/**
 * Anthropic Provider Adapter（P3）
 *
 * Anthropic Messages API（/v1/messages）原生协议，支持 Tool Calling、流式输出、
 * 扩展思考（thinking + budget_tokens）、多模态图片（base64）。
 *
 * 与 OpenAI 兼容 API 的关键差异：
 * - 认证头：x-api-key + anthropic-version（非 Authorization Bearer）
 * - 消息结构：content 为块数组（text / tool_use / tool_result / image），
 *   且要求 user/assistant 严格交替（连续同角色需合并）
 * - 工具定义：input_schema（非 parameters）；工具结果以 user 角色 tool_result 块回传
 * - SSE 事件：message_start / content_block_start / content_block_delta /
 *   content_block_stop / message_delta / message_stop（非 OpenAI chunk 格式）
 * - 图片：仅支持 base64 source（URL 需下载后转换）
 *
 * @see https://docs.anthropic.com/en/api/messages
 */

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

export class AnthropicAdapter extends BaseAdapter {
  override readonly providerId: string = 'anthropic';
  readonly supportedModels = ['claude-sonnet-4-5', 'claude-opus-4-1', 'claude-haiku-4-5'];
  readonly supportsToolCalling = true;
  readonly supportsThinking = true;

  private static readonly MODEL_INFO: Record<string, MetonaModelInfo> = {
    'claude-sonnet-4-5': {
      id: 'claude-sonnet-4-5',
      name: 'Claude Sonnet 4.5',
      contextWindow: 200_000,
      maxOutputTokens: 64_000,
      supportsToolCalling: true,
      supportsThinking: true,
      description: 'Anthropic 旗舰模型，200K 上下文，支持扩展思考与工具调用',
    },
    'claude-opus-4-1': {
      id: 'claude-opus-4-1',
      name: 'Claude Opus 4.1',
      contextWindow: 200_000,
      maxOutputTokens: 32_000,
      supportsToolCalling: true,
      supportsThinking: true,
      description: 'Anthropic 深度推理模型',
    },
    'claude-haiku-4-5': {
      id: 'claude-haiku-4-5',
      name: 'Claude Haiku 4.5',
      contextWindow: 200_000,
      maxOutputTokens: 32_000,
      supportsToolCalling: true,
      supportsThinking: true,
      description: 'Anthropic 低延迟模型',
    },
  };

  private buildHeaders(): Record<string, string> {
    return {
      'Content-Type': 'application/json',
      'x-api-key': this.config.apiKey ?? '',
      'anthropic-version': '2023-06-01',
      ...this.config.headers,
    };
  }

  // ===== POST /v1/messages（非流式） =====

  async send(request: MetonaRequest): Promise<MetonaResponse> {
    const body = await this.toNativeRequest(request, false);
    const response = await this.fetchWithTimeout(
      `${this.config.baseURL}/v1/messages`,
      {
        method: 'POST',
        headers: this.buildHeaders(),
        body: JSON.stringify(body),
      },
      this.config.timeoutMs ?? 120_000,
    );

    if (!response.ok) {
      await this.throwHttpError(response, 'Anthropic API error');
    }

    const data = (await response.json()) as Record<string, unknown>;
    return this.toMetonaResponse(data, request.meta.requestId);
  }

  // ===== POST /v1/messages（流式） =====

  async *sendStream(request: MetonaRequest): AsyncIterable<MetonaStreamEvent> {
    const body = await this.toNativeRequest(request, true);
    const response = await this.fetchWithTimeout(
      `${this.config.baseURL}/v1/messages`,
      {
        method: 'POST',
        headers: this.buildHeaders(),
        body: JSON.stringify(body),
      },
      this.config.timeoutMs ?? 300_000,
    );

    if (!response.ok || !response.body) {
      await this.throwHttpError(response, 'Anthropic stream error');
    }

    // 非空断言：上方 if 已确保 response.body 不为 null
    const reader = response.body!.getReader();
    const decoder = new TextDecoder();
    let seq = 0;
    let buffer = '';
    let eventName = '';
    let streamEndedNormally = false;

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

    const base = () => ({
      requestId: request.meta.requestId,
      sessionId: request.meta.sessionId,
      iteration: request.meta.iteration,
      seq: seq++,
      timestamp: Date.now(),
    });

    const processEvent = (name: string, data: Record<string, unknown>): MetonaStreamEvent[] => {
      const events: MetonaStreamEvent[] = [];
      switch (name) {
        case 'content_block_start': {
          const block = data.content_block as Record<string, unknown> | undefined;
          const index = (data.index as number) ?? 0;
          if (block?.type === 'tool_use') {
            toolBlocks.set(index, {
              id: (block.id as string) ?? `tc_${nanoid(8)}`,
              name: (block.name as string) ?? '',
              argsBuffer: '',
            });
          }
          break;
        }
        case 'content_block_delta': {
          const delta = data.delta as Record<string, unknown> | undefined;
          const index = (data.index as number) ?? 0;
          if (delta?.type === 'text_delta' && typeof delta.text === 'string') {
            events.push({ type: MetonaStreamEventType.TEXT_DELTA, ...base(), delta: delta.text });
          } else if (delta?.type === 'thinking_delta' && typeof delta.thinking === 'string') {
            events.push({
              type: MetonaStreamEventType.REASONING_DELTA,
              ...base(),
              delta: delta.thinking,
            });
          } else if (delta?.type === 'input_json_delta' && typeof delta.partial_json === 'string') {
            const block = toolBlocks.get(index);
            if (block) {
              block.argsBuffer += delta.partial_json;
              events.push({
                type: MetonaStreamEventType.TOOL_CALL_DELTA,
                ...base(),
                toolCallDelta: { index, name: block.name, argsDelta: delta.partial_json },
              });
            }
          }
          break;
        }
        case 'content_block_stop': {
          const index = (data.index as number) ?? 0;
          const block = toolBlocks.get(index);
          if (block) {
            let args: Record<string, unknown> = {};
            try {
              args = block.argsBuffer ? JSON.parse(block.argsBuffer) : {};
            } catch {
              args = {};
            }
            events.push({
              type: MetonaStreamEventType.TOOL_CALL_COMPLETE,
              ...base(),
              toolCall: {
                id: block.id,
                name: block.name,
                args,
                iteration: request.meta.iteration,
                timestamp: Date.now(),
              },
            });
            toolBlocks.delete(index);
          }
          break;
        }
        case 'message_delta': {
          // 结束时的 usage 统计（output_tokens 增量在此事件携带）
          const usage = data.usage as Record<string, unknown> | undefined;
          if (usage) {
            events.push({
              type: MetonaStreamEventType.USAGE,
              ...base(),
              usage: {
                inputTokens: (this.lastInputTokens as number) ?? 0,
                outputTokens: (usage.output_tokens as number) ?? 0,
                totalTokens:
                  ((this.lastInputTokens as number) ?? 0) + ((usage.output_tokens as number) ?? 0),
              },
            });
          }
          break;
        }
        case 'message_stop': {
          streamEndedNormally = true;
          events.push({ type: MetonaStreamEventType.DONE, ...base() });
          break;
        }
        case 'error': {
          const err = data.error as Record<string, unknown> | undefined;
          events.push({
            type: MetonaStreamEventType.ERROR,
            ...base(),
            error: {
              code: 'unknown' as never,
              message: (err?.message as string) ?? 'Anthropic stream error',
              retryable: false,
            },
          });
          break;
        }
      }
      return events;
    };

    // message_start 事件携带 input_tokens（记录到 this.lastInputTokens 供 USAGE 汇总）
    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) continue;
        if (trimmed.startsWith('event:')) {
          eventName = trimmed.slice(6).trim();
          continue;
        }
        if (!trimmed.startsWith('data:')) continue;
        const dataStr = trimmed.slice(5).trim();
        if (dataStr === '[DONE]') continue;

        try {
          const data = JSON.parse(dataStr) as Record<string, unknown>;
          // message_start 携带 input_tokens
          if (eventName === 'message_start') {
            const msg = data.message as Record<string, unknown> | undefined;
            const usage = msg?.usage as Record<string, unknown> | undefined;
            this.lastInputTokens = (usage?.input_tokens as number) ?? 0;
            continue;
          }
          for (const ev of processEvent(eventName, data)) {
            yield ev;
          }
        } catch (parseErr) {
          log.warn(
            `[Anthropic] Failed to parse SSE line: ${(parseErr as Error).message}`,
            trimmed.slice(0, 200),
          );
        }
      }
    }

    // 流中断（连接断开等）补发 DONE，防止 Agent Loop 挂起（与 Ollama 行为一致）
    if (!streamEndedNormally) {
      yield { type: MetonaStreamEventType.DONE, ...base() };
    }
  }

  /** message_start 捕获的 input_tokens（供 message_delta 汇总 usage） */
  private lastInputTokens = 0;

  // ===== 模型与上下文窗口 =====

  override async listModels(): Promise<MetonaModelInfo[]> {
    // Anthropic 无公开 /models 列表端点，返回本地元数据
    return this.supportedModels.map((id) => AnthropicAdapter.MODEL_INFO[id] ?? { id });
  }

  override getContextWindow(): number {
    if (typeof this.config.contextWindow === 'number' && this.config.contextWindow > 0) {
      return this.config.contextWindow;
    }
    const modelInfo = AnthropicAdapter.MODEL_INFO[this.config.defaultModel];
    return modelInfo?.contextWindow ?? 200_000;
  }

  // ========== 私有方法 ==========

  /**
   * 构建 Anthropic 原生请求体
   *
   * 转换要点：
   * 1. MetonaMessage → Anthropic 消息（content 块数组）
   * 2. tool 消息 → user 角色 tool_result 块
   * 3. assistant 工具调用 → tool_use 块
   * 4. 连续同角色消息合并（API 要求严格交替）
   * 5. 首条消息必须为 user（历史以 assistant 开头时补占位）
   */
  private async toNativeRequest(
    request: MetonaRequest,
    stream: boolean,
  ): Promise<Record<string, unknown>> {
    // System Prompt 拼接（Anthropic 使用顶层 system 字段）
    const system = [
      request.systemPrompt.roleDefinition,
      request.systemPrompt.outputConstraints,
      request.systemPrompt.safetyGuidelines,
      request.systemPrompt.dynamicReminders,
    ]
      .filter(Boolean)
      .join('\n\n');

    // 转换消息（非 system）
    const converted: Array<{
      role: 'user' | 'assistant';
      content: Array<Record<string, unknown>>;
    }> = [];
    for (const m of request.messages) {
      if (m.role === 'system') continue;

      if (m.role === 'tool' && m.toolResult) {
        // 工具结果 → user 角色 tool_result 块
        const contentStr = m.toolResult.error
          ? m.toolResult.error
          : typeof m.toolResult.result === 'string'
            ? m.toolResult.result
            : JSON.stringify(m.toolResult.result);
        converted.push({
          role: 'user',
          content: [
            { type: 'tool_result', tool_use_id: m.toolResult.toolCallId, content: contentStr },
          ],
        });
        continue;
      }

      if (m.role === 'assistant') {
        const content: Array<Record<string, unknown>> = [];
        if (m.content) content.push({ type: 'text', text: m.content });
        for (const tc of m.toolCalls ?? []) {
          content.push({ type: 'tool_use', id: tc.id, name: tc.name, input: tc.args });
        }
        if (content.length > 0) {
          converted.push({ role: 'assistant', content });
        }
        continue;
      }

      // user 消息（含多模态图片）
      const content: Array<Record<string, unknown>> = [];
      if (m.content) content.push({ type: 'text', text: m.content });
      for (const img of m.images ?? []) {
        const block = await this.toImageBlock(img.url);
        if (block) content.push(block);
      }
      if (content.length === 0) content.push({ type: 'text', text: '' });
      converted.push({ role: 'user', content });
    }

    // 合并连续同角色消息（Anthropic 要求 user/assistant 交替）
    const merged: Array<{ role: 'user' | 'assistant'; content: Array<Record<string, unknown>> }> =
      [];
    for (const msg of converted) {
      const last = merged[merged.length - 1];
      if (last && last.role === msg.role) {
        last.content.push(...msg.content);
      } else {
        merged.push({ ...msg });
      }
    }

    // 首条消息必须为 user
    if (merged.length === 0 || merged[0].role !== 'user') {
      merged.unshift({
        role: 'user',
        content: [{ type: 'text', text: '[Conversation history follows]' }],
      });
    }

    // v0.5.3: max_tokens 按模型上限钳制（sonnet 64000 / opus 32000 / haiku 32000）—
    // 引擎默认 63488 超过 opus/haiku 上限时 API 直接 400；thinking budget 已在此值内二分
    const anthropicMaxOutput =
      AnthropicAdapter.MODEL_INFO[this.config.defaultModel]?.maxOutputTokens ?? 64_000;

    const body: Record<string, unknown> = {
      model: this.config.defaultModel,
      max_tokens: Math.min(request.params.maxTokens ?? 8192, anthropicMaxOutput),
      system,
      messages: merged,
      stream,
    };

    // 工具定义（input_schema 命名）
    if (request.tools?.length) {
      body.tools = request.tools.map((t) => ({
        name: t.name,
        description: t.description,
        input_schema: t.parameters,
      }));
    }

    // Thinking 模式：budget_tokens（必须小于 max_tokens，此处钳制到一半）
    if (request.params.thinkingEnabled) {
      const budgetMap: Record<string, number> = {
        low: 1024,
        medium: 4096,
        high: 16384,
        max: 32768,
      };
      const budget = Math.min(
        budgetMap[request.params.thinkingEffort ?? 'high'] ?? 16384,
        Math.floor((body.max_tokens as number) / 2),
      );
      body.thinking = { type: 'enabled', budget_tokens: budget };
    } else {
      body.temperature = request.params.temperature;
    }

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

    return body;
  }

  /**
   * 图片 URL → Anthropic image 块
   * data URI 直接解析；http(s) URL 下载后转 base64（Anthropic 不支持 URL 引用）
   */
  private async toImageBlock(url: string): Promise<Record<string, unknown> | null> {
    try {
      if (url.startsWith('data:')) {
        // data:image/png;base64,xxx → { media_type, data }
        const match = url.match(/^data:([^;]+);base64,(.*)$/s);
        if (!match) return null;
        return { type: 'image', source: { type: 'base64', media_type: match[1], data: match[2] } };
      }
      if (url.startsWith('http://') || url.startsWith('https://')) {
        const res = await this.fetchWithTimeout(url, {}, 30_000);
        if (!res.ok) throw new Error(`HTTP ${res.status}`);
        const contentType = res.headers.get('content-type') ?? 'image/png';
        const buf = Buffer.from(await res.arrayBuffer());
        return {
          type: 'image',
          source: { type: 'base64', media_type: contentType, data: buf.toString('base64') },
        };
      }
      return null;
    } catch (err) {
      log.warn(`[Anthropic] Failed to load image: ${(err as Error).message}`);
      return null;
    }
  }

  /** 非流式响应 → MetonaResponse */
  private toMetonaResponse(data: Record<string, unknown>, requestId: string): MetonaResponse {
    const contentBlocks = (data.content as Array<Record<string, unknown>>) ?? [];
    let text = '';
    let reasoningContent: string | undefined;
    const toolCalls: MetonaResponse['toolCalls'] = [];

    for (const block of contentBlocks) {
      if (block.type === 'text') text += (block.text as string) ?? '';
      else if (block.type === 'thinking')
        reasoningContent = (block.thinking as string) ?? undefined;
      else if (block.type === 'tool_use') {
        let args: Record<string, unknown> = {};
        const rawInput = block.input;
        if (rawInput && typeof rawInput === 'object') args = rawInput as Record<string, unknown>;
        toolCalls?.push({
          id: (block.id as string) ?? `tc_${nanoid(8)}`,
          name: (block.name as string) ?? '',
          args,
          iteration: 0,
          timestamp: Date.now(),
        });
      }
    }

    const usage = (data.usage as Record<string, number>) ?? {};
    const stopReason = (data.stop_reason as string) ?? 'end_turn';
    const finishReason: MetonaFinishReason =
      stopReason === 'tool_use'
        ? MetonaFinishReason.TOOL_CALLS
        : stopReason === 'max_tokens'
          ? MetonaFinishReason.LENGTH
          : MetonaFinishReason.STOP;

    return {
      meta: {
        requestId,
        provider: this.providerId,
        model: (data.model as string) ?? this.config.defaultModel,
        latencyMs: 0,
        timestamp: Date.now(),
      },
      content: text,
      reasoningContent,
      toolCalls,
      usage: {
        inputTokens: usage.input_tokens ?? 0,
        outputTokens: usage.output_tokens ?? 0,
        totalTokens: (usage.input_tokens ?? 0) + (usage.output_tokens ?? 0),
      },
      finishReason,
    };
  }
}