package arm

// Code to resolve resources that are required by the API.  These resources
// can most likely be resolved without asking the user, thereby reducing the
// amount of configuration they need to provide.
//
// Resource resolver differs from config retriever because resource resolver
// requires a client to communicate with the Azure API.  A config retriever is
// used to determine values without use of a client.

import (
	"fmt"
	"strings"
)

type resourceResolver struct {
	client                          *AzureClient
	findVirtualNetworkResourceGroup func(*AzureClient, string) (string, error)
	findVirtualNetworkSubnet        func(*AzureClient, string, string) (string, error)
}

func newResourceResolver(client *AzureClient) *resourceResolver {
	return &resourceResolver{
		client: client,
		findVirtualNetworkResourceGroup: findVirtualNetworkResourceGroup,
		findVirtualNetworkSubnet:        findVirtualNetworkSubnet,
	}
}

func (s *resourceResolver) Resolve(c *Config) error {
	if s.shouldResolveResourceGroup(c) {
		resourceGroupName, err := s.findVirtualNetworkResourceGroup(s.client, c.VirtualNetworkName)
		if err != nil {
			return err
		}

		subnetName, err := s.findVirtualNetworkSubnet(s.client, resourceGroupName, c.VirtualNetworkName)
		if err != nil {
			return err
		}

		c.VirtualNetworkResourceGroupName = resourceGroupName
		c.VirtualNetworkSubnetName = subnetName
	}

	return nil
}

func (s *resourceResolver) shouldResolveResourceGroup(c *Config) bool {
	return c.VirtualNetworkName != "" && c.VirtualNetworkResourceGroupName == ""
}

func getResourceGroupNameFromId(id string) string {
	// "/subscriptions/3f499422-dd76-4114-8859-86d526c9deb6/resourceGroups/packer-Resource-Group-yylnwsl30j/providers/...
	xs := strings.Split(id, "/")
	return xs[4]
}

func findVirtualNetworkResourceGroup(client *AzureClient, name string) (string, error) {
	virtualNetworks, err := client.VirtualNetworksClient.ListAll()
	if err != nil {
		return "", err
	}

	resourceGroupNames := make([]string, 0)

	for _, virtualNetwork := range *virtualNetworks.Value {
		if strings.EqualFold(name, *virtualNetwork.Name) {
			rgn := getResourceGroupNameFromId(*virtualNetwork.ID)
			resourceGroupNames = append(resourceGroupNames, rgn)
		}
	}

	if len(resourceGroupNames) == 0 {
		return "", fmt.Errorf("Cannot find a resource group with a virtual network called %q", name)
	}

	if len(resourceGroupNames) > 1 {
		return "", fmt.Errorf("Found multiple resource groups with a virtual network called %q, please use virtual_network_resource_group_name to disambiguate", name)
	}

	return resourceGroupNames[0], nil
}

func findVirtualNetworkSubnet(client *AzureClient, resourceGroupName string, name string) (string, error) {
	subnets, err := client.SubnetsClient.List(resourceGroupName, name)
	if err != nil {
		return "", err
	}

	if len(*subnets.Value) == 0 {
		return "", fmt.Errorf("Cannot find a subnet in the resource group %q associated with the virtual network called %q", resourceGroupName, name)
	}

	if len(*subnets.Value) > 1 {
		return "", fmt.Errorf("Found multiple subnets in the resource group %q associated with the  virtual network called %q, please use virtual_network_subnet_name to disambiguate", resourceGroupName, name)
	}

	subnet := (*subnets.Value)[0]
	return *subnet.Name, nil
}