import * as forge from 'node-forge';

import { EncryptionType } from '../enums/encryptionType';

import { CipherString } from '../models/domain/cipherString';
import { EncryptedObject } from '../models/domain/encryptedObject';
import { SymmetricCryptoKey } from '../models/domain/symmetricCryptoKey';
import { ProfileOrganizationResponse } from '../models/response/profileOrganizationResponse';

import { CryptoService as CryptoServiceAbstraction } from '../abstractions/crypto.service';
import { CryptoFunctionService } from '../abstractions/cryptoFunction.service';
import { StorageService } from '../abstractions/storage.service';

import { ConstantsService } from './constants.service';

import { Utils } from '../misc/utils';

const Keys = {
    key: 'key',
    encOrgKeys: 'encOrgKeys',
    encPrivateKey: 'encPrivateKey',
    encKey: 'encKey',
    keyHash: 'keyHash',
};

export class CryptoService implements CryptoServiceAbstraction {
    private key: SymmetricCryptoKey;
    private encKey: SymmetricCryptoKey;
    private legacyEtmKey: SymmetricCryptoKey;
    private keyHash: string;
    private privateKey: ArrayBuffer;
    private orgKeys: Map<string, SymmetricCryptoKey>;

    constructor(private storageService: StorageService, private secureStorageService: StorageService,
        private cryptoFunctionService: CryptoFunctionService) { }

    async setKey(key: SymmetricCryptoKey): Promise<any> {
        this.key = key;

        const option = await this.storageService.get<number>(ConstantsService.lockOptionKey);
        if (option != null) {
            // if we have a lock option set, we do not store the key
            return;
        }

        return this.secureStorageService.save(Keys.key, key.keyB64);
    }

    setKeyHash(keyHash: string): Promise<{}> {
        this.keyHash = keyHash;
        return this.storageService.save(Keys.keyHash, keyHash);
    }

    async setEncKey(encKey: string): Promise<{}> {
        if (encKey == null) {
            return;
        }

        await this.storageService.save(Keys.encKey, encKey);
        this.encKey = null;
    }

    async setEncPrivateKey(encPrivateKey: string): Promise<{}> {
        if (encPrivateKey == null) {
            return;
        }

        await this.storageService.save(Keys.encPrivateKey, encPrivateKey);
        this.privateKey = null;
    }

    setOrgKeys(orgs: ProfileOrganizationResponse[]): Promise<{}> {
        const orgKeys: any = {};
        orgs.forEach((org) => {
            orgKeys[org.id] = org.key;
        });

        return this.storageService.save(Keys.encOrgKeys, orgKeys);
    }

    async getKey(): Promise<SymmetricCryptoKey> {
        if (this.key != null) {
            return this.key;
        }

        const option = await this.storageService.get<number>(ConstantsService.lockOptionKey);
        if (option != null) {
            return null;
        }

        const key = await this.secureStorageService.get<string>(Keys.key);
        if (key != null) {
            this.key = new SymmetricCryptoKey(Utils.fromB64ToArray(key).buffer);
        }

        return key == null ? null : this.key;
    }

    getKeyHash(): Promise<string> {
        if (this.keyHash != null) {
            return Promise.resolve(this.keyHash);
        }

        return this.storageService.get<string>(Keys.keyHash);
    }

    async getEncKey(): Promise<SymmetricCryptoKey> {
        if (this.encKey != null) {
            return this.encKey;
        }

        const encKey = await this.storageService.get<string>(Keys.encKey);
        if (encKey == null) {
            return null;
        }

        const key = await this.getKey();
        if (key == null) {
            return null;
        }

        const decEncKey = await this.decrypt(new CipherString(encKey), key);
        if (decEncKey == null) {
            return null;
        }

        this.encKey = new SymmetricCryptoKey(decEncKey);
        return this.encKey;
    }

    async getPrivateKey(): Promise<ArrayBuffer> {
        if (this.privateKey != null) {
            return this.privateKey;
        }

        const encPrivateKey = await this.storageService.get<string>(Keys.encPrivateKey);
        if (encPrivateKey == null) {
            return null;
        }

        this.privateKey = await this.decrypt(new CipherString(encPrivateKey), null);
        return this.privateKey;
    }

    async getOrgKeys(): Promise<Map<string, SymmetricCryptoKey>> {
        if (this.orgKeys != null && this.orgKeys.size > 0) {
            return this.orgKeys;
        }

        const encOrgKeys = await this.storageService.get<any>(Keys.encOrgKeys);
        if (encOrgKeys == null) {
            return null;
        }

        const orgKeys: Map<string, SymmetricCryptoKey> = new Map<string, SymmetricCryptoKey>();
        let setKey = false;

        for (const orgId in encOrgKeys) {
            if (!encOrgKeys.hasOwnProperty(orgId)) {
                continue;
            }

            const decValue = await this.rsaDecrypt(encOrgKeys[orgId]);
            orgKeys.set(orgId, new SymmetricCryptoKey(decValue));
            setKey = true;
        }

        if (setKey) {
            this.orgKeys = orgKeys;
        }

        return this.orgKeys;
    }

    async getOrgKey(orgId: string): Promise<SymmetricCryptoKey> {
        if (orgId == null) {
            return null;
        }

        const orgKeys = await this.getOrgKeys();
        if (orgKeys == null || !orgKeys.has(orgId)) {
            return null;
        }

        return orgKeys.get(orgId);
    }

    clearKey(): Promise<any> {
        this.key = this.legacyEtmKey = null;
        return this.secureStorageService.remove(Keys.key);
    }

    clearKeyHash(): Promise<any> {
        this.keyHash = null;
        return this.storageService.remove(Keys.keyHash);
    }

    clearEncKey(memoryOnly?: boolean): Promise<any> {
        this.encKey = null;
        if (memoryOnly) {
            return Promise.resolve();
        }
        return this.storageService.remove(Keys.encKey);
    }

    clearPrivateKey(memoryOnly?: boolean): Promise<any> {
        this.privateKey = null;
        if (memoryOnly) {
            return Promise.resolve();
        }
        return this.storageService.remove(Keys.encPrivateKey);
    }

    clearOrgKeys(memoryOnly?: boolean): Promise<any> {
        this.orgKeys = null;
        if (memoryOnly) {
            return Promise.resolve();
        }
        return this.storageService.remove(Keys.encOrgKeys);
    }

    clearKeys(): Promise<any> {
        return Promise.all([
            this.clearKey(),
            this.clearKeyHash(),
            this.clearOrgKeys(),
            this.clearEncKey(),
            this.clearPrivateKey(),
        ]);
    }

    async toggleKey(): Promise<any> {
        const key = await this.getKey();
        const option = await this.storageService.get(ConstantsService.lockOptionKey);
        if (option != null || option === 0) {
            // if we have a lock option set, clear the key
            await this.clearKey();
            this.key = key;
            return;
        }

        await this.setKey(key);
    }

    async makeKey(password: string, salt: string): Promise<SymmetricCryptoKey> {
        const key = await this.cryptoFunctionService.pbkdf2(password, salt, 'sha256', 5000);
        return new SymmetricCryptoKey(key);
    }

    async hashPassword(password: string, key: SymmetricCryptoKey): Promise<string> {
        const storedKey = await this.getKey();
        key = key || storedKey;
        if (password == null || key == null) {
            throw new Error('Invalid parameters.');
        }

        const hash = await this.cryptoFunctionService.pbkdf2(key.key, password, 'sha256', 1);
        return Utils.fromBufferToB64(hash);
    }

    async makeEncKey(key: SymmetricCryptoKey): Promise<CipherString> {
        const bytes = await this.cryptoFunctionService.randomBytes(64);
        return this.encrypt(bytes, key);
    }

    async encrypt(plainValue: string | ArrayBuffer, key?: SymmetricCryptoKey): Promise<CipherString> {
        if (plainValue == null) {
            return Promise.resolve(null);
        }

        let plainBuf: ArrayBuffer;
        if (typeof (plainValue) === 'string') {
            plainBuf = Utils.fromUtf8ToArray(plainValue).buffer;
        } else {
            plainBuf = plainValue;
        }

        const encObj = await this.aesEncrypt(plainBuf, key);
        const iv = Utils.fromBufferToB64(encObj.iv);
        const ct = Utils.fromBufferToB64(encObj.ct);
        const mac = encObj.mac != null ? Utils.fromBufferToB64(encObj.mac) : null;
        return new CipherString(encObj.key.encType, iv, ct, mac);
    }

    async encryptToBytes(plainValue: ArrayBuffer, key?: SymmetricCryptoKey): Promise<ArrayBuffer> {
        const encValue = await this.aesEncrypt(plainValue, key);
        let macLen = 0;
        if (encValue.mac != null) {
            macLen = encValue.mac.byteLength;
        }

        const encBytes = new Uint8Array(1 + encValue.iv.byteLength + macLen + encValue.ct.byteLength);
        encBytes.set([encValue.key.encType]);
        encBytes.set(new Uint8Array(encValue.iv), 1);
        if (encValue.mac != null) {
            encBytes.set(new Uint8Array(encValue.mac), 1 + encValue.iv.byteLength);
        }

        encBytes.set(new Uint8Array(encValue.ct), 1 + encValue.iv.byteLength + macLen);
        return encBytes.buffer;
    }

    async decrypt(cipherString: CipherString, key?: SymmetricCryptoKey): Promise<ArrayBuffer> {
        const iv = Utils.fromB64ToArray(cipherString.initializationVector).buffer;
        const ct = Utils.fromB64ToArray(cipherString.cipherText).buffer;
        const mac = cipherString.mac ? Utils.fromB64ToArray(cipherString.mac).buffer : null;
        const decipher = await this.aesDecryptToBytes(cipherString.encryptionType, ct, iv, mac, key);
        if (decipher == null) {
            return null;
        }

        return decipher;
    }

    async decryptToUtf8(cipherString: CipherString, key?: SymmetricCryptoKey): Promise<string> {
        return await this.aesDecryptToUtf8(cipherString.encryptionType, cipherString.cipherText,
            cipherString.initializationVector, cipherString.mac, key);
    }

    async decryptFromBytes(encBuf: ArrayBuffer, key: SymmetricCryptoKey): Promise<ArrayBuffer> {
        if (encBuf == null) {
            throw new Error('no encBuf.');
        }

        const encBytes = new Uint8Array(encBuf);
        const encType = encBytes[0];
        let ctBytes: Uint8Array = null;
        let ivBytes: Uint8Array = null;
        let macBytes: Uint8Array = null;

        switch (encType) {
            case EncryptionType.AesCbc128_HmacSha256_B64:
            case EncryptionType.AesCbc256_HmacSha256_B64:
                if (encBytes.length <= 49) { // 1 + 16 + 32 + ctLength
                    return null;
                }

                ivBytes = encBytes.slice(1, 17);
                macBytes = encBytes.slice(17, 49);
                ctBytes = encBytes.slice(49);
                break;
            case EncryptionType.AesCbc256_B64:
                if (encBytes.length <= 17) { // 1 + 16 + ctLength
                    return null;
                }

                ivBytes = encBytes.slice(1, 17);
                ctBytes = encBytes.slice(17);
                break;
            default:
                return null;
        }

        return await this.aesDecryptToBytes(encType, ctBytes.buffer, ivBytes.buffer,
            macBytes != null ? macBytes.buffer : null, key);
    }

    // EFForg/OpenWireless
    // ref https://github.com/EFForg/OpenWireless/blob/master/app/js/diceware.js
    async randomNumber(min: number, max: number): Promise<number> {
        let rval = 0;
        const range = max - min + 1;
        const bitsNeeded = Math.ceil(Math.log2(range));
        if (bitsNeeded > 53) {
            throw new Error('We cannot generate numbers larger than 53 bits.');
        }

        const bytesNeeded = Math.ceil(bitsNeeded / 8);
        const mask = Math.pow(2, bitsNeeded) - 1;
        // 7776 -> (2^13 = 8192) -1 == 8191 or 0x00001111 11111111

        // Fill a byte array with N random numbers
        const byteArray = new Uint8Array(await this.cryptoFunctionService.randomBytes(bytesNeeded));

        let p = (bytesNeeded - 1) * 8;
        for (let i = 0; i < bytesNeeded; i++) {
            rval += byteArray[i] * Math.pow(2, p);
            p -= 8;
        }

        // Use & to apply the mask and reduce the number of recursive lookups
        // tslint:disable-next-line
        rval = rval & mask;

        if (rval >= range) {
            // Integer out of acceptable range
            return this.randomNumber(min, max);
        }

        // Return an integer that falls within the range
        return min + rval;
    }

    // Helpers

    private async aesEncrypt(plainValue: ArrayBuffer, key: SymmetricCryptoKey): Promise<EncryptedObject> {
        const obj = new EncryptedObject();
        obj.key = await this.getKeyForEncryption(key);
        obj.iv = await this.cryptoFunctionService.randomBytes(16);
        obj.ct = await this.cryptoFunctionService.aesEncrypt(plainValue, obj.iv, obj.key.encKey);

        if (obj.key.macKey != null) {
            const macData = new Uint8Array(obj.iv.byteLength + obj.ct.byteLength);
            macData.set(new Uint8Array(obj.iv), 0);
            macData.set(new Uint8Array(obj.ct), obj.iv.byteLength);
            obj.mac = await this.cryptoFunctionService.hmac(macData.buffer, obj.key.macKey, 'sha256');
        }

        return obj;
    }

    private async aesDecryptToUtf8(encType: EncryptionType, ct: string, iv: string, mac: string,
        key: SymmetricCryptoKey): Promise<string> {
        const keyForEnc = await this.getKeyForEncryption(key);
        const theKey = this.resolveLegacyKey(encType, keyForEnc);

        if (theKey.macKey != null && mac == null) {
            // tslint:disable-next-line
            console.error('mac required.');
            return null;
        }

        if (theKey.encType !== encType) {
            // tslint:disable-next-line
            console.error('encType unavailable.');
            return null;
        }

        const fastParams = this.cryptoFunctionService.aesDecryptFastParameters(ct, iv, mac, theKey);
        if (fastParams.macKey != null && fastParams.mac != null) {
            const computedMac = await this.cryptoFunctionService.hmacFast(fastParams.macData,
                fastParams.macKey, 'sha256');
            const macsEqual = await this.cryptoFunctionService.compareFast(fastParams.mac, computedMac);
            if (!macsEqual) {
                // tslint:disable-next-line
                console.error('mac failed.');
                return null;
            }
        }

        return this.cryptoFunctionService.aesDecryptFast(fastParams);
    }

    private async aesDecryptToBytes(encType: EncryptionType, ct: ArrayBuffer, iv: ArrayBuffer,
        mac: ArrayBuffer, key: SymmetricCryptoKey): Promise<ArrayBuffer> {
        const keyForEnc = await this.getKeyForEncryption(key);
        const theKey = this.resolveLegacyKey(encType, keyForEnc);

        if (theKey.macKey != null && mac == null) {
            return null;
        }

        if (theKey.encType !== encType) {
            return null;
        }

        if (theKey.macKey != null && mac != null) {
            const macData = new Uint8Array(iv.byteLength + ct.byteLength);
            macData.set(new Uint8Array(iv), 0);
            macData.set(new Uint8Array(ct), iv.byteLength);
            const computedMac = await this.cryptoFunctionService.hmac(macData.buffer, theKey.macKey, 'sha256');
            if (computedMac === null) {
                return null;
            }

            const macsMatch = await this.cryptoFunctionService.compare(mac, computedMac);
            if (!macsMatch) {
                // tslint:disable-next-line
                console.error('mac failed.');
                return null;
            }
        }

        return await this.cryptoFunctionService.aesDecrypt(ct, iv, theKey.encKey);
    }

    private async rsaDecrypt(encValue: string): Promise<ArrayBuffer> {
        const headerPieces = encValue.split('.');
        let encType: EncryptionType = null;
        let encPieces: string[];

        if (headerPieces.length === 1) {
            encType = EncryptionType.Rsa2048_OaepSha256_B64;
            encPieces = [headerPieces[0]];
        } else if (headerPieces.length === 2) {
            try {
                encType = parseInt(headerPieces[0], null);
                encPieces = headerPieces[1].split('|');
            } catch (e) { }
        }

        switch (encType) {
            case EncryptionType.Rsa2048_OaepSha256_B64:
            case EncryptionType.Rsa2048_OaepSha1_B64:
                if (encPieces.length !== 1) {
                    throw new Error('Invalid cipher format.');
                }
                break;
            case EncryptionType.Rsa2048_OaepSha256_HmacSha256_B64:
            case EncryptionType.Rsa2048_OaepSha1_HmacSha256_B64:
                if (encPieces.length !== 2) {
                    throw new Error('Invalid cipher format.');
                }
                break;
            default:
                throw new Error('encType unavailable.');
        }

        if (encPieces == null || encPieces.length <= 0) {
            throw new Error('encPieces unavailable.');
        }

        const ct = Utils.fromB64ToArray(encPieces[0]).buffer;
        const key = await this.getEncKey();
        if (key != null && key.macKey != null && encPieces.length > 1) {
            const mac = Utils.fromB64ToArray(encPieces[1]).buffer;
            const computedMac = await this.cryptoFunctionService.hmac(ct, key.macKey, 'sha256');
            const macsEqual = await this.cryptoFunctionService.compare(mac, computedMac);
            if (!macsEqual) {
                throw new Error('MAC failed.');
            }
        }

        const privateKey = await this.getPrivateKey();
        if (privateKey == null) {
            throw new Error('No private key.');
        }

        let alg: 'sha1' | 'sha256' = 'sha1';
        switch (encType) {
            case EncryptionType.Rsa2048_OaepSha256_B64:
            case EncryptionType.Rsa2048_OaepSha256_HmacSha256_B64:
                alg = 'sha256';
                break;
            case EncryptionType.Rsa2048_OaepSha1_B64:
            case EncryptionType.Rsa2048_OaepSha1_HmacSha256_B64:
                break;
            default:
                throw new Error('encType unavailable.');
        }

        return this.cryptoFunctionService.rsaDecrypt(ct, privateKey, alg);
    }

    private async getKeyForEncryption(key?: SymmetricCryptoKey): Promise<SymmetricCryptoKey> {
        if (key != null) {
            return key;
        }

        const encKey = await this.getEncKey();
        if (encKey != null) {
            return encKey;
        }

        return await this.getKey();
    }

    private resolveLegacyKey(encType: EncryptionType, key: SymmetricCryptoKey): SymmetricCryptoKey {
        if (encType === EncryptionType.AesCbc128_HmacSha256_B64 &&
            key.encType === EncryptionType.AesCbc256_B64) {
            // Old encrypt-then-mac scheme, make a new key
            if (this.legacyEtmKey == null) {
                this.legacyEtmKey = new SymmetricCryptoKey(key.key, EncryptionType.AesCbc128_HmacSha256_B64);
            }
            return this.legacyEtmKey;
        }

        return key;
    }
}