#!/usr/bin/env python
#
# Read the block database, parse and dump out results
#
from bsddb.db import *
from datetime import date
import logging
import os
import sys

from BCDataStream import *
from block import scan_blocks, _open_blkindex, read_block
from collections import defaultdict
from deserialize import parse_Block
from util import determine_db_dir, create_env

def target(bits):
    first = bits >> (6*4)
    last = bits & (~0xff000000)

    return last * 2**(8*(first - 3))

def diff_perc(h, bits):
    d = float(h) / target(bits)

    if d > 1:
        print d, bits, h
        raise ValueError

    print "%.11f" % d

    return d

def diff_minus(h, bits):
    d = target(bits) - h

    if d < 0:
        print d, h, bits
        raise ValueError

    print "%r" % d

    return d

max_diff = target(0x1d00ffff)

def diff_hybrid(h, bits):
    max_diff =
    t = target(bits)

    diff = t - h

    d = diff / float(t)

    if d > 1:
        print d, t, h

    print "%.11f" % d

    return d

def main():
  import optparse
  parser = optparse.OptionParser(usage="%prog [options]")
  parser.add_option("--datadir", dest="datadir", default=None,
                    help="Look for files here (defaults to bitcoin default)")
  (options, args) = parser.parse_args()

  if options.datadir is None:
    db_dir = determine_db_dir()
  else:
    db_dir = options.datadir

  try:
    db_env = create_env(db_dir)
  except DBNoSuchFileError:
    logging.error("Couldn't open " + db_dir)
    sys.exit(1)

  blockfile = open(os.path.join(db_dir, "blk%04d.dat"%(1,)), "rb")
  block_datastream = BCDataStream()
  block_datastream.map_file(blockfile, 0)

  num_blocks = 1

  db = _open_blkindex(db_env)

  kds = BCDataStream()
  vds = BCDataStream()
  
  # Read the hashBestChain record:
  cursor = db.cursor()
  (key, value) = cursor.set_range("\x0dhashBestChain")
  vds.write(value)
  hashBestChain = vds.read_bytes(32)

  block_data = read_block(cursor, hashBestChain)

  last_hash = -1

  while True:
    if block_data['nHeight'] == 0:
      break;

    block_data = read_block(cursor, block_data['hashPrev'])
    block_datastream.seek_file(block_data['nBlockPos'])
    data = parse_Block(block_datastream)

    if last_hash == -1:
        last_hash = int('0x' + data['hashPrev'][::-1].encode('hex_codec'), 16)
        continue

    d = diff_perc(last_hash, data['nBits'])

    last_hash = int('0x' + data['hashPrev'][::-1].encode('hex_codec'), 16)
    num_blocks += 1

  db_env.close()

if __name__ == '__main__':
    main()