package aws

import (
	"bytes"
	"encoding/json"
	"fmt"
	"time"

	"github.com/edgelesssys/constellation/coordinator/oid"
)

// https://aws-nitro-enclaves.amazonaws.com/AWS_NitroEnclaves_Root-G1.zip
var awsNitroEnclavesRoot = []byte{
	0x30, 0x82, 0x02, 0x11, 0x30, 0x82, 0x01, 0x96, 0xa0, 0x03, 0x02, 0x01, 0x02, 0x02, 0x11, 0x00,
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	0xea, 0x21, 0x1b, 0x66, 0xe7, 0x52, 0xcf, 0x7d, 0xd1, 0xdd, 0x09, 0x5f, 0x6f, 0x13, 0x70, 0xf4,
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	0xd2, 0x55, 0x03, 0x8e, 0x1f, 0x03, 0x43, 0xf9, 0x5b, 0x63, 0xa9, 0x62, 0x8c, 0x3d, 0x39, 0x80,
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	0x7f, 0x9c, 0xda, 0xf5, 0xd9, 0x43, 0xbc, 0x61, 0xfc, 0x2b, 0xeb, 0x03, 0xcb, 0x6f, 0xee, 0x8d,
	0x23, 0x02, 0xf3, 0xdf, 0xf6,
}

type attestationDocument struct {
	ModuleID  string `json:"module_id"`
	Digest    string
	Timestamp int
	Pcrs      map[string]string
	PublicKey []byte `json:"public_key"`
	UserData  []byte `json:"user_data"`
	Nonce     []byte
}

type VerifyFunc func(adBlob []byte, rootCertDer []byte, ts time.Time) (string, error)

type Validator struct {
	oid.AWS
	getVerifiedPayloadAsJson VerifyFunc
}

func NewValidator(getVerifiedPayloadAsJson VerifyFunc) *Validator {
	return &Validator{getVerifiedPayloadAsJson: getVerifiedPayloadAsJson}
}

func (a *Validator) Validate(attDoc []byte, nonce []byte) ([]byte, error) {
	jsonStr, err := a.getVerifiedPayloadAsJson(attDoc, awsNitroEnclavesRoot, time.Now())
	if err != nil {
		return nil, err
	}

	var parsedAttDoc attestationDocument
	if err := json.Unmarshal([]byte(jsonStr), &parsedAttDoc); err != nil {
		return nil, err
	}

	if !bytes.Equal(parsedAttDoc.Nonce, nonce) {
		return nil, fmt.Errorf("validator: failed nonce freshness for nonce: %s", parsedAttDoc.Nonce)
	}

	// TODO: Choose PCRs for validation

	return parsedAttDoc.UserData, nil
}