export class OllamaError extends Error {
  constructor(status, body) { super(`ollama ${status}: ${body}`); this.status = status; }
}

export async function embedText(text, { model = 'nomic-embed-text', timeoutMs = 60_000 } = {}) {
  const url = (process.env.OLLAMA_URL || 'http://192.168.1.185:11434') + '/api/embeddings';
  const res = await fetch(url, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ model, prompt: text }),
    signal: AbortSignal.timeout(timeoutMs)
  });
  if (!res.ok) throw new OllamaError(res.status, await res.text());
  const j = await res.json();
  return j.embedding;
}

export function padTo(vector, dim) {
  if (vector.length === dim) return vector;
  if (vector.length > dim) return vector.slice(0, dim);
  const out = vector.slice();
  while (out.length < dim) out.push(0);
  return out;
}

// Split text into chunks of at most `size` chars, breaking on line boundaries
// where possible (never mid-word-loss): accumulate lines until adding the next
// would exceed `size`. A single over-long line is hard-split. Returns [] for empty.
export function chunkText(text, size = 1500) {
  const s = (text || '').trim();
  if (!s) return [];
  const chunks = [];
  let cur = '';
  for (const line of s.split('\n')) {
    if (line.length > size) {
      if (cur) { chunks.push(cur); cur = ''; }
      for (let i = 0; i < line.length; i += size) chunks.push(line.slice(i, i + size));
      continue;
    }
    if (cur.length + line.length + 1 > size) { if (cur) chunks.push(cur); cur = line; }
    else { cur = cur ? cur + '\n' + line : line; }
  }
  if (cur) chunks.push(cur);
  return chunks;
}

// Embed possibly-long text by chunking, embedding each chunk, and mean-pooling
// the resulting vectors element-wise. Returns a single embedding vector.
// 1 chunk => identical to embedText. Caps the number of chunks to bound cost.
export async function embedTextPooled(text, { model = 'nomic-embed-text', timeoutMs = 60_000, maxChunks = 64, chunkSize = 1500 } = {}) {
  let chunks = chunkText(text, chunkSize);
  if (chunks.length === 0) chunks = [''];
  if (chunks.length > maxChunks) chunks = chunks.slice(0, maxChunks);
  const vecs = [];
  for (const c of chunks) vecs.push(await embedText(c, { model, timeoutMs }));
  const dim = vecs[0].length;
  const pooled = new Array(dim).fill(0);
  for (const v of vecs) for (let i = 0; i < dim; i++) pooled[i] += (v[i] || 0);
  for (let i = 0; i < dim; i++) pooled[i] /= vecs.length;
  return pooled;
}