ethereum_receipts

build

$ make build

start

$ make start

Open http://localhost in your browser.

design

The overall design of the system:

  api servers    browser 
    -> geth        -> metamask

      |            |
      |            |
      \           /

  controller contract

          |
          |

  storage contract

storage contract

Used for underlying storage - this is the stateful contract and should never need updating.

It has a simple map[string]string structure and does not understand the structure of keys

state

• values - map[string]string
• controllerAddress - address

methods

function write(key, value) {
  if(sender.address != controllerAddress) return
  values[key] = value
}

function updateControllerAddress(address) {
  if(sender.address != contract.owner) return
  controllerAddress = address
}

controller contract

data structure

The underlying key structure for receipts:

owner + previousHash + contentHash

properties

• storageContractAddress - address

methods

function findReceipts(field, value) {
  let results = []
  for (key, content in storage.values) {
    const {owner, previousHash, contentHash} = receipt = key.split()
    receipt.content = receipt
    if(key == 'owner' && owner == value) results.push(receipt)
    if(key == 'previousHash' && previousHash == value) results.push(receipt)
    if(key == 'contentHash' && contentHash == value) results.push(receipt)
  }
  return results
}

function findReceipt(field, value) {
  results = findReceipts(field, value)
  return results[0]
}

function loadReceiptChain(id) {
  let currentChain = findReceipt('contentHash', id)
  let results = [currentChain]

  while(currentChain.previousHash) {
    currentChain = findReceipt('contentHash', currentChain.previousHash)
    results.unshift(currentChain)
  }
  return results
}

function loadAllChains(owner) {
  const allReceipts = findReceipts('owner', owner)
  let receipts = {}
  let chains = {}

  // TODO: work out how to return an array of chains where
  // each item is the last thing in the chain
}

function getOwner() {
  return sender.data.apiKey || sender.address
}

function create(content, previousHash) {
  const owner = getOwner()
  const contentHash = sha256(content)
  if(previousHash) {
    const previousReceipt = findReceipt('previousHash', previousHash)
    if(previousReceipt.owner != owner) return
  }
  else {
    previousHash sha256('')
  }
  storage.write([owner, previousHash, contentHash].join(':'), content)
}

function updateControllerAddress(address) {
  if(sender.address != contract.owner) return
  controllerAddress = address
}

start linked to template stack

If you are wanting to edit templtestack whilst hot reloading - then:

$ make linked
$ make frontend.cli
$ yarn run watch