chore: move the go code into a subfolder

apps/api/internal/idp/providers/oauth/oauth2.go

@@ -0,0 +1,143 @@
+package oauth
+
+import (
+	"context"
+
+	"github.com/zitadel/oidc/v3/pkg/client/rp"
+	"github.com/zitadel/oidc/v3/pkg/oidc"
+	"golang.org/x/oauth2"
+
+	"github.com/zitadel/zitadel/internal/idp"
+)
+
+var _ idp.Provider = (*Provider)(nil)
+
+// Provider is the [idp.Provider] implementation for a generic OAuth 2.0 provider
+type Provider struct {
+	rp.RelyingParty
+	options           []rp.Option
+	name              string
+	userEndpoint      string
+	user              func() idp.User
+	isLinkingAllowed  bool
+	isCreationAllowed bool
+	isAutoCreation    bool
+	isAutoUpdate      bool
+	generateVerifier  func() string
+}
+
+type ProviderOpts func(provider *Provider)
+
+// WithLinkingAllowed allows end users to link the federated user to an existing one.
+func WithLinkingAllowed() ProviderOpts {
+	return func(p *Provider) {
+		p.isLinkingAllowed = true
+	}
+}
+
+// WithCreationAllowed allows end users to create a new user using the federated information.
+func WithCreationAllowed() ProviderOpts {
+	return func(p *Provider) {
+		p.isCreationAllowed = true
+	}
+}
+
+// WithAutoCreation enables that federated users are automatically created if not already existing.
+func WithAutoCreation() ProviderOpts {
+	return func(p *Provider) {
+		p.isAutoCreation = true
+	}
+}
+
+// WithAutoUpdate enables that information retrieved from the provider is automatically used to update
+// the existing user on each authentication.
+func WithAutoUpdate() ProviderOpts {
+	return func(p *Provider) {
+		p.isAutoUpdate = true
+	}
+}
+
+// WithRelyingPartyOption allows to set an additional [rp.Option] like [rp.WithPKCE].
+func WithRelyingPartyOption(option rp.Option) ProviderOpts {
+	return func(p *Provider) {
+		p.options = append(p.options, option)
+	}
+}
+
+// New creates a generic OAuth 2.0 provider
+func New(config *oauth2.Config, name, userEndpoint string, user func() idp.User, options ...ProviderOpts) (provider *Provider, err error) {
+	provider = &Provider{
+		name:             name,
+		userEndpoint:     userEndpoint,
+		user:             user,
+		generateVerifier: oauth2.GenerateVerifier,
+	}
+	for _, option := range options {
+		option(provider)
+	}
+	provider.RelyingParty, err = rp.NewRelyingPartyOAuth(config, provider.options...)
+	if err != nil {
+		return nil, err
+	}
+	return provider, nil
+}
+
+// Name implements the [idp.Provider] interface
+func (p *Provider) Name() string {
+	return p.name
+}
+
+// BeginAuth implements the [idp.Provider] interface.
+// It will create a [Session] with an OAuth2.0 authorization request as AuthURL.
+func (p *Provider) BeginAuth(ctx context.Context, state string, params ...idp.Parameter) (idp.Session, error) {
+	opts := make([]rp.AuthURLOpt, 0)
+	var loginHintSet bool
+	for _, param := range params {
+		if username, ok := param.(idp.LoginHintParam); ok {
+			loginHintSet = true
+			opts = append(opts, loginHint(string(username)))
+		}
+	}
+	if !loginHintSet {
+		opts = append(opts, rp.WithPrompt(oidc.PromptSelectAccount))
+	}
+
+	var codeVerifier string
+	if p.RelyingParty.IsPKCE() {
+		codeVerifier = p.generateVerifier()
+		opts = append(opts, rp.WithCodeChallenge(oidc.NewSHACodeChallenge(codeVerifier)))
+	}
+
+	url := rp.AuthURL(state, p.RelyingParty, opts...)
+	return &Session{AuthURL: url, Provider: p, CodeVerifier: codeVerifier}, nil
+}
+
+func loginHint(hint string) rp.AuthURLOpt {
+	return func() []oauth2.AuthCodeOption {
+		return []oauth2.AuthCodeOption{oauth2.SetAuthURLParam("login_hint", hint)}
+	}
+}
+
+// IsLinkingAllowed implements the [idp.Provider] interface.
+func (p *Provider) IsLinkingAllowed() bool {
+	return p.isLinkingAllowed
+}
+
+// IsCreationAllowed implements the [idp.Provider] interface.
+func (p *Provider) IsCreationAllowed() bool {
+	return p.isCreationAllowed
+}
+
+// IsAutoCreation implements the [idp.Provider] interface.
+func (p *Provider) IsAutoCreation() bool {
+	return p.isAutoCreation
+}
+
+// IsAutoUpdate implements the [idp.Provider] interface.
+func (p *Provider) IsAutoUpdate() bool {
+	return p.isAutoUpdate
+}
+
+func (p *Provider) User() idp.User {
+	return p.user()
+}