feat: add Koios auth

Signed-off-by: Marko Kungla <marko@mkungla.dev>

auth.go

@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: Apache-2.0
+//
+// Copyright © 2022 The Cardano Community Authors
+
+package koios
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"math"
+	"strings"
+	"time"
+)
+
+func GetTokenAuthInfo(jwt string) (AuthInfo, error) {
+	auth, err := decodeJWT(jwt)
+	if err != nil {
+		fmt.Printf("Error decoding JWT: %v\n", err)
+		return AuthInfo{}, fmt.Errorf("%w: error decoding JWT %v", ErrAuth, err)
+	}
+	return *auth, nil
+}
+
+func (c *Client) SetAuth(jwt string) error {
+	auth, err := GetTokenAuthInfo(jwt)
+	if err != nil {
+		return err
+	}
+	c.auth = &auth
+	return nil
+}
+
+func (c *Client) getAuth() AuthInfo {
+	if c.auth == nil {
+		return AuthInfo{}
+	}
+	auth := *c.auth
+	return auth
+}
+
+type AuthInfo struct {
+	// AuthType is the type of authentication used.
+	Tier    AuthTier    `json:"tier"`
+	ProjID  string      `json:"projID"`
+	Addr    string      `json:"addr"`
+	Expires AuthExpires `json:"expires"`
+
+	MaxRequests     uint          `json:"max_requests"`
+	MaxRPS          uint          `json:"max_rps"`
+	MaxQueryTimeout time.Duration `json:"query_timeout"`
+	CORSRestricted  bool          `json:"cors_restricted"`
+	token           string
+}
+
+func (a *AuthInfo) MarshalJSON() ([]byte, error) {
+	return json.Marshal(&struct {
+		Tier    string      `json:"tier"`
+		ProjID  string      `json:"projID,omitempty"`
+		Addr    string      `json:"addr,omitempty"`
+		Expires AuthExpires `json:"expires"`
+
+		MaxRequests     uint   `json:"max_requests"`
+		MaxRPS          uint   `json:"max_rps"`
+		MaxQueryTimeout string `json:"query_timeout"`
+		CORSRestricted  bool   `json:"cors_restricted"`
+	}{
+		Tier:            a.Tier.String(),
+		MaxRequests:     a.Tier.MaxRequest(),
+		MaxRPS:          a.Tier.MaxRPS(),
+		MaxQueryTimeout: a.Tier.MaxQueryTimeout().String(),
+		CORSRestricted:  a.Tier.CORSRestricted(),
+		Expires:         a.Expires,
+		Addr:            a.Addr,
+		ProjID:          a.ProjID,
+	})
+}
+
+type AuthTier uint8
+
+const (
+	// AutTierPublic gives everyone Free access to our API services so everyone is ready to start building.
+	AutTierPublic = iota
+	// AutTierFree Once familiar with our platform, consider our Advanced solution for "production ready" deployment.
+	AutTierFree
+	// AuthTierPro Enhanced resource capabilities that enable you to develop your application with ease.
+	AuthTierPro
+	// AuthTierPremium Top-notch resource capabilities, allowing you to relax and not worry about resource consumption.
+	AuthTierPremium
+	// AuthTierCustom A tailor made infrastructure design around your requirements, for optimal resource management, giving you peace of mind.
+	AuthTierCustom
+)
+
+func (at AuthTier) String() string {
+	switch at {
+	case AutTierPublic:
+		return "public"
+	case AutTierFree:
+		return "free"
+	case AuthTierPro:
+		return "pro"
+	case AuthTierPremium:
+		return "premium"
+	case AuthTierCustom:
+		return "custom"
+	default:
+		return "unknown"
+	}
+}
+
+func (at AuthTier) MaxRequest() uint {
+	switch at {
+	case AutTierPublic:
+		return 5000
+	case AutTierFree:
+		return 50000
+	case AuthTierPro:
+		return 500000
+	case AuthTierPremium:
+		return 1200000
+	case AuthTierCustom:
+		return math.MaxUint
+	default:
+		return 0
+	}
+}
+
+func (at AuthTier) MaxRPS() uint {
+	switch at {
+	case AutTierPublic, AutTierFree:
+		return 10
+	case AuthTierPro:
+		return 25
+	case AuthTierPremium:
+		return 500
+	case AuthTierCustom:
+		return math.MaxUint
+	default:
+		return 0
+	}
+}
+
+func (at AuthTier) MaxQueryTimeout() time.Duration {
+	switch at {
+	case AutTierPublic, AutTierFree:
+		return 30 * time.Second
+	case AuthTierPro:
+		return time.Minute
+	case AuthTierPremium:
+		return 2 * time.Minute
+	case AuthTierCustom:
+		return time.Duration(math.MaxInt64)
+	default:
+		return 0
+	}
+}
+
+func (at AuthTier) CORSRestricted() bool {
+	switch at {
+	case AutTierPublic:
+		return true
+	default:
+		return false
+	}
+}
+
+func (at AuthTier) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + at.String() + `"`), nil
+}
+
+type AuthExpires time.Time
+
+func (ae AuthExpires) MarshalJSON() ([]byte, error) {
+	if time.Time(ae).IsZero() {
+		return []byte("\"No expiration date\""), nil
+	}
+	return json.Marshal(ae.String())
+}
+
+func (ae AuthExpires) Time() time.Time {
+	return time.Time(ae)
+}
+
+func (ae AuthExpires) String() string {
+	return time.Time(ae).String()
+}
+
+// decodeBase64URL decodes a Base64URL string.
+func decodeBase64URL(s string) (string, error) {
+	b, err := base64.RawURLEncoding.DecodeString(s)
+	if err != nil {
+		return "", err
+	}
+	return string(b), nil
+}
+
+// decodeJWT decodes the payload of a JWT.
+func decodeJWT(token string) (*AuthInfo, error) {
+	parts := strings.Split(token, ".")
+	if len(parts) != 3 {
+		return nil, fmt.Errorf("invalid JWT format")
+	}
+
+	decoded, err := decodeBase64URL(parts[1])
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode payload: %w", err)
+	}
+
+	var payload struct {
+		Addr   string    `json:"addr"`
+		Tier   AuthTier  `json:"tier"`
+		ProjID string    `json:"projID"`
+		Exp    Timestamp `json:"exp"`
+	}
+	err = json.Unmarshal([]byte(decoded), &payload)
+	if err != nil {
+		return nil, fmt.Errorf("failed to unmarshal payload: %w", err)
+	}
+
+	var auth AuthInfo
+	auth.Addr = payload.Addr
+	auth.Tier = payload.Tier
+	auth.ProjID = payload.ProjID
+	auth.Expires = AuthExpires(payload.Exp.Time)
+	auth.token = token
+
+	auth.MaxRequests = payload.Tier.MaxRequest()
+	auth.MaxRPS = payload.Tier.MaxRPS()
+	auth.MaxQueryTimeout = payload.Tier.MaxQueryTimeout()
+
+	return &auth, nil
+}