const VOYAGE_API_URL = "https://api.voyageai.com/v1";
const EMBED_MODEL = "voyage-3";
const RERANK_MODEL = "rerank-2";
const EMBED_BATCH_SIZE = 32;

function getApiKey() {
    const key = process.env.VOYAGE_API_KEY;
    if (!key) throw new Error("VOYAGE_API_KEY is not set");
    return key;
}

async function voyagePost(path, body) {
    const res = await fetch(`${VOYAGE_API_URL}${path}`, {
        method: "POST",
        headers: {
            "Content-Type": "application/json",
            Authorization: `Bearer ${getApiKey()}`,
        },
        body: JSON.stringify(body),
    });

    if (!res.ok) {
        const text = await res.text();
        throw new Error(`Voyage ${path} failed (${res.status}): ${text}`);
    }

    return res.json();
}

// Embed text -  voyage-3. inputType must be "document" (ingest) or "query" (search).

export async function embedTexts(texts, inputType = "document") {
    if (texts.length === 0) return [];

    const embeddings = [];
    for (let i = 0; i < texts.length; i += EMBED_BATCH_SIZE) {
        const batch = texts.slice(i, i + EMBED_BATCH_SIZE);
        const json = await voyagePost("/embeddings", {
            model: EMBED_MODEL,
            input: batch,
            input_type: inputType,
        });
        const ordered = (json.data || [])
            .slice()
            .sort((a, b) => (a.index ?? 0) - (b.index ?? 0));
        embeddings.push(...ordered.map((d) => d.embedding));
    }
    return embeddings;
}

export async function rerank(query, documents) {
    if (!documents || documents.length === 0) return [];

    const texts = documents.map((d) => (typeof d === "string" ? d : d.text));
    const json = await voyagePost("/rerank", {
        model: RERANK_MODEL,
        query,
        documents: texts,
    });

    return (json.data || []).map((item) => ({
        index: item.index,
        document: documents[item.index],
        relevanceScore: item.relevance_score,
    }));
}