import React, { useState } from 'react';
import { useSessions } from '../../hooks/useSleepSession';
import { useSettings } from '../../hooks/useSettings';
import { Pagination } from './Pagination';
import { Edit2, Check, X, Trash2 } from 'lucide-react';
import type { SleepSessionRead } from '../../types';
import { formatDateTime, toLocalDatetimeInputValue, getDurationMinutes, formatMinutes } from '../../utils/time';

export function SessionList() {
  const { sessions, isLoading, updateSession, deleteSession, isDeleting } = useSessions();
  const { settings } = useSettings();
  const sessionsPerPage = settings.sessionsPerPage;

  const [currentPage, setCurrentPage] = useState(1);
  const [editingId, setEditingId] = useState<number | null>(null);
  const [editStart, setEditStart] = useState<string>('');
  const [editEnd, setEditEnd] = useState<string>('');

  const totalPages = Math.ceil(sessions.length / sessionsPerPage);
  const clampedPage = Math.max(1, Math.min(currentPage, totalPages || 1));

  const paginatedSessions = sessions.slice(
    (clampedPage - 1) * sessionsPerPage,
    clampedPage * sessionsPerPage
  );

  if (isLoading) return <div className="text-center p-4">Loading sessions...</div>;
  if (!sessions.length) return <div className="text-center p-4 text-gray-500">No sessions recorded.</div>;

  const handleSave = async (id: number) => {
    try {
       await updateSession({
         sessionId: id,
         payload: {
           start_time: new Date(editStart).toISOString(),
           end_time: editEnd ? new Date(editEnd).toISOString() : undefined,
         }
       });
      setEditingId(null);
    } catch (err) {
      console.error(err);
      alert('Failed to update session');
    }
  };

  const handleDelete = async (e: React.MouseEvent, id: number) => {
    e.stopPropagation();
    if (window.confirm('Are you sure you want to delete this sleep session?')) {
      try {
        await deleteSession(id);
      } catch (err) {
        console.error(err);
        alert('Failed to delete session');
      }
    }
  };

  const startEditing = (s: SleepSessionRead) => {
    setEditingId(s.id);
    setEditStart(toLocalDatetimeInputValue(new Date(s.start_time)));
    setEditEnd(s.end_time ? toLocalDatetimeInputValue(new Date(s.end_time)) : '');
  };

  const handleCancel = () => {
    setEditingId(null);
  };

  return (
    <div className="session-list bg-white p-4 rounded-xl shadow-sm border border-gray-200">
      <h3 className="text-lg font-semibold mb-4 text-gray-800">Sleep Sessions</h3>
      <div className="space-y-2">
        {paginatedSessions.map((s) => (
          <div key={s.id} className="border-b border-gray-100 last:border-0 py-3 sm:py-2">
            {editingId === s.id ? (
              <div className="flex flex-col space-y-3 py-1">
                <div className="grid grid-cols-1 gap-3 text-xs text-gray-500">
                  <div className="flex flex-col gap-1">
                    <span className="font-medium text-gray-700">Start Time</span>
                    <input
                      type="datetime-local"
                      className="border rounded px-2 py-1.5 text-sm text-black w-full focus:ring-2 focus:ring-blue-500 outline-none"
                      value={editStart}
                      onChange={(e) => setEditStart(e.target.value)}
                    />
                  </div>
                  <div className="flex flex-col gap-1">
                    <span className="font-medium text-gray-700">End Time</span>
                    <input
                      type="datetime-local"
                      className="border rounded px-2 py-1.5 text-sm text-black w-full focus:ring-2 focus:ring-blue-500 outline-none"
                      value={editEnd}
                      onChange={(e) => setEditEnd(e.target.value)}
                    />
                  </div>
                </div>
                <div className="flex justify-end space-x-4">
                  <button 
                    onClick={handleCancel} 
                    className="flex items-center gap-1 px-3 py-1.5 text-sm text-gray-500 hover:text-gray-700 bg-gray-100 rounded-lg transition-colors"
                    title="Cancel"
                  >
                    <X size={16} />
                    <span>Cancel</span>
                  </button>
                  <button 
                    onClick={() => handleSave(s.id)} 
                    className="flex items-center gap-1 px-3 py-1.5 text-sm text-white bg-green-600 hover:text-green-700 rounded-lg transition-colors"
                    title="Save"
                  >
                    <Check size={16} />
                    <span>Save</span>
                  </button>
                </div>
              </div>
            ) : (
              <div 
                className="flex flex-col sm:flex-row sm:justify-between sm:items-center cursor-pointer hover:bg-gray-50 transition-colors rounded-lg px-2"
                onClick={() => startEditing(s)}
              >
                <div className="flex flex-col sm:flex-row sm:items-baseline sm:gap-3">
                  <div className="flex flex-col sm:flex-row sm:items-baseline sm:gap-2">
                    <span className="text-gray-900 font-bold text-base sm:text-sm">
                      {formatDateTime(s.start_time)}
                    </span>
                    <span className="text-blue-600 font-semibold text-xs sm:text-sm">
                      {s.end_time && s.start_time ? formatMinutes(getDurationMinutes(s.start_time, s.end_time)) : '—'}
                    </span>
                  </div>
                  <span className="text-gray-500 text-xs">
                    {s.end_time ? `${formatDateTime(s.start_time)} → ${formatDateTime(s.end_time)}` : 'In progress'}
                  </span>
                </div>

                <div className="flex items-center justify-end space-x-2 sm:space-x-4 pt-3 sm:pt-0">
                  <div className="flex items-center gap-2 sm:hidden text-blue-600 font-semibold text-sm">
                    <span>{s.end_time && s.start_time ? formatMinutes(getDurationMinutes(s.start_time, s.end_time)) : '—'}</span>
                  </div>
                  <div className="flex items-center gap-1 sm:gap-2">
                    <button
                      onClick={(e) => handleDelete(e, s.id)}
                      disabled={isDeleting}
                      className="p-2 text-red-400 hover:text-red-600 disabled:opacity-50 transition-colors"
                      title="Delete session"
                    >
                      <Trash2 size={18} />
                    </button>
                    <div className="p-2 text-gray-400">
                      <Edit2 size={18} />
                    </div>
                  </div>
                </div>
              </div>
            )}
          </div>
        ))}
      </div>
      {sessions.length > sessionsPerPage && (
        <Pagination 
          currentPage={clampedPage} 
          totalPages={totalPages} 
          onPageChange={setCurrentPage} 
        />
      )}
    </div>
  );
}