package api

import (
	"net/http"
	"net/url"
	"strings"
	"time"

	"reanimator/internal/domain"
	"reanimator/internal/repository/registry"
)

type RegistryDependencies struct {
	Customers   *registry.CustomerRepository
	Projects    *registry.ProjectRepository
	Locations   *registry.LocationRepository
	Assets      *registry.AssetRepository
	Components  *registry.ComponentRepository
	Lots        *registry.LotRepository
	LotMappings *registry.LotModelMappingRepository
}

type registryHandlers struct {
	deps RegistryDependencies
}

func RegisterRegistryRoutes(mux *http.ServeMux, deps RegistryDependencies) {
	h := registryHandlers{deps: deps}

	mux.HandleFunc("/customers", h.handleCustomers)
	mux.HandleFunc("/customers/", h.handleCustomerByID)

	mux.HandleFunc("/projects", h.handleProjects)
	mux.HandleFunc("/projects/", h.handleProjectByID)
	mux.HandleFunc("/locations", h.handleLocations)
	mux.HandleFunc("/locations/", h.handleLocationByID)

	mux.HandleFunc("/assets", h.handleAssets)
	mux.HandleFunc("/registry/assets/", h.handleAssetByID)
	mux.HandleFunc("/machines/dispatch", h.handleMachineDispatch)
	mux.HandleFunc("/machines/return-to-stock", h.handleMachineReturnToStock)

	mux.HandleFunc("/components", h.handleComponents)
	mux.HandleFunc("/lots", h.handleLots)
	mux.HandleFunc("/lot-mappings", h.handleLotMappings)
	mux.HandleFunc("/lot-mappings/", h.handleLotMappingByModel)
}

func (h registryHandlers) handleCustomers(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		items, err := h.deps.Customers.List(r.Context())
		if err != nil {
			writeError(w, http.StatusInternalServerError, "list customers failed")
			return
		}
		writeJSON(w, http.StatusOK, items)
	case http.MethodPost:
		var req struct {
			Name string `json:"name"`
		}
		if err := decodeJSON(r, &req); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		if strings.TrimSpace(req.Name) == "" {
			writeError(w, http.StatusBadRequest, "name is required")
			return
		}

		item, err := h.deps.Customers.Create(r.Context(), strings.TrimSpace(req.Name))
		if err != nil {
			switch err {
			case registry.ErrConflict:
				writeError(w, http.StatusConflict, "customer conflict")
			default:
				writeError(w, http.StatusInternalServerError, "create customer failed")
			}
			return
		}
		writeJSON(w, http.StatusCreated, item)
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}

func (h registryHandlers) handleCustomerByID(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	id, ok := parseID(r.URL.Path, "/customers/")
	if !ok {
		writeError(w, http.StatusNotFound, "customer not found")
		return
	}

	item, err := h.deps.Customers.Get(r.Context(), id)
	if err != nil {
		switch err {
		case registry.ErrNotFound:
			writeError(w, http.StatusNotFound, "customer not found")
		default:
			writeError(w, http.StatusInternalServerError, "get customer failed")
		}
		return
	}
	writeJSON(w, http.StatusOK, item)
}

func (h registryHandlers) handleProjects(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		items, err := h.deps.Projects.List(r.Context())
		if err != nil {
			writeError(w, http.StatusInternalServerError, "list projects failed")
			return
		}
		writeJSON(w, http.StatusOK, items)
	case http.MethodPost:
		var req struct {
			CustomerID string `json:"customer_id"`
			Name       string `json:"name"`
		}
		if err := decodeJSON(r, &req); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		if req.CustomerID == "" {
			writeError(w, http.StatusBadRequest, "customer_id is required")
			return
		}
		if strings.TrimSpace(req.Name) == "" {
			writeError(w, http.StatusBadRequest, "name is required")
			return
		}

		item, err := h.deps.Projects.Create(r.Context(), req.CustomerID, strings.TrimSpace(req.Name))
		if err != nil {
			switch err {
			case registry.ErrConflict:
				writeError(w, http.StatusConflict, "project conflict")
			default:
				writeError(w, http.StatusInternalServerError, "create project failed")
			}
			return
		}
		writeJSON(w, http.StatusCreated, item)
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}

func (h registryHandlers) handleProjectByID(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	id, ok := parseID(r.URL.Path, "/projects/")
	if !ok {
		writeError(w, http.StatusNotFound, "project not found")
		return
	}

	item, err := h.deps.Projects.Get(r.Context(), id)
	if err != nil {
		switch err {
		case registry.ErrNotFound:
			writeError(w, http.StatusNotFound, "project not found")
		default:
			writeError(w, http.StatusInternalServerError, "get project failed")
		}
		return
	}
	writeJSON(w, http.StatusOK, item)
}

func (h registryHandlers) handleLocations(w http.ResponseWriter, r *http.Request) {
	if h.deps.Locations == nil {
		writeError(w, http.StatusInternalServerError, "locations unavailable")
		return
	}

	switch r.Method {
	case http.MethodGet:
		items, err := h.deps.Locations.List(r.Context())
		if err != nil {
			writeError(w, http.StatusInternalServerError, "list locations failed")
			return
		}
		writeJSON(w, http.StatusOK, items)
	case http.MethodPost:
		var req struct {
			Name string  `json:"name"`
			Kind *string `json:"kind"`
		}
		if err := decodeJSON(r, &req); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		name := strings.TrimSpace(req.Name)
		if name == "" {
			writeError(w, http.StatusBadRequest, "name is required")
			return
		}
		item, err := h.deps.Locations.Create(r.Context(), name, normalizeOptionalString(req.Kind))
		if err != nil {
			switch err {
			case registry.ErrConflict:
				writeError(w, http.StatusConflict, "location conflict")
			default:
				writeError(w, http.StatusInternalServerError, "create location failed")
			}
			return
		}
		writeJSON(w, http.StatusCreated, item)
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}

func (h registryHandlers) handleLocationByID(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}
	if h.deps.Locations == nil {
		writeError(w, http.StatusInternalServerError, "locations unavailable")
		return
	}
	id, ok := parseID(r.URL.Path, "/locations/")
	if !ok {
		writeError(w, http.StatusNotFound, "location not found")
		return
	}
	item, err := h.deps.Locations.Get(r.Context(), id)
	if err != nil {
		switch err {
		case registry.ErrNotFound:
			writeError(w, http.StatusNotFound, "location not found")
		default:
			writeError(w, http.StatusInternalServerError, "get location failed")
		}
		return
	}
	writeJSON(w, http.StatusOK, item)
}

func (h registryHandlers) handleAssets(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		items, err := h.deps.Assets.List(r.Context())
		if err != nil {
			writeError(w, http.StatusInternalServerError, "list assets failed")
			return
		}
		writeJSON(w, http.StatusOK, items)
	case http.MethodPost:
		var req struct {
			ProjectID    *string `json:"project_id"`
			CustomerID   *string `json:"customer_id"`
			LocationID   *string `json:"location_id"`
			Name         string  `json:"name"`
			Vendor       *string `json:"vendor"`
			Model        *string `json:"model"`
			VendorSerial string  `json:"vendor_serial"`
			AssetTag     *string `json:"asset_tag"`
		}
		if err := decodeJSON(r, &req); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		if strings.TrimSpace(req.Name) == "" {
			writeError(w, http.StatusBadRequest, "name is required")
			return
		}
		if strings.TrimSpace(req.VendorSerial) == "" {
			writeError(w, http.StatusBadRequest, "vendor_serial is required")
			return
		}

		projectID := ""
		if req.ProjectID != nil {
			projectID = strings.TrimSpace(*req.ProjectID)
		}
		asset := domain.Asset{
			ProjectID:    projectID,
			CustomerID:   normalizeOptionalString(req.CustomerID),
			LocationID:   normalizeOptionalString(req.LocationID),
			Name:         strings.TrimSpace(req.Name),
			Vendor:       normalizeOptionalString(req.Vendor),
			Model:        normalizeOptionalString(req.Model),
			VendorSerial: strings.TrimSpace(req.VendorSerial),
			MachineTag:   normalizeOptionalString(req.AssetTag),
		}

		item, err := h.deps.Assets.Create(r.Context(), asset)
		if err != nil {
			switch err {
			case registry.ErrConflict:
				writeError(w, http.StatusConflict, "asset conflict")
			default:
				writeError(w, http.StatusInternalServerError, "create asset failed")
			}
			return
		}
		writeJSON(w, http.StatusCreated, item)
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}

func (h registryHandlers) handleAssetByID(w http.ResponseWriter, r *http.Request) {
	id, ok := parseID(r.URL.Path, "/registry/assets/")
	if !ok {
		writeError(w, http.StatusNotFound, "asset not found")
		return
	}

	switch r.Method {
	case http.MethodGet:
		item, err := h.deps.Assets.Get(r.Context(), id)
		if err != nil {
			switch err {
			case registry.ErrNotFound:
				writeError(w, http.StatusNotFound, "asset not found")
			default:
				writeError(w, http.StatusInternalServerError, "get asset failed")
			}
			return
		}
		writeJSON(w, http.StatusOK, item)
	case http.MethodDelete:
		result, err := h.deps.Assets.DeleteWithDetails(r.Context(), id)
		if err != nil {
			switch err {
			case registry.ErrNotFound:
				writeError(w, http.StatusNotFound, "asset not found")
			default:
				writeError(w, http.StatusInternalServerError, "delete asset failed")
			}
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{
			"deleted":       true,
			"deleted_parts": result.DeletedParts,
		})
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}

func (h registryHandlers) handleMachineDispatch(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}
	if h.deps.Assets == nil {
		writeError(w, http.StatusInternalServerError, "machines unavailable")
		return
	}

	var req struct {
		SerialNumbers []string `json:"serial_numbers"`
		CustomerID    string   `json:"customer_id"`
		LocationID    *string  `json:"location_id"`
	}
	if err := decodeJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, err.Error())
		return
	}
	serials := normalizeSerialInput(req.SerialNumbers)
	if len(serials) == 0 {
		writeError(w, http.StatusBadRequest, "serial_numbers is required")
		return
	}
	customerID := strings.TrimSpace(req.CustomerID)
	if customerID == "" {
		writeError(w, http.StatusBadRequest, "customer_id is required")
		return
	}

	locationID := normalizeOptionalString(req.LocationID)
	result, err := h.deps.Assets.DispatchBySerials(r.Context(), serials, customerID, locationID, time.Now().UTC())
	if err != nil {
		if err == registry.ErrConflict {
			writeError(w, http.StatusConflict, "invalid customer_id or location_id")
			return
		}
		writeError(w, http.StatusInternalServerError, "dispatch failed")
		return
	}
	if len(result.MissingSerials) > 0 {
		writeJSON(w, http.StatusNotFound, map[string]any{
			"error":           "machines not found",
			"missing_serials": result.MissingSerials,
		})
		return
	}
	if len(result.AlreadyAssignedSerials) > 0 {
		writeJSON(w, http.StatusConflict, map[string]any{
			"error":                    "machines already assigned",
			"already_assigned_serials": result.AlreadyAssignedSerials,
		})
		return
	}

	writeJSON(w, http.StatusOK, map[string]any{
		"updated": result.Updated,
	})
}

func (h registryHandlers) handleMachineReturnToStock(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}
	if h.deps.Assets == nil {
		writeError(w, http.StatusInternalServerError, "machines unavailable")
		return
	}

	var req struct {
		SerialNumbers []string `json:"serial_numbers"`
	}
	if err := decodeJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, err.Error())
		return
	}
	serials := normalizeSerialInput(req.SerialNumbers)
	if len(serials) == 0 {
		writeError(w, http.StatusBadRequest, "serial_numbers is required")
		return
	}

	result, err := h.deps.Assets.ReturnToStockBySerials(r.Context(), serials, time.Now().UTC())
	if err != nil {
		writeError(w, http.StatusInternalServerError, "return to stock failed")
		return
	}
	if len(result.MissingSerials) > 0 {
		writeJSON(w, http.StatusNotFound, map[string]any{
			"error":           "machines not found",
			"missing_serials": result.MissingSerials,
		})
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{
		"updated": result.Updated,
	})
}

func (h registryHandlers) handleComponents(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		items, err := h.deps.Components.List(r.Context())
		if err != nil {
			writeError(w, http.StatusInternalServerError, "list components failed")
			return
		}
		writeJSON(w, http.StatusOK, items)
	case http.MethodPost:
		var req struct {
			LotID        *string `json:"lot_id"`
			Vendor       *string `json:"vendor"`
			Model        *string `json:"model"`
			VendorSerial string  `json:"vendor_serial"`
		}
		if err := decodeJSON(r, &req); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		if strings.TrimSpace(req.VendorSerial) == "" {
			writeError(w, http.StatusBadRequest, "vendor_serial is required")
			return
		}

		component := domain.Component{
			LotID:        req.LotID,
			Vendor:       req.Vendor,
			Model:        req.Model,
			VendorSerial: strings.TrimSpace(req.VendorSerial),
		}

		item, err := h.deps.Components.Create(r.Context(), component)
		if err != nil {
			switch err {
			case registry.ErrConflict:
				writeError(w, http.StatusConflict, "component conflict")
			default:
				writeError(w, http.StatusInternalServerError, "create component failed")
			}
			return
		}
		writeJSON(w, http.StatusCreated, item)
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}

func (h registryHandlers) handleLots(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}
	if h.deps.Lots == nil {
		writeError(w, http.StatusInternalServerError, "lots unavailable")
		return
	}
	items, err := h.deps.Lots.List(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, "list lots failed")
		return
	}
	writeJSON(w, http.StatusOK, items)
}

func (h registryHandlers) handleLotMappings(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		w.WriteHeader(http.StatusMethodNotAllowed)
		return
	}
	if h.deps.LotMappings == nil {
		writeError(w, http.StatusInternalServerError, "lot mappings unavailable")
		return
	}
	items, err := h.deps.LotMappings.List(r.Context())
	if err != nil {
		writeError(w, http.StatusInternalServerError, "list lot mappings failed")
		return
	}
	writeJSON(w, http.StatusOK, items)
}

func (h registryHandlers) handleLotMappingByModel(w http.ResponseWriter, r *http.Request) {
	if h.deps.Lots == nil || h.deps.LotMappings == nil {
		writeError(w, http.StatusInternalServerError, "lot mapping dependencies unavailable")
		return
	}

	model, ok := parseModelPathParam(r.URL.Path, "/lot-mappings/")
	if !ok {
		writeError(w, http.StatusBadRequest, "model is required")
		return
	}

	switch r.Method {
	case http.MethodPut:
		var req struct {
			LotCode string `json:"lot_code"`
		}
		if err := decodeJSON(r, &req); err != nil {
			writeError(w, http.StatusBadRequest, err.Error())
			return
		}
		lotCode := normalizeMappingValue(req.LotCode)
		if lotCode == "" {
			writeError(w, http.StatusBadRequest, "lot_code is required")
			return
		}

		lot, err := h.deps.Lots.EnsureByCode(r.Context(), lotCode)
		if err != nil {
			if err == registry.ErrConflict {
				writeError(w, http.StatusConflict, "lot conflict")
				return
			}
			writeError(w, http.StatusInternalServerError, "ensure lot failed")
			return
		}

		item, created, affectedParts, err := h.deps.LotMappings.UpsertByModelWithBackfill(r.Context(), model, lot.ID)
		if err != nil {
			if err == registry.ErrConflict {
				writeError(w, http.StatusConflict, "lot mapping conflict")
				return
			}
			writeError(w, http.StatusInternalServerError, "upsert lot mapping failed")
			return
		}

		status := http.StatusOK
		if created {
			status = http.StatusCreated
		}
		writeJSON(w, status, map[string]any{
			"mapping":              item,
			"affected_parts_count": affectedParts,
		})
	case http.MethodDelete:
		affectedParts, err := h.deps.LotMappings.DeleteByModelWithReset(r.Context(), model)
		if err != nil {
			switch err {
			case registry.ErrNotFound:
				writeError(w, http.StatusNotFound, "lot mapping not found")
			default:
				writeError(w, http.StatusInternalServerError, "delete lot mapping failed")
			}
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{
			"deleted":              true,
			"affected_parts_count": affectedParts,
		})
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
	}
}

func normalizeOptionalString(value *string) *string {
	if value == nil {
		return nil
	}
	trimmed := strings.TrimSpace(*value)
	if trimmed == "" {
		return nil
	}
	return &trimmed
}

func normalizeSerialInput(values []string) []string {
	seen := make(map[string]struct{}, len(values))
	serials := make([]string, 0, len(values))
	for _, value := range values {
		trimmed := strings.TrimSpace(value)
		if trimmed == "" {
			continue
		}
		if _, exists := seen[trimmed]; exists {
			continue
		}
		seen[trimmed] = struct{}{}
		serials = append(serials, trimmed)
	}
	return serials
}

func parseModelPathParam(path, prefix string) (string, bool) {
	if !strings.HasPrefix(path, prefix) {
		return "", false
	}
	raw := strings.TrimPrefix(path, prefix)
	if raw == "" || strings.Contains(raw, "/") {
		return "", false
	}
	decoded, err := url.PathUnescape(raw)
	if err != nil {
		return "", false
	}
	model := normalizeMappingValue(decoded)
	if model == "" {
		return "", false
	}
	return model, true
}

func normalizeMappingValue(value string) string {
	trimmed := strings.TrimSpace(value)
	if len(trimmed) >= 2 {
		if (strings.HasPrefix(trimmed, "\"") && strings.HasSuffix(trimmed, "\"")) ||
			(strings.HasPrefix(trimmed, "'") && strings.HasSuffix(trimmed, "'")) {
			trimmed = strings.TrimSpace(trimmed[1 : len(trimmed)-1])
		}
	}
	return trimmed
}