feat(api-ai): add provider registry and routing fallback

2026-04-06 11:44:05 +08:00
parent 019436507e
commit 180f7a9baa
11 changed files with 1425 additions and 1 deletions
@@ -0,0 +1,203 @@
+import { Injectable } from "@nestjs/common";
+import {
+  AiChannelExecutor,
+  AiChatInput,
+  AiChatResult,
+  AiResolvedRouteCandidate,
+  AiRouteFailureError
+} from "../ai.types";
+
+@Injectable()
+export class OpenAiCompatibleProvider implements AiChannelExecutor {
+  async execute(candidate: AiResolvedRouteCandidate, input: AiChatInput): Promise<AiChatResult> {
+    if (!candidate.endpoint) {
+      throw new AiRouteFailureError(
+        candidate.channel,
+        candidate.providerName,
+        "MISSING_ENDPOINT",
+        "缺少 AI 服务地址配置"
+      );
+    }
+
+    if (!candidate.apiKey) {
+      throw new AiRouteFailureError(
+        candidate.channel,
+        candidate.providerName,
+        "MISSING_API_KEY",
+        "缺少 AI 服务密钥配置"
+      );
+    }
+
+    if (!candidate.model) {
+      throw new AiRouteFailureError(
+        candidate.channel,
+        candidate.providerName,
+        "MISSING_MODEL",
+        "缺少 AI 模型配置"
+      );
+    }
+
+    const requestUrl = this.buildRequestUrl(candidate.endpoint);
+
+    let response: Response;
+    try {
+      response = await fetch(requestUrl, {
+        method: "POST",
+        headers: {
+          "Content-Type": "application/json",
+          Authorization: `Bearer ${candidate.apiKey}`
+        },
+        body: JSON.stringify({
+          model: candidate.model,
+          messages: [
+            {
+              role: "user",
+              content: input.message
+            }
+          ],
+          stream: false
+        }),
+        signal: AbortSignal.timeout(30000)
+      });
+    } catch (error) {
+      throw new AiRouteFailureError(
+        candidate.channel,
+        candidate.providerName,
+        "UPSTREAM_UNREACHABLE",
+        this.toErrorMessage(error, "AI 服务请求失败")
+      );
+    }
+
+    let payload: unknown;
+    try {
+      payload = await response.json();
+    } catch (error) {
+      throw new AiRouteFailureError(
+        candidate.channel,
+        candidate.providerName,
+        "INVALID_RESPONSE",
+        this.toErrorMessage(error, "AI 服务返回了无法解析的数据")
+      );
+    }
+
+    if (!response.ok) {
+      throw new AiRouteFailureError(
+        candidate.channel,
+        candidate.providerName,
+        `UPSTREAM_HTTP_${response.status}`,
+        this.extractErrorMessage(payload, `AI 服务调用失败，状态码 ${response.status}`)
+      );
+    }
+
+    const content = this.extractAssistantText(payload);
+    if (!content.trim()) {
+      throw new AiRouteFailureError(
+        candidate.channel,
+        candidate.providerName,
+        "EMPTY_RESPONSE",
+        "AI 服务没有返回有效内容"
+      );
+    }
+
+    return {
+      channel: candidate.channel,
+      providerName: candidate.providerName,
+      model: this.extractModel(payload) ?? candidate.model,
+      content,
+      sessionId: input.sessionId,
+      raw: payload
+    };
+  }
+
+  private buildRequestUrl(endpoint: string): string {
+    const normalizedEndpoint = endpoint.replace(/\/+$/, "");
+    if (normalizedEndpoint.endsWith("/chat/completions")) {
+      return normalizedEndpoint;
+    }
+    if (normalizedEndpoint.endsWith("/v1")) {
+      return `${normalizedEndpoint}/chat/completions`;
+    }
+    return `${normalizedEndpoint}/v1/chat/completions`;
+  }
+
+  private extractAssistantText(payload: unknown): string {
+    if (!this.isRecord(payload)) {
+      return "";
+    }
+
+    const choices = payload["choices"];
+    if (!Array.isArray(choices) || choices.length === 0) {
+      return "";
+    }
+
+    const firstChoice = choices[0];
+    if (!this.isRecord(firstChoice)) {
+      return "";
+    }
+
+    const message = firstChoice["message"];
+    if (!this.isRecord(message)) {
+      return "";
+    }
+
+    return this.extractMessageContent(message["content"]);
+  }
+
+  private extractMessageContent(content: unknown): string {
+    if (typeof content === "string") {
+      return content;
+    }
+
+    if (!Array.isArray(content)) {
+      return "";
+    }
+
+    return content
+      .map((item) => {
+        if (!this.isRecord(item)) {
+          return "";
+        }
+
+        if (typeof item["text"] === "string") {
+          return item["text"];
+        }
+
+        return "";
+      })
+      .filter((item) => item.length > 0)
+      .join("\n");
+  }
+
+  private extractModel(payload: unknown): string | null {
+    if (!this.isRecord(payload) || typeof payload["model"] !== "string") {
+      return null;
+    }
+
+    return payload["model"];
+  }
+
+  private extractErrorMessage(payload: unknown, fallback: string): string {
+    if (!this.isRecord(payload)) {
+      return fallback;
+    }
+
+    const error = payload["error"];
+    if (!this.isRecord(error) || typeof error["message"] !== "string") {
+      return fallback;
+    }
+
+    return error["message"];
+  }
+
+  private isRecord(value: unknown): value is Record<string, unknown> {
+    return typeof value === "object" && value !== null;
+  }
+
+  private toErrorMessage(error: unknown, fallback: string): string {
+    if (error instanceof Error && error.message) {
+      return error.message;
+    }
+
+    return fallback;
+  }
+}