'use strict';

import * as bufferUtil from '../BitcoreBuffer'
import * as assert from 'assert'

export class BufferWriter{
  public bufLen: number;
  public bufs: any[];
  constructor(obj?: object) {
    if (!(this instanceof BufferWriter))
      return new BufferWriter(obj);
    this.bufLen = 0;
    if (obj)
      this.set(obj);
    else
      this.bufs = [];
  }

  public set(obj) {
    this.bufs = obj.bufs || this.bufs || [];
    this.bufLen = this.bufs.reduce(function(prev, buf){ return prev + buf.length; }, 0);
    return this;
  };

  public toBuffer() {
    return this.concat();
  };

  public concat() {
    return Buffer.concat(this.bufs, this.bufLen);
  };

  public write(buf) {
    assert(bufferUtil.isBuffer(buf));
    this.bufs.push(buf);
    this.bufLen += buf.length;
    return this;
  };

  public writeReverse(buf) {
    assert(bufferUtil.isBuffer(buf));
    this.bufs.push(bufferUtil.reverse(buf));
    this.bufLen += buf.length;
    return this;
  };

  public writeUInt8(n) {
    var buf = Buffer.alloc(1);
    buf.writeUInt8(n, 0);
    this.write(buf);
    return this;
  };

  public writeUInt16BE(n) {
    var buf = Buffer.alloc(2);
    buf.writeUInt16BE(n, 0);
    this.write(buf);
    return this;
  };

  public writeUInt16LE(n) {
    var buf = Buffer.alloc(2);
    buf.writeUInt16LE(n, 0);
    this.write(buf);
    return this;
  };

  public writeUInt32BE(n) {
    var buf = Buffer.alloc(4);
    buf.writeUInt32BE(n, 0);
    this.write(buf);
    return this;
  };

  public writeInt32LE(n) {
    var buf = Buffer.alloc(4);
    buf.writeInt32LE(n, 0);
    this.write(buf);
    return this;
  };

  public writeUInt32LE(n) {
    var buf = Buffer.alloc(4);
    buf.writeUInt32LE(n, 0);
    this.write(buf);
    return this;
  };

  public writeUInt64BEBN(bn) {
    var buf = bn.toBuffer({size: 8});
    this.write(buf);
    return this;
  };

  public writeUInt64LEBN(bn) {
    var buf = bn.toBuffer({size: 8});
    this.writeReverse(buf);
    return this;
  };

  public writeVarintNum(n) {
    var buf = this.varintBufNum(n);
    this.write(buf);
    return this;
  };

  public writeVarintBN(bn) {
    var buf = this.varintBufBN(bn);
    this.write(buf);
    return this;
  };

  private varintBufNum(n) {
    var buf = undefined;
    if (n < 253) {
      buf = Buffer.alloc(1);
      buf.writeUInt8(n, 0);
    } else if (n < 0x10000) {
      buf = Buffer.alloc(1 + 2);
      buf.writeUInt8(253, 0);
      buf.writeUInt16LE(n, 1);
    } else if (n < 0x100000000) {
      buf = Buffer.alloc(1 + 4);
      buf.writeUInt8(254, 0);
      buf.writeUInt32LE(n, 1);
    } else {
      buf = Buffer.alloc(1 + 8);
      buf.writeUInt8(255, 0);
      buf.writeInt32LE(n & -1, 1);
      buf.writeUInt32LE(Math.floor(n / 0x100000000), 5);
    }
    return buf;
  };

  private varintBufBN(bn) {
    var buf = undefined;
    var n = bn.toNumber();
    if (n < 253) {
      buf = Buffer.alloc(1);
      buf.writeUInt8(n, 0);
    } else if (n < 0x10000) {
      buf = Buffer.alloc(1 + 2);
      buf.writeUInt8(253, 0);
      buf.writeUInt16LE(n, 1);
    } else if (n < 0x100000000) {
      buf = Buffer.alloc(1 + 4);
      buf.writeUInt8(254, 0);
      buf.writeUInt32LE(n, 1);
    } else {
      var bw = new BufferWriter(null);
      bw.writeUInt8(255);
      bw.writeUInt64LEBN(bn);
      var buf: any = bw.concat();
    }
    return buf;
  };
}