import React, { useState, useEffect, useCallback } from 'react';
import { useAuth } from '../context/AuthContext';
import { useToast } from '../components/Toast';
import api from '../api/axios';
import { formatLocalDateTime, formatLocalDate, formatLocalTime } from '../utils/dateUtils';
import PopularityBadge from '../components/PopularityBadge';

function History() {
  const { isAuthenticated } = useAuth();
  const { error, success } = useToast();
  const [sessions, setSessions] = useState([]);
  const [selectedSession, setSelectedSession] = useState(null);
  const [sessionGames, setSessionGames] = useState([]);
  const [loading, setLoading] = useState(true);
  const [showChatImport, setShowChatImport] = useState(false);
  const [closingSession, setClosingSession] = useState(null);
  const [showAllSessions, setShowAllSessions] = useState(false);
  const [deletingSession, setDeletingSession] = useState(null);

  const loadSessions = useCallback(async () => {
    try {
      const response = await api.get('/sessions');
      setSessions(response.data);
    } catch (err) {
      console.error('Failed to load sessions', err);
    } finally {
      setLoading(false);
    }
  }, []);

  const refreshSessionGames = useCallback(async (sessionId, silent = false) => {
    try {
      const response = await api.get(`/sessions/${sessionId}/games`);
      // Reverse chronological order (most recent first)
      setSessionGames(response.data.reverse());
    } catch (err) {
      if (!silent) {
        console.error('Failed to load session games', err);
      }
    }
  }, []);

  useEffect(() => {
    loadSessions();
  }, [loadSessions]);

  // Auto-select active session if navigating from picker
  useEffect(() => {
    if (sessions.length > 0 && !selectedSession) {
      const activeSession = sessions.find(s => s.is_active === 1);
      if (activeSession) {
        loadSessionGames(activeSession.id);
      }
    }
  }, [sessions, selectedSession]);

  // Poll for session list updates (to detect when sessions end/start)
  useEffect(() => {
    const interval = setInterval(() => {
      loadSessions();
    }, 3000);
    
    return () => clearInterval(interval);
  }, [loadSessions]);

  // Poll for updates on active session games
  useEffect(() => {
    if (!selectedSession) return;
    
    const currentSession = sessions.find(s => s.id === selectedSession);
    if (!currentSession || currentSession.is_active !== 1) return;
    
    // Refresh games every 3 seconds for active session
    const interval = setInterval(() => {
      refreshSessionGames(selectedSession, true); // silent refresh
    }, 3000);
    
    return () => clearInterval(interval);
  }, [selectedSession, sessions, refreshSessionGames]);

  const handleExport = async (sessionId, format) => {
    try {
      const response = await api.get(`/sessions/${sessionId}/export?format=${format}`, {
        responseType: 'blob'
      });
      
      // Create download link
      const url = window.URL.createObjectURL(new Blob([response.data]));
      const link = document.createElement('a');
      link.href = url;
      link.setAttribute('download', `session-${sessionId}.${format === 'json' ? 'json' : 'txt'}`);
      document.body.appendChild(link);
      link.click();
      link.parentNode.removeChild(link);
      window.URL.revokeObjectURL(url);
      
      success(`Session exported as ${format.toUpperCase()}`);
    } catch (err) {
      console.error('Failed to export session', err);
      error('Failed to export session');
    }
  };

  const loadSessionGames = async (sessionId, silent = false) => {
    try {
      const response = await api.get(`/sessions/${sessionId}/games`);
      setSessionGames(response.data);
      if (!silent) {
        setSelectedSession(sessionId);
      }
    } catch (err) {
      if (!silent) {
        console.error('Failed to load session games', err);
      }
    }
  };

  const handleCloseSession = async (sessionId, notes) => {
    try {
      await api.post(`/sessions/${sessionId}/close`, { notes });
      await loadSessions();
      setClosingSession(null);
      if (selectedSession === sessionId) {
        // Reload the session details to show updated state
        loadSessionGames(sessionId);
      }
      success('Session ended successfully');
    } catch (err) {
      error('Failed to close session');
    }
  };

  const handleDeleteSession = async (sessionId) => {
    try {
      await api.delete(`/sessions/${sessionId}`);
      await loadSessions();
      setDeletingSession(null);
      if (selectedSession === sessionId) {
        setSelectedSession(null);
        setSessionGames([]);
      }
      success('Session deleted successfully');
    } catch (err) {
      error('Failed to delete session: ' + (err.response?.data?.error || err.message));
    }
  };

  if (loading) {
    return (
      <div className="flex justify-center items-center h-64">
        <div className="text-xl text-gray-600 dark:text-gray-400">Loading...</div>
      </div>
    );
  }

  return (
    <div className="max-w-7xl mx-auto">
      <h1 className="text-4xl font-bold mb-8 text-gray-800 dark:text-gray-100">Session History</h1>

      <div className="grid md:grid-cols-3 gap-6">
        {/* Sessions List */}
        <div className="md:col-span-1">
          <div className="bg-white dark:bg-gray-800 rounded-lg shadow-lg p-6">
            <div className="flex justify-between items-center mb-4">
              <h2 className="text-2xl font-semibold text-gray-800 dark:text-gray-100">Sessions</h2>
              {sessions.length > 3 && (
                <button
                  onClick={() => setShowAllSessions(!showAllSessions)}
                  className="text-sm text-indigo-600 dark:text-indigo-400 hover:text-indigo-800 dark:hover:text-indigo-300 transition"
                >
                  {showAllSessions ? 'Show Recent' : `Show All (${sessions.length})`}
                </button>
              )}
            </div>
            
            {sessions.length === 0 ? (
              <p className="text-gray-500 dark:text-gray-400">No sessions found</p>
            ) : (
              <div className="space-y-1 max-h-[600px] overflow-y-auto">
                {(showAllSessions ? sessions : sessions.slice(0, 3)).map(session => (
                  <div
                    key={session.id}
                    className={`border rounded-lg transition ${
                      selectedSession === session.id
                        ? 'border-indigo-500 bg-indigo-50 dark:bg-indigo-900/30'
                        : 'border-gray-300 dark:border-gray-600 hover:border-indigo-300 dark:hover:border-indigo-600'
                    }`}
                  >
                    {/* Main session info - clickable */}
                    <div 
                      onClick={() => loadSessionGames(session.id)}
                      className="p-3 cursor-pointer"
                    >
                      <div className="flex flex-col sm:flex-row sm:justify-between sm:items-center gap-2">
                        <div className="flex-1 min-w-0">
                          <div className="flex items-center gap-2 mb-1">
                            <span className="font-semibold text-sm text-gray-800 dark:text-gray-100">
                              Session #{session.id}
                            </span>
                            {session.is_active === 1 && (
                              <span className="bg-green-100 dark:bg-green-900 text-green-800 dark:text-green-200 text-xs px-2 py-0.5 rounded flex-shrink-0">
                                Active
                              </span>
                            )}
                          </div>
                          <div className="flex flex-wrap gap-x-2 text-xs text-gray-500 dark:text-gray-400">
                            <span>{formatLocalDate(session.created_at)}</span>
                            <span>•</span>
                            <span>{session.games_played} game{session.games_played !== 1 ? 's' : ''}</span>
                          </div>
                        </div>
                      </div>
                    </div>
                    
                    {/* Action buttons for authenticated users */}
                    {isAuthenticated && (
                      <div className="px-3 pb-3 pt-0 flex gap-2">
                        {session.is_active === 1 ? (
                          <button
                            onClick={(e) => {
                              e.stopPropagation();
                              setClosingSession(session.id);
                            }}
                            className="w-full bg-orange-600 dark:bg-orange-700 text-white px-4 py-2 rounded text-sm hover:bg-orange-700 dark:hover:bg-orange-800 transition"
                          >
                            End Session
                          </button>
                        ) : (
                          <button
                            onClick={(e) => {
                              e.stopPropagation();
                              setDeletingSession(session.id);
                            }}
                            className="w-full bg-red-600 dark:bg-red-700 text-white px-4 py-2 rounded text-sm hover:bg-red-700 dark:hover:bg-red-800 transition"
                          >
                            Delete Session
                          </button>
                        )}
                      </div>
                    )}
                  </div>
                ))}
              </div>
            )}
          </div>
        </div>

        {/* Session Details */}
        <div className="md:col-span-2">
          {selectedSession ? (
            <div className="bg-white dark:bg-gray-800 rounded-lg shadow-lg p-4 sm:p-6">
              <div className="flex flex-col gap-4 mb-6">
                <div className="flex-1">
                  <div className="flex flex-col sm:flex-row sm:items-center gap-2 mb-2">
                    <h2 className="text-xl sm:text-2xl font-semibold text-gray-800 dark:text-gray-100">
                      Session #{selectedSession}
                    </h2>
                    {sessions.find(s => s.id === selectedSession)?.is_active === 1 && (
                      <span className="bg-green-100 dark:bg-green-900 text-green-800 dark:text-green-200 text-xs sm:text-sm px-2 sm:px-3 py-1 rounded-full font-semibold animate-pulse inline-flex items-center gap-1 w-fit">
                        🟢 Active
                      </span>
                    )}
                  </div>
                  <p className="text-sm sm:text-base text-gray-600 dark:text-gray-400">
                    {sessions.find(s => s.id === selectedSession)?.created_at && 
                      formatLocalDateTime(sessions.find(s => s.id === selectedSession).created_at)}
                  </p>
                  {sessions.find(s => s.id === selectedSession)?.is_active === 1 && (
                    <p className="text-xs sm:text-sm text-gray-500 dark:text-gray-500 mt-1 italic">
                      Games update automatically
                    </p>
                  )}
                </div>
                
                <div className="flex flex-col sm:flex-row gap-2">
                  {isAuthenticated && sessions.find(s => s.id === selectedSession)?.is_active === 1 && (
                    <button
                      onClick={() => setShowChatImport(true)}
                      className="bg-indigo-600 dark:bg-indigo-700 text-white px-4 py-2 rounded-lg hover:bg-indigo-700 dark:hover:bg-indigo-800 transition text-sm sm:text-base w-full sm:w-auto"
                    >
                      Import Chat Log
                    </button>
                  )}
                  {isAuthenticated && (
                    <>
                      <button
                        onClick={() => handleExport(selectedSession, 'txt')}
                        className="bg-gray-600 dark:bg-gray-700 text-white px-4 py-2 rounded-lg hover:bg-gray-700 dark:hover:bg-gray-800 transition text-sm sm:text-base w-full sm:w-auto"
                      >
                        Export as Text
                      </button>
                      <button
                        onClick={() => handleExport(selectedSession, 'json')}
                        className="bg-gray-600 dark:bg-gray-700 text-white px-4 py-2 rounded-lg hover:bg-gray-700 dark:hover:bg-gray-800 transition text-sm sm:text-base w-full sm:w-auto"
                      >
                        Export as JSON
                      </button>
                    </>
                  )}
                </div>
              </div>

              {showChatImport && (
                <ChatImportPanel
                  sessionId={selectedSession}
                  onClose={() => setShowChatImport(false)}
                  onImportComplete={() => {
                    loadSessionGames(selectedSession);
                    setShowChatImport(false);
                  }}
                />
              )}

              {sessionGames.length === 0 ? (
                <p className="text-gray-500 dark:text-gray-400">No games played in this session</p>
              ) : (
                <div>
                  <h3 className="text-xl font-semibold mb-4 text-gray-700 dark:text-gray-200">
                    Games Played ({sessionGames.length})
                  </h3>
                  <div className="space-y-3">
                    {[...sessionGames].reverse().map((game, index) => (
                      <div key={game.id} className="border border-gray-200 dark:border-gray-700 rounded-lg p-4 bg-gray-50 dark:bg-gray-700/50">
                        <div className="flex justify-between items-start mb-2">
                          <div>
                            <div className="font-semibold text-lg text-gray-800 dark:text-gray-100">
                              {sessionGames.length - index}. {game.title}
                            </div>
                            <div className="text-gray-600 dark:text-gray-400">{game.pack_name}</div>
                          </div>
                          <div className="text-right">
                            <div className="text-sm text-gray-500 dark:text-gray-400">
                              {formatLocalTime(game.played_at)}
                            </div>
                            {game.manually_added === 1 && (
                              <span className="inline-block mt-1 text-xs bg-yellow-100 dark:bg-yellow-900 text-yellow-800 dark:text-yellow-200 px-2 py-1 rounded">
                                Manual
                              </span>
                            )}
                          </div>
                        </div>
                        
                        <div className="grid grid-cols-2 md:grid-cols-4 gap-2 text-sm text-gray-600 dark:text-gray-400">
                          <div>
                            <span className="font-semibold">Players:</span> {game.min_players}-{game.max_players}
                          </div>
                          <div>
                            <span className="font-semibold">Type:</span> {game.game_type || 'N/A'}
                          </div>
                          <div className="flex items-center gap-2">
                            <span 
                              className="font-semibold"
                              title="Popularity is cumulative across all sessions where this game was played"
                            >
                              Popularity:
                            </span>
                            <PopularityBadge 
                              upvotes={game.upvotes || 0}
                              downvotes={game.downvotes || 0}
                              popularityScore={game.popularity_score || 0}
                              size="sm"
                              showCounts={true}
                              showNet={true}
                              showRatio={true}
                            />
                          </div>
                        </div>
                      </div>
                    ))}
                  </div>
                </div>
              )}
            </div>
          ) : (
            <div className="bg-white dark:bg-gray-800 rounded-lg shadow-lg p-6 flex items-center justify-center h-64">
              <p className="text-gray-500 dark:text-gray-400 text-lg">Select a session to view details</p>
            </div>
          )}
        </div>
      </div>

      {/* End Session Modal */}
      {closingSession && (
        <EndSessionModal
          sessionId={closingSession}
          sessionGames={closingSession === selectedSession ? sessionGames : []}
          onClose={() => setClosingSession(null)}
          onConfirm={handleCloseSession}
          onShowChatImport={() => {
            setShowChatImport(true);
            if (closingSession !== selectedSession) {
              loadSessionGames(closingSession);
            }
          }}
        />
      )}

      {/* Delete Confirmation Modal */}
      {deletingSession && (
        <div className="fixed inset-0 bg-black bg-opacity-50 flex items-center justify-center z-50 p-4">
          <div className="bg-white dark:bg-gray-800 rounded-lg p-8 max-w-md w-full">
            <h2 className="text-2xl font-bold mb-4 text-red-600 dark:text-red-400">Delete Session?</h2>
            <p className="text-gray-700 dark:text-gray-300 mb-6">
              Are you sure you want to delete Session #{deletingSession}? 
              This will permanently delete all games and chat logs associated with this session. This action cannot be undone.
            </p>
            <div className="flex gap-4">
              <button
                onClick={() => handleDeleteSession(deletingSession)}
                className="flex-1 bg-red-600 dark:bg-red-700 text-white py-3 rounded-lg hover:bg-red-700 dark:hover:bg-red-800 transition font-semibold"
              >
                Delete Permanently
              </button>
              <button
                onClick={() => setDeletingSession(null)}
                className="flex-1 bg-gray-600 dark:bg-gray-700 text-white py-3 rounded-lg hover:bg-gray-700 dark:hover:bg-gray-800 transition"
              >
                Cancel
              </button>
            </div>
          </div>
        </div>
      )}
    </div>
  );
}

function EndSessionModal({ sessionId, sessionGames, onClose, onConfirm, onShowChatImport }) {
  const [notes, setNotes] = useState('');
  
  // Check if any games have been voted on (popularity != 0)
  const hasPopularityData = sessionGames.some(game => game.popularity_score !== 0);
  const showPopularityWarning = sessionGames.length > 0 && !hasPopularityData;

  return (
    <div className="fixed inset-0 bg-black bg-opacity-50 flex items-center justify-center z-50 p-4">
      <div className="bg-white dark:bg-gray-800 rounded-lg p-8 max-w-md w-full">
        <h2 className="text-2xl font-bold mb-4 dark:text-gray-100">End Session #{sessionId}</h2>
        
        {/* Popularity Warning */}
        {showPopularityWarning && (
          <div className="mb-4 p-4 bg-yellow-50 dark:bg-yellow-900/30 border border-yellow-300 dark:border-yellow-700 rounded-lg">
            <div className="flex items-start gap-2">
              <span className="text-yellow-600 dark:text-yellow-400 text-xl">⚠️</span>
              <div className="flex-1">
                <p className="font-semibold text-yellow-800 dark:text-yellow-200 mb-1">
                  No Popularity Data
                </p>
                <p className="text-sm text-yellow-700 dark:text-yellow-300 mb-3">
                  You haven't imported chat reactions yet. Import now to track which games your players loved!
                </p>
                <button
                  onClick={() => {
                    onClose();
                    onShowChatImport();
                  }}
                  className="text-sm bg-yellow-600 dark:bg-yellow-700 text-white px-4 py-2 rounded hover:bg-yellow-700 dark:hover:bg-yellow-800 transition"
                >
                  Import Chat Log
                </button>
              </div>
            </div>
          </div>
        )}
        
        <div className="mb-4">
          <label className="block text-gray-700 dark:text-gray-300 font-semibold mb-2">
            Session Notes (optional)
          </label>
          <textarea
            value={notes}
            onChange={(e) => setNotes(e.target.value)}
            className="w-full px-4 py-2 border border-gray-300 dark:border-gray-600 rounded-lg h-32 bg-white dark:bg-gray-700 text-gray-900 dark:text-gray-100"
            placeholder="Add any notes about this session..."
          />
        </div>
        
        <div className="flex gap-4">
          <button
            onClick={() => onConfirm(sessionId, notes)}
            className="flex-1 bg-orange-600 dark:bg-orange-700 text-white py-3 rounded-lg hover:bg-orange-700 dark:hover:bg-orange-800 transition"
          >
            End Session
          </button>
          <button
            onClick={onClose}
            className="flex-1 bg-gray-600 dark:bg-gray-700 text-white py-3 rounded-lg hover:bg-gray-700 dark:hover:bg-gray-800 transition"
          >
            Cancel
          </button>
        </div>
      </div>
    </div>
  );
}

function ChatImportPanel({ sessionId, onClose, onImportComplete }) {
  const [chatData, setChatData] = useState('');
  const [importing, setImporting] = useState(false);
  const [result, setResult] = useState(null);
  const { error, success } = useToast();

  const handleFileUpload = async (event) => {
    const file = event.target.files[0];
    if (!file) return;

    try {
      const text = await file.text();
      setChatData(text);
      success('File loaded successfully');
    } catch (err) {
      error('Failed to read file: ' + err.message);
    }
  };

  const handleImport = async () => {
    if (!chatData.trim()) {
      error('Please enter chat data or upload a file');
      return;
    }

    setImporting(true);
    setResult(null);

    try {
      const parsedData = JSON.parse(chatData);
      const response = await api.post(`/sessions/${sessionId}/chat-import`, {
        chatData: parsedData
      });
      setResult(response.data);
      success('Chat log imported successfully');
      setTimeout(() => {
        onImportComplete();
      }, 2000);
    } catch (err) {
      error('Import failed: ' + (err.response?.data?.error || err.message));
    } finally {
      setImporting(false);
    }
  };

  return (
    <div className="bg-gray-50 dark:bg-gray-700/50 border border-gray-300 dark:border-gray-600 rounded-lg p-6 mb-6">
      <h3 className="text-xl font-semibold mb-4 dark:text-gray-100">Import Chat Log</h3>
      
      <p className="text-sm text-gray-600 dark:text-gray-400 mb-4">
        Upload a JSON file or paste JSON array with format: [{"{"}"username": "...", "message": "...", "timestamp": "..."{"}"}]
        <br />
        The system will detect "thisgame++" and "thisgame--" patterns and update game popularity.
        <br />
        <span className="text-xs italic">
          Note: Popularity is cumulative - votes are added to each game's all-time totals.
        </span>
      </p>
      
      {/* File Upload */}
      <div className="mb-4">
        <label className="block text-gray-700 dark:text-gray-300 font-semibold mb-2">Upload JSON File</label>
        <input
          type="file"
          accept=".json"
          onChange={handleFileUpload}
          disabled={importing}
          className="block w-full text-sm text-gray-900 dark:text-gray-100 
                     file:mr-4 file:py-2 file:px-4
                     file:rounded-lg file:border-0
                     file:text-sm file:font-semibold
                     file:bg-indigo-50 file:text-indigo-700
                     dark:file:bg-indigo-900/30 dark:file:text-indigo-300
                     hover:file:bg-indigo-100 dark:hover:file:bg-indigo-900/50
                     file:cursor-pointer cursor-pointer
                     disabled:opacity-50 disabled:cursor-not-allowed"
        />
      </div>

      <div className="mb-4 text-center text-gray-500 dark:text-gray-400 text-sm">
        — or —
      </div>
      
      <div className="mb-4">
        <label className="block text-gray-700 dark:text-gray-300 font-semibold mb-2">Paste Chat JSON Data</label>
        <textarea
          value={chatData}
          onChange={(e) => setChatData(e.target.value)}
          className="w-full px-4 py-2 border border-gray-300 dark:border-gray-600 rounded-lg h-48 font-mono text-sm bg-white dark:bg-gray-800 text-gray-900 dark:text-gray-100"
          placeholder='[{"username":"Alice","message":"thisgame++","timestamp":"2024-01-01T12:00:00Z"}]'
          disabled={importing}
        />
      </div>
      
      {result && (
        <div className="mb-4 p-4 bg-green-50 dark:bg-green-900/30 border border-green-300 dark:border-green-700 rounded-lg">
          <p className="font-semibold text-green-800 dark:text-green-200">Import Successful!</p>
          <p className="text-sm text-green-700 dark:text-green-300">
            Imported {result.messagesImported} messages, processed {result.votesProcessed} votes
            {result.duplicatesSkipped > 0 && (
              <span className="block mt-1 text-xs italic opacity-75">
                ({result.duplicatesSkipped} duplicate{result.duplicatesSkipped !== 1 ? 's' : ''} skipped)
              </span>
            )}
          </p>
          {result.votesByGame && Object.keys(result.votesByGame).length > 0 && (
            <div className="mt-2 text-sm text-green-700 dark:text-green-300">
              <p className="font-semibold">Votes by game:</p>
              <ul className="list-disc list-inside">
                {Object.values(result.votesByGame).map((vote, i) => (
                  <li key={i}>
                    {vote.title}: +{vote.upvotes} / -{vote.downvotes}
                  </li>
                ))}
              </ul>
              <p className="text-xs mt-2 italic opacity-80">
                Note: Popularity is cumulative across all sessions. If a game is played multiple times, votes apply to the game itself.
              </p>
            </div>
          )}
          
          {/* Debug Info */}
          {result.debug && (
            <details className="mt-4">
              <summary className="cursor-pointer font-semibold text-green-800 dark:text-green-200">
                Debug Info (click to expand)
              </summary>
              <div className="mt-2 text-xs text-green-700 dark:text-green-300 space-y-2">
                {/* Session Timeline */}
                <div>
                  <p className="font-semibold">Session Timeline:</p>
                  <ul className="list-disc list-inside ml-2">
                    {result.debug.sessionGamesTimeline?.map((game, i) => (
                      <li key={i}>
                        {game.title} - {new Date(game.played_at).toLocaleString()}
                      </li>
                    ))}
                  </ul>
                </div>
                
                {/* Vote Matches */}
                {result.debug.voteMatches && result.debug.voteMatches.length > 0 && (
                  <div>
                    <p className="font-semibold">Vote Matches ({result.debug.voteMatches.length}):</p>
                    <ul className="list-disc list-inside ml-2 max-h-48 overflow-y-auto">
                      {result.debug.voteMatches.map((match, i) => (
                        <li key={i}>
                          {match.username}: {match.vote} at {new Date(match.timestamp).toLocaleString()} → matched to "{match.matched_game}" (played at {new Date(match.game_played_at).toLocaleString()})
                        </li>
                      ))}
                    </ul>
                  </div>
                )}
              </div>
            </details>
          )}
        </div>
      )}
      
      <div className="flex gap-4">
        <button
          onClick={handleImport}
          disabled={importing}
          className="bg-indigo-600 text-white px-6 py-2 rounded-lg hover:bg-indigo-700 transition disabled:bg-gray-400 dark:disabled:bg-gray-600"
        >
          {importing ? 'Importing...' : 'Import'}
        </button>
        <button
          onClick={onClose}
          className="bg-gray-600 dark:bg-gray-700 text-white px-6 py-2 rounded-lg hover:bg-gray-700 dark:hover:bg-gray-800 transition"
        >
          Close
        </button>
      </div>
    </div>
  );
}

export default History;