Add: Discord Login Provider (#135)

internal/provider/providers/discord.go

@@ -0,0 +1,86 @@
+package providers
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	json "github.com/json-iterator/go"
+	"github.com/synctv-org/synctv/internal/provider"
+	"golang.org/x/oauth2"
+)
+
+type DiscordProvider struct {
+	config oauth2.Config
+}
+
+func newDiscordProvider() provider.ProviderInterface {
+	return &DiscordProvider{
+		config: oauth2.Config{
+			Scopes: []string{"identify"},
+			Endpoint: oauth2.Endpoint{
+				AuthURL:  "https://discord.com/oauth2/authorize",
+				TokenURL: "https://discord.com/api/oauth2/token",
+			},
+		},
+	}
+}
+
+func (p *DiscordProvider) Init(c provider.Oauth2Option) {
+	p.config.ClientID = c.ClientID
+	p.config.ClientSecret = c.ClientSecret
+	p.config.RedirectURL = c.RedirectURL
+}
+
+func (p *DiscordProvider) Provider() provider.OAuth2Provider {
+	return "discord"
+}
+
+func (p *DiscordProvider) NewAuthURL(ctx context.Context, state string) (string, error) {
+	return p.config.AuthCodeURL(state, oauth2.AccessTypeOnline), nil
+}
+
+func (p *DiscordProvider) GetToken(ctx context.Context, code string) (*oauth2.Token, error) {
+	return p.config.Exchange(ctx, code)
+}
+
+func (p *DiscordProvider) RefreshToken(ctx context.Context, tk string) (*oauth2.Token, error) {
+	return p.config.TokenSource(ctx, &oauth2.Token{RefreshToken: tk}).Token()
+}
+
+func (p *DiscordProvider) GetUserInfo(ctx context.Context, code string) (*provider.UserInfo, error) {
+	tk, err := p.config.Exchange(ctx, code)
+	if err != nil {
+		return nil, err
+	}
+	client := p.config.Client(ctx, tk)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fmt.Sprintf("https://discord.com/api/v10/oauth2/@me"), nil)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	ui := discordUserInfo{}
+	err = json.NewDecoder(resp.Body).Decode(&ui)
+	if err != nil {
+		return nil, err
+	}
+	return &provider.UserInfo{
+		Username:       ui.Data.Name,
+		ProviderUserID: ui.Data.Id,
+	}, nil
+}
+
+type discordUserInfo struct {
+	Data struct {
+		Id   string `json:"id"`
+		Name string `json:"username"`
+	} `json:"user"`
+}
+
+func init() {
+	RegisterProvider(newDiscordProvider())
+}