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const Streams = require('mississippi')
const StreamProvider = require('web3-stream-provider')
const ObjectMultiplex = require('./obj-multiplex')
const RemoteStore = require('./remote-store.js').RemoteStore
const createRandomId = require('./random-id')
module.exports = MetamaskInpageProvider
function MetamaskInpageProvider (connectionStream) {
const self = this
// setup connectionStream multiplexing
var multiStream = ObjectMultiplex()
Streams.pipe(connectionStream, multiStream, connectionStream, function (err) {
let warningMsg = 'MetamaskInpageProvider - lost connection to MetaMask'
if (err) warningMsg += '\n' + err.stack
console.warn(warningMsg)
})
self.multiStream = multiStream
// subscribe to metamask public config
var publicConfigStore = remoteStoreWithLocalStorageCache('MetaMask-Config')
var storeStream = publicConfigStore.createStream()
Streams.pipe(storeStream, multiStream.createStream('publicConfig'), storeStream, function (err) {
let warningMsg = 'MetamaskInpageProvider - lost connection to MetaMask publicConfig'
if (err) warningMsg += '\n' + err.stack
console.warn(warningMsg)
})
self.publicConfigStore = publicConfigStore
// connect to async provider
var asyncProvider = new StreamProvider()
Streams.pipe(asyncProvider, multiStream.createStream('provider'), asyncProvider, function (err) {
let warningMsg = 'MetamaskInpageProvider - lost connection to MetaMask provider'
if (err) warningMsg += '\n' + err.stack
console.warn(warningMsg)
})
asyncProvider.on('error', console.error.bind(console))
self.asyncProvider = asyncProvider
self.idMap = {}
// handle sendAsync requests via asyncProvider
self.sendAsync = function (payload, cb) {
// rewrite request ids
var request = eachJsonMessage(payload, (message) => {
var newId = createRandomId()
self.idMap[newId] = message.id
message.id = newId
return message
})
// forward to asyncProvider
asyncProvider.sendAsync(request, function (err, res) {
if (err) return cb(err)
// transform messages to original ids
eachJsonMessage(res, (message) => {
var oldId = self.idMap[message.id]
delete self.idMap[message.id]
message.id = oldId
return message
})
cb(null, res)
})
}
}
MetamaskInpageProvider.prototype.send = function (payload) {
const self = this
let selectedAccount
let result = null
switch (payload.method) {
case 'eth_accounts':
// read from localStorage
selectedAccount = self.publicConfigStore.get('selectedAccount')
result = selectedAccount ? [selectedAccount] : []
break
case 'eth_coinbase':
// read from localStorage
selectedAccount = self.publicConfigStore.get('selectedAccount')
result = selectedAccount || '0x0000000000000000000000000000000000000000'
break
case 'eth_uninstallFilter':
self.sendAsync(payload, noop)
result = true
break
// throw not-supported Error
default:
var link = 'https://github.com/MetaMask/faq/blob/master/DEVELOPERS.md#dizzy-all-async---think-of-metamask-as-a-light-client'
var message = `The MetaMask Web3 object does not support synchronous methods like ${payload.method} without a callback parameter. See ${link} for details.`
throw new Error(message)
}
// return the result
return {
id: payload.id,
jsonrpc: payload.jsonrpc,
result: result,
}
}
MetamaskInpageProvider.prototype.sendAsync = function () {
throw new Error('MetamaskInpageProvider - sendAsync not overwritten')
}
MetamaskInpageProvider.prototype.isConnected = function () {
return true
}
MetamaskInpageProvider.prototype.isMetaMask = true
// util
function remoteStoreWithLocalStorageCache (storageKey) {
// read local cache
var initState = JSON.parse(localStorage[storageKey] || '{}')
var store = new RemoteStore(initState)
// cache the latest state locally
store.subscribe(function (state) {
localStorage[storageKey] = JSON.stringify(state)
})
return store
}
function eachJsonMessage (payload, transformFn) {
if (Array.isArray(payload)) {
return payload.map(transformFn)
} else {
return transformFn(payload)
}
}
function noop () {}
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