<?php
include "jsonRPCClient.php";


$username = 'you';
$password = 'wish';
$ip = 'id';
$port = tell;


$info = rpc_command( 'getinfo' );
if( is_array( $info) ) {
        $required = array( 'difficulty', 'blocks' );
        $numeric_data = get_numeric_data( $info, $required );
        if( !$numeric_data ) {
                exit( "get_info() failed to acquire needed data." );
        }
        extract( $numeric_data );

        $write_arr[ 'timestamp' ] = time();
        $write_arr[ 'estimated_difficulty' ] = $difficulty;
        $write_arr += compact( 'difficulty', 'blocks' );

        $blocks_since_difficulty_change = $blocks % 2016;
        if( $blocks_since_difficulty_change ) {
                $previous_difficulty_change = $blocks - $blocks_since_difficulty_change;

                $current_block_timestamp = get_block_timestamp( $blocks );
                $previous_block_timestamp = get_block_timestamp( $previous_difficulty_change );

                if( ! $current_block_timestamp || ! $previous_block_timestamp ) {
                        exit( 'Could not get block timestamps' );
                }

                $average_block_time = ($current_block_timestamp - $previous_block_timestamp) / $blocks_since_difficulty_change;
                $estimated_difficulty = $difficulty * 600 / $average_block_time;
                $write_arr[ 'estimated_difficulty' ] = $estimated_difficulty;
        }
        write_file( $write_arr );
} else {
        exit( 'Could not getinfo(). getinfo() output is not an array.' );
}

function rpc_command( $command, $arg = '' ) {
        global $username, $password, $ip, $port;
        static $rpc;
        if( ! $rpc ) {
                $rpc = new jsonRPCClient( "http://$username:$password@$ip:$port" );
        }
        try {
                if( ! empty( $arg ) ) {
                        $ret = $rpc->$command( $arg );
                } else {
                        $ret = $rpc->$command();
                }
        } catch ( Exception $e ) {
                trigger_error( "Exception in rpc_command(). Command is $command. Error is: " . $e->getMessage() );
                $ret = false;
        }
        return $ret;
}

function get_numeric_data( $info, $keys ) {
        $ret = array();
        foreach( $keys as $key ) {
                if( isset( $info[ $key ] ) && is_numeric( $info[ $key ] ) ) {
                        $ret[ $key ] = $info[ $key ];
                } else {
                        $ret = false;
                        break;
                }
        }
        return $ret;
}

function get_block_timestamp( $block ) {
        if( !is_numeric( $block ) ) {
                return false;
        }
        $block_hash = rpc_command( 'getblockhash', $block );
        if( $block_hash !== false && preg_match( '/^[0-9a-f]+$/i', $block_hash ) ) {
                $block_data = rpc_command( 'getblock', $block_hash );
                if( is_array( $block_data ) && isset( $block_data[ 'time' ] ) && is_numeric( $block_data[ 'time' ] ) ) {
                        return $block_data[ 'time' ];
                } else {
                        trigger_error( "Error in get_block_timestamp(). Time in blockdata not found or not numeric. Block is $block" );
                }
        } else {
                trigger_error( "Error in get_block_timestamp() could not getblockhash for block $block. Hash is $block_hash" );
        }
        return false;
}

function write_file( $data ) {
        if( is_array( $data  ) ) {
                $h = fopen( 'getinfo.php', 'w' );
                fwrite( $h, "<?php \$bitcoind_getinfo = " . var_export( $data, true  ) . ";" );
                fclose( $h );
                return true;
        } else {
                trigger_error( 'Error in write_file(). Data is not an array.' );
                return false;
        }
}