import { useState, type FormEvent } from 'react'
import { Alert } from '@/components/ui/Alert'
import { Button } from '@/components/ui/Button'
import { Dialog } from '@/components/ui/Dialog'
import { SelectField, TextAreaField, TextField } from '@/components/ui/Field'
import { errorMessage } from '@/lib/api'
import type { Plant } from '@/lib/plants'
import {
  conflictSeedLot,
  LOT_UNITS,
  safeExternalUrl,
  useCreateSeedLot,
  useUpdateSeedLot,
  type LotUnit,
  type SeedLot,
} from '@/lib/seedLots'

const unitOptions = LOT_UNITS.map((u) => ({ value: u.value, label: u.label }))

/**
 * Record a purchase, or correct one. Everything except quantity and unit is
 * optional — the point is to make writing it down cheap enough to bother with.
 */
export function SeedLotDialog({ plant, lot, onClose }: { plant: Plant; lot?: SeedLot; onClose: () => void }) {
  const isEdit = !!lot
  const create = useCreateSeedLot()
  const update = useUpdateSeedLot()
  const pending = create.isPending || update.isPending

  const [vendor, setVendor] = useState(lot?.vendor ?? plant.vendor ?? '')
  const [sourceUrl, setSourceUrl] = useState(lot?.sourceUrl ?? plant.sourceUrl ?? '')
  const [quantity, setQuantity] = useState(lot ? String(lot.quantity) : '')
  const [unit, setUnit] = useState<LotUnit>(lot?.unit ?? 'seeds')
  const [purchasedAt, setPurchasedAt] = useState(lot?.purchasedAt ?? '')
  const [packedForYear, setPackedForYear] = useState(lot?.packedForYear != null ? String(lot.packedForYear) : '')
  const [cost, setCost] = useState(lot?.costCents != null ? (lot.costCents / 100).toFixed(2) : '')
  const [germination, setGermination] = useState(lot?.germinationPct != null ? String(lot.germinationPct) : '')
  const [sku, setSku] = useState(lot?.sku ?? '')
  const [lotCode, setLotCode] = useState(lot?.lotCode ?? '')
  const [notes, setNotes] = useState(lot?.notes ?? '')
  const [version, setVersion] = useState(lot?.version ?? 0)
  const [conflict, setConflict] = useState<string | null>(null)
  const [error, setError] = useState<string | null>(null)

  async function onSubmit(e: FormEvent) {
    e.preventDefault()
    setError(null)
    setConflict(null)
    const qty = quantity.trim() === '' ? 0 : Number(quantity)
    if (!Number.isFinite(qty) || qty < 0) return setError('Quantity must be a number, or blank.')
    if (sourceUrl.trim() && !safeExternalUrl(sourceUrl.trim()))
      return setError('The source link needs to be a full http:// or https:// address.')
    let year: number | null = null
    if (packedForYear.trim()) {
      const y = Number(packedForYear)
      if (!Number.isInteger(y) || y < 1900 || y > 2200) return setError('Packed-for should be a four-digit year.')
      year = y
    }
    let costCents: number | null = null
    if (cost.trim()) {
      const c = Number(cost)
      if (!Number.isFinite(c) || c < 0) return setError('Cost must be an amount, or blank.')
      costCents = Math.round(c * 100)
    }
    let germinationPct: number | null = null
    if (germination.trim()) {
      const g = Number(germination)
      if (!Number.isFinite(g) || g < 0 || g > 100) return setError('Germination is a percentage between 0 and 100.')
      germinationPct = g
    }
    const input = {
      plantId: plant.id,
      vendor: vendor.trim(),
      sourceUrl: sourceUrl.trim(),
      sku: sku.trim(),
      lotCode: lotCode.trim(),
      purchasedAt: purchasedAt.trim() === '' ? null : purchasedAt.trim(),
      packedForYear: year,
      quantity: qty,
      unit,
      costCents,
      germinationPct,
      notes: notes.trim(),
    }
    try {
      if (isEdit) await update.mutateAsync({ id: lot.id, version, ...input })
      else await create.mutateAsync(input)
      onClose()
    } catch (err) {
      const current = conflictSeedLot(err)
      if (current) {
        setVersion(current.version)
        setVendor(current.vendor)
        setSourceUrl(current.sourceUrl)
        setQuantity(String(current.quantity))
        setUnit(current.unit)
        setPurchasedAt(current.purchasedAt ?? '')
        setPackedForYear(current.packedForYear != null ? String(current.packedForYear) : '')
        setCost(current.costCents != null ? (current.costCents / 100).toFixed(2) : '')
        setGermination(current.germinationPct != null ? String(current.germinationPct) : '')
        setSku(current.sku)
        setLotCode(current.lotCode)
        setNotes(current.notes)
        setConflict('This lot changed elsewhere. The latest values are shown — look them over and save again.')
        return
      }
      setError(errorMessage(err, isEdit ? 'Could not save the lot.' : 'Could not record the lot.'))
    }
  }

  return (
    <Dialog title={isEdit ? 'Edit the lot' : `A lot of ${plant.name}`} onClose={onClose} busy={pending} width={460}>
      <form onSubmit={onSubmit} className="flex flex-col gap-3.5">
        {conflict && <Alert tone="info">{conflict}</Alert>}
        <div className="grid grid-cols-2 gap-2.5">
          <TextField label="Quantity" name="quantity" type="number" inputMode="decimal" step="any" min="0" autoFocus value={quantity} onChange={(e) => setQuantity(e.target.value)} />
          <SelectField label="Unit" name="unit" value={unit} onChange={(e) => setUnit(e.target.value as LotUnit)} options={unitOptions} />
          <TextField label="Vendor" name="vendor" value={vendor} onChange={(e) => setVendor(e.target.value)} />
          <TextField label="Packed for" name="packedForYear" type="number" inputMode="numeric" placeholder="2026" value={packedForYear} onChange={(e) => setPackedForYear(e.target.value)} />
          <TextField label="Purchased" name="purchasedAt" type="date" value={purchasedAt} onChange={(e) => setPurchasedAt(e.target.value)} />
          <TextField label="Cost" name="cost" type="number" inputMode="decimal" step="0.01" min="0" placeholder="4.99" value={cost} onChange={(e) => setCost(e.target.value)} />
          <TextField label="Germination %" name="germination" type="number" inputMode="decimal" step="any" min="0" max="100" value={germination} onChange={(e) => setGermination(e.target.value)} />
          <TextField label="Source link" name="sourceUrl" type="url" inputMode="url" placeholder="https://…" value={sourceUrl} onChange={(e) => setSourceUrl(e.target.value)} />
          <TextField label="SKU" name="sku" value={sku} onChange={(e) => setSku(e.target.value)} />
          <TextField label="Lot code" name="lotCode" value={lotCode} onChange={(e) => setLotCode(e.target.value)} />
        </div>
        <TextAreaField label="Notes" name="lotNotes" rows={2} value={notes} onChange={(e) => setNotes(e.target.value)} />
        {error && <Alert>{error}</Alert>}
        <div className="flex justify-end gap-2">
          <Button type="button" onClick={onClose} disabled={pending}>
            Never mind
          </Button>
          <Button type="submit" variant="primary" disabled={pending}>
            {pending ? 'Saving…' : isEdit ? 'Save' : 'Record the lot'}
          </Button>
        </div>
      </form>
    </Dialog>
  )
}