// Local-LLM auto-discovery: probes the loopback addresses a local Ollama
// normally binds to, and — if one answers — recommends a model to connect
// with, so a user with Ollama already running never has to type a base URL
// or a model name by hand.
//
// One network call is enough: Ollama's own `/api/tags` already reports
// per-model `capabilities` (completion/embedding/tools/thinking/vision),
// `size`, and `details.parameter_size` — everything the recommendation
// heuristic below needs, with no follow-up `/api/show` round trips.

export interface DiscoveredLocalModel {
  name: string;
  capabilities: string[];
  parameterSize: string;
  sizeBytes: number;
}

export interface LocalDiscoveryResult {
  baseUrl: string;
  models: DiscoveredLocalModel[];
}

interface OllamaTagsResponse {
  models?: Array<{
    name: string;
    capabilities?: string[];
    size?: number;
    details?: { parameter_size?: string };
  }>;
}

// Ollama's own default bind address, plus the hostname form — some setups
// (notably OLLAMA_ORIGINS-restricted CORS allowlists keyed by hostname
// rather than IP) answer one but not the other.
const DEFAULT_PROBE_URLS = ['http://127.0.0.1:11434', 'http://localhost:11434'];
const PROBE_TIMEOUT_MS = 1200;

async function probeOne(baseUrl: string): Promise<LocalDiscoveryResult | null> {
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), PROBE_TIMEOUT_MS);
  try {
    const res = await fetch(`${baseUrl}/api/tags`, { signal: controller.signal });
    if (!res.ok) return null;
    const body = (await res.json()) as OllamaTagsResponse;
    const models = (body.models ?? [])
      .filter((m) => typeof m.name === 'string' && m.name)
      .map((m) => ({
        name: m.name,
        capabilities: m.capabilities ?? [],
        parameterSize: m.details?.parameter_size ?? '',
        sizeBytes: m.size ?? 0,
      }));
    return models.length > 0 ? { baseUrl, models } : null;
  } catch {
    return null;
  } finally {
    clearTimeout(timer);
  }
}

/** Tries each candidate in turn (not in parallel — the common case is the
 *  first one answering, and probing sequentially avoids a burst of
 *  simultaneous loopback connection attempts for no benefit). */
export async function discoverLocalOllama(
  candidateBaseUrls: readonly string[] = DEFAULT_PROBE_URLS,
): Promise<LocalDiscoveryResult | null> {
  for (const baseUrl of candidateBaseUrls) {
    const result = await probeOne(baseUrl);
    if (result) return result;
  }
  return null;
}

/**
 * Picks one sensible default out of whatever's installed, so "Connect"
 * needs no follow-up decision. Chat-capable models only (never an
 * embedding-only model like nomic-embed-text). Among those, prefers
 * non-"thinking" models — a reasoning model's chain-of-thought preamble
 * reads as a broken first response in a guided setup, however good the
 * final answer is — and then the smallest by download size, on the theory
 * that the fastest first reply makes the best first impression; a user who
 * wants the largest/most capable model for real work can still pick it from
 * the full list this only pre-selects.
 */
export function recommendDefaultModel(models: readonly DiscoveredLocalModel[]): string | null {
  const chatCapable = models.filter((m) => m.capabilities.includes('completion'));
  if (chatCapable.length === 0) return null;
  const nonReasoning = chatCapable.filter((m) => !m.capabilities.includes('thinking'));
  const pool = nonReasoning.length > 0 ? nonReasoning : chatCapable;
  return [...pool].sort((a, b) => a.sizeBytes - b.sizeBytes)[0].name;
}

/** The largest chat-capable model, for the "most capable" callout next to
 *  the speed-optimized recommendation above — skipped in the UI when it's
 *  the same model `recommendDefaultModel` already picked. */
export function largestModel(models: readonly DiscoveredLocalModel[]): string | null {
  const chatCapable = models.filter((m) => m.capabilities.includes('completion'));
  if (chatCapable.length === 0) return null;
  return [...chatCapable].sort((a, b) => b.sizeBytes - a.sizeBytes)[0].name;
}

const DISMISSED_KEY = 'vncmail:ai:local-discovery-dismissed';

export function isLocalDiscoveryDismissed(): boolean {
  if (typeof window === 'undefined') return true;
  return window.localStorage.getItem(DISMISSED_KEY) === 'true';
}

export function dismissLocalDiscovery(): void {
  if (typeof window === 'undefined') return;
  window.localStorage.setItem(DISMISSED_KEY, 'true');
}