/// <summary> /// Get a prevoius Hash. /// </summary> /// <returns>Return with a last block's hash.</returns> private string GetPreviousHash() => Chain.GetBlockchain().Last().Hash;
//TODO Überprüfung einfügen, ob Chain eingefügt werden soll oder nicht (Collision Management)
//TODO Rückgabewert auf Chain ändern, und alle Blocks zurück geben, die gelöscht werden
public List <Block> Add(Chain chain)
{
List <Block> ret = new List <Block>();
//If chain is currently empty, set Blockhead to inserted chain's Blockhead and return true
if (Blockhead == null)
{
Blockhead = chain.Blockhead;
return(ret);
}
if (chain.Blockhead.Index <= Blockhead.Index)
{
return(ret);
}
//Get first block in chain
var firstBlock = chain.Blockhead;
while (firstBlock.PreviousBlock != null)
{
firstBlock = firstBlock.PreviousBlock;
}
//Add chain directly if hashes and indexes match to Blockhead
if ((firstBlock.PreviousHash == Blockhead.Hash && firstBlock.Index == Blockhead.Index + 1))
{
firstBlock.PreviousBlock = Blockhead;
Blockhead = chain.Blockhead;
return(ret);
}
else
{
//Search matching block if the chain replaces previous blocks
var referenceBlock = Blockhead;
while (referenceBlock != null &&
firstBlock.PreviousHash != referenceBlock.Hash &&
firstBlock.Index >= referenceBlock.Index)
{
ret.Add(referenceBlock);
referenceBlock = referenceBlock.PreviousBlock;
}
//Attach chain at correct position if possible
if (referenceBlock != null &&
firstBlock.PreviousHash == referenceBlock.Hash &&
firstBlock.Index == referenceBlock.Index + 1)
{
firstBlock.PreviousBlock = referenceBlock;
firstBlock.ValidateSequence();
Blockhead = chain.Blockhead;
return(ret);
}
}
//If no matching position is found in the blockchain, return false
return(new List <Block>());
}