Is this a good way to get a random number on solidity? [duplicate]

Question

I need to generate a random number for betting games. Is this pattern safety solution?

mapping(uint => address) playerMapping;

address[] players;

// here is contract will save block.number of player
function bet() { 
  ...   
  playerMapping[block.number] = msg.sender;
  players.push(playerMapping[block.number]); // blockhash(block.number) will be unknown at this stage 
  ... 
}

// this function will called by bot
function reveal(uint blockNumber) {
   ...
   uint random = blockhash(blockNumber); 
   ... 
}