// Copyright 2017-2021 DERO Project. All rights reserved.
// Use of this source code in any form is governed by RESEARCH license.
// license can be found in the LICENSE file.
// GPG: 0F39 E425 8C65 3947 702A  8234 08B2 0360 A03A 9DE8
//
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package blockchain

import "fmt"

//import "time"

import "encoding/binary"

import "github.com/deroproject/derohe/block"
import "github.com/deroproject/derohe/cryptography/crypto"

import "golang.org/x/crypto/sha3"

const miniblock_genesis_distance = 0
const miniblock_normal_distance = 2

// last miniblock must be extra checked for corruption/attacks
func (chain *Blockchain) Verify_MiniBlocks_HashCheck(cbl *block.Complete_Block) (err error) {
	last_mini_block := cbl.Bl.MiniBlocks[len(cbl.Bl.MiniBlocks)-1]

	if !last_mini_block.Final {
		return fmt.Errorf("corrupted block")
	}

	block_header_hash := sha3.Sum256(cbl.Bl.SerializeWithoutLastMiniBlock())
	for i := 0; i < 16; i++ {
		if last_mini_block.KeyHash[i] != block_header_hash[i] {
			return fmt.Errorf("MiniBlock has corrupted header expected %x  actual %x", block_header_hash[:], last_mini_block.KeyHash[:])
		}
	}
	return nil
}

// verifies the consensus rules completely for miniblocks
func Verify_MiniBlocks(bl block.Block) (err error) {

	if bl.Height == 0 && len(bl.MiniBlocks) != 0 {
		err = fmt.Errorf("Genesis block cannot have miniblocks")
		return
	}

	if bl.Height == 0 {
		return nil
	}

	if bl.Height != 0 && len(bl.MiniBlocks) == 0 {
		err = fmt.Errorf("All blocks except genesis must have miniblocks")
		return
	}

	final_count := 0
	for _, mbl := range bl.MiniBlocks {
		if mbl.Final { // 50 ms passing allowed
			final_count++
		}
	}
	if final_count != 1 {
		err = fmt.Errorf("No final miniblock")
		return
	}

	// check whether the genesis blocks are all equal
	for _, mbl := range bl.MiniBlocks {

		if bl.Height != mbl.Height {
			return fmt.Errorf("MiniBlock has invalid height block height %d mbl height %d", bl.Height, mbl.Height)
		}
		if len(bl.Tips) != int(mbl.PastCount) {
			return fmt.Errorf("MiniBlock has wrong number of tips")
		}
		if len(bl.Tips) == 0 {
			panic("all miniblocks genesis must point to tip")
		} else if len(bl.Tips) == 1 {
			if binary.BigEndian.Uint32(bl.Tips[0][:]) != mbl.Past[0] {
				return fmt.Errorf("MiniBlock has invalid tip")
			}
		} else if len(bl.Tips) == 2 {
			if binary.BigEndian.Uint32(bl.Tips[0][:]) != mbl.Past[0] {
				return fmt.Errorf("MiniBlock has invalid tip")
			}
			if binary.BigEndian.Uint32(bl.Tips[1][:]) != mbl.Past[1] {
				return fmt.Errorf("MiniBlock has invalid tip")
			}
			if mbl.Past[0] == mbl.Past[1] {
				return fmt.Errorf("MiniBlock refers to same tip twice")
			}
		} else {
			panic("we only support  2 tips")
		}
	}

	return nil
}

// insert a miniblock to chain and if successfull inserted, notify everyone in need
func (chain *Blockchain) InsertMiniBlock(mbl block.MiniBlock) (err error, result bool) {
	var miner_hash crypto.Hash
	copy(miner_hash[:], mbl.KeyHash[:])
	if !chain.IsAddressHashValid(true, miner_hash) {
		logger.V(1).Error(err, "Invalid miner address")
		err = fmt.Errorf("Invalid miner address")
		return err, false
	}

	if err, result = chain.MiniBlocks.InsertMiniBlock(mbl); result == true {
		chain.RPC_NotifyNewMiniBlock.L.Lock()
		chain.RPC_NotifyNewMiniBlock.Broadcast()
		chain.RPC_NotifyNewMiniBlock.L.Unlock()
	}
	return err, result
}