package networks

import (
	"github.com/gophercloud/gophercloud"
	"github.com/gophercloud/gophercloud/pagination"
)

type commonResult struct {
	gophercloud.Result
}

// Extract is a function that accepts a result and extracts a network resource.
func (r commonResult) Extract() (*Network, error) {
	var s Network
	err := r.ExtractInto(&s)
	return &s, err
}

func (r commonResult) ExtractInto(v interface{}) error {
	return r.Result.ExtractIntoStructPtr(v, "network")
}

// CreateResult represents the result of a create operation. Call its Extract
// method to interpret it as a Network.
type CreateResult struct {
	commonResult
}

// GetResult represents the result of a get operation. Call its Extract
// method to interpret it as a Network.
type GetResult struct {
	commonResult
}

// UpdateResult represents the result of an update operation. Call its Extract
// method to interpret it as a Network.
type UpdateResult struct {
	commonResult
}

// DeleteResult represents the result of a delete operation. Call its
// ExtractErr method to determine if the request succeeded or failed.
type DeleteResult struct {
	gophercloud.ErrResult
}

// Network represents, well, a network.
type Network struct {
	// UUID for the network
	ID string `json:"id"`

	// Human-readable name for the network. Might not be unique.
	Name string `json:"name"`

	// The administrative state of network. If false (down), the network does not
	// forward packets.
	AdminStateUp bool `json:"admin_state_up"`

	// Indicates whether network is currently operational. Possible values include
	// `ACTIVE', `DOWN', `BUILD', or `ERROR'. Plug-ins might define additional
	// values.
	Status string `json:"status"`

	// Subnets associated with this network.
	Subnets []string `json:"subnets"`

	// Owner of network.
	TenantID string `json:"tenant_id"`

	// Specifies whether the network resource can be accessed by any tenant.
	Shared bool `json:"shared"`
}

// NetworkPage is the page returned by a pager when traversing over a
// collection of networks.
type NetworkPage struct {
	pagination.LinkedPageBase
}

// NextPageURL is invoked when a paginated collection of networks has reached
// the end of a page and the pager seeks to traverse over a new one. In order
// to do this, it needs to construct the next page's URL.
func (r NetworkPage) NextPageURL() (string, error) {
	var s struct {
		Links []gophercloud.Link `json:"networks_links"`
	}
	err := r.ExtractInto(&s)
	if err != nil {
		return "", err
	}
	return gophercloud.ExtractNextURL(s.Links)
}

// IsEmpty checks whether a NetworkPage struct is empty.
func (r NetworkPage) IsEmpty() (bool, error) {
	is, err := ExtractNetworks(r)
	return len(is) == 0, err
}

// ExtractNetworks accepts a Page struct, specifically a NetworkPage struct,
// and extracts the elements into a slice of Network structs. In other words,
// a generic collection is mapped into a relevant slice.
func ExtractNetworks(r pagination.Page) ([]Network, error) {
	var s []Network
	err := ExtractNetworksInto(r, &s)
	return s, err
}

func ExtractNetworksInto(r pagination.Page, v interface{}) error {
	return r.(NetworkPage).Result.ExtractIntoSlicePtr(v, "networks")
}
