import { LocalStorage } from "@vicinae/api";
import { z } from "zod";
import { errorMessage } from "./utils";

/**
 * IP geolocation, opt-in.
 *
 * This is the one place in the extension that tells a third party anything about
 * the user. The README said no geolocation service ever saw the user's address,
 * and this is what makes that conditional, so it is off unless asked for, it is
 * skipped entirely when the user has already said where they are, and the tool
 * output names the provider so the model can qualify what it repeats.
 *
 * The answer is cached for hours rather than looked up per call. A city does not
 * change between questions, and every lookup hands the provider another copy of
 * the user's IP address.
 *
 * Imports Vicinae for `LocalStorage` only, which is the same footing as
 * `sessions.ts` and `vision.ts`. Everything else about it is plain `fetch`, so
 * the parsing and the cache are unit tested without a runtime.
 */

/** Where the lookup goes. Swapping providers means changing this and the parser below. */
export const GEO_PROVIDER = "https://ipapi.co/json/";
export const GEO_PROVIDER_NAME = "ipapi.co";

/** How long a resolved place is trusted. Long enough to not re-leak the IP on every question. */
export const GEO_TTL_MS = 6 * 60 * 60 * 1000;

/** An IP lookup is a nice-to-have, so it must never hold up an answer. */
const GEO_TIMEOUT_MS = 8_000;

const STORAGE_KEY = "lam.geo";

export interface GeoPlace {
  /** Ready to show, e.g. "Cebu City, Central Visayas, Philippines". */
  place: string;
  city?: string;
  region?: string;
  country?: string;
  latitude?: number;
  longitude?: number;
  timezone?: string;
  /** Named in the tool output, so the model can say where this came from. */
  source: string;
  fetchedAt: number;
}

export type GeoLookup = { status: "ok"; place: GeoPlace } | { status: "failed"; message: string };

export interface GeoOptions {
  signal?: AbortSignal;
  /** Injected so the cache is deterministic under test. */
  now?: number;
  /** Ignores a cached answer. */
  refresh?: boolean;
}

const CachedSchema = z.object({
  place: z.string(),
  city: z.string().optional(),
  region: z.string().optional(),
  country: z.string().optional(),
  latitude: z.number().optional(),
  longitude: z.number().optional(),
  timezone: z.string().optional(),
  source: z.string(),
  fetchedAt: z.number(),
});

/** The subset of ipapi.co's response this needs, with every field optional so a shape change degrades instead of throwing. */
const ResponseSchema = z.object({
  error: z.unknown().optional(),
  reason: z.string().optional(),
  message: z.string().optional(),
  city: z.string().nullable().optional(),
  region: z.string().nullable().optional(),
  country_name: z.string().nullable().optional(),
  latitude: z.number().nullable().optional(),
  longitude: z.number().nullable().optional(),
  timezone: z.string().nullable().optional(),
});

/**
 * Joins the parts of a place, dropping duplicates.
 *
 * Providers often return the city twice (once as `city`, once as `region`) for
 * city-states and single-city regions, and "Singapore, Singapore, Singapore"
 * reads like a bug.
 */
export function buildPlace(parts: { city?: string; region?: string; country?: string }): string {
  const seen = new Set<string>();
  const kept: string[] = [];

  for (const part of [parts.city, parts.region, parts.country]) {
    const trimmed = part?.trim();
    const key = trimmed?.toLowerCase();
    if (!trimmed || !key || seen.has(key)) continue;

    seen.add(key);
    kept.push(trimmed);
  }

  return kept.join(", ");
}

/** Aborts on either the caller's signal or a timeout, whichever comes first. */
async function fetchWithTimeout(
  url: string,
  signal: AbortSignal | undefined,
  timeoutMs: number,
): Promise<Response> {
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), timeoutMs);
  const forward = () => controller.abort();

  signal?.addEventListener("abort", forward, { once: true });

  try {
    return await fetch(url, { signal: controller.signal, headers: { Accept: "application/json" } });
  } finally {
    clearTimeout(timer);
    signal?.removeEventListener("abort", forward);
  }
}

async function readCache(now: number): Promise<GeoPlace | undefined> {
  try {
    const raw = await LocalStorage.getItem<string>(STORAGE_KEY);
    if (!raw) return undefined;

    const parsed = CachedSchema.safeParse(JSON.parse(raw));
    if (!parsed.success) return undefined;
    if (now - parsed.data.fetchedAt > GEO_TTL_MS) return undefined;

    return parsed.data;
  } catch {
    return undefined;
  }
}

async function writeCache(place: GeoPlace): Promise<void> {
  await LocalStorage.setItem(STORAGE_KEY, JSON.stringify(place)).catch(() => undefined);
}

/**
 * Resolves the user's rough place from their IP address.
 *
 * Never throws: a lookup failure leaves the region-level answer intact, and the
 * message is passed on so the model can say what went wrong rather than quietly
 * presenting a coarser answer as though it were the same thing.
 */
export async function ipPlace(options: GeoOptions = {}): Promise<GeoLookup> {
  const now = options.now ?? Date.now();

  if (!options.refresh) {
    const cached = await readCache(now);
    if (cached) return { status: "ok", place: cached };
  }

  let response: Response;
  try {
    response = await fetchWithTimeout(GEO_PROVIDER, options.signal, GEO_TIMEOUT_MS);
  } catch (thrown) {
    return { status: "failed", message: `could not reach ${GEO_PROVIDER_NAME} (${errorMessage(thrown)})` };
  }

  if (!response.ok) {
    return { status: "failed", message: `${GEO_PROVIDER_NAME} answered HTTP ${response.status}` };
  }

  let payload: unknown;
  try {
    payload = await response.json();
  } catch {
    return { status: "failed", message: `${GEO_PROVIDER_NAME} did not answer with JSON` };
  }

  const parsed = ResponseSchema.safeParse(payload);
  if (!parsed.success) {
    return { status: "failed", message: `${GEO_PROVIDER_NAME} answered in an unexpected shape` };
  }

  const data = parsed.data;
  if (data.error) {
    return {
      status: "failed",
      message: data.message ?? data.reason ?? `${GEO_PROVIDER_NAME} refused the lookup`,
    };
  }

  const city = data.city ?? undefined;
  const region = data.region ?? undefined;
  const country = data.country_name ?? undefined;
  const place = buildPlace({ city, region, country });

  if (!place) {
    return { status: "failed", message: `${GEO_PROVIDER_NAME} returned no usable place` };
  }

  const resolved: GeoPlace = {
    place,
    city,
    region,
    country,
    latitude: data.latitude ?? undefined,
    longitude: data.longitude ?? undefined,
    timezone: data.timezone ?? undefined,
    source: GEO_PROVIDER_NAME,
    fetchedAt: now,
  };

  await writeCache(resolved);
  return { status: "ok", place: resolved };
}

/** Drops the cached place, so a move or a provider change is not pinned for hours. */
export async function forgetGeoPlace(): Promise<void> {
  await LocalStorage.removeItem(STORAGE_KEY).catch(() => undefined);
}