More work on modelProviders

I think everything that's OpenAI-specific is inside modelProviders at this point, so we can get started adding more providers.

src/server/utils/openai.ts

@@ -1,64 +1,5 @@
-import { omit } from "lodash-es";
 import { env } from "~/env.mjs";
 
 import OpenAI from "openai";
-import {
-  type ChatCompletion,
-  type ChatCompletionChunk,
-  type CompletionCreateParams,
-} from "openai/resources/chat";
 
 export const openai = new OpenAI({ apiKey: env.OPENAI_API_KEY });
-
-export const mergeStreamedChunks = (
-  base: ChatCompletion | null,
-  chunk: ChatCompletionChunk,
-): ChatCompletion => {
-  if (base === null) {
-    return mergeStreamedChunks({ ...chunk, choices: [] }, chunk);
-  }
-
-  const choices = [...base.choices];
-  for (const choice of chunk.choices) {
-    const baseChoice = choices.find((c) => c.index === choice.index);
-    if (baseChoice) {
-      baseChoice.finish_reason = choice.finish_reason ?? baseChoice.finish_reason;
-      baseChoice.message = baseChoice.message ?? { role: "assistant" };
-
-      if (choice.delta?.content)
-        baseChoice.message.content =
-          ((baseChoice.message.content as string) ?? "") + (choice.delta.content ?? "");
-      if (choice.delta?.function_call) {
-        const fnCall = baseChoice.message.function_call ?? {};
-        fnCall.name =
-          ((fnCall.name as string) ?? "") + ((choice.delta.function_call.name as string) ?? "");
-        fnCall.arguments =
-          ((fnCall.arguments as string) ?? "") +
-          ((choice.delta.function_call.arguments as string) ?? "");
-      }
-    } else {
-      choices.push({ ...omit(choice, "delta"), message: { role: "assistant", ...choice.delta } });
-    }
-  }
-
-  const merged: ChatCompletion = {
-    ...base,
-    choices,
-  };
-
-  return merged;
-};
-
-export const streamChatCompletion = async function* (body: CompletionCreateParams) {
-  // eslint-disable-next-line @typescript-eslint/no-unsafe-call
-  const resp = await openai.chat.completions.create({
-    ...body,
-    stream: true,
-  });
-
-  let mergedChunks: ChatCompletion | null = null;
-  for await (const part of resp) {
-    mergedChunks = mergeStreamedChunks(mergedChunks, part);
-    yield mergedChunks;
-  }
-};