import { computed, onMounted, reactive, ref, watch } from 'vue'
import { useRouter } from '#imports'
import { usePieceTypes } from '~/composables/usePieceTypes'
import { usePieces } from '~/composables/usePieces'
import { useCustomFields } from '~/composables/useCustomFields'
import { useApi } from '~/composables/useApi'
import { useToast } from '~/composables/useToast'
import { useDocuments } from '~/composables/useDocuments'
import { useConstructeurs } from '~/composables/useConstructeurs'
import { usePieceHistory } from '~/composables/usePieceHistory'
import { extractRelationId } from '~/shared/apiRelations'
import { canPreviewDocument } from '~/utils/documentPreview'
import { formatPieceStructurePreview } from '~/shared/modelUtils'
import { uniqueConstructeurIds } from '~/shared/constructeurUtils'
import type { PieceModelStructure } from '~/shared/types/inventory'
import type { ModelType } from '~/services/modelTypes'
import {
  getStructureProducts,
  buildProductRequirementDescriptions,
  buildProductRequirementEntries,
  resizeProductSelections,
  areProductSelectionsFilled,
  applyProductSelection,
  collectNormalizedProductIds,
} from '~/shared/utils/pieceProductSelectionUtils'
import { getModelType } from '~/services/modelTypes'
import {
  type CustomFieldInput,
  buildCustomFieldInputs,
  requiredCustomFieldsFilled as _requiredCustomFieldsFilled,
  saveCustomFieldValues as _saveCustomFieldValues,
} from '~/shared/utils/customFieldFormUtils'

interface PieceCatalogType extends ModelType {
  structure: PieceModelStructure | null
  customFields?: Array<Record<string, any>>
}

export function usePieceEdit(pieceId: string) {
  const { canEdit } = usePermissions()
  const router = useRouter()
  const { get } = useApi()
  const { pieceTypes, loadPieceTypes } = usePieceTypes()
  const { updatePiece } = usePieces()
  const { upsertCustomFieldValue, updateCustomFieldValue } = useCustomFields()
  const toast = useToast()
  const { loadDocumentsByPiece, uploadDocuments, deleteDocument } = useDocuments()
  const { ensureConstructeurs } = useConstructeurs()
  const {
    history,
    loading: historyLoading,
    error: historyError,
    loadHistory,
  } = usePieceHistory()

  const piece = ref<any | null>(null)
  const loading = ref(true)
  const saving = ref(false)
  const selectedFiles = ref<File[]>([])
  const uploadingDocuments = ref(false)
  const loadingDocuments = ref(false)
  const pieceDocuments = ref<any[]>([])
  const previewDocument = ref<any | null>(null)
  const previewVisible = ref(false)

  const historyFieldLabels: Record<string, string> = {
    name: 'Nom',
    reference: 'Référence',
    prix: 'Prix',
    typePiece: 'Catégorie',
    product: 'Produit lié',
    productIds: 'Produits liés',
    constructeurIds: 'Fournisseurs',
  }

  const selectedTypeId = ref<string>('')
  const pieceTypeDetails = ref<any | null>(null)
  const editionForm = reactive({
    name: '' as string,
    description: '' as string,
    reference: '' as string,
    constructeurIds: [] as string[],
    prix: '' as string,
  })
  const productSelections = ref<(string | null)[]>([])

  const customFieldInputs = ref<CustomFieldInput[]>([])
  const resolvedStructure = computed<PieceModelStructure | null>(() =>
    pieceTypeDetails.value?.structure ?? selectedType.value?.structure ?? null,
  )

  const refreshCustomFieldInputs = (
    structureOverride?: PieceModelStructure | null,
    valuesOverride?: any[] | null,
  ) => {
    const structure = structureOverride ?? resolvedStructure.value ?? null
    const values = valuesOverride ?? piece.value?.customFieldValues ?? null
    customFieldInputs.value = buildCustomFieldInputs(structure, values)
  }

  const openPreview = (doc: any) => {
    if (!doc || !canPreviewDocument(doc)) {
      return
    }
    previewDocument.value = doc
    previewVisible.value = true
  }

  const closePreview = () => {
    previewVisible.value = false
    previewDocument.value = null
  }

  const removeDocument = async (documentId: string | number | null | undefined) => {
    if (!documentId) {
      return
    }
    const result = await deleteDocument(documentId, { updateStore: false })
    if (result.success) {
      pieceDocuments.value = pieceDocuments.value.filter((doc) => doc.id !== documentId)
    }
  }

  const handleFilesAdded = async (files: File[]) => {
    if (!files?.length || !piece.value?.id) {
      return
    }
    uploadingDocuments.value = true
    try {
      const result = await uploadDocuments(
        {
          files,
          context: { pieceId: piece.value.id },
        },
        { updateStore: false },
      )
      if (result.success) {
        selectedFiles.value = []
        await refreshDocuments()
      }
    }
    finally {
      uploadingDocuments.value = false
    }
  }

  const refreshDocuments = async () => {
    if (!piece.value?.id) {
      pieceDocuments.value = []
      return
    }
    loadingDocuments.value = true
    try {
      const result = await loadDocumentsByPiece(piece.value.id, { updateStore: false })
      if (result.success) {
        pieceDocuments.value = Array.isArray(result.data) ? result.data : result.data ? [result.data] : []
      }
    }
    finally {
      loadingDocuments.value = false
    }
  }

  const pieceTypeList = computed<PieceCatalogType[]>(() => (pieceTypes.value || []) as PieceCatalogType[])

  const selectedType = computed(() => {
    if (!selectedTypeId.value) {
      return null
    }
    return pieceTypeList.value.find((type) => type.id === selectedTypeId.value) ?? null
  })

  const structureProducts = computed(() =>
    getStructureProducts(resolvedStructure.value),
  )

  const requiresProductSelection = computed(() => structureProducts.value.length > 0)

  const productRequirementDescriptions = computed(() =>
    buildProductRequirementDescriptions(structureProducts.value),
  )

  const ensureProductSelections = (count: number) => {
    productSelections.value = resizeProductSelections(productSelections.value, count)
  }

  let pendingProductIds: string[] = []

  const productRequirementEntries = computed(() =>
    buildProductRequirementEntries(structureProducts.value, 'piece-product-requirement'),
  )

  const productSelectionsFilled = computed(() =>
    areProductSelectionsFilled(
      requiresProductSelection.value,
      productRequirementEntries.value,
      productSelections.value,
    ),
  )

  const setProductSelection = (index: number, value: string | null) => {
    productSelections.value = applyProductSelection(productSelections.value, index, value)
  }

  watch(structureProducts, (products) => {
    ensureProductSelections(products.length)
    if (!pendingProductIds.length || products.length === 0) {
      return
    }
    const next = Array.from(
      { length: products.length },
      (_, index) => pendingProductIds[index] ?? null,
    )
    productSelections.value = next
    pendingProductIds = []
  })

  const requiredCustomFieldsFilled = computed(() =>
    _requiredCustomFieldsFilled(customFieldInputs.value),
  )

  const canSubmit = computed(() =>
    Boolean(
      canEdit.value
      && piece.value
      && editionForm.name
      && requiredCustomFieldsFilled.value
      && productSelectionsFilled.value
      && !saving.value,
    ),
  )

  const fetchPiece = async () => {
    if (!pieceId || typeof pieceId !== 'string') {
      piece.value = null
      pieceDocuments.value = []
      return
    }
    const result = await get(`/pieces/${pieceId}`)
    if (result.success) {
      piece.value = result.data
      pieceDocuments.value = Array.isArray(result.data?.documents) ? result.data.documents : []

      // Use customFieldValues from entity response (enriched with customField definitions via serialization groups)
      const customValues = Array.isArray(result.data?.customFieldValues) ? result.data.customFieldValues : []
      refreshCustomFieldInputs(undefined, customValues)

      // Use cached type from loadPieceTypes() instead of separate getModelType() call
      loadPieceTypeDetailsFromCache(result.data)

      // History is non-blocking — template handles its own loading state
      loadHistory(result.data.id).catch(() => {})
    }
    else {
      piece.value = null
      pieceDocuments.value = []
    }
  }

  const loadPieceTypeDetailsFromCache = (currentPiece: any) => {
    const typeId = currentPiece?.typePieceId
      || extractRelationId(currentPiece?.typePiece)
      || ''
    if (!typeId) {
      pieceTypeDetails.value = null
      return
    }
    // Look up in the already-loaded pieceTypes cache (from loadPieceTypes in onMounted)
    const cachedType = (pieceTypes.value || []).find((t: any) => t.id === typeId) ?? null
    if (cachedType) {
      pieceTypeDetails.value = cachedType
      refreshCustomFieldInputs((cachedType.structure as PieceModelStructure | null) ?? null, currentPiece?.customFieldValues ?? null)
      return
    }
    // Fallback: fetch if not in cache (edge case)
    getModelType(typeId).then((type) => {
      if (type && typeof type === 'object') {
        pieceTypeDetails.value = type
        refreshCustomFieldInputs((type.structure as PieceModelStructure | null) ?? null, currentPiece?.customFieldValues ?? null)
      }
    }).catch(() => {
      pieceTypeDetails.value = null
    })
  }

  let initialized = false

  watch(
    [piece, selectedType],
    ([currentPiece, _currentType]) => {
      if (!currentPiece || initialized) {
        return
      }

      const resolvedTypeId = currentPiece.typePieceId
        || extractRelationId(currentPiece.typePiece)
        || ''
      if (resolvedTypeId && !currentPiece.typePieceId) {
        currentPiece.typePieceId = resolvedTypeId
      }
      selectedTypeId.value = resolvedTypeId

      editionForm.name = currentPiece.name || ''
      editionForm.description = currentPiece.description || ''
      editionForm.reference = currentPiece.reference || ''
      editionForm.constructeurIds = uniqueConstructeurIds(
        currentPiece,
        Array.isArray(currentPiece.constructeurs) ? currentPiece.constructeurs : [],
        currentPiece.constructeur ? [currentPiece.constructeur] : [],
      )
      editionForm.prix = currentPiece.prix !== null && currentPiece.prix !== undefined ? String(currentPiece.prix) : ''
      if (editionForm.constructeurIds.length) {
        void ensureConstructeurs(editionForm.constructeurIds)
      }

      const existingProductIds = Array.isArray(currentPiece.productIds) && currentPiece.productIds.length
        ? currentPiece.productIds.map((id: unknown) => String(id))
        : currentPiece.product?.id || currentPiece.productId
          ? [String(currentPiece.product?.id || currentPiece.productId)]
          : []
      pendingProductIds = existingProductIds
      ensureProductSelections(structureProducts.value.length)
      if (existingProductIds.length && structureProducts.value.length) {
        const next = Array.from(
          { length: structureProducts.value.length },
          (_, index) => existingProductIds[index] ?? null,
        )
        productSelections.value = next
        pendingProductIds = []
      }

      // After setting selectedTypeId, read selectedType.value (now updated) instead of
      // the stale destructured currentType which was captured before the ID change.
      const resolvedType = selectedType.value ?? pieceTypeDetails.value ?? null
      refreshCustomFieldInputs(resolvedType?.structure ?? null, currentPiece.customFieldValues)

      initialized = true
    },
    { immediate: true },
  )

  watch(selectedType, (currentType) => {
    if (!piece.value || !currentType) {
      return
    }
    refreshCustomFieldInputs(currentType.structure, piece.value.customFieldValues)
  })

  watch(resolvedStructure, (currentStructure) => {
    if (!piece.value) {
      return
    }
    ensureProductSelections(structureProducts.value.length)
    refreshCustomFieldInputs(currentStructure, piece.value.customFieldValues)
  })

  const submitEdition = async () => {
    if (!piece.value) {
      return
    }

    if (!productSelectionsFilled.value) {
      toast.showError('Sélectionnez un produit conforme au squelette.')
      return
    }

    const rawPrice = typeof editionForm.prix === 'string'
      ? editionForm.prix.trim()
      : editionForm.prix === null || editionForm.prix === undefined
        ? ''
        : String(editionForm.prix).trim()

    const constructeurIds = uniqueConstructeurIds(editionForm.constructeurIds)

    const payload: Record<string, any> = {
      name: editionForm.name.trim(),
      description: editionForm.description.trim() || null,
      constructeurIds,
    }

    const reference = editionForm.reference.trim()
    payload.reference = reference ? reference : null

    const normalizedProductIds = collectNormalizedProductIds(
      productRequirementEntries.value,
      productSelections.value,
    )

    payload.productIds = normalizedProductIds
    payload.productId = normalizedProductIds[0] || null

    if (rawPrice) {
      const parsed = Number(rawPrice)
      if (!Number.isNaN(parsed)) {
        payload.prix = String(parsed)
      }
    }
    else {
      payload.prix = null
    }

    saving.value = true
    try {
      const result = await updatePiece(piece.value.id, payload)
      if (result.success && result.data) {
        const updatedPiece = result.data as Record<string, any>
        await _saveCustomFieldValues(
          'piece',
          updatedPiece.id,
          [
            updatedPiece?.typePiece?.pieceCustomFields,
          ],
          { customFieldInputs, upsertCustomFieldValue, updateCustomFieldValue, toast },
        )
        toast.showSuccess('Pièce mise à jour avec succès.')
      }
    }
    catch (error: any) {
      toast.showError(error?.message || 'Erreur lors de la mise à jour de la pièce')
    }
    finally {
      saving.value = false
    }
  }

  onMounted(async () => {
    await Promise.allSettled([loadPieceTypes(), fetchPiece()])
    loading.value = false
  })

  return {
    // State
    piece,
    loading,
    saving,
    selectedFiles,
    uploadingDocuments,
    loadingDocuments,
    pieceDocuments,
    previewDocument,
    previewVisible,
    selectedTypeId,
    editionForm,
    productSelections,
    customFieldInputs,
    canEdit,

    // Computed
    pieceTypeList,
    selectedType,
    resolvedStructure,
    structureProducts,
    productRequirementDescriptions,
    productRequirementEntries,
    canSubmit,
    historyFieldLabels,

    // History
    history,
    historyLoading,
    historyError,

    // Methods
    openPreview,
    closePreview,
    removeDocument,
    handleFilesAdded,
    setProductSelection,
    submitEdition,
    formatPieceStructurePreview,
  }
}