package pool

import (
	"bytes"
	"encoding/hex"
	"fmt"
	"time"

	"github.com/asaskevich/EventBus"

	"github.com/sirupsen/logrus"

	"github.com/Secured-Finance/dione/blockchain/types"
	"github.com/Secured-Finance/dione/cache"
)

// BlockPool is pool for blocks that isn't not validated or committed yet
type BlockPool struct {
	mempool        *Mempool
	knownBlocks    cache.Cache
	acceptedBlocks cache.Cache
	bus            EventBus.Bus
}

func NewBlockPool(mp *Mempool, bus EventBus.Bus) (*BlockPool, error) {
	bp := &BlockPool{
		acceptedBlocks: cache.NewInMemoryCache(), // here we need to use separate cache
		knownBlocks:    cache.NewInMemoryCache(),
		mempool:        mp,
		bus:            bus,
	}

	return bp, nil
}

func (bp *BlockPool) AddBlock(block *types.Block) error {
	err := bp.knownBlocks.StoreWithTTL(hex.EncodeToString(block.Header.Hash), block, 10*time.Minute)
	if err != nil {
		return err
	}
	logrus.WithField("hash", fmt.Sprintf("%x", block.Header.Hash)).Debug("New block discovered")
	bp.bus.Publish("blockpool:knownBlockAdded", block)
	return nil
}

func (bp *BlockPool) GetBlock(blockhash []byte) (*types.Block, error) {
	var block types.Block
	err := bp.knownBlocks.Get(hex.EncodeToString(blockhash), &block)
	return &block, err
}

// PruneBlocks cleans known blocks list. It is called when new consensus round starts.
func (bp *BlockPool) PruneBlocks() {
	for k := range bp.knownBlocks.Items() {
		bp.knownBlocks.Delete(k)
	}
	bp.bus.Publish("blockpool:pruned")
}

func (bp *BlockPool) AddAcceptedBlock(block *types.Block) error {
	err := bp.acceptedBlocks.Store(hex.EncodeToString(block.Header.Hash), block)
	if err != nil {
		return err
	}
	bp.bus.Publish("blockpool:acceptedBlockAdded", block)
	return nil
}

func (bp *BlockPool) GetAllAcceptedBlocks() []*types.Block {
	var blocks []*types.Block
	for _, v := range bp.acceptedBlocks.Items() {
		blocks = append(blocks, v.(*types.Block))
	}
	return blocks
}

// PruneAcceptedBlocks cleans accepted blocks list. It is called when new consensus round starts.
func (bp *BlockPool) PruneAcceptedBlocks(committedBlock *types.Block) {
	for k, v := range bp.acceptedBlocks.Items() {
		block := v.(*types.Block)
		for _, v := range block.Data {
			if !containsTx(committedBlock.Data, v) {
				v.MerkleProof = nil
				err := bp.mempool.StoreTx(v) // return transactions back to mempool
				if err != nil {
					logrus.Error(err)
				}
			}
		}
		bp.acceptedBlocks.Delete(k)
	}
}

func containsTx(s []*types.Transaction, e *types.Transaction) bool {
	for _, a := range s {
		if bytes.Equal(a.Hash, e.Hash) {
			return true
		}
	}
	return false
}