const app = require('j7/app');
const utils = require('j7/utils');
const bcutils = require('j7/bcutils');
const log = require('j7/log');
const bc = require('../blockchain');
const BaseService = require('./baseservice');

class EventProcess extends BaseService {

  async init(conn, instance, cb) {
    this.conn = conn;
    this.instance = instance;
    this.cb = cb;
    this.lastBlockNumber = 0;
    await this.start();
  }

  async start() {
    while (true) {
      await this.pullEvent();
      await utils.sleep(8000 + utils.randRange(500, 1500));
    }
  }

  async pullEvent() {
    const logClass = this.getInstanceName() + ' pullEvent:';
    while (true) {
      try {
        const fromBlock = await this.getFromBlock();
        const toBlock = await this.calcToBlock(fromBlock);
        if (toBlock >= fromBlock) {
          const events = await bc[this.getInstanceName()].getPastEvents(
            this.instance['eventName'],
            {
              fromBlock: fromBlock,
              toBlock: toBlock,
            },
          );
          this.instance['fromBlock'] = fromBlock;
          this.instance['toBlock'] = toBlock;
          this.instance['currBlock'] = bc.getCurrBlockNumber();
          this.instance['eventCount'] += events.length;
          if (events.length > 0) {
            console.log(events);
          }
          await this.processEvents(events, toBlock);
          await this.saveLastBlockNumber(toBlock);
        }
        ++this.instance['pullCount'];
        return;
      } catch (err) {
        log.error(logClass + err);
      }
    }
  }

  getInstanceName() {
    return this.instance['name'];
  }

  async processEvents(events, toBlock) {
    for (let i in events) {
      while (true) {
        try {
          await this.cb(events[i]);
          break;
        } catch (err) {
          log.error(err);
        }
        await utils.sleep(8000 + utils.randRange(500, 1500));
      }
    }
  }

  async getFromBlock() {
    const firstBlockNumber  = await bc.getFirstBlockNumber();
    while (this.lastBlockNumber < 1) {
      try {
        const {err, row} = await this.conn.ormSelectOne(
          't_parameter',
          [
            ['name', this.getBlockNumberDbName()]
          ]
        );
        if (!err) {
          if (row) {
            this.lastBlockNumber = Number(row['value']);
          } else {
            this.lastBlockNumber = firstBlockNumber;
          }
        }
        while (this.lastBlockNumber + 8 > bc.getCurrBlockNumber()) {
          await utils.sleep(1000 + utils.randRange(500, 1500));
        }
        continue;
      } catch (err) {
        log.log(err);
      }
      await utils.sleep(5000 + utils.randRange(500, 1500));
    }
    return this.lastBlockNumber;
  }

  async calcToBlock(fromBlock) {
    const currBlockNumber = bc.getCurrBlockNumber();
    const distanceBlock = currBlockNumber - fromBlock - 8;
    if (distanceBlock > 0) {
      if (distanceBlock > 3000) {
        return fromBlock + 3000;
      } else {
        return fromBlock + distanceBlock;
      }
    }
    return fromBlock;
  }

  async saveLastBlockNumber(blockNumber) {
    while (true) {
      const {err} = await this.conn.upsert(
        't_parameter',
        [
          ['name', this.getBlockNumberDbName()]
        ],
        [
          ['value', blockNumber],
        ],
        [
          ['name', this.getBlockNumberDbName()],
          ['value', blockNumber],
        ]
      );
      if (!err) {
        break;
      }
      await utils.sleep(5000 + utils.randRange(500, 1500));
    }
    this.lastBlockNumber = blockNumber;
  }

  getBlockNumberDbName() {
    return this.instance['name'] + '.' + this.instance['eventName'] + '.last_block_number';
  }

}

module.exports = EventProcess;