var express = require('express');
var router = express.Router();
var KyotoTycoon = require('kyoto-tycoon').KyotoTycoon;

var CryptoJS = require('crypto-js');

var kt = new KyotoTycoon();

function randomString(length) {
  chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
  var result = '';
  for (var i = length; i > 0; --i) result += chars[Math.floor(Math.random() * chars.length)];
  return result;
}

function mineBlock(block, requirement) {
  rand = '';
  i = 0;
  
  while(CryptoJS.SHA512(JSON.stringify(block.content)).toString().substring(0, requirement.length) != requirement) {
    rand = randomString(32);
    block.content.rand = rand;
    i++;
    console.log(i + ': ' + rand + ' : ' + CryptoJS.SHA512(JSON.stringify(block.content)).toString());
  }
  block.hash = CryptoJS.SHA512(JSON.stringify(block.content)).toString();
}

function checkBlock(id, badId, goodId) {
  kt.get(id, function(err, data) {
    if(err) {
      console.log('Error getting block id ' + id);
      return -1;
    } else {
      kt.get(id - 1, function(err, prevData){
        if(err) {
          console.log('Error getting block id ' + id - 1);
	}
        block = JSON.parse(data);
        if((CryptoJS.SHA512(JSON.stringify(block.content)).toString() === block.hash) && (block.content.prevhash === JSON.parse(prevData).hash)) {
          console.log('Block ' + block.content.id + ' is OK');
          if(goodId) {
            goodId(block.content.id);
	  }
        } else {
          console.log('Block ' + block.content.id + ' is bad');
	  if(badId) {
            badId(block.content.id);
	  }
        }
      });
    }
  });
}

function checkChain() {
  j = 0;
  kt.status(':', async function (err, data) {
    if(err) {
      console.log('Error getting chain data.');
      return -1;
    } else {
      for(i = 1; i < data.count; i++) {
        await checkBlock(i, function(id) {
          console.log('Handle badId: ' + id);
          deleteChain(id, data.count - 1);
	}, function(id) {
          console.log('Handle goodId: ' + id)
	});
      }
    }
  });
}

function deleteChain(firstId, lastId) {
  for(i = firstId; i <= lastId; i++) {
    console.log('Deleteing block id ' + i);
    kt.remove(i);
  }
}

function getLastTransactions(count, next) {
  result = [];
  j = 0;
  kt.status(':', async function(err, data) {
    if(err) {
      console.log('Error getting chain data.');
      return -1;
    }
    for(i = data.count - count; i < data.count; i++) {
      result.push(new Promise((resolve, reject) => {
        kt.get(i, async function(err, block) {
          if(err) reject(err);
          resolve(JSON.parse(block));
        });
      }));
    }
    if(next) {
      next(await Promise.all(result));
    }
  });
}

/* GET home page. */
router.get('/', function(req, res, next) {
  getLastTransactions(15, async function(data) {
    await console.log(JSON.stringify(data));
    breadcrumb = [{title:'home', url:'/', stat:'active'}]
    await res.render('index', { title: 'mCoin', data: data, breadcrumb: breadcrumb });
  });
});

router.get('/new', function(req, res, next) {
  block = {
    content: {
      message: {
        from: 'Simona',
        to: 'Matjaz',
        amount: '200',
        timestamp: '1234',
      },
      id: 1,
      previd: 0,
      prevhash: 'abc',
      rand: '',
      timestamp: '',
      unixtime: '',
    },
    hash: '',
    difficulty: '',
    version: '0.01',
  };
  difficulty = '000';

  kt.status(':', function(err, data) {
    if(err) {
      console.log(err);
    }
    kt.get(data.count - 1, function(err, prevData) {
      if(err) {
        console.log(err);
      }
      const utcDate = new Date();
      block.content.timestamp = utcDate.toUTCString();
      block.content.unixtime = Math.floor(new Date().getTime() / 1000);
      block.content.prevhash = JSON.parse(prevData).hash;
      block.content.id = data.count;
      block.content.previd = data.count - 1;
      block.difficulty = difficulty;
      mineBlock(block, difficulty);
      console.log(JSON.stringify(block));
      kt.set(block.content.id.toString(), JSON.stringify(block), function() {
        console.log('Block Written');
      });
    });
  });
});

router.get('/check', function(req, res, next) {
  badBlock = 0;
  console.log('Checking the chain');
  checkChain();
});

module.exports = router;