"use strict";

(function registerStoragePlugin() {
  const storageKey = "tdkpin.save.v1";
  const encoder = new TextEncoder();
  const decoder = new TextDecoder();
  const highScoreApi = "api/highscores";
  const highScoreRetryInitialDelayMs = 250;
  const highScoreRetryMaxDelayMs = 30_000;
  let lastRevision = 0;
  let lastHighScoreRevision = 0;
  let highScoreRequestInFlight = false;
  let highScoreGeneration = 0;
  let highScoreSubmissionWarningShown = false;
  let highScoreRetryDelayMs = highScoreRetryInitialDelayMs;
  let highScoreRetryAt = 0;

  function browserStorage() {
    try {
      return window.localStorage;
    } catch (_error) {
      return null;
    }
  }

  function sendSavedDataToRust() {
    wasm_exports.tdkpin_browser_storage_clear();
    const storage = browserStorage();
    let saved = null;
    try {
      saved = storage?.getItem(storageKey);
    } catch (_error) {
      saved = null;
    }
    if (saved !== null && saved !== undefined) {
      for (const byte of encoder.encode(saved)) {
        wasm_exports.tdkpin_browser_storage_push(byte);
      }
    }
    wasm_exports.tdkpin_browser_storage_finish();
  }

  function flushRustSave() {
    const revision = wasm_exports.tdkpin_browser_storage_save_revision();
    if (revision === lastRevision) {
      return;
    }

    const bytes = new Uint8Array(
      wasm_exports.tdkpin_browser_storage_save_length(),
    );
    for (let index = 0; index < bytes.length; index += 1) {
      bytes[index] = wasm_exports.tdkpin_browser_storage_save_byte(index);
    }

    const storage = browserStorage();
    try {
      storage?.setItem(storageKey, decoder.decode(bytes));
    } catch (_error) {
      // Private browsing or a full quota should not stop the game loop.
    }
    wasm_exports.tdkpin_browser_storage_save_ack();
    lastRevision = revision;
  }

  function deliverHighScores(json) {
    wasm_exports.tdkpin_browser_high_scores_clear();
    for (const byte of encoder.encode(json)) {
      wasm_exports.tdkpin_browser_high_scores_push(byte);
    }
    wasm_exports.tdkpin_browser_high_scores_finish();
  }

  async function fetchHighScores() {
    const generation = ++highScoreGeneration;
    try {
      const response = await fetch(highScoreApi, {
        cache: "no-store",
        headers: { Accept: "application/json" },
      });
      if (!response.ok) {
        throw new Error(`high-score request failed (${response.status})`);
      }
      const json = await response.text();
      if (generation === highScoreGeneration) {
        deliverHighScores(json);
      }
    } catch (error) {
      console.warn("shared high scores unavailable; using local scores", error);
    }
  }

  function retryAfterDelay(response) {
    if (response.status !== 429 && response.status !== 503) {
      return null;
    }
    const value = response.headers.get("Retry-After")?.trim();
    if (!value) {
      return null;
    }

    const seconds = Number(value);
    if (Number.isFinite(seconds) && seconds >= 0) {
      const delay = seconds * 1000;
      return Number.isFinite(delay) ? delay : null;
    }

    const timestamp = Date.parse(value);
    return Number.isFinite(timestamp)
      ? Math.max(0, timestamp - Date.now())
      : null;
  }

  function scheduleHighScoreRetry(retryAfterMs) {
    const jitteredDelay = highScoreRetryDelayMs * (0.5 + Math.random());
    const delay =
      retryAfterMs === null ? jitteredDelay : retryAfterMs + jitteredDelay;
    highScoreRetryAt = Date.now() + delay;
    highScoreRetryDelayMs = Math.min(
      highScoreRetryDelayMs * 2,
      highScoreRetryMaxDelayMs,
    );
  }

  function resetHighScoreRetry() {
    highScoreRetryDelayMs = highScoreRetryInitialDelayMs;
    highScoreRetryAt = 0;
  }

  async function flushHighScoreSubmission() {
    if (highScoreRequestInFlight) {
      return;
    }
    if (Date.now() < highScoreRetryAt) {
      return;
    }
    const revision = wasm_exports.tdkpin_browser_high_score_revision();
    if (revision === lastHighScoreRevision) {
      return;
    }
    const bytes = new Uint8Array(
      wasm_exports.tdkpin_browser_high_score_length(),
    );
    for (let index = 0; index < bytes.length; index += 1) {
      bytes[index] = wasm_exports.tdkpin_browser_high_score_byte(index);
    }

    highScoreRequestInFlight = true;
    let retryAfterMs = null;
    try {
      const response = await fetch(highScoreApi, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: decoder.decode(bytes),
        keepalive: true,
      });
      if (!response.ok) {
        retryAfterMs = retryAfterDelay(response);
        throw new Error(`high-score submission failed (${response.status})`);
      }
      const json = await response.text();
      highScoreGeneration += 1;
      deliverHighScores(json);
      wasm_exports.tdkpin_browser_high_score_ack(revision);
      lastHighScoreRevision = revision;
      highScoreSubmissionWarningShown = false;
      resetHighScoreRetry();
    } catch (error) {
      scheduleHighScoreRetry(retryAfterMs);
      if (!highScoreSubmissionWarningShown) {
        console.warn("shared high-score submission failed; will retry", error);
        highScoreSubmissionWarningShown = true;
      }
    } finally {
      highScoreRequestInFlight = false;
    }
  }

  function onInit() {
    sendSavedDataToRust();
    lastRevision = wasm_exports.tdkpin_browser_storage_save_revision();
    void fetchHighScores();
    window.setInterval(flushRustSave, 50);
    window.setInterval(() => void flushHighScoreSubmission(), 50);
    window.addEventListener("beforeunload", flushRustSave);
  }

  miniquad_add_plugin({
    name: "tdkpin_storage",
    on_init: onInit,
    version: 1,
  });
})();