' });
              }
              const buf = toolCallsBuffer.get(idx)!;
              if (tc.function?.name) buf.name = tc.function.name;
              if (tc.function?.arguments) buf.argsBuffer += tc.function.arguments;

              yield {
                type: MetonaStreamEventType.TOOL_CALL_DELTA,
                requestId: request.meta.requestId,
                sessionId: request.meta.sessionId,
                iteration: request.meta.iteration,
                seq: seq++,
                timestamp: Date.now(),
                toolCallDelta: {
                  index: idx,
                  name: tc.function?.name,
                  argsDelta: tc.function?.arguments,
                },
              };
            }
          }

          // 流结束时的 usage 信息
          if (chunk.usage) {
            yield {
              type: MetonaStreamEventType.USAGE,
              requestId: request.meta.requestId,
              sessionId: request.meta.sessionId,
              iteration: request.meta.iteration,
              seq: seq++,
              timestamp: Date.now(),
              usage: {
                inputTokens: chunk.usage.prompt_tokens ?? 0,
                outputTokens: chunk.usage.completion_tokens ?? 0,
                totalTokens: chunk.usage.total_tokens ?? 0,
                reasoningTokens: chunk.usage.completion_tokens_details?.reasoning_tokens,
                cacheHitTokens: chunk.usage.prompt_cache_hit_tokens,
                cacheMissTokens: chunk.usage.prompt_cache_miss_tokens,
              },
            };
          }
        } catch {
          // 跳过解析失败的行
        }
      }
    }
  }

  /**
   * 列出可用模型
   */
  async listModels(): Promise<string[]> {
    try {
      const response = await fetch(`${this.config.baseURL}/models`, {
        headers: { Authorization: `Bearer ${this.config.apiKey}` },
        signal: AbortSignal.timeout(10_000),
      });
      if (!response.ok) return this.supportedModels;
      const data = await response.json() as { data?: Array<{ id: string }> };
      return data.data?.map((m) => m.id) ?? this.supportedModels;
    } catch {
      return this.supportedModels;
    }
  }

  /**
   * 查询账户余额
   */
  async getBalance(): Promise<{ currency: string; totalBalance: string; grantedBalance: string; toppedUpBalance: string } | null> {
    try {
      const response = await fetch(`${this.config.baseURL}/user/balance`, {
        headers: { Authorization: `Bearer ${this.config.apiKey}` },
        signal: AbortSignal.timeout(10_000),
      });
      if (!response.ok) return null;
      const data = await response.json() as { currency?: string; total_balance?: string; granted_balance?: string; topped_up_balance?: string };
      return {
        currency: data.currency ?? 'CNY',
        totalBalance: data.total_balance ?? '0',
        grantedBalance: data.granted_balance ?? '0',
        toppedUpBalance: data.topped_up_balance ?? '0',
      };
    } catch {
      return null;
    }
  }

  // ========== 私有转换方法 ==========

  /**
   * 将 MetonaRequest 转换为 OpenAI 兼容的原生请求格式
   */
  protected toNativeRequest(request: MetonaRequest): Record<string, unknown> {
    const messages = [
      {
        role: 'system',
        content: [
          request.systemPrompt.roleDefinition,
          request.systemPrompt.outputConstraints,
          request.systemPrompt.safetyGuidelines,
          request.systemPrompt.dynamicReminders,
        ].filter(Boolean).join('\n\n'),
      },
      ...request.messages.filter((m) => m.role !== 'system').map((m) => {
        const msg: Record<string, unknown> = { role: m.role, content: m.content };
        if (m.role === 'assistant' && m.toolCalls?.length) {
          msg.tool_calls = m.toolCalls.map((tc) => ({
            id: tc.id,
            type: 'function',
            function: { name: tc.name, arguments: JSON.stringify(tc.args) },
          }));
          // 工具调用轮次的 reasoning_content 必须携带回上下文
          if (m.reasoningContent) {
            msg.reasoning_content = m.reasoningContent;
          }
        }
        if (m.role === 'tool' && m.toolResult) {
          msg.tool_call_id = m.toolResult.toolCallId;
          msg.content = typeof m.toolResult.result === 'string'
            ? m.toolResult.result
            : JSON.stringify(m.toolResult.result);
        }
        return msg;
      }),
    ];

    const body: Record<string, unknown> = {
      model: this.config.defaultModel,
      messages,
      temperature: request.params.temperature ?? 0,
      max_tokens: request.params.maxTokens,
      stream: request.params.stream ?? false,
    };

    // Tool Calling
    if (request.tools?.length) {
      body.tools = request.tools.map((t) => ({
        type: 'function',
        function: {
          name: t.name,
          description: t.description,
          parameters: t.parameters,
        },
      }));
    }

    // Thinking 模式
    if (request.params.thinkingEnabled) {
      body.thinking = { type: 'enabled' };
      // reasoning_effort 映射
      const effortMap: Record<string, string> = { low: 'high', medium: 'high', high: 'high', max: 'max' };
      body.reasoning_effort = effortMap[request.params.thinkingEffort ?? 'high'] ?? 'high';
    }

    // 停止序列
    if (request.params.stopSequences?.length) {
      body.stop = request.params.stopSequences;
    }

    // 安全约束
    if (request.constraints?.allowedTools?.length) {
      body.tool_choice = 'auto';
    }

    return body;
  }

  private toMetonaResponse(data: Record<string, unknown>, requestId: string): MetonaResponse {
    const choice = (data.choices as Array<Record<string, unknown>>)?.[0];
    const message = choice?.message as Record<string, unknown> | undefined;
    const usage = data.usage as Record<string, unknown> | undefined;
    const toolCalls = message?.tool_calls as Array<Record<string, unknown>> | undefined;

    return {
      meta: {
        requestId,
        provider: this.provider,
        model: (data.model as string) ?? this.config.defaultModel,
        latencyMs: 0,
        timestamp: Date.now(),
      },
      content: (message?.content as string) ?? '',
      reasoningContent: message?.reasoning_content as string | undefined,
      toolCalls: toolCalls?.map((tc) => {
        const fn = tc.function as Record<string, unknown>;
        return {
          id: tc.id as string,
          name: fn.name as string,
          args: JSON.parse(fn.arguments as string),
          iteration: 0,
          timestamp: Date.now(),
        };
      }),
      usage: {
        inputTokens: (usage?.prompt_tokens as number) ?? 0,
        outputTokens: (usage?.completion_tokens as number) ?? 0,
        totalTokens: (usage?.total_tokens as number) ?? 0,
        reasoningTokens: (usage?.completion_tokens_details as Record<string, unknown>)?.reasoning_tokens as number | undefined,
        cacheHitTokens: usage?.prompt_cache_hit_tokens as number | undefined,
        cacheMissTokens: usage?.prompt_cache_miss_tokens as number | undefined,
      },
      finishReason: this.mapFinishReason(choice?.finish_reason as string),
    };
  }

  private mapFinishReason(reason: string): MetonaFinishReason {
    switch (reason) {
      case 'stop': return MetonaFinishReason.STOP;
      case 'length': return MetonaFinishReason.LENGTH;
      case 'tool_calls': return MetonaFinishReason.TOOL_CALLS;
      case 'content_filter': return MetonaFinishReason.CONTENT_FILTER;
      default: return MetonaFinishReason.STOP;
    }
  }
}