pragma solidity ^0.4.12;

contract IMigrationContract {
function migrate(address addr, uint256 nas) returns (bool success);
}

/* 灵感来自于NAS  coin*/
contract SafeMath {


function safeAdd(uint256 x, uint256 y) internal returns(uint256) {
uint256 z = x + y;
assert((z >= x) && (z >= y));
return z;
}

function safeSubtract(uint256 x, uint256 y) internal returns(uint256) {
assert(x >= y);
uint256 z = x - y;
return z;
}

function safeMult(uint256 x, uint256 y) internal returns(uint256) {
uint256 z = x * y;
assert((x == 0)||(z/x == y));
return z;
}

}

contract Token {
uint256 public totalSupply;
function balanceOf(address _owner) constant returns (uint256 balance);
function transfer(address _to, uint256 _value) returns (bool success);
function transferFrom(address _from, address _to, uint256 _value) returns (bool success);
function approve(address _spender, uint256 _value) returns (bool success);
function allowance(address _owner, address _spender) constant returns (uint256 remaining);
event Transfer(address indexed _from, address indexed _to, uint256 _value);
event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}


/*  ERC 20 token */
contract StandardToken is Token {

function transfer(address _to, uint256 _value) returns (bool success) {
if (balances[msg.sender] >= _value && _value > 0) {
balances[msg.sender] -= _value;
balances[_to] += _value;
Transfer(msg.sender, _to, _value);
return true;
} else {
return false;
}
}

function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0) {
balances[_to] += _value;
balances[_from] -= _value;
allowed[_from][msg.sender] -= _value;
Transfer(_from, _to, _value);
return true;
} else {
return false;
}
}

function balanceOf(address _owner) constant returns (uint256 balance) {
return balances[_owner];
}

function approve(address _spender, uint256 _value) returns (bool success) {
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
return true;
}

function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
return allowed[_owner][_spender];
}

mapping (address => uint256) balances;
mapping (address => mapping (address => uint256)) allowed;
}

contract UECToken is StandardToken, SafeMath {

// metadata
string  public constant name = "User Experience";
string  public constant symbol = "UEC";
uint256 public constant decimals = 18;
string  public version = "1.0";

// contracts
address public ethFundDeposit;          // ETH存放地址
address public newContractAddr;         // token更新地址

// crowdsale parameters
bool    public isFunding;                // 状态切换到true
uint256 public fundingStartBlock;
uint256 public fundingStopBlock;

uint256 public currentSupply;           // 正在售卖中的tokens数量
uint256 public tokenRaised = 0;         // 总的售卖数量token
uint256 public tokenMigrated = 0;     // 总的已经交易的 token
uint256 public tokenExchangeRate = 625;             // 625 BILIBILI 兑换 1 ETH

// events
event AllocateToken(address indexed _to, uint256 _value);   // 分配的私有交易token;
event IssueToken(address indexed _to, uint256 _value);      // 公开发行售卖的token;
event IncreaseSupply(uint256 _value);
event DecreaseSupply(uint256 _value);
event Migrate(address indexed _to, uint256 _value);

// 转换
function formatDecimals(uint256 _value) internal returns (uint256 ) {
return _value * 10 ** decimals;
}

// constructor
function UECToken(
address _ethFundDeposit,
uint256 _currentSupply)
{
ethFundDeposit = _ethFundDeposit;

isFunding = false;                           //通过控制预CrowdS ale状态
fundingStartBlock = 0;
fundingStopBlock = 0;

currentSupply = formatDecimals(_currentSupply);
totalSupply = formatDecimals(10000000000);
balances[msg.sender] = totalSupply;
if(currentSupply > totalSupply) throw;
}

modifier isOwner()  { require(msg.sender == ethFundDeposit); _; }

///  设置token汇率
function setTokenExchangeRate(uint256 _tokenExchangeRate) isOwner external {
if (_tokenExchangeRate == 0) throw;
if (_tokenExchangeRate == tokenExchangeRate) throw;

tokenExchangeRate = _tokenExchangeRate;
}

/// @dev 超发token处理
function increaseSupply (uint256 _value) isOwner external {
uint256 value = formatDecimals(_value);
if (value + currentSupply > totalSupply) throw;
currentSupply = safeAdd(currentSupply, value);
IncreaseSupply(value);
}

/// @dev 被盗token处理
function decreaseSupply (uint256 _value) isOwner external {
uint256 value = formatDecimals(_value);
if (value + tokenRaised > currentSupply) throw;

currentSupply = safeSubtract(currentSupply, value);
DecreaseSupply(value);
}

///  启动区块检测 异常的处理
function startFunding (uint256 _fundingStartBlock, uint256 _fundingStopBlock) isOwner external {
if (isFunding) throw;
if (_fundingStartBlock >= _fundingStopBlock) throw;
if (block.number >= _fundingStartBlock) throw;

fundingStartBlock = _fundingStartBlock;
fundingStopBlock = _fundingStopBlock;
isFunding = true;
}

///  关闭区块异常处理
function stopFunding() isOwner external {
if (!isFunding) throw;
isFunding = false;
}

/// 开发了一个新的合同来接收token（或者更新token）
function setMigrateContract(address _newContractAddr) isOwner external {
if (_newContractAddr == newContractAddr) throw;
newContractAddr = _newContractAddr;
}

/// 设置新的所有者地址
function changeOwner(address _newFundDeposit) isOwner() external {
if (_newFundDeposit == address(0x0)) throw;
ethFundDeposit = _newFundDeposit;
}

///转移token到新的合约
function migrate() external {
if(isFunding) throw;
if(newContractAddr == address(0x0)) throw;

uint256 tokens = balances[msg.sender];
if (tokens == 0) throw;

balances[msg.sender] = 0;
tokenMigrated = safeAdd(tokenMigrated, tokens);

IMigrationContract newContract = IMigrationContract(newContractAddr);
if (!newContract.migrate(msg.sender, tokens)) throw;

Migrate(msg.sender, tokens);               // log it
}

/// 转账ETH 到BILIBILI团队
function transferETH() isOwner external {
if (this.balance == 0) throw;
if (!ethFundDeposit.send(this.balance)) throw;
}

///  将BILIBILI token分配到预处理地址。
function allocateToken (address _addr, uint256 _eth) isOwner external {
if (_eth == 0) throw;
if (_addr == address(0x0)) throw;

uint256 tokens = safeMult(formatDecimals(_eth), tokenExchangeRate);
if (tokens + tokenRaised > currentSupply) throw;

tokenRaised = safeAdd(tokenRaised, tokens);
balances[_addr] += tokens;

AllocateToken(_addr, tokens);  // 记录token日志
}

/// 购买token
function () payable {
if (!isFunding) throw;
if (msg.value == 0) throw;

if (block.number < fundingStartBlock) throw;
if (block.number > fundingStopBlock) throw;

uint256 tokens = safeMult(msg.value, tokenExchangeRate);
if (tokens + tokenRaised > currentSupply) throw;

tokenRaised = safeAdd(tokenRaised, tokens);
balances[msg.sender] += tokens;

IssueToken(msg.sender, tokens);  //记录日志
}
}