package msrcgo

import (
	"errors"
	"io"
	"io/ioutil"
	"net/http"
)

const (
	APIVersion = "?api-version=2016-08-01"
	UpdatesURI = "/Updates"
	CvrfURI    = "/cvrf/"
	URL        = "https://api.msrc.microsoft.com"

	APIKeyHeader = "api-key"
	AcceptHeader = "Accept"
	AcceptValue  = "application/json"
	GET          = "GET"
)

// Client represents the API client
type Client struct {
	key        string
	allUpdates *http.Request
}

// NewClient returns a new Client instance
func NewClient(key string) *Client {
	all, _ := http.NewRequest(GET, URL+UpdatesURI+APIVersion, nil)
	all.Header.Set(AcceptHeader, AcceptValue)
	all.Header.Set(APIKeyHeader, key)
	return &Client{key, all}
}

// GetAllUpdates returns the Update struct (a list of all bulletins)
func (c *Client) GetAllUpdates() (*Update, error) {
	return c.getUpdate(c.allUpdates)
}

// GetUpdateID returns a Update struct of the given id
// Example id: "2016-Sep"
func (c *Client) GetUpdateID(id string) (*Update, error) {
	req, _ := http.NewRequest(GET, URL+UpdatesURI+"('"+id+"')"+APIVersion, nil)
	req.Header.Set(AcceptHeader, AcceptValue)
	req.Header.Set(APIKeyHeader, c.key)
	return c.getUpdate(req)
}

// GetCVRF returns the CVRF struct of the given id
// Example id: "2016-Sep"
func (c *Client) GetCVRF(id string) (*CVRF, error) {
	req, _ := http.NewRequest(GET, URL+CvrfURI+id+APIVersion, nil)
	req.Header.Set(AcceptHeader, AcceptValue)
	req.Header.Set(APIKeyHeader, c.key)
	return c.getCVRF(req)
}

func (c *Client) request(req *http.Request) (body io.ReadCloser, err error) {
	resp, err := (&http.Client{}).Do(req)
	if err != nil {
		return
	}
	if resp.StatusCode != http.StatusOK {
		b, e := ioutil.ReadAll(resp.Body)
		defer resp.Body.Close()
		if e == nil {
			err = errors.New(string(b))
		}
		return
	}
	body = resp.Body
	return
}

func (c *Client) getUpdate(req *http.Request) (u *Update, err error) {
	body, err := c.request(req)
	if err != nil {
		return
	}
	defer body.Close()
	return DecodeUpdate(body)
}

func (c *Client) getCVRF(req *http.Request) (u *CVRF, err error) {
	body, err := c.request(req)
	if err != nil {
		return
	}
	defer body.Close()
	return DecodeCVRF(body)
}