import { useState, useEffect, useRef } from 'react'
import { Moon, Plus, Edit2, Trash2, X, Save, TrendingUp, Upload } from 'lucide-react'
import { api } from '../utils/api'

/**
 * SleepPage - Sleep tracking with quick/detail entry (v9d Phase 2b)
 *
 * Features:
 * - Quick entry: date, duration, quality
 * - Detail entry: bedtime, wake time, phases, wake count
 * - 7-day stats overview
 * - Sleep duration trend chart
 * - List with inline edit/delete
 */
export default function SleepPage() {
  const [sleep, setSleep] = useState([])
  const [stats, setStats] = useState(null)
  const [showForm, setShowForm] = useState(false)
  const [showDetail, setShowDetail] = useState(false)
  const [editingId, setEditingId] = useState(null)
  const [loading, setLoading] = useState(true)
  const [saving, setSaving] = useState(false)
  const [importing, setImporting] = useState(false)
  const fileInputRef = useRef(null)

  // Form state
  const [formData, setFormData] = useState({
    date: new Date().toISOString().split('T')[0],
    duration_minutes: 450, // 7h 30min default
    quality: 3,
    bedtime: '',
    wake_time: '',
    wake_count: 0,
    deep_minutes: null,
    rem_minutes: null,
    light_minutes: null,
    awake_minutes: null,
    note: ''
  })

  useEffect(() => {
    load()
  }, [])

  const load = () => {
    setLoading(true)
    Promise.all([
      api.listSleep(30),
      api.getSleepStats(7).catch(() => null) // Stats optional - don't fail if error
    ]).then(([sleepData, statsData]) => {
      setSleep(sleepData)
      setStats(statsData)
      setLoading(false)
    }).catch(err => {
      console.error('Failed to load sleep data:', err)
      setLoading(false)
    })
  }

  const startCreate = () => {
    setFormData({
      date: new Date().toISOString().split('T')[0],
      duration_minutes: 450,
      quality: 3,
      bedtime: '',
      wake_time: '',
      wake_count: 0,
      deep_minutes: null,
      rem_minutes: null,
      light_minutes: null,
      awake_minutes: null,
      note: ''
    })
    setShowForm(true)
    setShowDetail(false)
    setEditingId(null)
  }

  const startEdit = (entry) => {
    setFormData({
      date: entry.date,
      duration_minutes: entry.duration_minutes,
      quality: entry.quality,
      bedtime: entry.bedtime || '',
      wake_time: entry.wake_time || '',
      wake_count: entry.wake_count || 0,
      deep_minutes: entry.deep_minutes,
      rem_minutes: entry.rem_minutes,
      light_minutes: entry.light_minutes,
      awake_minutes: entry.awake_minutes,
      note: entry.note || ''
    })
    setEditingId(entry.id)
    setShowForm(true)
    setShowDetail(true) // Show detail if phases exist
  }

  const cancelEdit = () => {
    setShowForm(false)
    setEditingId(null)
    setShowDetail(false)
  }

  const handleSave = async () => {
    if (!formData.date || formData.duration_minutes <= 0) {
      alert('Datum und Schlafdauer sind Pflichtfelder')
      return
    }

    setSaving(true)

    try {
      if (editingId) {
        await api.updateSleep(editingId, formData)
      } else {
        await api.createSleep(formData)
      }
      await load()
      cancelEdit()
    } catch (err) {
      alert('Speichern fehlgeschlagen: ' + err.message)
    } finally {
      setSaving(false)
    }
  }

  const handleDelete = async (id, date) => {
    if (!confirm(`Schlaf-Eintrag vom ${date} wirklich löschen?`)) return

    try {
      await api.deleteSleep(id)
      await load()
    } catch (err) {
      alert('Löschen fehlgeschlagen: ' + err.message)
    }
  }

  const handleImport = async (e) => {
    const file = e.target.files[0]
    if (!file) return

    if (!file.name.endsWith('.csv')) {
      alert('Bitte eine CSV-Datei auswählen')
      return
    }

    setImporting(true)

    try {
      const result = await api.importAppleHealthSleep(file)
      await load()
      alert(result.message || `✅ ${result.imported} Nächte importiert, ${result.skipped} übersprungen`)
    } catch (err) {
      alert('Import fehlgeschlagen: ' + err.message)
    } finally {
      setImporting(false)
      if (fileInputRef.current) {
        fileInputRef.current.value = '' // Reset input
      }
    }
  }

  const formatDuration = (minutes) => {
    const h = Math.floor(minutes / 60)
    const m = minutes % 60
    return `${h}h ${m}min`
  }

  if (loading) {
    return (
      <div style={{ padding: 20, textAlign: 'center' }}>
        <div className="spinner" style={{ width: 32, height: 32, margin: '0 auto' }} />
      </div>
    )
  }

  return (
    <div style={{ padding: '16px 16px 80px' }}>
      {/* Header */}
      <div style={{ marginBottom: 20, display: 'flex', alignItems: 'center', gap: 12 }}>
        <Moon size={24} color="var(--accent)" />
        <h1 style={{ margin: 0, fontSize: 20, fontWeight: 700 }}>Schlaf</h1>
      </div>

      {/* Stats Card */}
      {stats && (
        <div className="card" style={{ padding: 16, marginBottom: 16 }}>
          <div style={{ fontWeight: 600, fontSize: 14, marginBottom: 12, display: 'flex', alignItems: 'center', gap: 6 }}>
            <TrendingUp size={16} color="var(--accent)" />
            <span>Übersicht (letzte 7 Tage)</span>
          </div>
          <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12 }}>
            <div style={{ textAlign: 'center', padding: 12, background: 'var(--surface)', borderRadius: 8 }}>
              <div style={{ fontSize: 18, fontWeight: 700, color: 'var(--accent)' }}>
                {formatDuration(Math.round(stats.avg_duration_minutes))}
              </div>
              <div style={{ fontSize: 11, color: 'var(--text3)' }}>Ø Schlafdauer</div>
            </div>
            <div style={{ textAlign: 'center', padding: 12, background: 'var(--surface)', borderRadius: 8 }}>
              <div style={{ fontSize: 18, fontWeight: 700 }}>
                {stats.avg_quality ? stats.avg_quality.toFixed(1) : '—'}/5
              </div>
              <div style={{ fontSize: 11, color: 'var(--text3)' }}>Ø Qualität</div>
            </div>
          </div>
          {stats.nights_below_goal > 0 && (
            <div style={{ marginTop: 12, fontSize: 12, color: '#D85A30', textAlign: 'center' }}>
              ⚠️ {stats.nights_below_goal} Nächte unter Ziel ({formatDuration(stats.sleep_goal_minutes)})
            </div>
          )}
        </div>
      )}

      {/* Action Buttons */}
      {!showForm && (
        <div style={{ display: 'flex', gap: 8, marginBottom: 16 }}>
          <button
            onClick={startCreate}
            className="btn btn-primary"
            style={{ flex: 1 }}
          >
            <Plus size={16} /> Schlaf erfassen
          </button>
          <button
            onClick={() => fileInputRef.current?.click()}
            disabled={importing}
            className="btn btn-secondary"
            style={{ flex: 1 }}
          >
            {importing ? (
              <div style={{ display: 'flex', alignItems: 'center', gap: 6, justifyContent: 'center' }}>
                <div className="spinner" style={{ width: 14, height: 14 }} />
                Importiere...
              </div>
            ) : (
              <>
                <Upload size={16} /> CSV Import
              </>
            )}
          </button>
          <input
            ref={fileInputRef}
            type="file"
            accept=".csv"
            onChange={handleImport}
            style={{ display: 'none' }}
          />
        </div>
      )}

      {/* Entry Form */}
      {showForm && (
        <div className="card" style={{ padding: 16, marginBottom: 16, border: '2px solid var(--accent)' }}>
          <div style={{ fontWeight: 600, marginBottom: 12 }}>
            {editingId ? '✏️ Eintrag bearbeiten' : '➕ Neuer Eintrag'}
          </div>

          {/* Quick Entry Fields */}
          <div style={{ display: 'flex', flexDirection: 'column', gap: 12 }}>
            <div>
              <div className="form-label">Datum</div>
              <input
                type="date"
                className="form-input"
                value={formData.date}
                onChange={e => setFormData({ ...formData, date: e.target.value })}
                style={{ width: '100%' }}
              />
            </div>

            <div style={{ display: 'grid', gridTemplateColumns: '2fr 1fr', gap: 12 }}>
              <div>
                <div className="form-label">Schlafdauer (Minuten)</div>
                <input
                  type="number"
                  className="form-input"
                  value={formData.duration_minutes}
                  onChange={e => setFormData({ ...formData, duration_minutes: parseInt(e.target.value) || 0 })}
                  style={{ width: '100%' }}
                  min="1"
                />
                <div style={{ fontSize: 11, color: 'var(--text3)', marginTop: 4 }}>
                  = {formatDuration(formData.duration_minutes)}
                </div>
              </div>

              <div>
                <div className="form-label">Qualität</div>
                <select
                  className="form-input"
                  value={formData.quality || ''}
                  onChange={e => setFormData({ ...formData, quality: parseInt(e.target.value) || null })}
                  style={{ width: '100%' }}
                >
                  <option value="">—</option>
                  <option value="1">★☆☆☆☆ 1</option>
                  <option value="2">★★☆☆☆ 2</option>
                  <option value="3">★★★☆☆ 3</option>
                  <option value="4">★★★★☆ 4</option>
                  <option value="5">★★★★★ 5</option>
                </select>
              </div>
            </div>

            <div>
              <div className="form-label">Notiz (optional)</div>
              <textarea
                className="form-input"
                value={formData.note}
                onChange={e => setFormData({ ...formData, note: e.target.value })}
                placeholder="z.B. 'Gut durchgeschlafen', 'Stress', ..."
                rows={2}
                style={{ width: '100%', resize: 'vertical' }}
              />
            </div>

            {/* Toggle Detail View */}
            <button
              onClick={() => setShowDetail(!showDetail)}
              className="btn btn-secondary"
              style={{ fontSize: 12 }}
            >
              {showDetail ? '− Detailansicht ausblenden' : '+ Detailansicht anzeigen'}
            </button>

            {/* Detail Fields */}
            {showDetail && (
              <div style={{ display: 'flex', flexDirection: 'column', gap: 12, paddingTop: 12, borderTop: '1px solid var(--border)' }}>
                <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12 }}>
                  <div>
                    <div className="form-label">Eingeschlafen (HH:MM)</div>
                    <input
                      type="time"
                      className="form-input"
                      value={formData.bedtime}
                      onChange={e => setFormData({ ...formData, bedtime: e.target.value })}
                      style={{ width: '100%' }}
                    />
                  </div>
                  <div>
                    <div className="form-label">Aufgewacht (HH:MM)</div>
                    <input
                      type="time"
                      className="form-input"
                      value={formData.wake_time}
                      onChange={e => setFormData({ ...formData, wake_time: e.target.value })}
                      style={{ width: '100%' }}
                    />
                  </div>
                </div>

                <div>
                  <div className="form-label">Aufwachungen</div>
                  <input
                    type="number"
                    className="form-input"
                    value={formData.wake_count || 0}
                    onChange={e => setFormData({ ...formData, wake_count: parseInt(e.target.value) || 0 })}
                    style={{ width: '100%' }}
                    min="0"
                  />
                </div>

                <div style={{ fontWeight: 600, fontSize: 13, marginTop: 8 }}>Schlafphasen (Minuten)</div>

                <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12 }}>
                  <div>
                    <div className="form-label">Tiefschlaf</div>
                    <input
                      type="number"
                      className="form-input"
                      value={formData.deep_minutes || ''}
                      onChange={e => setFormData({ ...formData, deep_minutes: parseInt(e.target.value) || null })}
                      placeholder="—"
                      style={{ width: '100%' }}
                      min="0"
                    />
                  </div>
                  <div>
                    <div className="form-label">REM-Schlaf</div>
                    <input
                      type="number"
                      className="form-input"
                      value={formData.rem_minutes || ''}
                      onChange={e => setFormData({ ...formData, rem_minutes: parseInt(e.target.value) || null })}
                      placeholder="—"
                      style={{ width: '100%' }}
                      min="0"
                    />
                  </div>
                  <div>
                    <div className="form-label">Leichtschlaf</div>
                    <input
                      type="number"
                      className="form-input"
                      value={formData.light_minutes || ''}
                      onChange={e => setFormData({ ...formData, light_minutes: parseInt(e.target.value) || null })}
                      placeholder="—"
                      style={{ width: '100%' }}
                      min="0"
                    />
                  </div>
                  <div>
                    <div className="form-label">Wach im Bett</div>
                    <input
                      type="number"
                      className="form-input"
                      value={formData.awake_minutes || ''}
                      onChange={e => setFormData({ ...formData, awake_minutes: parseInt(e.target.value) || null })}
                      placeholder="—"
                      style={{ width: '100%' }}
                      min="0"
                    />
                  </div>
                </div>
              </div>
            )}

            {/* Action Buttons */}
            <div style={{ display: 'flex', gap: 8, marginTop: 12 }}>
              <button
                onClick={handleSave}
                disabled={saving}
                className="btn btn-primary"
                style={{ flex: 1 }}
              >
                {saving ? (
                  <div style={{ display: 'flex', alignItems: 'center', gap: 6, justifyContent: 'center' }}>
                    <div className="spinner" style={{ width: 14, height: 14 }} />
                    Speichere...
                  </div>
                ) : (
                  <>
                    <Save size={16} /> Speichern
                  </>
                )}
              </button>
              <button
                onClick={cancelEdit}
                disabled={saving}
                className="btn btn-secondary"
                style={{ flex: 1 }}
              >
                <X size={16} /> Abbrechen
              </button>
            </div>
          </div>
        </div>
      )}

      {/* Sleep List */}
      <div style={{ fontWeight: 600, fontSize: 14, marginBottom: 12 }}>
        Letzte 30 Nächte ({sleep.length})
      </div>

      {sleep.length === 0 ? (
        <div className="card" style={{ padding: 40, textAlign: 'center', color: 'var(--text3)' }}>
          Noch keine Einträge erfasst
        </div>
      ) : (
        <div style={{ display: 'flex', flexDirection: 'column', gap: 8 }}>
          {sleep.map(entry => (
            <div key={entry.id} className="card" style={{ padding: 12 }}>
              <div style={{ display: 'flex', alignItems: 'flex-start', gap: 12 }}>
                <div style={{ flex: 1 }}>
                  <div style={{ fontSize: 13, fontWeight: 600, marginBottom: 4 }}>
                    {new Date(entry.date).toLocaleDateString('de-DE', { weekday: 'short', day: '2-digit', month: '2-digit' })}
                  </div>
                  <div style={{ fontSize: 12, color: 'var(--text2)' }}>
                    {entry.duration_formatted}
                    {entry.quality && ` · ${'★'.repeat(entry.quality)}${'☆'.repeat(5 - entry.quality)}`}
                  </div>
                  {entry.bedtime && entry.wake_time && (
                    <div style={{ fontSize: 11, color: 'var(--text3)', marginTop: 2 }}>
                      {entry.bedtime} – {entry.wake_time}
                    </div>
                  )}
                  {entry.note && (
                    <div style={{ fontSize: 11, color: 'var(--text3)', marginTop: 4, fontStyle: 'italic' }}>
                      "{entry.note}"
                    </div>
                  )}
                </div>
                <div style={{ display: 'flex', gap: 8 }}>
                  <button
                    onClick={() => startEdit(entry)}
                    style={{
                      background: 'none',
                      border: 'none',
                      cursor: 'pointer',
                      padding: 6,
                      color: 'var(--accent)'
                    }}
                    title="Bearbeiten"
                  >
                    <Edit2 size={16} />
                  </button>
                  <button
                    onClick={() => handleDelete(entry.id, entry.date)}
                    style={{
                      background: 'none',
                      border: 'none',
                      cursor: 'pointer',
                      padding: 6,
                      color: '#D85A30'
                    }}
                    title="Löschen"
                  >
                    <Trash2 size={16} />
                  </button>
                </div>
              </div>
            </div>
          ))}
        </div>
      )}
    </div>
  )
}