import type { SyncProduct, ShopifyProductFull, SyncChange, DiffResult } from '@/types/sync'

const COMPARABLE_FIELDS = ['title', 'description', 'price', 'status'] as const

function getChangedFields(
  sheet: SyncProduct,
  shopify: ShopifyProductFull,
): Array<{ field: string; from: string; to: string }> {
  return COMPARABLE_FIELDS
    .filter((field) => sheet[field] !== shopify[field])
    .map((field) => ({
      field,
      from: String(shopify[field]),
      to: String(sheet[field]),
    }))
}

/**
 * Calcule le diff entre les produits Sheets et Shopify.
 * Matching par handle (ref normalisée).
 * Si tabFilter est fourni, les désactivations sont ignorées : on ne peut pas savoir
 * si un produit Shopify absent du tab appartient à une autre famille ou a été supprimé.
 */
export function computeDiff(
  sheetProducts: SyncProduct[],
  shopifyProducts: ShopifyProductFull[],
  tabFilter?: string,
): DiffResult {
  const shopifyMap = new Map(shopifyProducts.map((p) => [p.handle, p]))
  const sheetHandles = new Set(sheetProducts.map((p) => p.handle))

  const changes: SyncChange[] = []

  for (const sheet of sheetProducts) {
    const shopify = shopifyMap.get(sheet.handle)
    if (!shopify) {
      changes.push({ type: 'create', ref: sheet.ref, sheetProduct: sheet })
    } else {
      const changedFields = getChangedFields(sheet, shopify)
      if (changedFields.length > 0) {
        changes.push({
          type: 'update',
          ref: sheet.ref,
          sheetProduct: sheet,
          shopifyProduct: shopify,
          changedFields,
        })
      } else {
        changes.push({ type: 'unchanged', ref: sheet.ref, sheetProduct: sheet, shopifyProduct: shopify })
      }
    }
  }

  // Désactivations uniquement en mode catalogue complet (sans filtre par famille)
  if (!tabFilter) {
    for (const shopify of shopifyProducts) {
      if (shopify.status === 'active' && !sheetHandles.has(shopify.handle)) {
        changes.push({ type: 'deactivate', ref: shopify.ref, shopifyProduct: shopify })
      }
    }
  }

  const summary = {
    create: changes.filter((c) => c.type === 'create').length,
    update: changes.filter((c) => c.type === 'update').length,
    deactivate: changes.filter((c) => c.type === 'deactivate').length,
    unchanged: changes.filter((c) => c.type === 'unchanged').length,
  }

  return { changes, summary }
}