/*
 * Copyright IBM Corp. All Rights Reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

import { Identity, Signer, signers } from '@hyperledger/fabric-gateway';
import { promises as fs } from 'fs';
import * as path from 'path';
import * as crypto from 'crypto';
import { errorMonitor } from 'events';

/** Internal interface used to describe all the possible components
 * of the identity
 */
interface JSONID {
    name: string;
    cert: string;
    ca: string;
    hsm: boolean;
    private_key?: string;
    privateKey?: string;
    mspId: string;
}

/**
 * This class can be used to map identities in a variety of JSON formats to the Identity and Signers required
 * for the gateway. For example if you have an application wallet, or have exported IDs from SaaS
 *
 * ```
 *   const jsonAdapter: JSONIDAdapter = new JSONIDAdapter(path.resolve(__dirname,'..','wallet'))
 *
 *   const gateway = connect({
 *       client,
 *       identity: await jsonAdapter.getIdentity("appuser"),
 *       signer: await jsonAdapter.getSigner("appuser"),
 *   });
 *  ```
 *
 * Though they are JSON files, typically they files will have the .id extension. Therefore
 * if no extension is provided `.id` is added
 */
export default class JSONIDAdapter {
    private idFilesDir: string;
    private mspId = '';

    /**
     * @param idFilesDir Directory to load the files from
     * @param mspId optional MSPID to apply to all identities returned if they are missing it
     */
    public constructor(idFilesDir: string, mspId?: string) {
        this.idFilesDir = path.resolve(idFilesDir);

        if (mspId) {
            this.mspId = mspId;
        }
    }

    private async readIDFile(idFile: string): Promise<JSONID> {
        let idJsonFile = path.resolve(path.join(this.idFilesDir, idFile));

        // check if there's no extension probably means it's a waller id file
        if (path.extname(idJsonFile) === '') {
            idJsonFile = `${idJsonFile}.id`;
        }

        let id: JSONID;
        const json = JSON.parse(await fs.readFile(idJsonFile, 'utf-8'));

        // look for the nested credentials element
        const credentials = json['credentials'];

        if (credentials) {
            // v2 SDK Wallet format
            id = {
                name: idFile,
                cert: credentials['certificate'],
                ca: '',
                hsm: false,
                private_key: credentials['privateKey'],
                mspId: json.mspId,
            };
        } else {
            // IBP exported ID style format
            id = {
                name: json.name,
                cert: Buffer.from(json.cert, 'base64').toString(),
                ca: Buffer.from(json.ca, 'base64').toString(),
                hsm: json.js,
                private_key: Buffer.from(json.private_key, 'base64').toString(),
                mspId: this.mspId,
            };
        }
        return id;
    }

    /**
     *
     * @param idFile the name of the identity to load (if no extension is provided `.id` is added)
     * @returns Identity to use with the GatewayBuilder
     */
    public async getIdentity(idFile: string): Promise<Identity> {
        const id = await this.readIDFile(idFile);

        const identity: Identity = {
            credentials: Buffer.from(id.cert),
            mspId: id.mspId,
        };

        return identity;
    }

    /**
     *
     * @param idFile the name of the identity to load (if no extension is provided `.id` is added)
     * @returns Signer to use with the GatewayBuilder
     */
    public async getSigner(idFile: string): Promise<Signer> {
        const id = await this.readIDFile(idFile);
        let pk;
        if (id.private_key) {
            pk = id.private_key;
        } else if ('privateKey' in id) {
            pk = id['privateKey'];
        } else {
            throw new Error('Unable to parse the identity json file');
        }
        const privateKey = crypto.createPrivateKey(pk as string);
        return signers.newPrivateKeySigner(privateKey);
    }
}