import Foundation

enum RedditLoginBridgeStyle {
    static let messageHandlerName = "reddoraLogin"

    /// Intercepts Log In and blocks Reddit's embedded auth modal, which cannot complete
    /// credential sign-in reliably in WKWebView ("Server error. Try again later.").
    static let injectionScript = """
    (function() {
      if (window.__reddoraLoginBridgeInstalled) return;
      window.__reddoraLoginBridgeInstalled = true;

      const LOGIN_PATTERN = /log\\s*in/i;
      const HEADER_SELECTORS = 'header, [role="banner"], #header, faceplate-header, nav, shreddit-header-action';
      const CLICKABLE_SELECTORS = 'button, a, [role="button"], faceplate-tracker, faceplate-button';
      const AUTH_MODAL_SELECTORS = [
        'auth-flow-modal',
        '[data-testid="login-modal"]',
        '#credentials-login-popup',
        'shreddit-signup-drawer',
        'faceplate-modal[slot="login"]',
        'faceplate-modal[open]'
      ].join(', ');

      const boundLoginTriggers = new WeakSet();

      function nodeLabel(node) {
        if (!(node instanceof Element)) return '';
        return (
          (node.textContent || '') + ' ' +
          (node.getAttribute('aria-label') || '') + ' ' +
          (node.getAttribute('title') || '') + ' ' +
          (node.getAttribute('href') || '')
        ).trim();
      }

      function isLoginPage() {
        const host = window.location.hostname.toLowerCase();
        return (host === 'www.reddit.com' || host === 'reddit.com' || host === 'new.reddit.com')
          && /^\\/login\\/?$/i.test(window.location.pathname);
      }

      function requestInAppLogin() {
        if (isLoginPage()) return;
        if (window.__reddoraLoginPanelRequested) return;
        window.__reddoraLoginPanelRequested = true;
        setTimeout(function() {
          window.__reddoraLoginPanelRequested = false;
        }, 1000);

        if (
          window.webkit &&
          window.webkit.messageHandlers &&
          window.webkit.messageHandlers.reddoraLogin
        ) {
          window.webkit.messageHandlers.reddoraLogin.postMessage('open');
        }
      }

      function interceptLoginEvent(event) {
        if (isLoginPage()) return false;
        if (eventMatchesLoginTrigger(event)) {
          event.preventDefault();
          event.stopImmediatePropagation();
          window.__reddoraCloseRedditAuthModal && window.__reddoraCloseRedditAuthModal();
          requestInAppLogin();
          return true;
        }

        const loginButton = document.getElementById('login-button');
        if (loginButton && eventMatchesButtonBounds(event, loginButton)) {
          event.preventDefault();
          event.stopImmediatePropagation();
          window.__reddoraCloseRedditAuthModal && window.__reddoraCloseRedditAuthModal();
          requestInAppLogin();
          return true;
        }

        return false;
      }

      function eventMatchesButtonBounds(event, button) {
        if (!(button instanceof Element)) return false;
        if (!(event instanceof MouseEvent) && event.type !== 'pointerdown' && event.type !== 'mousedown') {
          return false;
        }
        if (button.contains(event.target)) return false;

        const rect = button.getBoundingClientRect();
        const x = event.clientX;
        const y = event.clientY;
        return x >= rect.left && x <= rect.right && y >= rect.top && y <= rect.bottom;
      }

      function eventMatchesLoginTrigger(event) {
        const path = event.composedPath ? event.composedPath() : [event.target];
        for (let i = 0; i < path.length; i++) {
          if (resolveLoginTrigger(path[i])) return true;
        }
        return false;
      }

      function resolveLoginTrigger(node) {
        if (!(node instanceof Element)) return null;

        if (node.id === 'login-button') return node;
        if (node.getAttribute('data-testid') === 'login-button') return node;

        const clickable = node.matches(CLICKABLE_SELECTORS)
          ? node
          : node.closest(CLICKABLE_SELECTORS);
        if (!clickable) return null;

        if (clickable.id === 'login-button') return clickable;
        if (clickable.getAttribute('data-testid') === 'login-button') return clickable;

        const href = (clickable.getAttribute('href') || '').toLowerCase();
        if (href.includes('/login')) return clickable;

        const label = nodeLabel(clickable);
        if (!LOGIN_PATTERN.test(label)) return null;

        if (clickable.closest(HEADER_SELECTORS)) return clickable;

        const rect = clickable.getBoundingClientRect();
        if (rect.top >= 0 && rect.top < 96 && rect.width > 0 && rect.height > 0) {
          return clickable;
        }

        return null;
      }

      function isLoginTriggerElement(node) {
        return resolveLoginTrigger(node) !== null;
      }

      function isAuthModal(element) {
        if (!(element instanceof Element)) return false;
        if (element.matches(
          'auth-flow-modal, [data-testid="login-modal"], #credentials-login-popup, shreddit-signup-drawer'
        )) {
          return true;
        }
        if (element.matches('shreddit-overlay-display')) {
          return !!element.querySelector(
            'shreddit-signup-drawer, auth-flow-modal, input[type="password"]'
          );
        }
        if (element.matches('faceplate-modal')) {
          const label = nodeLabel(element);
          return LOGIN_PATTERN.test(label) || !!element.querySelector('input[type="password"]');
        }
        return false;
      }

      window.__reddoraCloseRedditAuthModal = function() {
        document.querySelectorAll(AUTH_MODAL_SELECTORS).forEach(function(element) {
          if (!isAuthModal(element)) return;
          const closeButton = element.querySelector(
            '[aria-label="Close"], [aria-label="close"], button[close]'
          );
          if (closeButton) {
            closeButton.click();
          } else {
            element.remove();
          }
        });
      };

      function bindDirectLoginListeners(root) {
        function walk(node) {
          if (!(node instanceof Element)) return;

          const trigger = resolveLoginTrigger(node);
          if (trigger && !boundLoginTriggers.has(trigger)) {
            boundLoginTriggers.add(trigger);
            ['pointerdown', 'mousedown', 'click'].forEach(function(type) {
              trigger.addEventListener(type, interceptLoginEvent, true);
            });
          }

          if (node.shadowRoot) walk(node.shadowRoot);
          const children = node.children;
          for (let i = 0; i < children.length; i++) {
            walk(children[i]);
          }
        }

        walk(root || document.documentElement);
      }

      function installAuthModalBlocker() {
        if (isLoginPage()) return;

        const STYLE_ID = 'reddora-auth-block-style';
        if (!document.getElementById(STYLE_ID)) {
          const style = document.createElement('style');
          style.id = STYLE_ID;
          style.textContent = [
            'auth-flow-modal,',
            '[data-testid="login-modal"],',
            '#credentials-login-popup,',
            'shreddit-signup-drawer {',
            '  display: none !important;',
            '  pointer-events: none !important;',
            '}'
          ].join('\\n');
          (document.head || document.documentElement).appendChild(style);
        }

        const observer = new MutationObserver(function() {
          if (isLoginPage()) return;
          bindDirectLoginListeners(document.documentElement);

          let foundAuthModal = false;
          document.querySelectorAll(AUTH_MODAL_SELECTORS).forEach(function(element) {
            if (!isAuthModal(element)) return;
            foundAuthModal = true;
            element.remove();
          });
          if (foundAuthModal) {
            requestInAppLogin();
          }
        });

        observer.observe(document.documentElement, { childList: true, subtree: true });
      }

      ['pointerdown', 'mousedown', 'click'].forEach(function(type) {
        document.addEventListener(type, interceptLoginEvent, true);
      });

      bindDirectLoginListeners(document.documentElement);
      installAuthModalBlocker();

      [250, 750, 1500, 3000].forEach(function(delay) {
        setTimeout(function() {
          bindDirectLoginListeners(document.documentElement);
        }, delay);
      });
    })();
    """

    static let closeAuthModalScript = "window.__reddoraCloseRedditAuthModal && window.__reddoraCloseRedditAuthModal();"
}