import { useCallback, useEffect, useRef, useState } from 'react'
import { toast } from '@/components/ui/toast'

export interface QuantitySelectorDefaults {
  display: 'input' | 'dropdown' | 'buttons'
  choice_source: 'range' | 'custom'
  choices: string
  suffix: string
  width: number
}
const defaults: QuantitySelectorDefaults = { display: 'input', choice_source: 'range', choices: '', suffix: '', width: 100 }
const endpoint = () => `${(window.swiftCommerceData?.apiUrl || '/wp-json/swift-commerce/v1').replace(/\/$/, '')}/quantity-limits/selector-defaults`

export function parseSelectorDefaults(value: unknown): QuantitySelectorDefaults {
  const settings = value as QuantitySelectorDefaults | null
  if (!settings || !['input', 'dropdown', 'buttons'].includes(settings.display) || !['range', 'custom'].includes(settings.choice_source) || !Number.isInteger(settings.width) || settings.width < 80 || settings.width > 320 || typeof settings.choices !== 'string' || typeof settings.suffix !== 'string') throw new Error('Product defaults could not be read.')
  return {display: settings.display, choice_source: settings.choice_source, choices: settings.choices, suffix: settings.suffix, width: settings.width}
}

/** Pro-owned endpoint; a failed load never supplies writable fallback settings. */
export function useSelectorDefaults(enabled: boolean) {
  const [settings, setSettings] = useState<QuantitySelectorDefaults | null>(null)
  const [initial, setInitial] = useState<QuantitySelectorDefaults | null>(null)
  const [loading, setLoading] = useState(enabled)
  const [saving, setSaving] = useState(false)
  const [error, setError] = useState<string | null>(null)
  const [attempt, setAttempt] = useState(0)
  const saveLock = useRef(false)
  useEffect(() => {
    if (!enabled) { setSettings(null); setInitial(null); setLoading(false); return }
    const controller = new AbortController()
    setLoading(true); setError(null)
    fetch(endpoint(), {signal: controller.signal, headers: {'X-WP-Nonce': window.swiftCommerceData?.restNonce || ''}})
      .then(async response => { if (!response.ok) throw new Error('Could not load product defaults.'); return response.json() })
      .then(data => {
        const value = parseSelectorDefaults(data.settings)
        if (!controller.signal.aborted) { setSettings(value); setInitial(value) }
      })
      .catch(() => { if (!controller.signal.aborted) { setSettings(null); setInitial(null); setError('Product defaults could not be loaded. Please try again.') } })
      .finally(() => { if (!controller.signal.aborted) setLoading(false) })
    return () => controller.abort()
  }, [enabled, attempt])
  const save = async () => {
    if (!enabled || loading || saveLock.current || !settings || !initial || error) return false
    saveLock.current = true
    const submitted = settings
    setSaving(true)
    try {
      const response = await fetch(endpoint(), {method: 'POST', headers: {'Content-Type': 'application/json', 'X-WP-Nonce': window.swiftCommerceData?.restNonce || ''}, body: JSON.stringify({settings})})
      const data = await response.json()
      if (!response.ok || !data.success) throw new Error(data.message || 'Could not save product defaults.')
      const saved = parseSelectorDefaults(data.settings)
      setSettings(current => JSON.stringify(current) === JSON.stringify(submitted) ? saved : current)
      setInitial(saved)
      return true
    } catch (reason) { toast.error(reason instanceof Error ? reason.message : 'Could not save product defaults.'); return false }
    finally { saveLock.current = false; setSaving(false) }
  }
  return {settings, setSettings, loading, saving, error, save, hasChanges: !!settings && !!initial && JSON.stringify(settings) !== JSON.stringify(initial), retry: useCallback(() => setAttempt(value => value + 1), []), reset: () => { if (initial) setSettings({...defaults}) }}
}