// ==UserScript==
// @name         PEP WP Auto Play Helper
// @namespace    https://wp.pep.com.cn/
// @version      0.1.0
// @description  Best-effort autoplay and next-item helper for wp.pep.com.cn using visible controls only.
// @match        https://wp.pep.com.cn/*
// @match        http://wp.pep.com.cn/*
// @run-at       document-idle
// @allFrames    true
// @grant        none
// ==/UserScript==

(function () {
  'use strict';

  const LOG = '[PEP Auto]';
  const MIN_VISIBLE_WIDTH = 120;
  const MIN_VISIBLE_HEIGHT = 90;
  const prepared = new WeakSet();
  const stateByVideo = new WeakMap();
  let scanTimer = null;

  const PLAY_RE = /(继续播放|继续学习|开始播放|开始学习|播放|play|resume)/i;
  const NEXT_RE = /(下一(?:集|节|课|讲|页|章|个|视频|课时|单元|课程|门)|下一个|继续(?:学习|播放)?|next|continue)/i;
  const PREV_RE = /(上一(?:集|节|课|讲|页|章|个|视频|课时|单元|课程|门)|上一个|previous|prev|back)/i;
  const BAD_TEXT_RE = /(列表|设置|速度|画中画|全屏|音量|弹幕|字幕|收藏|分享|倍速|评论|刷新|下载|广告)/i;

  function log() {
    if (typeof console !== 'undefined' && console.debug) {
      console.debug(LOG, ...arguments);
    }
  }

  function textOf(el) {
    if (!el) return '';
    const parts = [
      el.getAttribute && el.getAttribute('aria-label'),
      el.getAttribute && el.getAttribute('title'),
      el.getAttribute && el.getAttribute('alt'),
      typeof el.value === 'string' ? el.value : '',
      el.innerText,
      el.textContent,
    ];
    return parts.filter(Boolean).join(' ').replace(/\s+/g, ' ').trim();
  }

  function isVisible(el) {
    if (!el || !el.getClientRects || !el.getClientRects().length) return false;
    const style = getComputedStyle(el);
    return style.display !== 'none' && style.visibility !== 'hidden' && Number(style.opacity || 1) > 0;
  }

  function isEnabled(el) {
    return !el.matches('[disabled], [aria-disabled="true"], .disabled, .is-disabled');
  }

  function interactiveCandidates(root) {
    const scope = root && root.querySelectorAll ? root : document;
    return Array.from(scope.querySelectorAll('button, a, [role="button"], input[type="button"], input[type="submit"]'));
  }

  function scorePlayCandidate(el) {
    const text = textOf(el);
    if (!text || !PLAY_RE.test(text) || BAD_TEXT_RE.test(text)) return 0;
    let score = 10;
    if (/^播放$/.test(text)) score += 40;
    if (/继续播放|开始播放|继续学习/.test(text)) score += 30;
    if (/play/i.test(text)) score += 10;
    return score;
  }

  function scoreNextCandidate(el) {
    const text = textOf(el);
    let score = 0;
    if (el.matches('a[rel="next"]')) score += 60;
    if (/next/i.test(el.getAttribute('href') || '')) score += 20;
    if (NEXT_RE.test(text)) score += 50;
    if (/下一/.test(text)) score += 20;
    if (/继续/.test(text)) score += 10;
    if (PREV_RE.test(text)) score -= 100;
    if (BAD_TEXT_RE.test(text) && !NEXT_RE.test(text)) score -= 15;
    return score;
  }

  function findPlayTarget(root) {
    let best = null;
    let bestScore = 0;
    for (const el of interactiveCandidates(root)) {
      if (!isVisible(el) || !isEnabled(el)) continue;
      const score = scorePlayCandidate(el);
      if (score > bestScore) {
        bestScore = score;
        best = el;
      }
    }
    return best;
  }

  function findNextTarget(root) {
    let best = null;
    let bestScore = 0;
    for (const el of interactiveCandidates(root)) {
      if (!isVisible(el) || !isEnabled(el)) continue;
      const score = scoreNextCandidate(el);
      if (score > bestScore) {
        bestScore = score;
        best = el;
      }
    }
    return bestScore > 0 ? best : null;
  }

  function findSiblingNextTarget(root) {
    const active = root.querySelector('[aria-current="true"], .active, .current, .on, .selected, .playing');
    if (!active) return null;
    const anchor = active.closest('a, button, [role="button"]') || active;
    const container = active.closest('ul, ol, nav, section, article, aside, div') || root;
    const items = interactiveCandidates(container).filter((el) => isVisible(el) && isEnabled(el));
    const index = items.findIndex((el) => el === anchor || el.contains(anchor) || anchor.contains(el));
    if (index >= 0) {
      for (let i = index + 1; i < items.length; i += 1) {
        const text = textOf(items[i]);
        if (!text) continue;
        if (PREV_RE.test(text)) continue;
        return items[i];
      }
    }
    return null;
  }

  function scopeForVideo(video) {
    return (
      video.closest('main, article, section, .player, .video-player, .lesson, .course, .content') ||
      document
    );
  }

  function videoState(video) {
    let state = stateByVideo.get(video);
    if (!state) {
      state = {
        lastSrc: '',
        gestureHooked: false,
        nextTriggered: false,
        autoplayAttempted: false,
        awaitingGesture: false,
      };
      stateByVideo.set(video, state);
    }
    const src = video.currentSrc || video.src || '';
    if (src && src !== state.lastSrc) {
      state.lastSrc = src;
      state.gestureHooked = false;
      state.nextTriggered = false;
      state.autoplayAttempted = false;
      state.awaitingGesture = false;
    }
    return state;
  }

  function clickElement(el) {
    if (!el) return false;
    try {
      el.click();
      return true;
    } catch (err) {
      log('click failed', err);
      return false;
    }
  }

  function clickPlayButton(video) {
    const root = scopeForVideo(video);
    const target = findPlayTarget(root) || findPlayTarget(document);
    if (target) {
      log('click play target', textOf(target));
      return clickElement(target);
    }
    return false;
  }

  function clickNextButton(video) {
    const root = scopeForVideo(video);
    const target = findNextTarget(root) || findNextTarget(document) || findSiblingNextTarget(root);
    if (target) {
      log('click next target', textOf(target));
      return clickElement(target);
    }
    return false;
  }

  function hookGestureRetry(video) {
    const state = videoState(video);
    if (state.gestureHooked) return;
    state.gestureHooked = true;
    state.awaitingGesture = true;

    const retry = () => {
      if (!video.isConnected) return;
      state.gestureHooked = false;
      tryAutoplay(video, 'gesture');
    };

    const opts = { capture: true, once: true };
    document.addEventListener('pointerdown', retry, opts);
    document.addEventListener('keydown', retry, opts);
  }

  function tryAutoplay(video, reason) {
    if (!video || !video.isConnected) return;
    const state = videoState(video);
    const isGestureRetry = reason === 'gesture' && state.awaitingGesture;
    const isHotkeyRetry = reason === 'hotkey';

    if (state.autoplayAttempted && !isGestureRetry && !isHotkeyRetry) return;
    if (!video.paused && !video.ended) {
      state.autoplayAttempted = true;
      state.awaitingGesture = false;
      return;
    }

    state.autoplayAttempted = true;
    video.autoplay = true;
    video.setAttribute('playsinline', '');
    video.setAttribute('webkit-playsinline', '');
    video.preload = 'auto';

    const playPromise = video.play();
    if (playPromise && typeof playPromise.catch === 'function') {
      playPromise.catch((err) => {
        const name = err && err.name ? err.name : '';
        if (name === 'NotAllowedError') {
          log('autoplay blocked, waiting for gesture', reason || '');
          state.awaitingGesture = true;
          hookGestureRetry(video);
          clickPlayButton(video);
        } else {
          log('play failed', name || err);
        }
      });
    }

    if (video.currentTime < 1) {
      state.nextTriggered = false;
    }
  }

  function prepareVideo(video) {
    if (!(video instanceof HTMLMediaElement) || prepared.has(video)) return;
    const rect = video.getBoundingClientRect();
    if (rect.width > 0 && rect.height > 0 && rect.width < MIN_VISIBLE_WIDTH && rect.height < MIN_VISIBLE_HEIGHT) {
      return;
    }

    prepared.add(video);

    const onReady = () => tryAutoplay(video, 'ready');
    const onEnded = () => {
      const state = videoState(video);
      if (state.nextTriggered) return;
      state.nextTriggered = true;
      if (!clickNextButton(video)) {
        log('no next target found');
      }
    };
    const onPlay = () => {
      const state = videoState(video);
      state.gestureHooked = false;
      state.autoplayAttempted = true;
      state.awaitingGesture = false;
      if (video.currentTime < 1) {
        state.nextTriggered = false;
      }
    };
    const onEmptied = () => {
      const state = videoState(video);
      state.lastSrc = video.currentSrc || video.src || '';
      state.gestureHooked = false;
      state.nextTriggered = false;
      state.autoplayAttempted = false;
      state.awaitingGesture = false;
    };

    ['loadedmetadata', 'loadeddata', 'canplay'].forEach((evt) => {
      video.addEventListener(evt, onReady, { passive: true });
    });
    video.addEventListener('ended', onEnded, { passive: true });
    video.addEventListener('play', onPlay, { passive: true });
    video.addEventListener('emptied', onEmptied, { passive: true });

    tryAutoplay(video, 'scan');
  }

  function scan() {
    for (const video of document.querySelectorAll('video')) {
      prepareVideo(video);
    }
  }

  function scheduleScan() {
    if (scanTimer) return;
    scanTimer = setTimeout(() => {
      scanTimer = null;
      scan();
    }, 120);
  }

  document.addEventListener('keydown', (event) => {
    if (!event.altKey || !event.shiftKey || event.defaultPrevented) return;
    if (event.code === 'KeyP') {
      const video = document.querySelector('video');
      if (video) {
        event.preventDefault();
        tryAutoplay(video, 'hotkey');
      }
    } else if (event.code === 'KeyN') {
      const video = document.querySelector('video');
      if (video) {
        event.preventDefault();
        clickNextButton(video);
      }
    }
  }, true);

  const observer = new MutationObserver(scheduleScan);
  const root = document.documentElement || document.body;
  if (root) {
    observer.observe(root, { childList: true, subtree: true });
  }

  window.addEventListener('load', scheduleScan, { passive: true });
  document.addEventListener('DOMContentLoaded', scheduleScan, { passive: true });

  scheduleScan();
})();