SelectCoinsRipd4rmBitcoinCore

"""
assumes you've entered (sendamount+fee) greater than Wallet balance
ignores special treatment of vout for coinbase tx
ignores fee considerations, assumes this is already part of nTargetValue
https://github.com/bitcoin/bitcoin/blob/v0.5.3/src/wallet.cpp#L760
http://bitcoin.stackexchange.com/questions/1077/what-is-the-coin-selection-algorithm
"""
import random

def SelectCoins():
    nTargetValue = 1.71#spend amount including fee
    print 'nTargetValue: ', str(nTargetValue)
    setCoinsRet = nValueRet = None
    try:
        print '1st pass:'
        return SelectCoinsMinConf(nTargetValue, 1, 6, setCoinsRet, nValueRet)
    except:
        try:
            print '2nd pass:'
            return SelectCoinsMinConf(nTargetValue, 1, 1, setCoinsRet, nValueRet)
        except:
            print '3rd pass:'
            return SelectCoinsMinConf(nTargetValue, 0, 1, setCoinsRet, nValueRet)

def SelectCoinsMinConf(nTargetValue, nConfMine, nConfTheirs, setCoinsRet=None, nValueRet=None):
    CWalletTx = [{'id':'utxoA','confs':1,'value':0.1, 'fromMe':True},
            {'id':'utxoB','confs':0,'value':0.3, 'fromMe':True},
            {'id':'utxoC','confs':1,'value':0.5, 'fromMe':False},
            {'id':'utxoD','confs':1,'value':1.0, 'fromMe':False},]
    for pcoin in CWalletTx:
        if pcoin['fromMe']:
            if pcoin['confs'] < nConfMine:
                CWalletTx[:] = [d for d in CWalletTx if d != pcoin]
        else:#not mine, conf acceptance further restricted:
            if pcoin['confs'] < nConfTheirs:
                CWalletTx[:] = [d for d in CWalletTx if d != pcoin]
    print 'currentwalletchoice:' + ','.join([coin['id'] for coin in CWalletTx])
    
    vCoins = []#list of utxos smaller than sendamount
    for coin in CWalletTx:
        n = coin['value']
        if n == nTargetValue:
            nBest = [coin]#converted nBest to list for future procs
            print '1. exact single utxo match found'
            break
        else:
            if n < nTargetValue:#adding utxo to vCoins if < sendamount 
                vCoins.append(coin)
    try:
        nBest#exit to end as nBest already located in prior section
    except:    
        nTotalLower = sum(coin['value'] for coin in vCoins)
        print 'nTotalLower: ', str(nTotalLower)
        if nTotalLower == nTargetValue:
            print '2. (sum(utxo<sendamt) == sendamount, usu. for a wallet sweep'
            nBest = vCoins
        else:
            print '3. (sum(utxo<sendamt) <> sendamount'
            if nTotalLower < nTargetValue:
                tmplist = [x['value'] for x in CWalletTx if x not in vCoins]#utxos@ >sendamount
                if len(tmplist) > 0:#coz else it fails @ nil utxo>sendamount
                    coinLowestLarger = CWalletTx[[x['value'] for x in CWalletTx].index(min(tmplist))]
                    #coinLowestLarger = min(x for x in CWalletTx if x not in vCoins)
                    print '3.+ coinLowestLarger: ', coinLowestLarger['id']
                    nBest = [coinLowestLarger]#converted nBest to list for future procs
            else:#nTotalLower > nTargetValue
                vfIncluded = []
                for nRep in range(1,1000):
                    rndcount = random.randint(2,len(vCoins))#choosing no. of selections
                    rndnumsample = random.sample(range(len(vCoins)), rndcount)#randchoice
                    vsmpl = [vCoins[rndnum] for rndnum in rndnumsample]
                    nTotal = sum(k['value'] for k in vsmpl)
                    if nTotal == nTargetValue:
                        nBest = vsmpl
                        print 'exact utxo combo match found'
                        break
                    else:#otherwise only considering sets@ sum > sendamount
                        if sum(coin['value'] for coin in vsmpl) > nTargetValue:
                            vfIncluded.append(vsmpl)
                try:
                    nBest#exit to end as nBest already located in prior section
                except:
                    sumlst = [sum(m[o]['value'] for o in range(len(m))) for m in vfIncluded]
                    idx1 =  sumlst.index(min(sumlst))
                    print '4. min of rndsmpl:', str(min(sumlst))
                    nBest = vfIncluded[idx1]
                    tmplist = [x['value'] for x in CWalletTx if x not in vCoins]#utxos@ >sendamount
                    if len(tmplist) > 0:#coz else it fails @ nil utxo>sendamount
                        coinLowestLarger = CWalletTx[[x['value'] for x in CWalletTx].index(min(tmplist))]
                        if coinLowestLarger['value'] < min(sumlst):
                            nBest = [coinLowestLarger]
    return nBest

#now actually running the above function:
nBest = SelectCoins()
vfBest = [coin['id'] for coin in nBest]
vValue = sum(coin['value'] for coin in nBest)
print ''
print 'nBest: '+ ','.join(vfBest) + ' = ' + str(vValue)