import {getProvider} from "./blockchain.js";
import {ethers} from "ethers";
import {erc20Abi} from "./abi.js";
import {pool} from "./db.js";

const BATCH_SIZE = 100 // the most blocks allowed per batch

async function watchChain(chainId, filterCallbacks) {
    const provider = getProvider(chainId)
    const db = await pool.connect()
    const block = await provider.getBlockNumber()
    let fromBlock, toBlock
    const result = await db.query('select block from progress where chain=$1', [chainId])
    if( result.rowCount === 0 ) {
        console.log('initializing chain', chainId)
        fromBlock = block
        db.query('insert into progress values ($1,$2)', [chainId, block-1])
    }
    else if( result.rowCount === 1 ) {
        fromBlock = result.rows[0].block + 1
    }
    else
        throw Error(`Found ${result.rowCount} rows for progress table chain ${chainId}`)
    try {
        do {
            toBlock = Math.min(block, fromBlock + BATCH_SIZE-1) // toBlock is inclusive
            const promises = []
            await db.query('BEGIN')
            for (const [filter, callback] of filterCallbacks) {
                filter.fromBlock = fromBlock
                filter.toBlock = toBlock
                console.log('filter', filter)
                const found = await provider.getLogs(filter)
                promises.push(callback(provider, db, found))
            }
            await Promise.all(promises)
            db.query('update progress set block=$1 where chain=$2', [toBlock, chainId])
            db.query('COMMIT')
            fromBlock = toBlock + 1
        } while (toBlock > block)
    } catch (e) {
        await db.query('ROLLBACK')
        throw e
    } finally {
        db.release()
    }
}


export function startWatcher(chainId, period, filterCallbacks) {
    setInterval(async () => await watchChain(chainId, filterCallbacks), period)
}


// test
// const erc20 = new ethers.Interface(erc20Abi);
// const filter = erc20.encodeFilterTopics('Transfer', [null, null])
// async function handle(provider, db, events) {
//     console.log(`got ${events.length} Transfers`)
// }
// startWatcher(42161, 1000, [[filter, handle]])