initial commit

src/runtime.ts

@@ -0,0 +1,139 @@
+import { loadWebSearchConfig, type ResolvedWebSearchConfig } from "./config.ts";
+import { createExaProvider } from "./providers/exa.ts";
+import { createTavilyProvider } from "./providers/tavily.ts";
+import type {
+  NormalizedFetchRequest,
+  NormalizedFetchResponse,
+  NormalizedSearchRequest,
+  NormalizedSearchResponse,
+  WebProvider,
+} from "./providers/types.ts";
+import type { WebSearchProviderConfig } from "./schema.ts";
+
+export interface ProviderExecutionMeta {
+  requestedProviderName?: string;
+  actualProviderName: string;
+  failoverFromProviderName?: string;
+  failoverReason?: string;
+}
+
+export interface RuntimeSearchResponse extends NormalizedSearchResponse {
+  execution: ProviderExecutionMeta;
+}
+
+export interface RuntimeFetchResponse extends NormalizedFetchResponse {
+  execution: ProviderExecutionMeta;
+}
+
+export function createWebSearchRuntime(
+  deps: {
+    loadConfig?: () => Promise<ResolvedWebSearchConfig>;
+    createProvider?: (providerConfig: WebSearchProviderConfig) => WebProvider;
+  } = {},
+) {
+  const loadConfig = deps.loadConfig ?? loadWebSearchConfig;
+  const createProvider = deps.createProvider ?? ((providerConfig: WebSearchProviderConfig) => {
+    switch (providerConfig.type) {
+      case "tavily":
+        return createTavilyProvider(providerConfig);
+      case "exa":
+        return createExaProvider(providerConfig);
+    }
+  });
+
+  async function resolveConfigAndProvider(providerName?: string) {
+    const config = await loadConfig();
+    const selectedName = providerName ?? config.defaultProviderName;
+    const selectedConfig = config.providersByName.get(selectedName);
+
+    if (!selectedConfig) {
+      throw new Error(
+        `Unknown web-search provider \"${selectedName}\". Configured providers: ${[...config.providersByName.keys()].join(", ")}`,
+      );
+    }
+
+    return {
+      config,
+      selectedName,
+      selectedConfig,
+      selectedProvider: createProvider(selectedConfig),
+    };
+  }
+
+  async function search(request: NormalizedSearchRequest): Promise<RuntimeSearchResponse> {
+    const { config, selectedName, selectedConfig, selectedProvider } = await resolveConfigAndProvider(request.provider);
+
+    try {
+      const response = await selectedProvider.search(request);
+      return {
+        ...response,
+        execution: {
+          requestedProviderName: request.provider,
+          actualProviderName: selectedName,
+        },
+      };
+    } catch (error) {
+      if (selectedConfig.type !== "tavily") {
+        throw error;
+      }
+
+      const fallbackConfig = [...config.providersByName.values()].find((provider) => provider.type === "exa");
+      if (!fallbackConfig) {
+        throw error;
+      }
+
+      const fallbackProvider = createProvider(fallbackConfig);
+      const fallbackResponse = await fallbackProvider.search({ ...request, provider: fallbackConfig.name });
+      return {
+        ...fallbackResponse,
+        execution: {
+          requestedProviderName: request.provider,
+          actualProviderName: fallbackConfig.name,
+          failoverFromProviderName: selectedName,
+          failoverReason: (error as Error).message,
+        },
+      };
+    }
+  }
+
+  async function fetch(request: NormalizedFetchRequest): Promise<RuntimeFetchResponse> {
+    const { config, selectedName, selectedConfig, selectedProvider } = await resolveConfigAndProvider(request.provider);
+
+    try {
+      const response = await selectedProvider.fetch(request);
+      return {
+        ...response,
+        execution: {
+          requestedProviderName: request.provider,
+          actualProviderName: selectedName,
+        },
+      };
+    } catch (error) {
+      if (selectedConfig.type !== "tavily") {
+        throw error;
+      }
+
+      const fallbackConfig = [...config.providersByName.values()].find((provider) => provider.type === "exa");
+      if (!fallbackConfig) {
+        throw error;
+      }
+
+      const fallbackProvider = createProvider(fallbackConfig);
+      const fallbackResponse = await fallbackProvider.fetch({ ...request, provider: fallbackConfig.name });
+      return {
+        ...fallbackResponse,
+        execution: {
+          requestedProviderName: request.provider,
+          actualProviderName: fallbackConfig.name,
+          failoverFromProviderName: selectedName,
+          failoverReason: (error as Error).message,
+        },
+      };
+    }
+  }
+
+  return {
+    search,
+    fetch,
+  };
+}