// Rust Bitcoin Library
// Written in 2019 by
//   The rust-bitcoin developers
//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to
// the public domain worldwide. This software is distributed without
// any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication
// along with this software.
// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
//

// This module was largely copied from https://github.com/rust-bitcoin/murmel/blob/master/src/blockfilter.rs
// on 11. June 2019 which is licensed under Apache, that file specifically
// was written entirely by Tamas Blummer, who is re-licensing its contents here as CC0.

//!
//! # BIP158 Compact Block Filters for Light Clients
//!
//! Implements a structure for compact filters on block data, for use in the BIP 157 light client protocol.
//! The filter construction proposed is an alternative to Bloom filters, as used in BIP 37,
//! that minimizes filter size by using Golomb-Rice coding for compression.
//!
//!  USE :
//!   // create a block filter for a block (server side)
//!
//!   fn get_script_for_coin (coin: &OutPoint) -> Result<Script, BlockFilterError> {
//!     // get utxo ...
//!   }
//!
//!   let filter = BlockFilter::new_script_filter (&block, get_script_for_coin)?;
//!
//!   // or create a filter from known raw data
//!   let filter = BlockFilter::new(content);
//!
//!   // read and evaluate a filter
//!
//!   let query: Iterator<Item=Script> = // .. some scripts you care about
//!   if filter.match_any (&block_hash, &mut query.map(|s| s.as_bytes())) {
//!     // get this block
//!   }
//!
//!

use std::{cmp, fmt, io};
use std::collections::HashSet;
use std::error;
use std::fmt::{Display, Formatter};
use std::io::Cursor;

use hash_types::BlockHash;
use hashes::{Hash, sha256d, siphash24};

use blockdata::block::Block;
use blockdata::script::Script;
use blockdata::transaction::OutPoint;
use consensus::{Decodable, Encodable};
use consensus::encode::VarInt;
use util::endian;
use util::hash::BitcoinHash;

/// Golomb encoding parameter as in BIP-158, see also https://gist.github.com/sipa/576d5f09c3b86c3b1b75598d799fc845
const P: u8 = 19;
const M: u64 = 784931;

/// Errors for blockfilter
#[derive(Debug)]
pub enum Error {
    /// missing UTXO, can not calculate script filter
    UtxoMissing(OutPoint),
    /// some IO error reading or writing binary serialization of the filter
    Io(io::Error),
}

impl error::Error for Error {
    fn description(&self) -> &str {
        match *self {
            Error::UtxoMissing(_) => "unresolved UTXO",
            Error::Io(_) => "IO Error"
        }
    }
}

impl Display for Error {
    fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
        match *self {
            Error::UtxoMissing(ref coin) => write!(f, "unresolved UTXO {}", coin),
            Error::Io(ref io) => write!(f, "{}", io)
        }
    }
}

impl From<io::Error> for Error {
    fn from(io: io::Error) -> Self {
        Error::Io(io)
    }
}


/// a computed or read block filter
pub struct BlockFilter {
    /// Golomb encoded filter
    pub content: Vec<u8>
}

impl BlockFilter {
    /// compute this filter's id in a chain of filters
    pub fn filter_id(&self, previous_filter_id: &sha256d::Hash) -> sha256d::Hash {
        let filter_hash = sha256d::Hash::hash(self.content.as_slice());
        let mut header_data = [0u8; 64];
        header_data[0..32].copy_from_slice(&filter_hash[..]);
        header_data[32..64].copy_from_slice(&previous_filter_id[..]);
        sha256d::Hash::hash(&header_data)
    }

    /// create a new filter from pre-computed data
    pub fn new (content: &[u8]) -> BlockFilter {
        BlockFilter { content: content.to_vec() }
    }

    /// Compute a SCRIPT_FILTER that contains spent and output scripts
    pub fn new_script_filter<M>(block: &Block, script_for_coin: M) -> Result<BlockFilter, Error>
        where M: Fn(&OutPoint) -> Result<Script, Error> {
        let mut out = Cursor::new(Vec::new());
        {
            let mut writer = BlockFilterWriter::new(&mut out, block);
            writer.add_output_scripts();
            writer.add_input_scripts(script_for_coin)?;
            writer.finish()?;
        }
        Ok(BlockFilter { content: out.into_inner() })
    }

    /// match any query pattern
    pub fn match_any(&self, block_hash: &BlockHash, query: &mut Iterator<Item=&[u8]>) -> Result<bool, Error> {
        let filter_reader = BlockFilterReader::new(block_hash);
        filter_reader.match_any(&mut Cursor::new(self.content.as_slice()), query)
    }

    /// match all query pattern
    pub fn match_all(&self, block_hash: &BlockHash, query: &mut Iterator<Item=&[u8]>) -> Result<bool, Error> {
        let filter_reader = BlockFilterReader::new(block_hash);
        filter_reader.match_all(&mut Cursor::new(self.content.as_slice()), query)
    }
}

/// Compiles and writes a block filter
pub struct BlockFilterWriter<'a> {
    block: &'a Block,
    writer: GCSFilterWriter<'a>,
}

impl<'a> BlockFilterWriter<'a> {
    /// Create a block filter writer
    pub fn new(writer: &'a mut io::Write, block: &'a Block) -> BlockFilterWriter<'a> {
        let block_hash_as_int = block.bitcoin_hash().into_inner();
        let k0 = endian::slice_to_u64_le(&block_hash_as_int[0..8]);
        let k1 = endian::slice_to_u64_le(&block_hash_as_int[8..16]);
        let writer = GCSFilterWriter::new(writer, k0, k1, M, P);
        BlockFilterWriter { block, writer }
    }

    /// Add output scripts of the block - excluding OP_RETURN scripts
    pub fn add_output_scripts(&mut self) {
        for transaction in &self.block.txdata {
            for output in &transaction.output {
                if !output.script_pubkey.is_op_return() {
                    self.add_element(output.script_pubkey.as_bytes());
                }
            }
        }
    }

    /// Add consumed output scripts of a block to filter
    pub fn add_input_scripts<M>(&mut self, script_for_coin: M) -> Result<(), Error>
        where M: Fn(&OutPoint) -> Result<Script, Error> {
        for script in self.block.txdata.iter()
            .skip(1) // skip coinbase
            .flat_map(|t| t.input.iter().map(|i| &i.previous_output))
            .map(script_for_coin) {
            match script {
                Ok(script) => self.add_element(script.as_bytes()),
                Err(e) => return Err(e)
            }
        }
        Ok(())
    }

    /// Add arbitrary element to a filter
    pub fn add_element(&mut self, data: &[u8]) {
        self.writer.add_element(data);
    }

    /// Write block filter
    pub fn finish(&mut self) -> Result<usize, io::Error> {
        self.writer.finish()
    }
}


/// Reads and interpret a block filter
pub struct BlockFilterReader {
    reader: GCSFilterReader
}

impl BlockFilterReader {
    /// Create a block filter reader
    pub fn new(block_hash: &BlockHash) -> BlockFilterReader {
        let block_hash_as_int = block_hash.into_inner();
        let k0 = endian::slice_to_u64_le(&block_hash_as_int[0..8]);
        let k1 = endian::slice_to_u64_le(&block_hash_as_int[8..16]);
        BlockFilterReader { reader: GCSFilterReader::new(k0, k1, M, P) }
    }

    /// match any query pattern
    pub fn match_any(&self, reader: &mut io::Read, query: &mut Iterator<Item=&[u8]>) -> Result<bool, Error> {
        self.reader.match_any(reader, query)
    }

    /// match all query pattern
    pub fn match_all(&self, reader: &mut io::Read, query: &mut Iterator<Item=&[u8]>) -> Result<bool, Error> {
        self.reader.match_all(reader, query)
    }
}


/// Golomb-Rice encoded filter reader
pub struct GCSFilterReader {
    filter: GCSFilter,
    m: u64
}

impl GCSFilterReader {
    /// Create a new filter reader with specific seed to siphash
    pub fn new(k0: u64, k1: u64, m: u64, p: u8) -> GCSFilterReader {
        GCSFilterReader { filter: GCSFilter::new(k0, k1, p), m }
    }

    /// match any query pattern
    pub fn match_any(&self, reader: &mut io::Read, query: &mut Iterator<Item=&[u8]>) -> Result<bool, Error> {
        let mut decoder = reader;
        let n_elements: VarInt = Decodable::consensus_decode(&mut decoder).unwrap_or(VarInt(0));
        let ref mut reader = decoder;
        // map hashes to [0, n_elements << grp]
        let nm = n_elements.0 * self.m;
        let mut mapped = query.map(|e| map_to_range(self.filter.hash(e), nm)).collect::<Vec<_>>();
        // sort
        mapped.sort();
        if mapped.is_empty() {
            return Ok(true);
        }
        if n_elements.0 == 0 {
            return Ok(false);
        }

        // find first match in two sorted arrays in one read pass
        let mut reader = BitStreamReader::new(reader);
        let mut data = self.filter.golomb_rice_decode(&mut reader)?;
        let mut remaining = n_elements.0 - 1;
        for p in mapped {
            loop {
                if data == p {
                    return Ok(true);
                } else if data < p {
                    if remaining > 0 {
                        data += self.filter.golomb_rice_decode(&mut reader)?;
                        remaining -= 1;
                    } else {
                        return Ok(false);
                    }
                } else {
                    break;
                }
            }
        }
        Ok(false)
    }

    /// match all query pattern
    pub fn match_all(&self, reader: &mut io::Read, query: &mut Iterator<Item=&[u8]>) -> Result<bool, Error> {
        let mut decoder = reader;
        let n_elements: VarInt = Decodable::consensus_decode(&mut decoder).unwrap_or(VarInt(0));
        let ref mut reader = decoder;
        // map hashes to [0, n_elements << grp]
        let nm = n_elements.0 * self.m;
        let mut mapped = query.map(|e| map_to_range(self.filter.hash(e), nm)).collect::<Vec<_>>();
        // sort
        mapped.sort();
        mapped.dedup();
        if mapped.is_empty() {
            return Ok(true);
        }
        if n_elements.0 == 0 {
            return Ok(false);
        }

        // figure if all mapped are there in one read pass
        let mut reader = BitStreamReader::new(reader);
        let mut data = self.filter.golomb_rice_decode(&mut reader)?;
        let mut remaining = n_elements.0 - 1;
        for p in mapped {
            loop {
                if data == p {
                    break;
                } else if data < p {
                    if remaining > 0 {
                        data += self.filter.golomb_rice_decode(&mut reader)?;
                        remaining -= 1;
                    } else {
                        return Ok(false);
                    }
                } else {
                    return Ok(false);
                }
            }
        }
        Ok(true)
    }
}

// fast reduction of hash to [0, nm) range
fn map_to_range(hash: u64, nm: u64) -> u64 {
    // Use this once we upgrade to rustc >= 1.26
    // ((hash as u128 * nm as u128) >> 64) as u64

    #[inline]
    fn l(n: u64) -> u64 { n & 0xffffffff }
    #[inline]
    fn h(n: u64) -> u64 { n >> 32 }

    let a = h(hash);
    let b = l(hash);
    let c = h(nm);
    let d = l(nm);

    a * c + h(a * d + c * b + h(b * d))
}

/// Colomb-Rice encoded filter writer
pub struct GCSFilterWriter<'a> {
    filter: GCSFilter,
    writer: &'a mut io::Write,
    elements: HashSet<Vec<u8>>,
    m: u64
}

impl<'a> GCSFilterWriter<'a> {
    /// Create a new GCS writer wrapping a generic writer, with specific seed to siphash
    pub fn new(writer: &'a mut io::Write, k0: u64, k1: u64, m: u64, p: u8) -> GCSFilterWriter<'a> {
        GCSFilterWriter {
            filter: GCSFilter::new(k0, k1, p),
            writer,
            elements: HashSet::new(),
            m
        }
    }

    /// Add some data to the filter
    pub fn add_element(&mut self, element: &[u8]) {
        if !element.is_empty() {
            self.elements.insert(element.to_vec());
        }
    }

    /// write the filter to the wrapped writer
    pub fn finish(&mut self) -> Result<usize, io::Error> {
        let nm = self.elements.len() as u64 * self.m;

        // map hashes to [0, n_elements * M)
        let mut mapped: Vec<_> = self.elements.iter()
            .map(|e| map_to_range(self.filter.hash(e.as_slice()), nm)).collect();
        mapped.sort();

        // write number of elements as varint
        let mut encoder = io::Cursor::new(Vec::new());
        VarInt(mapped.len() as u64).consensus_encode(&mut encoder).unwrap();
        let mut wrote = self.writer.write(encoder.into_inner().as_slice())?;

        // write out deltas of sorted values into a Golonb-Rice coded bit stream
        let mut writer = BitStreamWriter::new(self.writer);
        let mut last = 0;
        for data in mapped {
            wrote += self.filter.golomb_rice_encode(&mut writer, data - last)?;
            last = data;
        }
        wrote += writer.flush()?;
        Ok(wrote)
    }
}

/// Golomb Coded Set Filter
struct GCSFilter {
    k0: u64, // sip hash key
    k1: u64, // sip hash key
    p: u8
}

impl GCSFilter {
    /// Create a new filter
    fn new(k0: u64, k1: u64, p: u8) -> GCSFilter {
        GCSFilter { k0, k1, p }
    }

    /// Golomb-Rice encode a number n to a bit stream (Parameter 2^k)
    fn golomb_rice_encode(&self, writer: &mut BitStreamWriter, n: u64) -> Result<usize, io::Error> {
        let mut wrote = 0;
        let mut q = n >> self.p;
        while q > 0 {
            let nbits = cmp::min(q, 64);
            wrote += writer.write(!0u64, nbits as u8)?;
            q -= nbits;
        }
        wrote += writer.write(0, 1)?;
        wrote += writer.write(n, self.p)?;
        Ok(wrote)
    }

    /// Golomb-Rice decode a number from a bit stream (Parameter 2^k)
    fn golomb_rice_decode(&self, reader: &mut BitStreamReader) -> Result<u64, io::Error> {
        let mut q = 0u64;
        while reader.read(1)? == 1 {
            q += 1;
        }
        let r = reader.read(self.p)?;
        return Ok((q << self.p) + r);
    }

    /// Hash an arbitrary slice with siphash using parameters of this filter
    fn hash(&self, element: &[u8]) -> u64 {
        siphash24::Hash::hash_to_u64_with_keys(self.k0, self.k1, element)
    }
}

/// Bitwise stream reader
pub struct BitStreamReader<'a> {
    buffer: [u8; 1],
    offset: u8,
    reader: &'a mut io::Read,
}

impl<'a> BitStreamReader<'a> {
    /// Create a new BitStreamReader that reads bitwise from a given reader
    pub fn new(reader: &'a mut io::Read) -> BitStreamReader {
        BitStreamReader {
            buffer: [0u8],
            reader: reader,
            offset: 8,
        }
    }

    /// Read nbit bits
    pub fn read(&mut self, mut nbits: u8) -> Result<u64, io::Error> {
        if nbits > 64 {
            return Err(io::Error::new(io::ErrorKind::Other, "can not read more than 64 bits at once"));
        }
        let mut data = 0u64;
        while nbits > 0 {
            if self.offset == 8 {
                self.reader.read_exact(&mut self.buffer)?;
                self.offset = 0;
            }
            let bits = cmp::min(8 - self.offset, nbits);
            data <<= bits;
            data |= ((self.buffer[0] << self.offset) >> (8 - bits)) as u64;
            self.offset += bits;
            nbits -= bits;
        }
        Ok(data)
    }
}

/// Bitwise stream writer
pub struct BitStreamWriter<'a> {
    buffer: [u8; 1],
    offset: u8,
    writer: &'a mut io::Write,
}

impl<'a> BitStreamWriter<'a> {
    /// Create a new BitStreamWriter that writes bitwise to a given writer
    pub fn new(writer: &'a mut io::Write) -> BitStreamWriter {
        BitStreamWriter {
            buffer: [0u8],
            writer: writer,
            offset: 0,
        }
    }

    /// Write nbits bits from data
    pub fn write(&mut self, data: u64, mut nbits: u8) -> Result<usize, io::Error> {
        if nbits > 64 {
            return Err(io::Error::new(io::ErrorKind::Other, "can not write more than 64 bits at once"));
        }
        let mut wrote = 0;
        while nbits > 0 {
            let bits = cmp::min(8 - self.offset, nbits);
            self.buffer[0] |= ((data << (64 - nbits)) >> (64 - 8 + self.offset)) as u8;
            self.offset += bits;
            nbits -= bits;
            if self.offset == 8 {
                wrote += self.flush()?;
            }
        }
        Ok(wrote)
    }

    /// flush bits not yet written
    pub fn flush(&mut self) -> Result<usize, io::Error> {
        if self.offset > 0 {
            self.writer.write_all(&self.buffer)?;
            self.buffer[0] = 0u8;
            self.offset = 0;
            Ok(1)
        } else {
            Ok(0)
        }
    }
}

#[cfg(test)]
mod test {
    use std::collections::{HashSet, HashMap};
    use std::io::Cursor;

    use hash_types::BlockHash;
    use hashes::hex::FromHex;

    use super::*;

    extern crate hex;
    extern crate serde_json;
    use self::serde_json::{Value};

    use consensus::encode::deserialize;

    #[test]
    fn test_blockfilters() {

        // test vectors from: https://github.com/jimpo/bitcoin/blob/c7efb652f3543b001b4dd22186a354605b14f47e/src/test/data/blockfilters.json
        let data = r#"
        [
            ["Block Height,Block Hash,Block,[Prev Output Scripts for Block],Previous Basic Header,Basic Filter,Basic Header,Notes"],
            [0,"000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943","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",[],"0000000000000000000000000000000000000000000000000000000000000000","019dfca8","21584579b7eb08997773e5aeff3a7f932700042d0ed2a6129012b7d7ae81b750","Genesis block"],
            [2,"000000006c02c8ea6e4ff69651f7fcde348fb9d557a06e6957b65552002a7820","0100000006128e87be8b1b4dea47a7247d5528d2702c96826c7a648497e773b800000000e241352e3bec0a95a6217e10c3abb54adfa05abb12c126695595580fb92e222032e7494dffff001d00d235340101000000010000000000000000000000000000000000000000000000000000000000000000ffffffff0e0432e7494d010e062f503253482fffffffff0100f2052a010000002321038a7f6ef1c8ca0c588aa53fa860128077c9e6c11e6830f4d7ee4e763a56b7718fac00000000",[],"d7bdac13a59d745b1add0d2ce852f1a0442e8945fc1bf3848d3cbffd88c24fe1","0174a170","186afd11ef2b5e7e3504f2e8cbf8df28a1fd251fe53d60dff8b1467d1b386cf0",""],
            [3,"000000008b896e272758da5297bcd98fdc6d97c9b765ecec401e286dc1fdbe10","0100000020782a005255b657696ea057d5b98f34defcf75196f64f6eeac8026c0000000041ba5afc532aae03151b8aa87b65e1594f97504a768e010c98c0add79216247186e7494dffff001d058dc2b60101000000010000000000000000000000000000000000000000000000000000000000000000ffffffff0e0486e7494d0151062f503253482fffffffff0100f2052a01000000232103f6d9ff4c12959445ca5549c811683bf9c88e637b222dd2e0311154c4c85cf423ac00000000",[],"186afd11ef2b5e7e3504f2e8cbf8df28a1fd251fe53d60dff8b1467d1b386cf0","016cf7a0","8d63aadf5ab7257cb6d2316a57b16f517bff1c6388f124ec4c04af1212729d2a",""],
            [15007,"0000000038c44c703bae0f98cdd6bf30922326340a5996cc692aaae8bacf47ad","0100000002394092aa378fe35d7e9ac79c869b975c4de4374cd75eb5484b0e1e00000000eb9b8670abd44ad6c55cee18e3020fb0c6519e7004b01a16e9164867531b67afc33bc94fffff001d123f10050101000000010000000000000000000000000000000000000000000000000000000000000000ffffffff0e04c33bc94f0115062f503253482fffffffff0100f2052a01000000232103f268e9ae07e0f8cb2f6e901d87c510d650b97230c0365b021df8f467363cafb1ac00000000",[],"18b5c2b0146d2d09d24fb00ff5b52bd0742f36c9e65527abdb9de30c027a4748","013c3710","07384b01311867949e0c046607c66b7a766d338474bb67f66c8ae9dbd454b20e","Tx has non-standard OP_RETURN output followed by opcodes"],
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            [987876,"0000000000000c00901f2049055e2a437c819d79a3d54fd63e6af796cd7b8a79","000000202694f74969fdb542090e95a56bc8aa2d646e27033850e32f1c5f000000000000f7e53676b3f12d5beb524ed617f2d25f5a93b5f4f52c1ba2678260d72712f8dd0a6dfe5740257e1a4b1768960101000000010000000000000000000000000000000000000000000000000000000000000000ffffffff1603e4120ff9c30a1c216900002f424d4920546573742fffffff0001205fa012000000001e76a914c486de584a735ec2f22da7cd9681614681f92173d83d0aa68688ac00000000",[],"fe4d230dbb0f4fec9bed23a5283e08baf996e3f32b93f52c7de1f641ddfd04ad","010c0b40","0965a544743bbfa36f254446e75630c09404b3d164a261892372977538928ed5","Coinbase tx has unparseable output script"],
            [1263442,"000000006f27ddfe1dd680044a34548f41bed47eba9e6f0b310da21423bc5f33","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",["002027a5000c7917f785d8fc6e5a55adfca8717ecb973ebb7743849ff956d896a7ed"],"31d66d516a9eda7de865df29f6ef6cb8e4bf9309e5dac899968a9a62a5df61e3","0385acb4f0fe889ef0","4e6d564c2a2452065c205dd7eb2791124e0c4e0dbb064c410c24968572589dec","Includes witness data"],
            [1414221,"0000000000000027b2b3b3381f114f674f481544ff2be37ae3788d7e078383b1","000000204ea88307a7959d8207968f152bedca5a93aefab253f1fb2cfb032a400000000070cebb14ec6dbc27a9dfd066d9849a4d3bac5f674665f73a5fe1de01a022a0c851fda85bf05f4c19a779d1450102000000010000000000000000000000000000000000000000000000000000000000000000ffffffff18034d94154d696e6572476174653030310d000000f238f401ffffffff01c817a804000000000000000000",[],"5e5e12d90693c8e936f01847859404c67482439681928353ca1296982042864e","00","021e8882ef5a0ed932edeebbecfeda1d7ce528ec7b3daa27641acf1189d7b5dc","Empty data"]
        ]
        "#;

        let testdata = serde_json::from_str::<Value>(data).unwrap().as_array().unwrap().clone();
        for t in testdata.iter().skip(1) {
            let block_hash = BlockHash::from_hex(&t.get(1).unwrap().as_str().unwrap()).unwrap();
            let block: Block = deserialize(hex::decode(&t.get(2).unwrap().as_str().unwrap().as_bytes()).unwrap().as_slice()).unwrap();
            assert_eq!(block.bitcoin_hash(), block_hash);
            let scripts = t.get(3).unwrap().as_array().unwrap();
            let previous_filter_id = sha256d::Hash::from_hex(&t.get(4).unwrap().as_str().unwrap()).unwrap();
            let filter_content = hex::decode(&t.get(5).unwrap().as_str().unwrap().as_bytes()).unwrap();
            let filter_id = sha256d::Hash::from_hex(&t.get(6).unwrap().as_str().unwrap()).unwrap();

            let mut txmap = HashMap::new();
            let mut si = scripts.iter();
            for tx in block.txdata.iter().skip(1) {
                for input in tx.input.iter() {
                    txmap.insert(input.previous_output.clone(), Script::from(hex::decode(si.next().unwrap().as_str().unwrap()).unwrap()));
                }
            }

            let filter = BlockFilter::new_script_filter(&block,
                                        |o| if let Some(s) = txmap.get(o) {
                                            Ok(s.clone())
                                        } else {
                                            Err(Error::UtxoMissing(o.clone()))
                                        }).unwrap();

            let test_filter = BlockFilter::new(filter_content.as_slice());

            assert_eq!(test_filter.content, filter.content);

            let block_hash = &block.header.bitcoin_hash();
            assert!(filter.match_all(block_hash, &mut txmap.iter()
                .filter_map(|(_, s)| if !s.is_empty() { Some(s.as_bytes()) } else { None })).unwrap());

            for (_, script) in &txmap {
                let query = vec![script];
                if !script.is_empty () {
                    assert!(filter.match_any(&block_hash, &mut query.iter()
                        .map(|s| s.as_bytes())).unwrap());
                }
            }

            assert_eq!(filter_id, filter.filter_id(&previous_filter_id));
        }
    }

    #[test]
    fn test_filter () {
        let mut patterns = HashSet::new();

        patterns.insert(hex::decode("000000").unwrap());
        patterns.insert(hex::decode("111111").unwrap());
        patterns.insert(hex::decode("222222").unwrap());
        patterns.insert(hex::decode("333333").unwrap());
        patterns.insert(hex::decode("444444").unwrap());
        patterns.insert(hex::decode("555555").unwrap());
        patterns.insert(hex::decode("666666").unwrap());
        patterns.insert(hex::decode("777777").unwrap());
        patterns.insert(hex::decode("888888").unwrap());
        patterns.insert(hex::decode("999999").unwrap());
        patterns.insert(hex::decode("aaaaaa").unwrap());
        patterns.insert(hex::decode("bbbbbb").unwrap());
        patterns.insert(hex::decode("cccccc").unwrap());
        patterns.insert(hex::decode("dddddd").unwrap());
        patterns.insert(hex::decode("eeeeee").unwrap());
        patterns.insert(hex::decode("ffffff").unwrap());

        let mut out = Cursor::new(Vec::new());
        {
            let mut writer = GCSFilterWriter::new(&mut out, 0, 0, M, P);
            for p in &patterns {
                writer.add_element(p.as_slice());
            }
            writer.finish().unwrap();
        }

        let bytes = out.into_inner();

        {
            let mut query = Vec::new();
            query.push(hex::decode("abcdef").unwrap());
            query.push(hex::decode("eeeeee").unwrap());

            let reader = GCSFilterReader::new(0, 0, M, P);
            let mut input = Cursor::new(bytes.clone());
            assert!(reader.match_any(&mut input, &mut query.iter().map(|v| v.as_slice())).unwrap());
        }
        {
            let mut query = Vec::new();
            query.push(hex::decode("abcdef").unwrap());
            query.push(hex::decode("123456").unwrap());

            let reader = GCSFilterReader::new(0, 0, M, P);
            let mut input = Cursor::new(bytes.clone());
            assert!(!reader.match_any(&mut input, &mut query.iter().map(|v| v.as_slice())).unwrap());
        }
        {
            let reader = GCSFilterReader::new(0, 0, M, P);
            let mut query = Vec::new();
            for p in &patterns {
                query.push(p.clone());
            }
            let mut input = Cursor::new(bytes.clone());
            assert!(reader.match_all(&mut input, &mut query.iter().map(|v| v.as_slice())).unwrap());
        }
        {
            let reader = GCSFilterReader::new(0, 0, M, P);
            let mut query = Vec::new();
            for p in &patterns {
                query.push(p.clone());
            }
            query.push(hex::decode("abcdef").unwrap());
            let mut input = Cursor::new(bytes.clone());
            assert!(!reader.match_all(&mut input, &mut query.iter().map(|v| v.as_slice())).unwrap());
        }
    }

    #[test]
    fn test_bit_stream() {
        let mut out = Cursor::new(Vec::new());
        {
            let mut writer = BitStreamWriter::new(&mut out);
            writer.write(0, 1).unwrap(); // 0
            writer.write(2, 2).unwrap(); // 10
            writer.write(6, 3).unwrap(); // 110
            writer.write(11, 4).unwrap(); // 1011
            writer.write(1, 5).unwrap(); // 00001
            writer.write(32, 6).unwrap(); // 100000
            writer.write(7, 7).unwrap(); // 0000111
            writer.flush().unwrap();
        }
        let bytes = out.into_inner();
        assert_eq!("01011010110000110000000001110000", format!("{:08b}{:08b}{:08b}{:08b}", bytes[0], bytes[1], bytes[2], bytes[3]));
        {
            let mut input = Cursor::new(bytes);
            let mut reader = BitStreamReader::new(&mut input);
            assert_eq!(reader.read(1).unwrap(), 0);
            assert_eq!(reader.read(2).unwrap(), 2);
            assert_eq!(reader.read(3).unwrap(), 6);
            assert_eq!(reader.read(4).unwrap(), 11);
            assert_eq!(reader.read(5).unwrap(), 1);
            assert_eq!(reader.read(6).unwrap(), 32);
            assert_eq!(reader.read(7).unwrap(), 7);
            // 4 bits remained
            assert!(reader.read(5).is_err());
        }
    }
}