/*
 * Copyright 2018 The NATS Authors
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package jwt

import (
	"encoding/json"
	"errors"
	"strings"

	"github.com/nats-io/nkeys"
)

// GenericClaims can be used to read a JWT as a map for any non-generic fields
type GenericClaims struct {
	ClaimsData
	Data map[string]interface{} `json:"nats,omitempty"`
}

// NewGenericClaims creates a map-based Claims
func NewGenericClaims(subject string) *GenericClaims {
	if subject == "" {
		return nil
	}
	c := GenericClaims{}
	c.Subject = subject
	c.Data = make(map[string]interface{})
	return &c
}

// DecodeGeneric takes a JWT string and decodes it into a ClaimsData and map
func DecodeGeneric(token string) (*GenericClaims, error) {
	// must have 3 chunks
	chunks := strings.Split(token, ".")
	if len(chunks) != 3 {
		return nil, errors.New("expected 3 chunks")
	}

	// header
	if _, err := parseHeaders(chunks[0]); err != nil {
		return nil, err
	}
	// claim
	data, err := decodeString(chunks[1])
	if err != nil {
		return nil, err
	}

	var gc GenericClaims
	if err := json.Unmarshal(data, &gc); err != nil {
		return nil, err
	}

	// sig
	sig, err := decodeString(chunks[2])
	if err != nil {
		return nil, err
	}
	if !gc.Verify(chunks[1], sig) {
		return nil, errors.New("claim failed signature verification")
	}

	return &gc, nil
}

// Claims returns the standard part of the generic claim
func (gc *GenericClaims) Claims() *ClaimsData {
	return &gc.ClaimsData
}

// Payload returns the custom part of the claims data
func (gc *GenericClaims) Payload() interface{} {
	return &gc.Data
}

// Encode takes a generic claims and creates a JWT string
func (gc *GenericClaims) Encode(pair nkeys.KeyPair) (string, error) {
	return gc.ClaimsData.Encode(pair, gc)
}

// Validate checks the generic part of the claims data
func (gc *GenericClaims) Validate(vr *ValidationResults) {
	gc.ClaimsData.Validate(vr)
}

func (gc *GenericClaims) String() string {
	return gc.ClaimsData.String(gc)
}

// ExpectedPrefixes returns the types allowed to encode a generic JWT, which is nil for all
func (gc *GenericClaims) ExpectedPrefixes() []nkeys.PrefixByte {
	return nil
}

func (gc *GenericClaims) ClaimType() ClaimType {
	v, ok := gc.Data["type"]
	if !ok {
		v, ok = gc.Data["nats"]
		if ok {
			m, ok := v.(map[string]interface{})
			if ok {
				v = m["type"]
			}
		}
	}
	ct, ctok := v.(ClaimType)
	if ctok {
		return ct
	}
	return ""
}

func (gc *GenericClaims) updateVersion() {
	v, ok := gc.Data["nats"]
	if ok {
		m, ok := v.(map[string]interface{})
		if ok {
			m["version"] = libVersion
		}
	}
}
