/**
 * The `TEXT_EMBEDDING` model handler, POSTing directly to OpenRouter's
 * `/embeddings` endpoint. Validates the configured dimension against
 * `VECTOR_DIMS` and rejects a returned vector whose length disagrees — no silent
 * truncation. A `null` param yields a deterministic marker probe vector; oversized
 * input is truncated to ~8000 tokens with a warning. Emits a `MODEL_USED` event.
 */
import type { IAgentRuntime, TextEmbeddingParams } from "@elizaos/core";
import { logger, ModelType, VECTOR_DIMS } from "@elizaos/core";

import { getApiKey, getBaseURL, getEmbeddingModel, getSetting } from "../utils/config";
import { emitModelUsageEvent } from "../utils/events";

export async function handleTextEmbedding(
  runtime: IAgentRuntime,
  params: TextEmbeddingParams | string | null
): Promise<number[]> {
  const embeddingModelName = getEmbeddingModel(runtime);
  const embeddingDimension = Number.parseInt(
    getSetting(runtime, "OPENROUTER_EMBEDDING_DIMENSIONS") ??
      getSetting(runtime, "EMBEDDING_DIMENSIONS") ??
      "1536",
    10
  ) as (typeof VECTOR_DIMS)[keyof typeof VECTOR_DIMS];

  if (!Object.values(VECTOR_DIMS).includes(embeddingDimension)) {
    const errorMsg = `Invalid embedding dimension: ${embeddingDimension}. Must be one of: ${Object.values(VECTOR_DIMS).join(", ")}`;
    logger.error(errorMsg);
    throw new Error(errorMsg);
  }

  if (params === null) {
    const testVector = Array(embeddingDimension).fill(0) as number[];
    testVector[0] = 0.1;
    return testVector;
  }

  let text: string;
  if (typeof params === "string") {
    text = params;
  } else if (typeof params === "object" && typeof params.text === "string") {
    text = params.text;
  } else {
    const errorMsg = "Invalid input format for embedding";
    logger.error(errorMsg);
    throw new Error(errorMsg);
  }

  if (!text.trim()) {
    const errorMsg = "Empty text for embedding";
    logger.error(errorMsg);
    throw new Error(errorMsg);
  }

  // Truncate to stay within embedding model token limits (~4 chars per token)
  const maxChars = 8_000 * 4;
  if (text.length > maxChars) {
    logger.warn(
      `[OpenRouter] Embedding input too long (~${Math.ceil(text.length / 4)} tokens), truncating to ~8000 tokens`
    );
    text = text.slice(0, maxChars);
  }

  const apiKey = getApiKey(runtime);
  if (!apiKey) {
    const errorMsg = "OPENROUTER_API_KEY is not set";
    logger.error(errorMsg);
    throw new Error(errorMsg);
  }

  const baseURL = getBaseURL(runtime);

  try {
    // @trajectory-allow Embeddings return numeric retrieval vectors, not generative LLM text.
    const response = await fetch(`${baseURL}/embeddings`, {
      method: "POST",
      headers: {
        Authorization: `Bearer ${apiKey}`,
        "Content-Type": "application/json",
        "HTTP-Referer": getSetting(runtime, "OPENROUTER_HTTP_REFERER") || "",
        "X-Title": getSetting(runtime, "OPENROUTER_X_TITLE") || "ElizaOS",
      },
      body: JSON.stringify({
        model: embeddingModelName,
        input: text,
      }),
    });

    if (!response.ok) {
      logger.error(`OpenRouter API error: ${response.status} - ${response.statusText}`);
      throw new Error(`OpenRouter API error: ${response.status} - ${response.statusText}`);
    }

    const data = (await response.json()) as {
      data?: Array<{ embedding?: number[] }>;
      usage?: { prompt_tokens: number; total_tokens: number };
    };

    const embedding = data.data?.[0]?.embedding;
    if (!embedding) {
      logger.error("API returned invalid structure");
      throw new Error("API returned invalid structure");
    }

    if (!Array.isArray(embedding) || embedding.length !== embeddingDimension) {
      const errorMsg = `Embedding length ${embedding.length} does not match configured dimension ${embeddingDimension}`;
      logger.error(errorMsg);
      throw new Error(errorMsg);
    }

    if (data.usage) {
      const usage = {
        inputTokens: data.usage.prompt_tokens,
        outputTokens: 0,
        totalTokens: data.usage.total_tokens,
      };

      emitModelUsageEvent(runtime, ModelType.TEXT_EMBEDDING, text, usage, embeddingModelName);
    }

    return embedding;
  } catch (error: unknown) {
    // error-policy:J2 context-adding rethrow — never fabricate a vector; the
    // provider failure surfaces to the caller (#9324: throw, never fabricate).
    const message = error instanceof Error ? error.message : String(error);
    logger.error(`Error generating embedding: ${message}`);
    throw error instanceof Error ? error : new Error(message);
  }
}