import React, { useCallback, useEffect, useMemo, useState } from 'react'
import { useNavigate } from 'react-router-dom'
import FormActionBar from '../FormActionBar'
import FormModalOverlay from '../FormModalOverlay'
import api from '../../utils/api'
import { useToast } from '../../context/ToastContext'
import { useAuth } from '../../context/AuthContext'
import { activeClubMemberships } from '../../utils/activeClub'
import { collectExercisePlacementsForModule } from '../../utils/trainingPlanModuleFromUnit'
import { navigateWithAppReturn } from '../../utils/navReturnContext'

/**
 * Erstellt ein Trainingsmodul aus den Übungen einer gespeicherten Trainingseinheit (Mehrfachauswahl).
 */
export default function SaveExercisesAsModuleModal({
  open,
  onClose,
  unitId,
  planningModalClubId,
  returnContext,
  onSuccess,
}) {
  const navigate = useNavigate()
  const toast = useToast()
  const { user } = useAuth()
  const memberClubs = useMemo(() => activeClubMemberships(user?.clubs), [user?.clubs])
  const roleLc = String(user?.role || '').toLowerCase()
  const isSuperadmin = roleLc === 'superadmin'

  const [loading, setLoading] = useState(false)
  const [submitting, setSubmitting] = useState(false)
  const [loadErr, setLoadErr] = useState('')
  const [unitLabel, setUnitLabel] = useState('')
  const [candidates, setCandidates] = useState([])
  const [selected, setSelected] = useState(() => [])

  const [title, setTitle] = useState('')
  const [visibility, setVisibility] = useState('club')
  const [clubId, setClubId] = useState('')

  const resetLocal = useCallback(() => {
    setLoadErr('')
    setUnitLabel('')
    setCandidates([])
    setSelected([])
    setTitle('')
    setVisibility('club')
    setClubId('')
  }, [])

  useEffect(() => {
    if (!open || !unitId) {
      resetLocal()
      return
    }
    if (planningModalClubId != null && planningModalClubId !== '') {
      setClubId(String(planningModalClubId))
    } else if (memberClubs.length === 1) {
      setClubId(String(memberClubs[0].id))
    }
    setLoading(true)
    setLoadErr('')
    api
      .getTrainingUnit(unitId)
      .then((u) => {
        const dateStr = (u.planned_date || '').trim() || 'Training'
        setUnitLabel(dateStr)
        setTitle(`Modul · ${dateStr}`)
        const c = collectExercisePlacementsForModule(u)
        setCandidates(c)
        setSelected(c.map(() => true))
      })
      .catch((e) => {
        setLoadErr(e.message || 'Einheit konnte nicht geladen werden')
        setCandidates([])
        setSelected([])
      })
      .finally(() => setLoading(false))
  }, [open, unitId, planningModalClubId, memberClubs.length, resetLocal])

  const toggleOne = (idx) => {
    setSelected((prev) => {
      const next = [...prev]
      next[idx] = !next[idx]
      return next
    })
  }

  const setAll = (on) => {
    setSelected(candidates.map(() => on))
  }

  const selectedCount = selected.filter(Boolean).length

  const handleSubmit = async (e) => {
    e.preventDefault()
    if (!unitId || submitting) return
    const itemsPayload = []
    let oi = 0
    for (let i = 0; i < candidates.length; i += 1) {
      if (!selected[i]) continue
      const c = candidates[i]
      itemsPayload.push({
        item_type: 'exercise',
        order_index: oi,
        exercise_id: c.exercise_id,
        exercise_variant_id: c.exercise_variant_id,
        planned_duration_min: c.planned_duration_min,
        notes: c.notes,
      })
      oi += 1
    }
    if (!itemsPayload.length) {
      toast.error('Mindestens eine Übung auswählen.')
      return
    }
    const tit = (title || '').trim()
    if (!tit) {
      toast.error('Bitte einen Modultitel angeben.')
      return
    }
    let cid = visibility === 'club' && clubId ? parseInt(clubId, 10) : null
    if (visibility === 'club' && (!Number.isFinite(cid) || cid < 1)) {
      toast.error('Bitte einen Verein wählen (Sichtbarkeit „Verein“).')
      return
    }
    if (visibility !== 'club') cid = null

    setSubmitting(true)
    try {
      const created = await api.createTrainingModule({
        title: tit,
        visibility,
        club_id: cid,
        items: itemsPayload,
      })
      toast.success('Trainingsmodul gespeichert.')
      if (created?.id) {
        navigateWithAppReturn(navigate, `/planning/training-modules/${created.id}`, returnContext)
      }
      onSuccess?.()
      onClose()
    } catch (err) {
      toast.error(err.message || 'Speichern fehlgeschlagen')
    } finally {
      setSubmitting(false)
    }
  }

  if (!open) return null

  return (
    <FormModalOverlay open={open} raised onBackdropClick={onClose}>
      <div className="card modal-panel--form modal-panel--narrow">
        <h2 className="modal-panel__title">Übungen als Trainingsmodul</h2>
        <p className="modal-panel__intro">
          Es werden die <strong>gespeicherten</strong> Übungspositionen der Einheit vom{' '}
          <strong>{unitLabel || '…'}</strong> verwendet. Speichere die Planung vorher, wenn du den aktuellen Stand
          brauchst.
        </p>

        {loading ? (
          <p style={{ color: 'var(--text2)' }}>Laden …</p>
        ) : loadErr ? (
          <p style={{ color: 'var(--danger)' }}>{loadErr}</p>
        ) : candidates.length === 0 ? (
          <p style={{ color: 'var(--text2)' }}>In dieser Einheit sind keine Übungen im Ablauf hinterlegt.</p>
        ) : (
          <form id="save-module-form" className="modal-form-shell" onSubmit={handleSubmit}>
            <div className="modal-form-shell__body">
            <div style={{ marginBottom: '1rem' }}>
              <label className="form-label">Modultitel</label>
              <input
                className="form-input"
                value={title}
                onChange={(e) => setTitle(e.target.value)}
                required
                placeholder="z. B. Aufwärmsequenz"
              />
            </div>

            <div style={{ display: 'flex', flexWrap: 'wrap', gap: '10px', marginBottom: '0.75rem' }}>
              <button type="button" className="btn btn-secondary framework-ctrl framework-ctrl--xs" onClick={() => setAll(true)}>
                Alle
              </button>
              <button type="button" className="btn btn-secondary framework-ctrl framework-ctrl--xs" onClick={() => setAll(false)}>
                Keine
              </button>
              <span style={{ fontSize: '0.82rem', color: 'var(--text3)', alignSelf: 'center' }}>
                {selectedCount} von {candidates.length} gewählt (Reihenfolge wie im Plan)
              </span>
            </div>

            <div
              className="card"
              style={{
                marginBottom: '1rem',
                padding: '10px 12px',
                maxHeight: 'min(240px, 40vh)',
                overflowY: 'auto',
                background: 'var(--surface2)',
              }}
            >
              <ul style={{ listStyle: 'none', margin: 0, padding: 0 }}>
                {candidates.map((c, idx) => (
                  <li
                    key={`${c.exercise_id}-${idx}`}
                    style={{
                      display: 'flex',
                      gap: '10px',
                      alignItems: 'flex-start',
                      padding: '8px 0',
                      borderTop: idx === 0 ? 'none' : '1px solid var(--border)',
                    }}
                  >
                    <input
                      type="checkbox"
                      checked={!!selected[idx]}
                      onChange={() => toggleOne(idx)}
                      style={{ marginTop: 4 }}
                    />
                    <div style={{ minWidth: 0, flex: 1 }}>
                      <div style={{ fontWeight: 600, color: 'var(--text1)', fontSize: '0.92rem' }}>
                        {c.exercise_title}
                      </div>
                      {c.contextLabel ? (
                        <div style={{ fontSize: '0.78rem', color: 'var(--text3)', marginTop: 2 }}>{c.contextLabel}</div>
                      ) : null}
                      <div style={{ fontSize: '0.78rem', color: 'var(--text2)', marginTop: 2 }}>
                        {c.exercise_variant_id ? `Variante #${c.exercise_variant_id}` : 'Standard-Variante'}
                        {c.planned_duration_min != null && Number.isFinite(Number(c.planned_duration_min))
                          ? ` · ${c.planned_duration_min} Min (Plan)`
                          : ''}
                      </div>
                    </div>
                  </li>
                ))}
              </ul>
            </div>

            <div className="form-row" style={{ marginBottom: '0.85rem' }}>
              <label className="form-label">Sichtbarkeit</label>
              <select
                className="form-input"
                value={visibility}
                onChange={(e) => {
                  const v = e.target.value
                  setVisibility(v)
                  if (v === 'club' && !clubId && planningModalClubId != null) {
                    setClubId(String(planningModalClubId))
                  }
                }}
              >
                <option value="private">Privat</option>
                <option value="club">Verein</option>
                {isSuperadmin ? <option value="official">Offiziell</option> : null}
              </select>
            </div>
            {visibility === 'club' ? (
              <div className="form-row" style={{ marginBottom: '1rem' }}>
                <label className="form-label">Verein</label>
                <select className="form-input" value={clubId} onChange={(e) => setClubId(e.target.value)}>
                  <option value="">— Verein wählen —</option>
                  {memberClubs.map((cl) => (
                    <option key={cl.id} value={String(cl.id)}>
                      {cl.name || `Verein #${cl.id}`}
                    </option>
                  ))}
                </select>
              </div>
            ) : null}

            </div>

            <FormActionBar
              placement="bottom"
              variant="modal"
              formId="save-module-form"
              saving={submitting}
              showSave={false}
              saveAndCloseLabel="Modul anlegen"
              saveAndCloseShortLabel="Anlegen"
              onCancel={onClose}
            />
          </form>
        )}

        {loading ? (
          <div style={{ display: 'flex', justifyContent: 'flex-end', marginTop: '1rem' }}>
            <button type="button" className="btn btn-secondary" onClick={onClose}>
              Abbrechen
            </button>
          </div>
        ) : null}

        {!loading && loadErr ? (
          <div style={{ display: 'flex', justifyContent: 'flex-end', marginTop: '1rem' }}>
            <button type="button" className="btn btn-secondary" onClick={onClose}>
              Schließen
            </button>
          </div>
        ) : null}

        {!loading && !loadErr && candidates.length === 0 ? (
          <div style={{ display: 'flex', justifyContent: 'flex-end', marginTop: '1rem' }}>
            <button type="button" className="btn btn-secondary" onClick={onClose}>
              Schließen
            </button>
          </div>
        ) : null}
      </div>
    </FormModalOverlay>
  )
}
