WA-521 Mock signatures service in localstorage

src/utils/localStorage/signatures.js

@@ -0,0 +1,32 @@
+// @flow
+import { Map } from 'immutable'
+import { load } from '~/utils/localStorage'
+
+const getSignaturesKeyFrom = (safeAddress: string) => `TXS-SIGNATURES-${safeAddress}`
+
+export const storeSignature = (safeAddress: string, nonce: number, signature: string) => {
+  const signaturesKey = getSignaturesKeyFrom(safeAddress)
+  const subjects = Map(load(signaturesKey)) || Map()
+
+  try {
+    const key = `${nonce}`
+    const existingSignatures = subjects.get(key)
+    const signatures = existingSignatures ? existingSignatures + signature : signature
+    const updatedSubjects = subjects.set(key, signatures)
+    const serializedState = JSON.stringify(updatedSubjects)
+    localStorage.setItem(signaturesKey, serializedState)
+  } catch (err) {
+    // eslint-disable-next-line
+    console.log('Error storing signatures in localstorage')
+  }
+}
+
+export const getSignaturesFrom = (safeAddress: string, nonce: number) => {
+  const key = getSignaturesKeyFrom(safeAddress)
+  const data: any = load(key)
+
+  const signatures = data ? Map(data) : Map()
+  const txSigs = signatures.get(String(nonce)) || ''
+
+  return `0x${txSigs}`
+}