<?php

class Transaction {
    // reverse and remove all transactions from a block
    public function reverse($block){
        global $db;
        $acc=new Account;
        $r=$db->run("SELECT * FROM transactions WHERE block=:block",array(":block"=>$block));
        foreach($r as $x){
            if(empty($x['src'])) $x['src']=$acc->get_address($x['public_key']);
            $db->run("UPDATE accounts SET balance=balance-:val WHERE id=:id",array(":id"=>$x['dst'], ":val"=>$x['val']));

	    // on version 0 / reward transaction, don't credit anyone
            if($x['version']>0) $db->run("UPDATE accounts SET balance=balance+:val WHERE id=:id",array(":id"=>$x['src'], ":val"=>$x['val']+$x['fee']));
	
	   // add the transactions to mempool            
           if($x['version']>0) $this->add_mempool($x);
           $res= $db->run("DELETE FROM transactions WHERE id=:id",array(":id"=>$x['id']));
           if($res!=1) return false;
         }
    }
    // clears the mempool
    public function clean_mempool(){
        global $db;
        $block= new Block;
	    $current=$block->current();
        $height=$current['height'];
        $limit=$height-1000;
        $db->run("DELETE FROM mempool WHERE height<:limit",array(":limit"=>$limit));
    }
	
    // returns X  transactions from mempool
    public function mempool($max){
        global $db;
        $block=new Block;
        $current=$block->current();
        $height=$current['height']+1;
	// only get the transactions that are not locked with a future height
        $r=$db->run("SELECT * FROM mempool WHERE height<=:height ORDER by val/fee DESC LIMIT :max",array(":height"=>$height, ":max"=>$max+50));
        $transactions=array();
        if(count($r)>0){
            $i=0;
            $balance=array();
            foreach($r as $x){
                    $trans=array("id"=>$x['id'],"dst"=>$x['dst'],"val"=>$x['val'],"fee"=>$x['fee'],"signature"=>$x['signature'], "message"=>$x['message'],"version"=>$x['version'],"date"=>$x['date'], "public_key"=>$x['public_key']);
                
                    if($i>=$max) break;

                    if(empty($x['public_key'])){
                        _log("$x[id] - Transaction has empty public_key");
                        continue;
                    } 
                    if(empty($x['src'])){
                        _log("$x[id] - Transaction has empty src");
                        continue;
                    } 
                    if(!$this->check($trans, $current['height'])){
                        _log("$x[id] - Transaction Check Failed");
                        continue;
                    } 
                    
                    $balance[$x['src']]+=$x['val']+$x['fee'];
                    if($db->single("SELECT COUNT(1) FROM transactions WHERE id=:id",array(":id"=>$x['id']))>0) {
                        _log("$x[id] - Duplicate transaction");
                        continue; //duplicate transaction	
                    }
                    
                    $res=$db->single("SELECT COUNT(1) FROM accounts WHERE id=:id AND balance>=:balance",array(":id"=>$x['src'], ":balance"=>$balance[$x['src']]));
                    
                    if($res==0) {
                        _log("$x[id] - Not enough funds in balance");
                        continue; // not enough balance for the transactions	
                    } 
                    $i++;
                    ksort($trans);
                    $transactions[$x['id']]=$trans;
                }
        }
	// always sort the array
        ksort($transactions);

        return $transactions;
    }

    // add a new transaction to mempool and lock it with the current height
    public function add_mempool($x, $peer=""){
        global $db;
        $block= new Block;
	    $current=$block->current();
        $height=$current['height'];
        $x['id']=san($x['id']);
        $bind=array(":peer"=>$peer, ":id"=>$x['id'],"public_key"=>$x['public_key'], ":height"=>$height, ":src"=>$x['src'],":dst"=>$x['dst'],":val"=>$x['val'], ":fee"=>$x['fee'],":signature"=>$x['signature'], ":version"=>$x['version'],":date"=>$x['date'], ":message"=>$x['message']);
        $db->run("INSERT into mempool  SET peer=:peer, id=:id, public_key=:public_key, height=:height, src=:src, dst=:dst, val=:val, fee=:fee, signature=:signature, version=:version, message=:message, `date`=:date",$bind);
        return true;


    }

    // add a new transaction to the blockchain
    public function add($block,$height, $x){
        global $db;
        $acc= new Account;
        $acc->add($x['public_key'], $block);
        $acc->add_id($x['dst'],$block);
        $x['id']=san($x['id']);
        $bind=array(":id"=>$x['id'], ":public_key"=>$x['public_key'],":height"=>$height, ":block"=>$block, ":dst"=>$x['dst'],":val"=>$x['val'], ":fee"=>$x['fee'],":signature"=>$x['signature'], ":version"=>$x['version'],":date"=>$x['date'], ":message"=>$x['message']);
        $res=$db->run("INSERT into transactions SET id=:id, public_key=:public_key, block=:block,  height=:height, dst=:dst, val=:val, fee=:fee, signature=:signature, version=:version, message=:message, `date`=:date",$bind);
        if($res!=1) return false;
        $db->run("UPDATE accounts SET balance=balance+:val WHERE id=:id",array(":id"=>$x['dst'], ":val"=>$x['val']));
	// no debit when the transaction is reward
	if($x['version']>0) $db->run("UPDATE accounts SET balance=(balance-:val)-:fee WHERE id=:id",array(":id"=>$x['src'], ":val"=>$x['val'], ":fee"=>$x['fee']));
        $db->run("DELETE FROM mempool WHERE id=:id",array(":id"=>$x['id']));
        return true;


    }
	
    // hash the transaction's most important fields and create the transaction ID
    public function hash($x){
        $info=$x['val']."-".$x['fee']."-".$x['dst']."-".$x['message']."-".$x['version']."-".$x['public_key']."-".$x['date']."-".$x['signature'];
        $hash= hash("sha512",$info);
        return hex2coin($hash);   
    }
    
    // check the transaction for validity
    public function check($x, $height=0){
                // if no specific block, use current
		if($height===0){
			$block=new Block;
			$current=$block->current();
			$height=$current['height'];
		}
                $acc= new Account;
                $info=$x['val']."-".$x['fee']."-".$x['dst']."-".$x['message']."-".$x['version']."-".$x['public_key']."-".$x['date'];

		// the value must be >=0
                if($x['val']<0){ _log("$x[id] - Value below 0"); return false; }
       		
		// the fee must be >=0
	        if($x['fee']<0) { _log("$x[id] - Fee below 0"); return false; }
            
		// the fee is 0.25%, hardcoded
                $fee=$x['val']*0.0025;
		$fee=number_format($fee,8,".","");
                if($fee<0.00000001) $fee=0.00000001;
		// max fee after block 10800 is 10
		if($height>10800&&$fee>10) $fee=10; //10800
		// added fee does not match
                if($fee!=$x['fee']) { _log("$x[id] - Fee not 0.25%"); return false; }

		// invalid destination address
                if(!$acc->valid($x['dst'])) { _log("$x[id] - Invalid destination address"); return false; }
             
		// reward transactions are not added via this function
                if($x['version']<1) { _log("$x[id] - Invalid version <1"); return false; }
                //if($x['version']>1) { _log("$x[id] - Invalid version >1"); return false; }
        
		// public key must be at least 15 chars / probably should be replaced with the validator function        
	        if(strlen($x['public_key'])<15) { _log("$x[id] - Invalid public key size"); return false; }
 		// no transactions before the genesis
                if($x['date']<1511725068) { _log("$x[id] - Date before genesis"); return false; }
		// no future transactions
                if($x['date']>time()+86400) { _log("$x[id] - Date in the future"); return false; }
                // prevent the resending of broken base58 transactions
		if($height>16000&&$x['date']<1519326876) return false;
                $id=$this->hash($x);	
        	// the hash does not match our regenerated hash
	        if($x['id']!=$id) { 
			// fix for broken base58 library which was used until block 16900, accepts hashes without the first 1 or 2 bytes
			$xs=base58_decode($x['id']);
                        if(((strlen($xs)!=63||substr($id,1)!=$x['id'])&&(strlen($xs)!=62||substr($id,2)!=$x['id']))||$height>16900){
                                 _log("$x[id] - $id - Invalid hash");
                                return false;
                        }

		}
                
           	//verify the ecdsa signature
    		if(!$acc->check_signature($info, $x['signature'], $x['public_key'])) { _log("$x[id] - Invalid signature"); return false; }
               
	    return true;
    }
    // sign a transaction
    public function sign($x, $private_key){
        $info=$x['val']."-".$x['fee']."-".$x['dst']."-".$x['message']."-".$x['version']."-".$x['public_key']."-".$x['date'];
        $signature=ec_sign($info,$private_key);
        
        return $signature;

    }

    //export a mempool transaction
    public function export($id){
        global $db;
        $r=$db->row("SELECT * FROM mempool WHERE id=:id",array(":id"=>$id));
        return $r;

    }
    // get the transaction data as array
    public function get_transaction($id){
        global $db;
        $acc=new Account;
        $x=$db->row("SELECT * FROM transactions WHERE id=:id",array(":id"=>$id));
       
	    if(!$x) return false;
	    $trans=array("block"=>$x['block'],"height"=>$x['height'], "id"=>$x['id'],"dst"=>$x['dst'],"val"=>$x['val'],"fee"=>$x['fee'],"signature"=>$x['signature'], "message"=>$x['message'],"version"=>$x['version'],"date"=>$x['date'], "public_key"=>$x['public_key']);
            $trans['src']=$acc->get_address($x['public_key']);
            $trans['confirmations']=$current['height']-$x['height'];

			if($x['version']==0) $trans['type']="mining";
			elseif($x['version']==1){
				if($x['dst']==$id) $trans['type']="credit";
				else $trans['type']="debit";
			} else {
				$trans['type']="other";
			}
			ksort($trans);
			return $trans;
            
    }

   // return the transactions for a specific block id or height
   public function get_transactions($height="", $id=""){
        global $db;
        $acc=new Account;
	$height=san($height);
	$id=san($id);
	if(empty($id)&&empty($height)) return false;
	if(!empty($id)) $r=$db->run("SELECT * FROM transactions WHERE block=:id AND version>0",array(":id"=>$id));
	else $r=$db->run("SELECT * FROM transactions WHERE height=:height AND version>0",array(":height"=>$height));
	$res=array();
	foreach($r as $x){
            $trans=array("block"=>$x['block'],"height"=>$x['height'], "id"=>$x['id'],"dst"=>$x['dst'],"val"=>$x['val'],"fee"=>$x['fee'],"signature"=>$x['signature'], "message"=>$x['message'],"version"=>$x['version'],"date"=>$x['date'], "public_key"=>$x['public_key']);
            $trans['src']=$acc->get_address($x['public_key']);
            $trans['confirmations']=$current['height']-$x['height'];

                        if($x['version']==0) $trans['type']="mining";
                        elseif($x['version']==1){
                                if($x['dst']==$id) $trans['type']="credit";
                                else $trans['type']="debit";
                        } else {
                                $trans['type']="other";
                        }
                        ksort($trans);
			$res[]=$trans;
	}
	return $res;

    }

    // get a specific mempool transaction as array
    public function get_mempool_transaction($id){
        global $db;
        $x=$db->row("SELECT * FROM mempool WHERE id=:id",array(":id"=>$id));
		if(!$x) return false;
			$trans=array("block"=>$x['block'],"height"=>$x['height'], "id"=>$x['id'],"dst"=>$x['dst'],"val"=>$x['val'],"fee"=>$x['fee'],"signature"=>$x['signature'], "message"=>$x['message'],"version"=>$x['version'],"date"=>$x['date'], "public_key"=>$x['public_key']);
			$trans['src']=$x['src'];

			$trans['type']="mempool";
            $trans['confirmations']=-1;
			ksort($trans);
			return $trans;
            
    }

}


?>