import { createAnthropic } from "@ai-sdk/anthropic";
import { createGoogleGenerativeAI } from "@ai-sdk/google";
import { createOpenAI } from "@ai-sdk/openai";
import type { LanguageModel } from "ai";

import type { ResolvedModel } from "@tasks/shared/model-routing";

export type CreateLanguageModelResult =
  | { ok: true; model: LanguageModel }
  | { ok: false; reason: string };

/**
 * Build a Vercel AI SDK `LanguageModel` from a resolved registry config.
 * Callers must pass a fully resolved `ResolvedModel` (including apiKey).
 */
export function createLanguageModelFromResolved(
  resolved: ResolvedModel,
): CreateLanguageModelResult {
  try {
    switch (resolved.providerType) {
      case "anthropic": {
        const anthropic = createAnthropic({ apiKey: resolved.apiKey });
        return { ok: true, model: anthropic(resolved.modelId) };
      }
      case "openai":
      case "openai_compatible":
      case "azure_openai": {
        const openai = createOpenAI({
          apiKey: resolved.apiKey,
          baseURL: resolved.baseUrl,
        });
        return { ok: true, model: openai(resolved.modelId) };
      }
      case "google": {
        const google = createGoogleGenerativeAI({ apiKey: resolved.apiKey });
        return { ok: true, model: google(resolved.modelId) };
      }
      default:
        return {
          ok: false,
          reason: `Unsupported provider type: ${resolved.providerType as string}`,
        };
    }
  } catch (e) {
    const message = e instanceof Error ? e.message : String(e);
    return { ok: false, reason: message };
  }
}