/**
 * Change Highlighting Component
 * Displays visual indicators for recent changes in the editor
 */

import { Component, createEffect, createSignal, onMount, For } from 'solid-js';
import { Doc, Text } from 'yjs';
import { ChangeTracker, DocumentChange } from '../../lib/collaboration/change-tracker';

export interface ChangeHighlight {
  id: string;
  position: number;
  length: number;
  type: 'insert' | 'delete' | 'format' | 'move';
  userId: string;
  userName: string;
  timestamp: Date;
  color: string;
  accepted: boolean;
}

export interface ChangeHighlightingProps {
  doc: Doc;
  changeTracker: ChangeTracker;
  userId: string;
  showAccepted?: boolean;
  showRejected?: boolean;
  highlightDurationMs?: number;
}

export const ChangeHighlighting: Component<ChangeHighlightingProps> = (props) => {
  const [highlights, setHighlights] = createSignal<ChangeHighlight[]>([]);
  const [showHighlights, setShowHighlights] = createSignal(true);

  const showAccepted = props.showAccepted ?? true;
  const showRejected = props.showRejected ?? false;
  const highlightDurationMs = props.highlightDurationMs ?? 30000; // 30 seconds default

  // Color map for users
  const userColors = new Map<string, string>();
  const colors = [
    'rgba(239, 68, 68, 0.3)',    // red
    'rgba(59, 130, 246, 0.3)',   // blue
    'rgba(34, 197, 94, 0.3)',    // green
    'rgba(234, 179, 8, 0.3)',    // yellow
    'rgba(168, 85, 247, 0.3)',   // purple
    'rgba(236, 72, 153, 0.3)',   // pink
  ];

  const getUserColor = (userId: string): string => {
    if (!userColors.has(userId)) {
      let hash = 0;
      for (let i = 0; i < userId.length; i++) {
        hash = userId.charCodeAt(i) + ((hash << 5) - hash);
      }
      userColors.set(userId, colors[Math.abs(hash) % colors.length]!);
    }
    return userColors.get(userId)!;
  };

  onMount(() => {
    // Subscribe to change events
    props.changeTracker.onChange((change) => {
      const highlight: ChangeHighlight = {
        id: change.id,
        position: change.position,
        length: change.length,
        type: change.type,
        userId: change.userId,
        userName: change.userName,
        timestamp: change.timestamp,
        color: getUserColor(change.userId),
        accepted: change.accepted,
      };

      setHighlights((prev) => [...prev, highlight]);

      // Auto-remove highlight after duration
      setTimeout(() => {
        setHighlights((prev) => prev.filter((h) => h.id !== change.id));
      }, highlightDurationMs);
    });
  });

  // Filter highlights based on acceptance status
  const filteredHighlights = () => {
    return highlights().filter((h) => {
      if (h.accepted && !showAccepted) return false;
      if (!h.accepted && !showRejected) return false;
      return true;
    });
  };

  // Get highlight style for a position
  const getHighlightStyle = (position: number): string => {
    const highlight = filteredHighlights().find(
      (h) => position >= h.position && position < h.position + h.length
    );

    if (highlight) {
      return `background-color: ${highlight.color};`;
    }

    return '';
  };

  // Toggle highlight visibility
  const toggleHighlights = () => {
    setShowHighlights(!showHighlights());
  };

  return (
    <div class="change-highlighting">
      <div class="change-highlight-controls">
        <button onClick={toggleHighlights} class="toggle-highlights-btn">
          {showHighlights() ? 'Hide Changes' : 'Show Changes'}
        </button>
        <span class="change-count">
          {filteredHighlights().length} active changes
        </span>
      </div>

      {showHighlights() && (
        <div class="change-highlight-overlay">
          <For each={filteredHighlights()}>
            {(highlight) => (
              <div
                class="change-highlight-marker"
                style={{
                  left: `${highlight.position}px`,
                  width: `${highlight.length * 8.4}px`, // Approximate char width
                  'background-color': highlight.color,
                }}
                title={`${highlight.userName} - ${highlight.type} at ${highlight.timestamp.toLocaleTimeString()}`}
              />
            )}
          </For>
        </div>
      )}

      <style>{`
        .change-highlighting {
          position: relative;
        }

        .change-highlight-controls {
          display: flex;
          align-items: center;
          gap: 12px;
          padding: 8px;
          background: #f5f5f5;
          border-bottom: 1px solid #e0e0e0;
        }

        .toggle-highlights-btn {
          padding: 4px 12px;
          border: 1px solid #ccc;
          border-radius: 4px;
          background: white;
          cursor: pointer;
          font-size: 12px;
        }

        .toggle-highlights-btn:hover {
          background: #f0f0f0;
        }

        .change-count {
          font-size: 12px;
          color: #666;
        }

        .change-highlight-overlay {
          position: absolute;
          top: 0;
          left: 0;
          right: 0;
          bottom: 0;
          pointer-events: none;
          z-index: 10;
        }

        .change-highlight-marker {
          position: absolute;
          height: 20px;
          border-radius: 2px;
          transition: opacity 0.3s ease;
        }
      `}</style>
    </div>
  );
};

export default ChangeHighlighting;