package consensus

import (
	"encoding/json"
	"fmt"
	"github.com/kaspanet/kaspad/domain/consensus/model"
	"github.com/kaspanet/kaspad/domain/consensus/utils/hashset"
	"github.com/kaspanet/kaspad/util/staging"
	"io"

	"github.com/kaspanet/kaspad/domain/consensus/model/externalapi"
	"github.com/kaspanet/kaspad/domain/consensus/model/testapi"
	"github.com/kaspanet/kaspad/domain/consensus/utils/consensushashing"
	"github.com/kaspanet/kaspad/domain/dagconfig"
	"github.com/kaspanet/kaspad/infrastructure/db/database"
	"github.com/pkg/errors"
)

type testConsensus struct {
	*consensus
	dagParams *dagconfig.Params
	database  database.Database

	testBlockBuilder          testapi.TestBlockBuilder
	testReachabilityManager   testapi.TestReachabilityManager
	testConsensusStateManager testapi.TestConsensusStateManager
	testTransactionValidator  testapi.TestTransactionValidator

	buildBlockConsensus *consensus
}

func (tc *testConsensus) DAGParams() *dagconfig.Params {
	return tc.dagParams
}

func (tc *testConsensus) BuildBlockWithParents(parentHashes []*externalapi.DomainHash,
	coinbaseData *externalapi.DomainCoinbaseData, transactions []*externalapi.DomainTransaction) (
	*externalapi.DomainBlock, externalapi.UTXODiff, error) {

	// Require write lock because BuildBlockWithParents stages temporary data
	tc.lock.Lock()
	defer tc.lock.Unlock()

	block, diff, err := tc.testBlockBuilder.BuildBlockWithParents(parentHashes, coinbaseData, transactions)
	if err != nil {
		return nil, nil, err
	}

	return block, diff, nil
}

func (tc *testConsensus) AddBlock(parentHashes []*externalapi.DomainHash, coinbaseData *externalapi.DomainCoinbaseData,
	transactions []*externalapi.DomainTransaction) (*externalapi.DomainHash, *externalapi.VirtualChangeSet, error) {

	// Require write lock because BuildBlockWithParents stages temporary data
	tc.lock.Lock()
	defer tc.lock.Unlock()

	block, _, err := tc.testBlockBuilder.BuildBlockWithParents(parentHashes, coinbaseData, transactions)
	if err != nil {
		return nil, nil, err
	}

	virtualChangeSet, err := tc.validateAndInsertBlockNoLock(block, true)
	if err != nil {
		return nil, nil, err
	}

	return consensushashing.BlockHash(block), virtualChangeSet, nil
}

func (tc *testConsensus) AddUTXOInvalidHeader(parentHashes []*externalapi.DomainHash) (*externalapi.DomainHash,
	*externalapi.VirtualChangeSet, error) {

	// Require write lock because BuildBlockWithParents stages temporary data
	tc.lock.Lock()
	defer tc.lock.Unlock()

	header, err := tc.testBlockBuilder.BuildUTXOInvalidHeader(parentHashes)
	if err != nil {
		return nil, nil, err
	}

	virtualChangeSet, err := tc.validateAndInsertBlockNoLock(&externalapi.DomainBlock{
		Header:       header,
		Transactions: nil,
	}, true)
	if err != nil {
		return nil, nil, err
	}

	return consensushashing.HeaderHash(header), virtualChangeSet, nil
}

func (tc *testConsensus) AddUTXOInvalidBlock(parentHashes []*externalapi.DomainHash) (*externalapi.DomainHash,
	*externalapi.VirtualChangeSet, error) {

	// Require write lock because BuildBlockWithParents stages temporary data
	tc.lock.Lock()
	defer tc.lock.Unlock()

	block, err := tc.testBlockBuilder.BuildUTXOInvalidBlock(parentHashes)
	if err != nil {
		return nil, nil, err
	}

	virtualChangeSet, err := tc.validateAndInsertBlockNoLock(block, true)
	if err != nil {
		return nil, nil, err
	}

	return consensushashing.BlockHash(block), virtualChangeSet, nil
}

func (tc *testConsensus) ResolveVirtualWithMaxParam(maxBlocksToResolve uint64) (*externalapi.VirtualChangeSet, bool, error) {
	tc.lock.Lock()
	defer tc.lock.Unlock()

	return tc.resolveVirtualChunkNoLock(maxBlocksToResolve)
}

// jsonBlock is a json representation of a block in mine format
type jsonBlock struct {
	ID      string   `json:"id"`
	Parents []string `json:"parents"`
}

func (tc *testConsensus) MineJSON(r io.Reader, blockType testapi.MineJSONBlockType) (tips []*externalapi.DomainHash, err error) {
	tipSet := map[externalapi.DomainHash]*externalapi.DomainHash{}
	tipSet[*tc.dagParams.GenesisHash] = tc.dagParams.GenesisHash

	parentsMap := make(map[string]*externalapi.DomainHash)
	parentsMap["0"] = tc.dagParams.GenesisHash

	decoder := json.NewDecoder(r)
	// read open bracket
	_, err = decoder.Token()
	if err != nil {
		return nil, err
	}
	// while the array contains values
	for decoder.More() {
		var block jsonBlock
		// decode an array value (Message)
		err := decoder.Decode(&block)
		if err != nil {
			return nil, err
		}
		if block.ID == "0" {
			continue
		}
		parentHashes := make([]*externalapi.DomainHash, len(block.Parents))
		var ok bool
		for i, parentID := range block.Parents {
			parentHashes[i], ok = parentsMap[parentID]
			if !ok {
				return nil, errors.Errorf("Couldn't find blockID: %s", parentID)
			}
			delete(tipSet, *parentHashes[i])
		}

		var blockHash *externalapi.DomainHash
		switch blockType {
		case testapi.MineJSONBlockTypeUTXOValidBlock:
			blockHash, _, err = tc.AddBlock(parentHashes, nil, nil)
			if err != nil {
				return nil, err
			}
		case testapi.MineJSONBlockTypeUTXOInvalidBlock:
			blockHash, _, err = tc.AddUTXOInvalidBlock(parentHashes)
			if err != nil {
				return nil, err
			}
		case testapi.MineJSONBlockTypeUTXOInvalidHeader:
			blockHash, _, err = tc.AddUTXOInvalidHeader(parentHashes)
			if err != nil {
				return nil, err
			}
		default:
			return nil, errors.Errorf("unknwon block type %v", blockType)
		}

		parentsMap[block.ID] = blockHash
		tipSet[*blockHash] = blockHash
	}

	tips = make([]*externalapi.DomainHash, len(tipSet))
	i := 0
	for _, v := range tipSet {
		tips[i] = v
		i++
	}
	return tips, nil
}

func (tc *testConsensus) ToJSON(w io.Writer) error {
	hashToID := make(map[externalapi.DomainHash]string)
	lastID := 0

	encoder := json.NewEncoder(w)
	visited := hashset.New()
	queue := tc.dagTraversalManager.NewUpHeap(model.NewStagingArea())
	err := queue.Push(tc.dagParams.GenesisHash)
	if err != nil {
		return err
	}

	blocksToAdd := make([]jsonBlock, 0)
	for queue.Len() > 0 {
		current := queue.Pop()
		if visited.Contains(current) {
			continue
		}

		visited.Add(current)

		if current.Equal(model.VirtualBlockHash) {
			continue
		}

		header, err := tc.blockHeaderStore.BlockHeader(tc.databaseContext, model.NewStagingArea(), current)
		if err != nil {
			return err
		}

		directParents := header.DirectParents()

		parentIDs := make([]string, len(directParents))
		for i, parent := range directParents {
			parentIDs[i] = hashToID[*parent]
		}
		lastIDStr := fmt.Sprintf("%d", lastID)
		blocksToAdd = append(blocksToAdd, jsonBlock{
			ID:      lastIDStr,
			Parents: parentIDs,
		})
		hashToID[*current] = lastIDStr
		lastID++

		children, err := tc.dagTopologyManagers[0].Children(model.NewStagingArea(), current)
		if err != nil {
			return err
		}

		err = queue.PushSlice(children)
		if err != nil {
			return err
		}
	}

	return encoder.Encode(blocksToAdd)
}

func (tc *testConsensus) BuildUTXOInvalidBlock(parentHashes []*externalapi.DomainHash) (*externalapi.DomainBlock, error) {
	// Require write lock because BuildBlockWithParents stages temporary data
	tc.lock.Lock()
	defer tc.lock.Unlock()

	return tc.testBlockBuilder.BuildUTXOInvalidBlock(parentHashes)
}

func (tc *testConsensus) BuildHeaderWithParents(parentHashes []*externalapi.DomainHash) (externalapi.BlockHeader, error) {
	// Require write lock because BuildUTXOInvalidHeader stages temporary data
	tc.lock.Lock()
	defer tc.lock.Unlock()

	return tc.testBlockBuilder.BuildUTXOInvalidHeader(parentHashes)
}

func (tc *testConsensus) UpdatePruningPointByVirtual() error {
	tc.lock.Lock()
	defer tc.lock.Unlock()

	stagingArea := model.NewStagingArea()
	err := tc.pruningManager.UpdatePruningPointByVirtual(stagingArea)
	if err != nil {
		return err
	}

	return staging.CommitAllChanges(tc.databaseContext, stagingArea)
}