From a14424ae5f45784db5e75c2d6a9098dc96914c9e Mon Sep 17 00:00:00 2001
From: Leonid Logvinov <logvinov.leon@gmail.com>
Date: Mon, 11 Dec 2017 12:43:19 +0100
Subject: Move isAddress to shared utils and remove all dependencies on
 ethereum-address

---
 packages/utils/src/address_utils.ts | 34 ++++++++++++++++++++++++++++++++++
 packages/utils/src/index.ts         |  1 +
 2 files changed, 35 insertions(+)
 create mode 100644 packages/utils/src/address_utils.ts

(limited to 'packages/utils/src')

diff --git a/packages/utils/src/address_utils.ts b/packages/utils/src/address_utils.ts
new file mode 100644
index 000000000..bdbcd3a89
--- /dev/null
+++ b/packages/utils/src/address_utils.ts
@@ -0,0 +1,34 @@
+import * as jsSHA3 from 'js-sha3';
+
+const BASIC_ADDRESS_REGEX = /^(0x)?[0-9a-f]{40}$/i;
+const SAME_CASE_ADDRESS_REGEX = /^(0x)?([0-9a-f]{40}|[0-9A-F]{40})$/;
+
+export const addressUtils = {
+    isChecksumAddress(address: string): boolean {
+        // Check each case
+        const unprefixedAddress = address.replace('0x', '');
+        const addressHash = jsSHA3.keccak256(unprefixedAddress.toLowerCase());
+
+        for (let i = 0; i < 40; i++) {
+            // The nth letter should be uppercase if the nth digit of casemap is 1
+            if ((parseInt(addressHash[i], 16) > 7 && unprefixedAddress[i].toUpperCase() !== unprefixedAddress[i]) ||
+                (parseInt(addressHash[i], 16) <= 7 && unprefixedAddress[i].toLowerCase() !== unprefixedAddress[i])) {
+                return false;
+            }
+        }
+        return true;
+    },
+    isAddress(address: string): boolean {
+        if (!BASIC_ADDRESS_REGEX.test(address)) {
+            // Check if it has the basic requirements of an address
+            return false;
+        } else if (SAME_CASE_ADDRESS_REGEX.test(address)) {
+            // If it's all small caps or all all caps, return true
+            return true;
+        } else {
+            // Otherwise check each case
+            const isValidChecksummedAddress = addressUtils.isChecksumAddress(address);
+            return isValidChecksummedAddress;
+        }
+    },
+};
diff --git a/packages/utils/src/index.ts b/packages/utils/src/index.ts
index a61f04ad2..edfd192b2 100644
--- a/packages/utils/src/index.ts
+++ b/packages/utils/src/index.ts
@@ -1 +1,2 @@
 export {promisify} from './promisify';
+export {addressUtils} from './address_utils';
-- 
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