# all files / packages/web3-utils/src/ bloomFilter.js

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     /*jshint bitwise: false*/

    /*
     This file is part of web3.js.

     web3.js is free software: you can redistribute it and/or modify
     it under the terms of the GNU Lesser General Public License as published by
     the Free Software Foundation, either version 3 of the License, or
     (at your option) any later version.

     web3.js is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU Lesser General Public License for more details.

     You should have received a copy of the GNU Lesser General Public License
     along with web3.js.  If not, see <http://www.gnu.org/licenses/>.
     */

    /**
     * @file bloom.js
     * @author Bas van Kervel <bas@ethereum.org>
     * @date 2017
     */

    /**
     * Ethereum bloom filter support.
     *
     * TODO UNDOCUMENTED
     *
     * @module bloom
     * @class [bloom] bloom
     */

    var utils = require("./utils.js");

    function codePointToInt(codePoint) {
        if (codePoint >= 48 && codePoint <= 57) { /*['0'..'9'] -> [0..9]*/
            return codePoint-48;
        }

        Iif (codePoint >= 65 && codePoint <= 70) { /*['A'..'F'] -> [10..15]*/
            return codePoint-55;
        }

        Eif (codePoint >= 97 && codePoint <= 102) { /*['a'..'f'] -> [10..15]*/
            return codePoint-87;
        }

        throw "invalid bloom";
    }

    function testBytes(bloom, bytes) {
        var hash = utils.sha3(bytes).replace('0x','');

        for (var i = 0; i < 12; i += 4) {
            // calculate bit position in bloom filter that must be active
            var bitpos = ((parseInt(hash.substr(i, 2), 16) << 8) + parseInt(hash.substr((i+2), 2), 16)) & 2047;

            // test if bitpos in bloom is active
            var code = codePointToInt(bloom.charCodeAt(bloom.length - 1 - Math.floor(bitpos/4)));
            var offset = 1 << (bitpos % 4);

            if ((code&offset) !== offset) {
                return false;
            }
        }

        return true;
    }

    /**
     * Returns true if address is part of the given bloom.
     * note: false positives are possible.
     *
     * @method testAddress
     * @param {String} hex encoded bloom
     * @param {String} address in hex notation
     * @returns {Boolean} topic is (probably) part of the block
     */
    var testAddress = function(bloom, address) {
        Iif (!utils.isBloom(bloom)) {
            throw 'Invalid bloom given';
        }
        Iif (!utils.isAddress(address)) {
            throw 'Invalid address given: "'+ address +'\"';
        }

        return testBytes(bloom, address);
    };

    /**
     * Returns true if the topic is part of the given bloom.
     * note: false positives are possible.
     *
     * @method hasTopic
     * @param {String} hex encoded bloom
     * @param {String} address in hex notation
     * @returns {Boolean} topic is (probably) part of the block
     */
    var testTopic = function(bloom, topic) {
        Iif (!utils.isBloom(bloom)) throw "invalid bloom";
        Iif (!utils.isTopic(topic)) throw "invalid topic";

        return testBytes(bloom, topic);
    };

    module.exports = {
        testAddress: testAddress,
        testTopic:   testTopic
    };