refactor: use struct types for claim related types

BREAKING change.
The following types are changed from interface to struct type:

- AccessTokenClaims
- IDTokenClaims
- IntrospectionResponse
- UserInfo and related types.

The following methods of OPStorage now take a pointer to a struct type,
instead of an interface:

- SetUserinfoFromScopes
- SetUserinfoFromToken
- SetIntrospectionFromToken

The following functions are now generic, so that type-safe extension
of Claims is now possible:

- op.VerifyIDTokenHint
- op.VerifyAccessToken
- rp.VerifyTokens
- rp.VerifyIDToken

pkg/oidc/claims.go

@@ -0,0 +1,84 @@
+package oidc
+
+// Some expirimental stuff, no sure yet if it can be used
+// or deleted before final PR.
+
+/*
+// CustomClaims allows the joining of any type
+// with Registered fields and a map of custom Claims.
+type CustomClaims[R any] struct {
+	Registered R
+	Claims     map[string]any
+}
+
+func (c *CustomClaims[_]) AppendClaims(k string, v any) {
+	if c.Claims == nil {
+		c.Claims = make(map[string]any)
+	}
+	c.Claims[k] = v
+}
+
+// MarshalJSON implements the json.Marshaller interface.
+// The Registered and Claims map are merged into a
+// single JSON object. Registered fields overwrite
+// custom Claims.
+func (c *CustomClaims[_]) MarshalJSON() ([]byte, error) {
+	return mergeAndMarshalClaims(&c.Registered, c.Claims)
+}
+
+// UnmashalJSON implements the json.Unmarshaller interface.
+// Matching values from the JSON document are set in Registered.
+// The map Claims will contain all claims from the JSON document.
+func (c *CustomClaims[_]) UnmarshalJSON(data []byte) error {
+	return unmarshalJSONMulti(data, &c.Registered, &c.Claims)
+}
+
+// CustomTokenClaims allows the joining of a Claims
+// type with registered fields and a map of custom Claims.
+// CustomTokenClaims implements the Claims interface,
+// and any type that embeds TokenClaims can be used as
+// type argument.
+type CustomTokenClaims[TC Claims] struct {
+	Registered TC
+	Claims     map[string]any
+}
+
+func (c *CustomTokenClaims[_]) AppendClaims(k string, v any) {
+	if c.Claims == nil {
+		c.Claims = make(map[string]any)
+	}
+	c.Claims[k] = v
+}
+
+// MarshalJSON implements the json.Marshaller interface.
+// The Registered and Claims map are merged into a
+// single JSON object. Registered fields overwrite
+// custom Claims.
+func (c *CustomTokenClaims[_]) MarshalJSON() ([]byte, error) {
+	return mergeAndMarshalClaims(&c.Registered, c.Claims)
+}
+
+// UnmashalJSON implements the json.Unmarshaller interface.
+// Matching values from the JSON document are set in Registered.
+// The map Claims will contain all claims from the JSON document.
+func (c *CustomTokenClaims[_]) UnmarshalJSON(data []byte) error {
+	return unmarshalJSONMulti(data, &c.Registered, &c.Claims)
+}
+
+func (c *CustomTokenClaims[_]) GetIssuer() string        { return c.Registered.GetIssuer() }
+func (c *CustomTokenClaims[_]) GetSubject() string       { return c.Registered.GetSubject() }
+func (c *CustomTokenClaims[_]) GetAudience() []string    { return c.Registered.GetAudience() }
+func (c *CustomTokenClaims[_]) GetExpiration() time.Time { return c.Registered.GetExpiration() }
+func (c *CustomTokenClaims[_]) GetIssuedAt() time.Time   { return c.Registered.GetIssuedAt() }
+func (c *CustomTokenClaims[_]) GetNonce() string         { return c.Registered.GetNonce() }
+func (c *CustomTokenClaims[_]) GetAuthTime() time.Time   { return c.Registered.GetAuthTime() }
+func (c *CustomTokenClaims[_]) GetAuthorizedParty() string {
+	return c.Registered.GetAuthorizedParty()
+}
+func (c *CustomTokenClaims[_]) GetAuthenticationContextClassReference() string {
+	return c.Registered.GetAuthenticationContextClassReference()
+}
+func (c *CustomTokenClaims[_]) SetSignatureAlgorithm(algorithm jose.SignatureAlgorithm) {
+	c.Registered.SetSignatureAlgorithm(algorithm)
+}
+*/