// FetchBlockHeightBySha returns the block height for the given hash.  This is
// part of the database.Db interface implementation.
func (db *LevelDb) FetchBlockHeightBySha(sha *wire.ShaHash) (int64, error) {

	dblk, _ := db.FetchDBlockByHash(sha.ToFactomHash())

	var height int64 = -1
	if dblk != nil {
		height = int64(dblk.Header.DBHeight)
	}

	return height, nil
}

// DirBlockLocatorFromHash returns a block locator for the passed block hash.
// See BlockLocator for details on the algotirhm used to create a block locator.
//
// In addition to the general algorithm referenced above, there are a couple of
// special cases which are handled:
//
//  - If the genesis hash is passed, there are no previous hashes to add and
//    therefore the block locator will only consist of the genesis hash
//  - If the passed hash is not currently known, the block locator will only
//    consist of the passed hash
func DirBlockLocatorFromHash(hash *wire.ShaHash) blockchain.BlockLocator {
	// The locator contains the requested hash at the very least.
	locator := make(blockchain.BlockLocator, 0, wire.MaxBlockLocatorsPerMsg)
	locator = append(locator, hash)

	h, _ := common.HexToHash(common.GENESIS_DIR_BLOCK_HASH)
	genesisHash := wire.FactomHashToShaHash(h)
	// Nothing more to do if a locator for the genesis hash was requested.
	if genesisHash.IsEqual(hash) {
		return locator
	}

	// Attempt to find the height of the block that corresponds to the
	// passed hash, and if it's on a side chain, also find the height at
	// which it forks from the main chain.
	blockHeight := int64(-1)

	// Generate the block locators according to the algorithm described in
	// in the BlockLocator comment and make sure to leave room for the
	// final genesis hash.

	dblock, _ := db.FetchDBlockByHash(hash.ToFactomHash())
	if dblock != nil {
		blockHeight = int64(dblock.Header.DBHeight)
	}
	increment := int64(1)
	for len(locator) < wire.MaxBlockLocatorsPerMsg-1 {
		// Once there are 10 locators, exponentially increase the
		// distance between each block locator.
		if len(locator) > 10 {
			increment *= 2
		}
		blockHeight -= increment
		if blockHeight < 1 {
			break
		}

		blk, _ := db.FetchDBlockByHeight(uint32(blockHeight))
		if blk == nil {
			continue
		} else if blk.DBHash == nil {
			blk.DBHash, _ = common.CreateHash(blk)
		}

		locator = append(locator, wire.FactomHashToShaHash(blk.DBHash))
	}

	// Append the appropriate genesis block.
	locator = append(locator, genesisHash)
	return locator
}

// PushGetDirBlocksMsg sends a getdirblocks message for the provided block locator
// and stop hash.  It will ignore back-to-back duplicate requests.
func (p *peer) PushGetDirBlocksMsg(locator blockchain.BlockLocator, stopHash *wire.ShaHash) error {

	// Extract the begin hash from the block locator, if one was specified,
	// to use for filtering duplicate getblocks requests.
	// request.
	var beginHash *wire.ShaHash
	if len(locator) > 0 {
		beginHash = locator[0]
	}

	// Filter duplicate getdirblocks requests.
	if p.prevGetBlocksStop != nil && p.prevGetBlocksBegin != nil &&
		beginHash != nil && stopHash.IsEqual(p.prevGetBlocksStop) &&
		beginHash.IsEqual(p.prevGetBlocksBegin) {

		peerLog.Tracef("Filtering duplicate [getdirblocks] with begin "+
			"hash %v, stop hash %v", beginHash, stopHash)
		return nil
	}

	// Construct the getblocks request and queue it to be sent.
	msg := wire.NewMsgGetDirBlocks(stopHash)
	for _, hash := range locator {
		err := msg.AddBlockLocatorHash(hash)
		if err != nil {
			return err
		}
	}
	p.QueueMessage(msg, nil)

	// Update the previous getblocks request information for filtering
	// duplicates.
	p.prevGetBlocksBegin = beginHash
	p.prevGetBlocksStop = stopHash
	return nil
}

func shaSpentTxToKey(sha *wire.ShaHash) []byte {
	shaB := sha.Bytes()
	shaB = append(shaB, "sx"...)
	return shaB
}

func shaBlkToKey(sha *wire.ShaHash) []byte {
	shaB := sha.Bytes()
	return shaB
}

// pushDirBlockMsg sends a dir block message for the provided block hash to the
// connected peer.  An error is returned if the block hash is not known.
func (p *peer) pushDirBlockMsg(sha *wire.ShaHash, doneChan, waitChan chan struct{}) error {
	commonhash := new(common.Hash)
	commonhash.SetBytes(sha.Bytes())
	blk, err := db.FetchDBlockByHash(commonhash)

	if err != nil {
		peerLog.Tracef("Unable to fetch requested dir block sha %v: %v",
			sha, err)

		if doneChan != nil {
			doneChan <- struct{}{}
		}
		return err
	}

	// Once we have fetched data wait for any previous operation to finish.
	if waitChan != nil {
		<-waitChan
	}

	// We only send the channel for this message if we aren't sending(sha)
	// an inv straight after.
	var dc chan struct{}
	sendInv := p.continueHash != nil && p.continueHash.IsEqual(sha)
	if !sendInv {
		dc = doneChan
	}
	msg := wire.NewMsgDirBlock()
	msg.DBlk = blk
	p.QueueMessage(msg, dc) //blk.MsgBlock(), dc)

	// When the peer requests the final block that was advertised in
	// response to a getblocks message which requested more blocks than
	// would fit into a single message, send it a new inventory message
	// to trigger it to issue another getblocks message for the next
	// batch of inventory.
	if p.continueHash != nil && p.continueHash.IsEqual(sha) {
		peerLog.Debug("continueHash: " + spew.Sdump(sha))
		// Sleep for 5 seconds for the peer to catch up
		time.Sleep(5 * time.Second)

		//
		// Note: Rather than the latest block height, we should pass
		// the last block height of this batch of wire.MaxBlockLocatorsPerMsg
		// to signal this is the end of the batch and
		// to trigger a client to send a new GetDirBlocks message
		//
		//hash, _, err := db.FetchBlockHeightCache()
		//if err == nil {
		invMsg := wire.NewMsgDirInvSizeHint(1)
		iv := wire.NewInvVect(wire.InvTypeFactomDirBlock, sha) //hash)
		invMsg.AddInvVect(iv)
		p.QueueMessage(invMsg, doneChan)
		p.continueHash = nil
		//} else if doneChan != nil {
		if doneChan != nil {
			doneChan <- struct{}{}
		}
	}
	return nil
}