import { strict as assert } from "node:assert";
import { test } from "node:test";
import {
  BACKEND_API_BASE_URLS,
  getOfficialPositionResolverConfig,
} from "../lib/jrDataSystemEnvironment";
import {
  createOfficialPositionResolver,
  parseOfficialPositionResponse,
  type OfficialPositionCacheStore,
} from "../lib/officialPositionService";
import { officialPositionLookupKey } from "../lib/domain/railway";

const betaConfig = getOfficialPositionResolverConfig("experimental");

const backendPayload = (posNum: string | number = "109", extra: Record<string, unknown> = {}) => ({
  data: {
    position: {
      position_id: "b754e5fc-789b-419c-b5bc-97585cba793f",
      pos: "大歩危",
      line: "dosan",
      pos_num: posNum,
      position_type: "station",
      platform: "3",
      track: "3",
      note: null,
      enrichment_status: "unreviewed",
      first_seen_at: null,
      last_seen_at: null,
      revision: 2,
      ...extra,
    },
  },
});

const input = { line: "dosan", pos: "大歩危", posNum: "109" };

test("persistent cache renders the warm value before refreshing the API", async () => {
  const cachedPosition = parseOfficialPositionResponse(backendPayload());
  const cacheKey =
    betaConfig.backendApiBaseUrl + ":" + officialPositionLookupKey(input);
  let requestCount = 0;
  let savedEntries = new Map<string, typeof cachedPosition>();
  const cacheStore: OfficialPositionCacheStore = {
    load: async () => new Map([[cacheKey, cachedPosition]]),
    save: async (entries) => {
      savedEntries = new Map(entries);
    },
  };
  const resolver = createOfficialPositionResolver({
    persistentCache: cacheStore,
    fetchJson: async () => {
      requestCount += 1;
      return backendPayload("110");
    },
  });

  const warmValue = await resolver.resolve(input, betaConfig);
  assert.equal(warmValue?.posNum, "109");
  assert.equal(requestCount, 0);

  const refreshedValue = await resolver.resolve(input, betaConfig);
  assert.equal(refreshedValue?.posNum, "110");
  assert.equal(requestCount, 1);
  await new Promise<void>((resolve) => setImmediate(resolve));
  assert.equal(savedEntries.get(cacheKey)?.posNum, "110");
});

test("experimental resolver uses beta endpoint and preserves the canonical fields", async () => {
  const requests: Array<{ url: string; source: string | undefined }> = [];
  const resolver = createOfficialPositionResolver({
    fetchJson: async (url, options) => {
      requests.push({ url, source: options.source });
      return backendPayload();
    },
  });

  const position = await resolver.resolve(input, betaConfig);
  assert.equal(position?.positionId, "b754e5fc-789b-419c-b5bc-97585cba793f");
  assert.equal(position?.pos, "大歩危");
  assert.equal(position?.line, "dosan");
  assert.equal(position?.posNum, "109");
  assert.equal(position?.platform, "3");
  assert.equal(position?.track, "3");
  assert.equal(position?.note, null);
  assert.equal(requests.length, 1);
  const url = new URL(requests[0].url);
  assert.equal(url.origin, BACKEND_API_BASE_URLS.experimental);
  assert.equal(url.pathname, "/api/v1/official-positions/resolve");
  assert.equal(url.searchParams.get("line"), "dosan");
  assert.equal(url.searchParams.get("pos"), "大歩危");
  assert.equal(url.searchParams.get("pos_num"), "109");
  assert.equal(requests[0].source, "backend_api");
});

test("resolveMany keeps Takamatsu observations separate by line", async () => {
  const requests: string[] = [];
  const resolver = createOfficialPositionResolver({
    fetchJson: async (url) => {
      requests.push(url);
      const parsed = new URL(url);
      return backendPayload(parsed.searchParams.get("pos_num") ?? "279", {
        pos: parsed.searchParams.get("pos") ?? "高松",
        line: parsed.searchParams.get("line") ?? "",
      });
    },
  });
  const inputs = [
    { line: "yosan", pos: "高松", posNum: 279 },
    { line: "koutoku", pos: "高松", posNum: 279 },
  ];

  const result = await resolver.resolveMany(inputs, betaConfig);
  assert.equal(result.size, 2);
  assert.deepEqual(
    requests.map((url) => new URL(url).searchParams.get("line")).sort(),
    ["koutoku", "yosan"],
  );
  assert.equal(
    result.get(officialPositionLookupKey(inputs[0]))?.line,
    "yosan",
  );
  assert.equal(
    result.get(officialPositionLookupKey(inputs[1]))?.line,
    "koutoku",
  );
});

test("pos_num stays textual and the complete tuple forms the lookup key", () => {
  const withLeadingZero = parseOfficialPositionResponse(
    backendPayload("0279"),
  );
  const withLetters = parseOfficialPositionResponse(backendPayload("ABC"));
  assert.equal(withLeadingZero.posNum, "0279");
  assert.equal(withLetters.posNum, "ABC");
  assert.notEqual(
    officialPositionLookupKey({ ...input, pos: "大歩危" }),
    officialPositionLookupKey({ ...input, pos: "小歩危" }),
  );
  assert.notEqual(
    officialPositionLookupKey({ ...input, line: "dosan" }),
    officialPositionLookupKey({ ...input, line: "dosan2" }),
  );
});

test("ten simultaneous requests for one tuple share one HTTP request and later calls hit cache", async () => {
  let requestCount = 0;
  let release: (() => void) | undefined;
  const pending = new Promise<void>((resolve) => {
    release = resolve;
  });
  const resolver = createOfficialPositionResolver({
    fetchJson: async () => {
      requestCount += 1;
      await pending;
      return backendPayload();
    },
  });

  const requests = Array.from({ length: 10 }, () => resolver.resolve(input, betaConfig));
  assert.equal(requestCount, 1);
  release?.();
  const positions = await Promise.all(requests);
  assert.equal(positions.filter(Boolean).length, 10);
  assert.equal(resolver.getDiagnostics().inFlightDedupeCount, 9);
  await resolver.resolve(input, betaConfig);
  assert.equal(requestCount, 1);
  assert.equal(resolver.getDiagnostics().cacheHitCount, 1);
});

test("resolveMany limits initial fan-out to the configured concurrency", async () => {
  let active = 0;
  let maxActive = 0;
  let requestCount = 0;
  const resolver = createOfficialPositionResolver({
    maxConcurrency: 4,
    fetchJson: async () => {
      requestCount += 1;
      active += 1;
      maxActive = Math.max(maxActive, active);
      await new Promise((resolve) => setTimeout(resolve, 1));
      active -= 1;
      return backendPayload();
    },
  });
  const inputs = Array.from({ length: 12 }, (_, index) => ({
    line: "dosan",
    pos: "大歩危" + index,
    posNum: String(index),
  }));
  await resolver.resolveMany(inputs, betaConfig);
  assert.equal(requestCount, 12);
  assert.ok(maxActive <= 4);
});

test("404 becomes unresolved metadata and is cached without throwing", async () => {
  let requestCount = 0;
  const resolver = createOfficialPositionResolver({
    fetchJson: async () => {
      requestCount += 1;
      throw Object.assign(new Error("not found"), { status: 404 });
    },
  });
  assert.equal(await resolver.resolve(input, betaConfig), undefined);
  assert.equal(await resolver.resolve(input, betaConfig), undefined);
  assert.equal(requestCount, 1);
  assert.equal(resolver.getDiagnostics().unresolvedCount, 1);
});

test("network failure keeps a cached value during forced refresh", async () => {
  let shouldFail = false;
  const resolver = createOfficialPositionResolver({
    fetchJson: async () => {
      if (shouldFail) throw new Error("temporary network failure");
      return backendPayload();
    },
  });
  const first = await resolver.resolve(input, betaConfig);
  shouldFail = true;
  const refreshed = await resolver.resolve(input, betaConfig, { forceRefresh: true });
  assert.equal(refreshed?.positionId, first?.positionId);
  assert.equal(resolver.getDiagnostics().networkFailureCount, 1);
});

test("description remains compatible when the resolver field is renamed", () => {
  const parsed = parseOfficialPositionResponse(
    backendPayload("109", { note: undefined, description: "西側ホーム" }),
  );
  assert.equal(parsed.note, "西側ホーム");
});

test("null metadata is accepted", () => {
  const parsed = parseOfficialPositionResponse(
    backendPayload("109", { platform: null, track: null, note: null }),
  );
  assert.equal(parsed.platform, null);
  assert.equal(parsed.track, null);
  assert.equal(parsed.note, null);
});
test("production release uses the production OfficialPosition Backend", async () => {
  const requests: Array<{ url: string; source: string | undefined }> = [];
  const resolver = createOfficialPositionResolver({
    fetchJson: async (url, options) => {
      requests.push({ url, source: options.source });
      return backendPayload();
    },
  });

  const metadata = await resolver.resolve(
    input,
    getOfficialPositionResolverConfig("production_release"),
  );
  assert.equal(metadata?.positionId, "b754e5fc-789b-419c-b5bc-97585cba793f");
  assert.equal(requests.length, 1);
  assert.equal(requests[0].source, "backend_api");
  const url = new URL(requests[0].url);
  assert.equal(url.origin, BACKEND_API_BASE_URLS.production);
  assert.equal(url.pathname, "/api/v1/official-positions/resolve");
  assert.equal(url.searchParams.get("line"), "dosan");
  assert.equal(url.searchParams.get("pos"), "大歩危");
  assert.equal(url.searchParams.get("pos_num"), "109");
});