Billing updates (#178)

* add billing support

* update test

* rm extra lines

Co-authored-by: Mariah <mmclaughlin@choopa.com>

billing.go

@@ -0,0 +1,159 @@
+package govultr
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	"github.com/google/go-querystring/query"
+)
+
+// BillingService is the interface to interact with the billing endpoint on the Vultr API
+// Link : https://www.vultr.com/api/#tag/billing
+type BillingService interface {
+	ListHistory(ctx context.Context, options *ListOptions) ([]History, *Meta, error)
+	ListInvoices(ctx context.Context, options *ListOptions) ([]Invoice, *Meta, error)
+	GetInvoice(ctx context.Context, invoiceID string) (*Invoice, error)
+	ListInvoiceItems(ctx context.Context, invoiceID int, options *ListOptions) ([]InvoiceItem, *Meta, error)
+}
+
+// BillingServiceHandler handles interaction with the billing methods for the Vultr API
+type BillingServiceHandler struct {
+	client *Client
+}
+
+// History represents a billing history item on an account
+type History struct {
+	ID          int     `json:"id"`
+	Date        string  `json:"date"`
+	Type        string  `json:"type"`
+	Description string  `json:"description"`
+	Amount      float32 `json:"amount"`
+	Balance     float32 `json:"balance"`
+}
+
+// Invoice represents an invoice on an account
+type Invoice struct {
+	ID          int     `json:"id"`
+	Date        string  `json:"date"`
+	Description string  `json:"description"`
+	Amount      float32 `json:"amount"`
+	Balance     float32 `json:"balance"`
+}
+
+// InvoiceItem represents an item on an accounts invoice
+type InvoiceItem struct {
+	Description string  `json:"description"`
+	Product     string  `json:"product"`
+	StartDate   string  `json:"start_date"`
+	EndDate     string  `json:"end_date"`
+	Units       int     `json:"units"`
+	UnitType    string  `json:"unit_type"`
+	UnitPrice   float32 `json:"unit_price"`
+	Total       float32 `json:"total"`
+}
+
+type billingHistoryBase struct {
+	History []History `json:"billing_history"`
+	Meta    *Meta     `json:"meta"`
+}
+
+type invoicesBase struct {
+	Invoice []Invoice `json:"billing_invoices"`
+	Meta    *Meta     `json:"meta"`
+}
+
+type invoiceBase struct {
+	Invoice *Invoice `json:"billing_invoice"`
+}
+
+type invoiceItemsBase struct {
+	InvoiceItems []InvoiceItem `json:"invoice_items"`
+	Meta         *Meta         `json:"meta"`
+}
+
+// ListHistory retrieves a list of all billing history on the current account
+func (b *BillingServiceHandler) ListHistory(ctx context.Context, options *ListOptions) ([]History, *Meta, error) {
+	uri := "/v2/billing/history"
+	req, err := b.client.NewRequest(ctx, http.MethodGet, uri, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	newValues, err := query.Values(options)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	req.URL.RawQuery = newValues.Encode()
+
+	invoices := new(billingHistoryBase)
+	if err = b.client.DoWithContext(ctx, req, invoices); err != nil {
+		return nil, nil, err
+	}
+
+	return invoices.History, invoices.Meta, nil
+}
+
+// ListInvoices retrieves a list of all billing invoices on the current account
+func (b *BillingServiceHandler) ListInvoices(ctx context.Context, options *ListOptions) ([]Invoice, *Meta, error) {
+	uri := "/v2/billing/invoices"
+	req, err := b.client.NewRequest(ctx, http.MethodGet, uri, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	newValues, err := query.Values(options)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	req.URL.RawQuery = newValues.Encode()
+
+	invoices := new(invoicesBase)
+	if err = b.client.DoWithContext(ctx, req, invoices); err != nil {
+		return nil, nil, err
+	}
+
+	return invoices.Invoice, invoices.Meta, nil
+}
+
+// GetInvoice retrieves an invoice that matches the given invoiceID
+func (b *BillingServiceHandler) GetInvoice(ctx context.Context, invoiceID string) (*Invoice, error) {
+	uri := fmt.Sprintf("/v2/billing/invoices/%s", invoiceID)
+	req, err := b.client.NewRequest(ctx, http.MethodGet, uri, nil)
+
+	if err != nil {
+		return nil, err
+	}
+
+	invoice := new(invoiceBase)
+	if err := b.client.DoWithContext(ctx, req, invoice); err != nil {
+		return nil, err
+	}
+
+	return invoice.Invoice, nil
+}
+
+// ListInvoiceItems retrieves items in an invoice that matches the given invoiceID
+func (b *BillingServiceHandler) ListInvoiceItems(ctx context.Context, invoiceID int, options *ListOptions) ([]InvoiceItem, *Meta, error) {
+	uri := fmt.Sprintf("/v2/billing/invoices/%d/items", invoiceID)
+	req, err := b.client.NewRequest(ctx, http.MethodGet, uri, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	newValues, err := query.Values(options)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	req.URL.RawQuery = newValues.Encode()
+
+	invoice := new(invoiceItemsBase)
+	if err := b.client.DoWithContext(ctx, req, invoice); err != nil {
+		return nil, nil, err
+	}
+
+	return invoice.InvoiceItems, invoice.Meta, nil
+}