import { type FormEvent, useEffect, useMemo, useState } from 'react'
import { Link } from 'react-router-dom'
import { createEarlyDismissal, fetchEarlyDismissalStudentOptions } from '../../api/session'
import { EARLY_DISMISSALS_PATH } from './attendancePaths'

type StudentOpt = {
  id: number
  firstname: string
  lastname: string
  section?: string | null
}

/** Port of `Views/attendance/early_dismissals_add.php` */
export function EarlyDismissalsAddPage() {
  const [students, setStudents] = useState<StudentOpt[]>([])
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState<string | null>(null)
  const [msg, setMsg] = useState<string | null>(null)

  const [query, setQuery] = useState('')
  const [studentId, setStudentId] = useState<number | null>(null)
  const [label, setLabel] = useState('')
  const [date, setDate] = useState(() => new Date().toISOString().slice(0, 10))
  const [dismissTime, setDismissTime] = useState('')
  const [reason, setReason] = useState('')

  useEffect(() => {
    let cancelled = false
    ;(async () => {
      try {
        const data = await fetchEarlyDismissalStudentOptions()
        if (cancelled) return
        const raw = data.students ?? []
        setStudents(
          raw
            .map((s) => ({
              id: Number(s.id ?? 0),
              firstname: String(s.firstname ?? ''),
              lastname: String(s.lastname ?? ''),
              section: s.class_section_name ?? null,
            }))
            .filter((s) => s.id > 0),
        )
      } catch (e) {
        if (!cancelled) setError(e instanceof Error ? e.message : 'Unable to load students.')
      } finally {
        if (!cancelled) setLoading(false)
      }
    })()
    return () => {
      cancelled = true
    }
  }, [])

  const enriched = useMemo(() => {
    const norm = (s: string) => s.toLowerCase().trim()
    return students.map((s) => {
      const display = `${s.firstname} ${s.lastname}${s.section ? ` — ${s.section}` : ''}`
      const key = `${norm(s.firstname)} ${norm(s.lastname)} ${norm(s.section ?? '')}`
      return { ...s, display, key }
    })
  }, [students])

  const matches = useMemo(() => {
    const q = query.toLowerCase().trim()
    if (!q) return []
    return enriched.filter((s) => s.key.includes(q)).slice(0, 20)
  }, [enriched, query])

  async function onSubmit(e: FormEvent) {
    e.preventDefault()
    setError(null)
    setMsg(null)
    if (!studentId) {
      setError('Please select a student from the list.')
      return
    }
    try {
      await createEarlyDismissal({
        student_id: studentId,
        date,
        dismiss_time: dismissTime,
        reason: reason || null,
      })
      setMsg('Early dismissal saved.')
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Save failed.')
    }
  }

  return (
    <div className="container-xxl py-4">
      <div className="d-flex align-items-center justify-content-between flex-wrap gap-2 mb-3">
        <h2 className="mb-0">Add Early Dismissal</h2>
        <Link to={EARLY_DISMISSALS_PATH} className="btn btn-outline-secondary">
          Back to List
        </Link>
      </div>

      {error ? <div className="alert alert-danger">{error}</div> : null}
      {msg ? <div className="alert alert-success">{msg}</div> : null}

      <div className="card shadow-sm">
        <div className="card-body">
          <form onSubmit={onSubmit}>
            <div className="row gy-3">
              <div className="col-md-5 position-relative">
                <label className="form-label">Student</label>
                <input
                  type="text"
                  className={`form-control${error && !studentId ? ' is-invalid' : ''}`}
                  autoComplete="off"
                  placeholder="Type student name to search…"
                  value={label}
                  onChange={(ev) => {
                    setLabel(ev.target.value)
                    setStudentId(null)
                    setQuery(ev.target.value)
                  }}
                />
                {query.trim() && matches.length > 0 ? (
                  <div
                    className="list-group position-absolute w-100 shadow-sm"
                    style={{ zIndex: 1000, maxHeight: 240, overflow: 'auto' }}
                  >
                    {matches.map((m) => (
                      <button
                        key={m.id}
                        type="button"
                        className="list-group-item list-group-item-action"
                        onClick={() => {
                          setStudentId(m.id)
                          setLabel(m.display)
                          setQuery('')
                        }}
                      >
                        {m.display}
                      </button>
                    ))}
                  </div>
                ) : null}
                <div className="form-text">Start typing first or last name, then pick from the list.</div>
              </div>

              <div className="col-md-3">
                <label className="form-label">Date (Sunday)</label>
                <input
                  type="date"
                  className="form-control"
                  required
                  value={date}
                  onChange={(ev) => setDate(ev.target.value)}
                />
              </div>

              <div className="col-md-2">
                <label className="form-label">Dismissal Time</label>
                <input
                  type="time"
                  className="form-control"
                  required
                  value={dismissTime}
                  onChange={(ev) => setDismissTime(ev.target.value)}
                />
              </div>

              <div className="col-12">
                <label className="form-label">Reason (optional)</label>
                <textarea
                  name="reason"
                  className="form-control"
                  rows={2}
                  placeholder="e.g., Family appointment"
                  value={reason}
                  onChange={(ev) => setReason(ev.target.value)}
                />
              </div>

              <div className="col-12 d-flex gap-2">
                <button type="submit" className="btn btn-primary" disabled={loading}>
                  Save Early Dismissal
                </button>
                <Link to={EARLY_DISMISSALS_PATH} className="btn btn-outline-secondary">
                  Cancel
                </Link>
              </div>
            </div>
          </form>
        </div>
      </div>

      <div className="mt-3 small text-muted">
        Note: Early dismissals do not change daily present/absent status; they are shown for staff awareness and
        pickup coordination.
      </div>
    </div>
  )
}