// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

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

// Parity Ethereum 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 General Public License for more details.

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

//! Blooms migration from rocksdb to blooms-db

use super::{kvdb_rocksdb::DatabaseConfig, open_database};
use ethcore::error::Error;
use ethereum_types::Bloom;
use rlp;
use std::path::Path;

const LOG_BLOOMS_ELEMENTS_PER_INDEX: u64 = 16;

pub fn migrate_blooms<P: AsRef<Path>>(path: P, config: &DatabaseConfig) -> Result<(), Error> {
    // init
    let db = open_database(&path.as_ref().to_string_lossy(), config)?;

    // possible optimization:
    // pre-allocate space on disk for faster migration

    // iterate over header blooms and insert them in blooms-db
    // Some(3) -> COL_EXTRA
    // 3u8 -> ExtrasIndex::BlocksBlooms
    // 0u8 -> level 0
    let blooms_iterator = db
        .key_value()
        .iter_from_prefix(Some(3), &[3u8, 0u8])
        .filter(|(key, _)| key.len() == 6)
        .take_while(|(key, _)| key[0] == 3u8 && key[1] == 0u8)
        .map(|(key, group)| {
            let index = (key[2] as u64) << 24
                | (key[3] as u64) << 16
                | (key[4] as u64) << 8
                | (key[5] as u64);
            let number = index * LOG_BLOOMS_ELEMENTS_PER_INDEX;

            let blooms = rlp::decode_list::<Bloom>(&group);
            (number, blooms)
        });

    for (number, blooms) in blooms_iterator {
        db.blooms().insert_blooms(number, blooms.iter())?;
    }

    // iterate over trace blooms and insert them in blooms-db
    // Some(4) -> COL_TRACE
    // 1u8 -> TraceDBIndex::BloomGroups
    // 0u8 -> level 0
    let trace_blooms_iterator = db
        .key_value()
        .iter_from_prefix(Some(4), &[1u8, 0u8])
        .filter(|(key, _)| key.len() == 6)
        .take_while(|(key, _)| key[0] == 1u8 && key[1] == 0u8)
        .map(|(key, group)| {
            let index = (key[2] as u64)
                | (key[3] as u64) << 8
                | (key[4] as u64) << 16
                | (key[5] as u64) << 24;
            let number = index * LOG_BLOOMS_ELEMENTS_PER_INDEX;

            let blooms = rlp::decode_list::<Bloom>(&group);
            (number, blooms)
        });

    for (number, blooms) in trace_blooms_iterator {
        db.trace_blooms().insert_blooms(number, blooms.iter())?;
    }

    Ok(())
}