zincir

# Zincir

Simple distributed blockchain experiment written in [Crystal](https://crystal-lang.org)

 - [Documents](http://docs.zincir.xyz)
 - [Releases](https://github.com/oguzbilgic/zincir-crystal/releases)
 - [Network Explorer](http://explorer.zincir.xyz)

## Usage

### Build

To build zincir, you will need [Crystal](https://crystal-lang.org/) and
[OpenSSL](https://www.openssl.org/) installed on your system. You can use
[Homebrew](https://brew.sh/) on Mac to install these dependencies.

```bash
> git clone git@github.com:oguzbilgic/zincir-crystal.git
  ...
> shards install
  ...
> shards build --release
  Dependencies are satisfied
  Building: zincird
```

### Options

```shell
> ./bin/zincird --help
  Usage: zincir [arguments]
      -s IP, --seed-ip=IP              First node to connect, TestNet by default
      -i IP, --host-ip=IP              Node's public ip, If the node is public
      -p PORT, --port=PORT             Node's public port, If the node is public
      -l, --local-net                  Prevents node from connecting to public nodes
      -w, --web                        Start web server without making the node public
      -m, --mine                       Enable mining
      -h, --help                       Show this help
      -v, --version                    Show node version
```

### Start

```bash
> ./bin/zincird --mine
  Connecting to testnet.zincir.xyz:9147
  Added <1-0878bff02..ec7> 1544946023
  ...
```

Node will connect to `TestNet` by default and sync the blockchain, before mining.
Blockchain will be cached in `./blocks/` folder.

### Start a public node

```bash
> ./bin/zincird --ip mynode.mywebsite.com --port 1234 --mine
  Connecting to testnet.zincir.xyz:9147
  Added <1-0878bff02..ec7> 1544946023
  ...
```

In public mode, node will advertise it's ip and host to the network for other
nodes to connect. Therefore, node needs to be publicly accessible with the
provided ip and port configuration

## Development

### High Level Overview

- Read and add cached blocks from `.blocks/` folder to blockchain. Whenever a 
  new block is added to the chain, store it in the `.blocks/` folder
- Unless `--local-net` is set, connect to seed host (testnet by default, can be 
  updated with `--seed-ip` option)
  * Compare our last block to network's last block
  * Find the highest common block between network and local
  * If network has a higher last block download all blocks between `common_block` 
    and network's last block
  * If our last block is higher, broadcast all blocks between the `common_block` 
    and our last block
  * Once the network download or broadcast is complete, wait for 5 seconds and 
    compare local and network last block's to ensure network and local is synced
- If `--web` or `--port` option is provided start local web server
- If `--host-ip` option is provided start public web server and broadcast our ip to 
  all the connected hosts.
- If `--mine` option is set start the miner to mine new blocks. When a new block 
  is mined broadcast it to network

### Run tests

```bash
> crystal spec
  ...
```