v6 initial commit, maybe more to follow

blockchain/index.js

@@ -0,0 +1,45 @@
+const Block = require('./block');
+
+class Blockchain {
+  constructor() {
+    this.chain = [Block.genesis()];
+  }
+
+  addBlock(data) {
+    const block = Block.mineBlock(this.chain[this.chain.length-1], data);
+    this.chain.push(block);
+
+    return block;
+  }
+
+  isValidChain(chain) {
+    if(JSON.stringify(chain[0]) !== JSON.stringify(Block.genesis())) return false;
+
+    for (let i=1; i<chain.length; i++) {
+      const block = chain[i];
+      const lastBlock = chain[i-1];
+
+      if (block.lastHash !== lastBlock.hash ||
+          block.hash !== Block.blockHash(block)) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  replaceChain(newChain) {
+    if (newChain.length <= this.chain.length) {
+      console.log('Received chain is not longer than the current chain.');
+      return;
+    } else if (!this.isValidChain(newChain)) {
+      console.log('The received chain is not valid.');
+      return;
+    }
+
+    console.log('Replacing blockchain with the new chain.');
+    this.chain = newChain;
+  }
+}
+
+module.exports = Blockchain;