iroha-rest-api/app.py

from flask import Flask, request, jsonify
from json import JSONEncoder

# Here are Iroha dependencies.
# Python library generally consists of 3 parts:
# Iroha, IrohaCrypto and IrohaGrpc which we need to import:
import os
import binascii
from iroha import IrohaCrypto
from iroha import Iroha, IrohaGrpc
from werkzeug.wrappers import response

# Here is the information about the environment and admin account information:
IROHA_HOST_ADDR = os.getenv('IROHA_HOST_ADDR', '127.0.0.1')
IROHA_PORT = os.getenv('IROHA_PORT', '50051')
ADMIN_ACCOUNT_ID = os.getenv('ADMIN_ACCOUNT_ID', 'admin@test')
ADMIN_PRIVATE_KEY = os.getenv(
    'ADMIN_PRIVATE_KEY', 'f101537e319568c765b2cc89698325604991dca57b9716b58016b253506cab70')

# Here we will create user keys
user_private_key = IrohaCrypto.private_key()
user_public_key = IrohaCrypto.derive_public_key(user_private_key)
iroha = Iroha(ADMIN_ACCOUNT_ID)
net = IrohaGrpc('{}:{}'.format(IROHA_HOST_ADDR, IROHA_PORT))


class MyEncoder(JSONEncoder):
        def default(self, o):      
            if isinstance(o, bytes):
                return str(o, encoding='utf-8')
            return o.__dict__

app = Flask(__name__)
app.json_encoder = MyEncoder

class Asset:
    assetId = ""
    balance = 0

    def __init__(self, assetId = "", balance = 0):
        self.assetId = assetId
        self.balance = balance

class Assets:
    assets = []

class StatefulValidationError:
    name = ""    
    description = ""
    solution = ""

    def __init__(self, name = "", description = "", solution = ""):
        self.name = name
        self.description = description
        self.solution = solution

transferAssetsValidationErrors = [
    StatefulValidationError("Could not transfer asset", "Internal error happened", "Try again or contact developers"),
    StatefulValidationError("No such permissions", "Command's creator does not have permission to transfer asset from his account", "Grant the necessary permission"),
    StatefulValidationError("No such source account", "Cannot find account with such id to transfer money from", "Make sure source account id is correct"),
    StatefulValidationError("No such destination account", "Cannot find account with such id to transfer money to", "Make sure destination account id is correct"),
    StatefulValidationError("No such asset found", "Cannot find such asset", "Make sure asset name and precision are correct"),
    StatefulValidationError("Not enough balance", "Source account's balance is too low to perform the operation", "Add asset to account or choose lower value to subtract"),
    StatefulValidationError("Too much asset to transfer", "Resulting asset quantity of destination account would exceed the allowed maximum", "Make sure that the final destination value is less than 2^256 / 10^asset_precision"),
    StatefulValidationError("Too long description", "Too long description", "Ensure that description length matches the criteria above (or just shorten it)")
]    

@app.route("/accounts/<string:accountId>/assets/", methods=['GET'])
def get_account_assets(accountId): #TODO: add validation and error handling

    query = iroha.query('GetAccountAssets', account_id=accountId)
    IrohaCrypto.sign_query(query, ADMIN_PRIVATE_KEY)

    iroha_response = net.send_query(query)
    data = iroha_response.account_assets_response.account_assets
    
    response = Assets()
    response.assets = []

    if len(data) < 1:
        return '', 204

    for asset in data:
        response.assets.append(Asset(asset.asset_id, asset.balance))

    return jsonify(response)

@app.route("/assets/transfer/", methods=['POST'])
def transfer_assets():
    data = request.get_json()

    if data["transfers"] and len(data["transfers"]) > 0:
        commands = []

        for transfer in data["transfers"]:
            commands.append(
                iroha.command('TransferAsset', src_account_id = transfer["source"], dest_account_id = transfer["destination"],
                    asset_id = transfer["asset"], description = transfer["description"], amount = str(transfer["amount"]))
            )
        
        transaction = iroha.transaction(commands)
        hex_hash = binascii.hexlify(IrohaCrypto.hash(transaction))

        IrohaCrypto.sign_transaction(transaction, ADMIN_PRIVATE_KEY)
        net.send_tx(transaction)

        #TODO speed up status reading  
        transactionStates = []
        for status in net.tx_status_stream(transaction):
            transactionStates.append(status)

            if(status[0] == "STATEFUL_VALIDATION_SUCCESS"):
                break

            if(status[0] == "STATEFUL_VALIDATION_FAILED"):
                return jsonify({
                    "transactionHash" : hex_hash,
                    "error" : transferAssetsValidationErrors[status[2] - 1]
                }), 400

    #TODO send URL to newly created transaction in Content-Location header
    return jsonify({ 
        "transactionHash" : hex_hash,
        # "transactionStates" : transactionStates
         })