backend/src/services/embeddingService.ts

import { env, assertEmbeddingsConfigured } from "../config/env";

interface EmbeddingResponse {
  data?: Array<{
    embedding?: number[];
  }>;
}

export async function createEmbedding(input: string): Promise<number[]> {
  assertEmbeddingsConfigured();

  const response = await fetch(`${env.EMBEDDING_BASE_URL.replace(/\/$/, "")}/embeddings`, {
    method: "POST",
    headers: {
      Authorization: `Bearer ${env.EMBEDDING_API_KEY}`,
      "Content-Type": "application/json"
    },
    body: JSON.stringify({
      model: env.EMBEDDING_MODEL,
      input,
      dimensions: env.EMBEDDING_DIMENSIONS
    })
  });

  if (!response.ok) {
    const text = await response.text();
    throw new Error(`Embedding provider failed with ${response.status}: ${text}`);
  }

  const payload = (await response.json()) as EmbeddingResponse;
  const embedding = payload.data?.[0]?.embedding;
  if (!embedding || embedding.length !== env.EMBEDDING_DIMENSIONS) {
    throw new Error(`Embedding provider returned an invalid vector. Expected ${env.EMBEDDING_DIMENSIONS} dimensions.`);
  }

  return embedding;
}