/**
 * Диалог создания занятия в Material Design 3
 */

'use client';

import React, { useState, useEffect } from 'react';
import { loadComponent } from '@/lib/material-components';
import { createLesson } from '@/api/schedule';
import { getErrorMessage } from '@/lib/error-utils';
import { getStudents, Student } from '@/api/students';
import { getSubjects, getMentorSubjects, createMentorSubject, Subject, MentorSubject } from '@/api/subjects';
import { getCurrentUser, User } from '@/api/auth';
import { format } from 'date-fns';
import { DatePicker } from '@/components/common/DatePicker';
import { TimePicker } from '@/components/common/TimePicker';
import { createDateTimeInUserTimezone } from '@/utils/timezone';

interface CreateLessonDialogProps {
  open: boolean;
  onClose: () => void;
  onSuccess: () => void;
  defaultDate?: Date;
}

interface LessonFormData {
  client: string;
  title: string;
  subject_id?: number;
  mentor_subject_id?: number;
  subject_name?: string;
  description: string;
  start_date: string; // YYYY-MM-DD
  start_time: string; // HH:mm
  duration: number;
  price?: number;
  is_recurring: boolean;
}

export const CreateLessonDialog: React.FC<CreateLessonDialogProps> = ({
  open,
  onClose,
  onSuccess,
  defaultDate,
}) => {
  const [componentsLoaded, setComponentsLoaded] = useState(false);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  
  const [students, setStudents] = useState<Student[]>([]);
  const [subjects, setSubjects] = useState<Subject[]>([]);
  const [mentorSubjects, setMentorSubjects] = useState<MentorSubject[]>([]);
  const [currentUser, setCurrentUser] = useState<User | null>(null);
  
  const [selectedSubjectId, setSelectedSubjectId] = useState<number | null>(null);
  const [selectedMentorSubjectId, setSelectedMentorSubjectId] = useState<number | null>(null);
  const [customSubjectName, setCustomSubjectName] = useState<string>('');
  
  const [formData, setFormData] = useState<LessonFormData>({
    client: '',
    title: '',
    description: '',
    start_date: '',
    start_time: '',
    duration: 60,
    price: undefined,
    is_recurring: false,
  });

  useEffect(() => {
    if (open) {
      loadComponents();
      loadData();
    }
  }, [open]);

  useEffect(() => {
    if (open && defaultDate) {
      const start = new Date(defaultDate);
      
      const formatDate = (date: Date) => {
        const year = date.getFullYear();
        const month = String(date.getMonth() + 1).padStart(2, '0');
        const day = String(date.getDate()).padStart(2, '0');
        return `${year}-${month}-${day}`;
      };
      
      const formatTime = (date: Date) => {
        const hours = String(date.getHours()).padStart(2, '0');
        const minutes = String(date.getMinutes()).padStart(2, '0');
        return `${hours}:${minutes}`;
      };
      
      setFormData(prev => ({
        ...prev,
        start_date: formatDate(start),
        start_time: formatTime(start),
      }));
    }
  }, [open, defaultDate]);

  const loadComponents = async () => {
    try {
      await Promise.all([
        loadComponent('dialog'),
        loadComponent('filled-button'),
        loadComponent('text-button'),
        loadComponent('outlined-field'),
        loadComponent('select'),
        loadComponent('switch'),
        loadComponent('icon'),
      ]);
      setComponentsLoaded(true);
    } catch (error) {
      console.error('[CreateLessonDialog] Ошибка загрузки компонентов:', error);
    }
  };

  const loadData = async () => {
    try {
      const [studentsData, subjectsData, mentorSubjectsData, userData] = await Promise.all([
        getStudents({ page_size: 100 }),
        getSubjects(),
        getMentorSubjects(),
        getCurrentUser(),
      ]);
      
      const studentsList = Array.isArray(studentsData) ? studentsData : (studentsData.results || []);
      setStudents(studentsList);
      setSubjects(Array.isArray(subjectsData) ? subjectsData : []);
      setMentorSubjects(Array.isArray(mentorSubjectsData) ? mentorSubjectsData : []);
      setCurrentUser(userData);
    } catch (error) {
      console.error('[CreateLessonDialog] Ошибка загрузки данных:', error);
      setError('Ошибка загрузки данных');
    }
  };

  const generateTitle = (student: Student | null, subjectName: string): string => {
    if (!student || !subjectName || !currentUser) return '';
    
    const mentorName = `${currentUser.last_name} ${currentUser.first_name?.charAt(0) || ''}.`.trim();
    const studentName = `${student.user?.last_name || ''} ${student.user?.first_name?.charAt(0) || ''}.`.trim();
    
    return `${mentorName} ${studentName} ${subjectName}`.trim();
  };

  const getSubjectName = (): string => {
    if (selectedSubjectId) {
      const subject = subjects.find(s => s.id === selectedSubjectId);
      return subject?.name || '';
    }
    if (selectedMentorSubjectId) {
      const subject = mentorSubjects.find(s => s.id === selectedMentorSubjectId);
      return subject?.name || '';
    }
    return customSubjectName || '';
  };

  // Автогенерация названия
  useEffect(() => {
    if (formData.client && getSubjectName() && currentUser) {
      const selectedStudent = students.find(s => String(s.id) === formData.client);
      if (selectedStudent) {
        const subjectName = getSubjectName();
        const generatedTitle = generateTitle(selectedStudent, subjectName);
        setFormData(prev => ({ ...prev, title: generatedTitle }));
      }
    }
  }, [formData.client, selectedSubjectId, selectedMentorSubjectId, customSubjectName, students, currentUser, subjects, mentorSubjects]);

  const handleSubjectChange = async (value: string | number | null, isCustom: boolean, customName?: string) => {
    if (isCustom && customName) {
      setSelectedSubjectId(null);
      setSelectedMentorSubjectId(null);
      setCustomSubjectName(customName);
    } else if (value) {
      const subject = subjects.find(s => s.id === value);
      const mentorSubject = mentorSubjects.find(s => s.id === value);
      
      if (subject) {
        setSelectedSubjectId(subject.id);
        setSelectedMentorSubjectId(null);
        setCustomSubjectName('');
      } else if (mentorSubject) {
        setSelectedSubjectId(null);
        setSelectedMentorSubjectId(mentorSubject.id);
        setCustomSubjectName('');
      }
    } else {
      setSelectedSubjectId(null);
      setSelectedMentorSubjectId(null);
      setCustomSubjectName('');
    }
  };

  const handleCustomSubjectCreate = async (name: string): Promise<void> => {
    const newSubject = await createMentorSubject(name);
    setMentorSubjects(prev => [...prev, newSubject]);
    setSelectedMentorSubjectId(newSubject.id);
    setCustomSubjectName('');
  };

  const handleDateChange = (value: string) => {
    setFormData(prev => ({
      ...prev,
      start_date: value,
    }));
  };

  const handleTimeChange = (value: string) => {
    setFormData(prev => ({
      ...prev,
      start_time: value,
    }));
  };

  const handleDurationChange = (value: number) => {
    setFormData(prev => ({
      ...prev,
      duration: value,
    }));
  };

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    setLoading(true);
    setError(null);

    try {
      if (!formData.client) {
        setError('Выберите ученика');
        setLoading(false);
        return;
      }

      if (!selectedSubjectId && !selectedMentorSubjectId && !customSubjectName) {
        setError('Выберите или введите предмет');
        setLoading(false);
        return;
      }

      if (!formData.start_date || !formData.start_time) {
        setError('Укажите дату и время начала');
        setLoading(false);
        return;
      }

      if (!formData.price || formData.price <= 0) {
        setError('Укажите стоимость занятия');
        setLoading(false);
        return;
      }

      // Объединяем дату и время в ISO строку с учётом timezone пользователя
      const startUtc = createDateTimeInUserTimezone(
        formData.start_date,
        formData.start_time,
        currentUser?.timezone
      );

      const payload: any = {
        client: formData.client,
        title: formData.title || generateTitle(
          students.find(s => String(s.id) === formData.client) || null,
          getSubjectName()
        ),
        description: formData.description,
        start_time: startUtc,
        duration: formData.duration,
        price: formData.price,
        is_recurring: formData.is_recurring,
      };

      if (selectedSubjectId) {
        payload.subject_id = selectedSubjectId;
      } else if (selectedMentorSubjectId) {
        payload.mentor_subject_id = selectedMentorSubjectId;
      } else if (customSubjectName) {
        payload.subject_name = customSubjectName;
      }

      await createLesson(payload);
      
      // Сброс формы
      setFormData({
        client: '',
        title: '',
        description: '',
        start_date: '',
        start_time: '',
        duration: 60,
        price: undefined,
        is_recurring: false,
      });
      setSelectedSubjectId(null);
      setSelectedMentorSubjectId(null);
      setCustomSubjectName('');
      
      onSuccess();
      onClose();
    } catch (err: any) {
      console.error('[CreateLessonDialog] Ошибка создания занятия:', err);
      setError(getErrorMessage(err, 'Не удалось создать занятие. Проверьте данные.'));
    } finally {
      setLoading(false);
    }
  };

  const handleClose = () => {
    if (!loading) {
      setFormData({
        client: '',
        title: '',
        description: '',
        start_date: '',
        start_time: '',
        duration: 60,
        price: undefined,
        is_recurring: false,
      });
      setSelectedSubjectId(null);
      setSelectedMentorSubjectId(null);
      setCustomSubjectName('');
      setError(null);
      onClose();
    }
  };

  if (!open || !componentsLoaded) return null;

  return (
    <>
    <md-dialog
      open={open}
      onCancel={handleClose}
      style={{
        '--md-dialog-container-color': 'var(--md-sys-color-surface)',
        '--md-dialog-headline-color': 'var(--md-sys-color-on-surface)',
        '--md-dialog-supporting-text-color': 'var(--md-sys-color-on-surface-variant)',
      } as React.CSSProperties}
    >
      <div slot="headline" style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', width: '100%' }}>
        <span>Создать занятие</span>
        <button
          type="button"
          onClick={handleClose}
          className="create-lesson-dialog-close"
          aria-label="Закрыть"
          style={{
            all: 'unset',
            cursor: 'pointer',
            display: 'flex',
            alignItems: 'center',
            justifyContent: 'center',
            width: 32,
            height: 32,
            borderRadius: '50%',
            color: 'var(--md-sys-color-on-surface-variant)',
            flexShrink: 0,
          }}
        >
          <span className="material-symbols-outlined" style={{ fontSize: 22 }}>close</span>
        </button>
      </div>
      
      <form slot="content" method="dialog" onSubmit={(e) => { e.preventDefault(); handleSubmit(e); }} className="create-lesson-dialog" style={{ display: 'flex', flexDirection: 'column', gap: '20px', minWidth: 'min(500px, 90vw)', maxWidth: '600px' }}>
        {error && (
          <div style={{
            padding: '12px',
            borderRadius: '8px',
            background: 'var(--md-sys-color-error-container)',
            color: 'var(--md-sys-color-on-error-container)',
            fontSize: '14px',
            whiteSpace: 'pre-wrap',
          }}>
            {error}
          </div>
        )}

        {/* Ученик */}
        <div>
          <label style={{
            display: 'block',
            fontSize: '14px',
            fontWeight: '500',
            color: 'var(--md-sys-color-on-surface)',
            marginBottom: '8px',
          }}>
            Ученик *
          </label>
          <md-outlined-field label="Выберите ученика" style={{ width: '100%' }}>
            <select
              slot="input"
              value={formData.client}
              onChange={(e) => setFormData(prev => ({ ...prev, client: e.target.value }))}
              required
              disabled={loading}
              style={{
                border: 'none',
                outline: 'none',
                background: 'transparent',
                width: '100%',
                fontSize: '16px',
                color: 'var(--md-sys-color-on-surface)',
                fontFamily: 'inherit',
                cursor: loading ? 'not-allowed' : 'pointer',
              }}
            >
              <option value="">Выберите ученика</option>
              {students.map(student => (
                <option key={student.id} value={String(student.id)}>
                  {`${student.user?.first_name || ''} ${student.user?.last_name || ''}`.trim() || student.user?.email || ''}
                </option>
              ))}
            </select>
          </md-outlined-field>
        </div>

        {/* Предмет */}
        <div>
          <label style={{
            display: 'block',
            fontSize: '14px',
            fontWeight: '500',
            color: 'var(--md-sys-color-on-surface)',
            marginBottom: '8px',
          }}>
            Предмет *
          </label>
          <div style={{ display: 'flex', flexDirection: 'column', gap: '12px' }}>
            <md-outlined-field label="Выберите предмет" style={{ width: '100%' }}>
              <select
                slot="input"
                value={selectedSubjectId ? String(selectedSubjectId) : selectedMentorSubjectId ? String(selectedMentorSubjectId) : ''}
                onChange={(e: any) => {
                  const value = e.target.value;
                  if (value) {
                    handleSubjectChange(Number(value), false);
                  } else {
                    handleSubjectChange(null, false);
                  }
                }}
                disabled={loading}
                style={{
                  border: 'none',
                  outline: 'none',
                  background: 'transparent',
                  width: '100%',
                  fontSize: '16px',
                  color: 'var(--md-sys-color-on-surface)',
                  fontFamily: 'inherit',
                  cursor: loading ? 'not-allowed' : 'pointer',
                }}
              >
                <option value="">Выберите предмет</option>
                {subjects.map(subject => (
                  <option key={subject.id} value={String(subject.id)}>
                    {subject.name}
                  </option>
                ))}
                {mentorSubjects.map(subject => (
                  <option key={subject.id} value={String(subject.id)}>
                    {subject.name}
                  </option>
                ))}
              </select>
            </md-outlined-field>
            
            <md-outlined-field label="Или введите свой предмет" style={{ width: '100%' }}>
              <input
                slot="input"
                type="text"
                value={customSubjectName}
                onChange={(e) => {
                  setCustomSubjectName(e.target.value);
                  if (e.target.value) {
                    handleSubjectChange(null, true, e.target.value);
                  } else {
                    handleSubjectChange(null, false);
                  }
                }}
                placeholder="Название предмета"
                disabled={loading}
                style={{
                  border: 'none',
                  outline: 'none',
                  background: 'transparent',
                  width: '100%',
                  fontSize: '16px',
                  color: 'var(--md-sys-color-on-surface)',
                }}
              />
            </md-outlined-field>
          </div>
        </div>

        {/* Название */}
        <div>
          <label style={{
            display: 'block',
            fontSize: '14px',
            fontWeight: '500',
            color: 'var(--md-sys-color-on-surface)',
            marginBottom: '8px',
          }}>
            Название занятия
          </label>
          <md-outlined-field label="Название" style={{ width: '100%' }}>
            <input
              slot="input"
              type="text"
              value={formData.title}
              onChange={(e) => setFormData(prev => ({ ...prev, title: e.target.value }))}
              placeholder="Автоматически генерируется"
              disabled={loading}
              style={{
                border: 'none',
                outline: 'none',
                background: 'transparent',
                width: '100%',
                fontSize: '16px',
                color: 'var(--md-sys-color-on-surface)',
              }}
            />
          </md-outlined-field>
        </div>

        {/* Описание */}
        <div>
          <label style={{
            display: 'block',
            fontSize: '14px',
            fontWeight: '500',
            color: 'var(--md-sys-color-on-surface)',
            marginBottom: '8px',
          }}>
            Описание
          </label>
          <md-outlined-field label="Описание" style={{ width: '100%' }}>
            <textarea
              slot="input"
              value={formData.description}
              onChange={(e) => setFormData(prev => ({ ...prev, description: e.target.value }))}
              placeholder="Дополнительная информация о занятии"
              disabled={loading}
              rows={2}
              style={{
                border: 'none',
                outline: 'none',
                background: 'transparent',
                width: '100%',
                fontSize: '16px',
                color: 'var(--md-sys-color-on-surface)',
                resize: 'none',
                fontFamily: 'inherit',
              }}
            />
          </md-outlined-field>
        </div>

        {/* Дата начала */}
        <div>
          <label style={{
            display: 'block',
            fontSize: '14px',
            fontWeight: '500',
            color: 'var(--md-sys-color-on-surface)',
            marginBottom: '8px',
          }}>
            Дата начала *
          </label>
          <DatePicker
            value={formData.start_date}
            onChange={(v) => handleDateChange(v)}
            disabled={loading}
            required
            label="Дата начала"
          />
        </div>

        {/* Время начала и длительность */}
        <div className="create-lesson-time-row" style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: '16px' }}>
          <div>
            <label style={{
              display: 'block',
              fontSize: '14px',
              fontWeight: '500',
              color: 'var(--md-sys-color-on-surface)',
              marginBottom: '8px',
            }}>
              Время начала *
            </label>
            <TimePicker
              value={formData.start_time}
              onChange={(v) => handleTimeChange(v)}
              disabled={loading}
              required
            />
          </div>

          <div>
            <label style={{
              display: 'block',
              fontSize: '14px',
              fontWeight: '500',
              color: 'var(--md-sys-color-on-surface)',
              marginBottom: '8px',
            }}>
              Длительность (минуты) *
            </label>
            <md-outlined-field label="Длительность" style={{ width: '100%' }}>
              <select
                slot="input"
                value={formData.duration}
                onChange={(e) => handleDurationChange(Number(e.target.value))}
                required
                disabled={loading}
                style={{
                  border: 'none',
                  outline: 'none',
                  background: 'transparent',
                  width: '100%',
                  fontSize: '16px',
                  color: 'var(--md-sys-color-on-surface)',
                  fontFamily: 'inherit',
                  cursor: loading ? 'not-allowed' : 'pointer',
                }}
              >
                <option value={30}>30 минут</option>
                <option value={45}>45 минут</option>
                <option value={60}>1 час</option>
                <option value={90}>1.5 часа</option>
                <option value={120}>2 часа</option>
              </select>
            </md-outlined-field>
          </div>
        </div>

        {/* Цена */}
        <div>
          <label style={{
            display: 'block',
            fontSize: '14px',
            fontWeight: '500',
            color: 'var(--md-sys-color-on-surface)',
            marginBottom: '8px',
          }}>
            Стоимость (₽) *
          </label>
          <md-outlined-field label="Стоимость" style={{ width: '100%' }}>
            <input
              slot="input"
              type="number"
              value={formData.price || ''}
              onChange={(e) => setFormData(prev => ({ ...prev, price: Number(e.target.value) }))}
              required
              min={0}
              step={100}
              disabled={loading}
              style={{
                border: 'none',
                outline: 'none',
                background: 'transparent',
                width: '100%',
                fontSize: '16px',
                color: 'var(--md-sys-color-on-surface)',
              }}
            />
          </md-outlined-field>
        </div>

        {/* Постоянное занятие */}
        <div style={{ display: 'flex', alignItems: 'center', gap: '12px' }}>
          <md-switch
            checked={formData.is_recurring}
            onInput={(e: any) => setFormData(prev => ({ ...prev, is_recurring: e.target.checked }))}
            disabled={loading}
          />
          <label style={{
            fontSize: '14px',
            color: 'var(--md-sys-color-on-surface)',
            cursor: 'pointer',
          }}>
            Постоянное занятие (повторяется еженедельно)
          </label>
        </div>
      </form>

      <div slot="actions">
        <md-text-button onClick={handleClose} disabled={loading}>
          Отмена
        </md-text-button>
        <md-filled-button onClick={(e) => { e.preventDefault(); handleSubmit(e); }} disabled={loading}>
          {loading ? 'Создание...' : 'Создать'}
        </md-filled-button>
      </div>
    </md-dialog>
    <style jsx global>{`
      md-dialog {
        --md-dialog-container-shape: 28px;
        --md-dialog-container-max-width: 600px;
        --md-dialog-container-min-width: min(500px, 90vw);
      }
      
      md-dialog::part(container) {
        margin: auto;
        position: fixed;
        top: 50%;
        left: 50%;
        transform: translate(-50%, -50%);
        max-height: 90vh;
        overflow-y: auto;
      }
      
      md-dialog form {
        padding: 24px;
      }
      
      md-dialog [slot="actions"] {
        display: flex;
        gap: 8px;
        justify-content: flex-end;
        padding: 8px 24px 24px 24px;
      }
      
      md-outlined-field {
        width: 100%;
      }
      
      md-outlined-field input[type="date"],
      md-outlined-field input[type="time"] {
        font-family: inherit;
        font-size: 16px;
        color: var(--md-sys-color-on-surface);
      }
      
      md-outlined-field input[type="date"]::-webkit-calendar-picker-indicator,
      md-outlined-field input[type="time"]::-webkit-calendar-picker-indicator {
        cursor: pointer;
        opacity: 0.6;
      }
      
      md-outlined-field input[type="date"]::-webkit-calendar-picker-indicator:hover,
      md-outlined-field input[type="time"]::-webkit-calendar-picker-indicator:hover {
        opacity: 1;
      }
    `}</style>
    </>
  );
};
