/**
 * FEAT-6: Gewicht-Tab — Schnell-Erfassung (Datum vorbelegt mit heute,
 * großes touch-freundliches Gramm-Feld), Wachstumskurve (eigenes SVG,
 * keine Chart-Bibliothek) + Verlaufsliste mit Löschen.
 */
import { useState, type FormEvent } from 'react'
import { de } from '../strings/de'
import {
  createWeightRecord,
  deleteWeightRecord,
  listWeightRecords,
} from '../api/weightRecords'
import { useApi, useMutation } from '../hooks/useApi'
import { formatDate } from '../format/labels'
import { todayISO } from '../format/dates'
import LineChart from './LineChart'

export default function GerbilWeightTab({ gerbilId }: { gerbilId: string }) {
  const t = de.pages.tierTabs.weight

  const records = useApi(() => listWeightRecords(gerbilId), [gerbilId])

  const [date, setDate] = useState(todayISO())
  const [grams, setGrams] = useState('')
  const [errors, setErrors] = useState<{ date?: string; grams?: string }>({})

  const add = useMutation((weightGrams: number) =>
    createWeightRecord({ gerbilId, date, weightGrams }),
  )
  const removal = useMutation((recordId: string) => deleteWeightRecord(recordId))

  async function onSubmit(e: FormEvent) {
    e.preventDefault()
    const value = Number(grams)
    const next: { date?: string; grams?: string } = {}
    if (!date) next.date = t.validation.dateRequired
    if (grams.trim() === '' || Number.isNaN(value)) next.grams = t.validation.weightRequired
    else if (value < 1 || value > 500 || !Number.isInteger(value))
      next.grams = t.validation.weightRange
    setErrors(next)
    if (Object.keys(next).length > 0) return

    await add.run(value)
    setGrams('')
    setDate(todayISO())
    records.reload()
  }

  async function onDelete(recordId: string) {
    if (!window.confirm(t.deleteConfirm)) return
    await removal.run(recordId)
    records.reload()
  }

  const items = records.data ?? []

  return (
    <div>
      {/* Schnell-Erfassung: ein Daumen, eine Rennmaus in der anderen Hand. */}
      <form className="weight-quick-add" onSubmit={onSubmit} noValidate>
        <h4>{t.addTitle}</h4>
        <div className="weight-quick-add__row">
          <label className="field">
            <span>{t.fields.date}</span>
            <input
              type="date"
              className="input"
              value={date}
              onChange={(e) => setDate(e.target.value)}
              aria-invalid={Boolean(errors.date)}
            />
          </label>
          <label className="field">
            <span>{t.fields.weightGrams}</span>
            <input
              type="number"
              inputMode="numeric"
              min={1}
              max={500}
              step={1}
              className="input input--xl"
              value={grams}
              placeholder="0"
              onChange={(e) => setGrams(e.target.value)}
              aria-invalid={Boolean(errors.grams)}
            />
          </label>
          <button type="submit" className="btn btn--primary" disabled={add.pending}>
            {add.pending ? t.adding : t.addButton}
          </button>
        </div>
        {errors.date && <small className="error-text">{errors.date}</small>}
        {errors.grams && <small className="error-text">{errors.grams}</small>}
        {add.error && <div className="alert alert--error">{add.error}</div>}
      </form>

      {records.loading && <p className="muted">{de.common.loading}</p>}
      {records.error && (
        <div className="alert alert--error">
          <span>{records.error}</span>
          <button type="button" className="btn" onClick={records.reload}>
            {de.common.retry}
          </button>
        </div>
      )}
      {removal.error && <div className="alert alert--error">{removal.error}</div>}

      {!records.loading && !records.error && items.length === 0 && (
        <p className="muted">{t.empty}</p>
      )}

      {items.length > 0 && (
        <>
          <h4>{t.chartTitle}</h4>
          {items.length >= 2 ? (
            <LineChart
              title={t.chartTitle}
              unit={t.gramsSuffix}
              points={items.map((r) => ({ date: r.date, value: r.weightGrams }))}
            />
          ) : (
            <p className="muted">{t.chartNeedsTwo}</p>
          )}

          <h4>{t.historyTitle}</h4>
          <ul className="card-list">
            {items.map((r) => (
              <li key={r.id} className="record-card record-card--row">
                <span className="record-card__date">{formatDate(r.date)}</span>
                <strong>
                  {r.weightGrams} {t.gramsSuffix}
                </strong>
                <button
                  type="button"
                  className="btn btn--danger"
                  onClick={() => onDelete(r.id)}
                  disabled={removal.pending}
                >
                  {de.common.delete}
                </button>
              </li>
            ))}
          </ul>
        </>
      )}
    </div>
  )
}