package oasys

import (
	"encoding/json"
	"fmt"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/consensus"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/ethereum/go-ethereum/rpc"
)

// API is a user facing RPC API to allow controlling the signer and voting
// mechanisms of the proof-of-stake scheme.
type API struct {
	chain consensus.ChainHeaderReader
	oasys *Oasys
}

// GetSnapshot retrieves the state snapshot at a given block.
func (api *API) GetSnapshot(number *rpc.BlockNumber) (*Snapshot, error) {
	// Retrieve the requested block number (or current if none requested)
	var header *types.Header
	if number == nil || *number == rpc.LatestBlockNumber {
		header = api.chain.CurrentHeader()
	} else {
		header = api.chain.GetHeaderByNumber(uint64(number.Int64()))
	}
	// Ensure we have an actually valid block and return its snapshot
	if header == nil {
		return nil, errUnknownBlock
	}
	return api.oasys.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
}

// GetSnapshotAtHash retrieves the state snapshot at a given block.
func (api *API) GetSnapshotAtHash(hash common.Hash) (*Snapshot, error) {
	header := api.chain.GetHeaderByHash(hash)
	if header == nil {
		return nil, errUnknownBlock
	}
	return api.oasys.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
}

// GetSigners retrieves the list of authorized signers at the specified block.
func (api *API) GetSigners(number *rpc.BlockNumber) ([]common.Address, error) {
	// Retrieve the requested block number (or current if none requested)
	var header *types.Header
	if number == nil || *number == rpc.LatestBlockNumber {
		header = api.chain.CurrentHeader()
	} else {
		header = api.chain.GetHeaderByNumber(uint64(number.Int64()))
	}
	// Ensure we have an actually valid block and return the signers from its snapshot
	if header == nil {
		return nil, errUnknownBlock
	}
	snap, err := api.oasys.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
	if err != nil {
		return nil, err
	}
	return snap.validators(), nil
}

// GetSignersAtHash retrieves the list of authorized signers at the specified block.
func (api *API) GetSignersAtHash(hash common.Hash) ([]common.Address, error) {
	header := api.chain.GetHeaderByHash(hash)
	if header == nil {
		return nil, errUnknownBlock
	}
	snap, err := api.oasys.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
	if err != nil {
		return nil, err
	}
	return snap.validators(), nil
}

// Proposals returns the current proposals the node tries to uphold and vote on.
func (api *API) Proposals() map[common.Address]bool {
	api.oasys.lock.RLock()
	defer api.oasys.lock.RUnlock()

	proposals := make(map[common.Address]bool)
	for address, auth := range api.oasys.proposals {
		proposals[address] = auth
	}
	return proposals
}

// Propose injects a new authorization proposal that the signer will attempt to
// push through.
func (api *API) Propose(address common.Address, auth bool) {
	api.oasys.lock.Lock()
	defer api.oasys.lock.Unlock()

	api.oasys.proposals[address] = auth
}

// Discard drops a currently running proposal, stopping the signer from casting
// further votes (either for or against).
func (api *API) Discard(address common.Address) {
	api.oasys.lock.Lock()
	defer api.oasys.lock.Unlock()

	delete(api.oasys.proposals, address)
}

// type status struct {
// 	InturnPercent float64                `json:"inturnPercent"`
// 	SigningStatus map[common.Address]int `json:"sealerActivity"`
// 	NumBlocks     uint64                 `json:"numBlocks"`
// }
//
// // Status returns the status of the last N blocks,
// // - the number of active signers,
// // - the number of signers,
// // - the percentage of in-turn blocks
// func (api *API) Status() (*status, error) {
// 	var (
// 		numBlocks = uint64(64)
// 		header    = api.chain.CurrentHeader()
// 		diff      = uint64(0)
// 		optimals  = 0
// 	)
// 	snap, err := api.oasys.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
// 	if err != nil {
// 		return nil, err
// 	}
// 	var (
// 		signers = snap.Validators
// 		end     = header.Number.Uint64()
// 		start   = end - numBlocks
// 	)
// 	if numBlocks > end {
// 		start = 1
// 		numBlocks = end - start
// 	}
// 	signStatus := make(map[common.Address]int)
// 	for _, s := range signers {
// 		signStatus[s] = 0
// 	}
// 	for n := start; n < end; n++ {
// 		h := api.chain.GetHeaderByNumber(n)
// 		if h == nil {
// 			return nil, fmt.Errorf("missing block %d", n)
// 		}
// 		if h.Difficulty.Cmp(diffInTurn) == 0 {
// 			optimals++
// 		}
// 		diff += h.Difficulty.Uint64()
// 		sealer, err := api.oasys.Author(h)
// 		if err != nil {
// 			return nil, err
// 		}
// 		signStatus[sealer]++
// 	}
// 	return &status{
// 		InturnPercent: float64(100*optimals) / float64(numBlocks),
// 		SigningStatus: signStatus,
// 		NumBlocks:     numBlocks,
// 	}, nil
// }

type blockNumberOrHashOrRLP struct {
	*rpc.BlockNumberOrHash
	RLP hexutil.Bytes `json:"rlp,omitempty"`
}

func (sb *blockNumberOrHashOrRLP) UnmarshalJSON(data []byte) error {
	bnOrHash := new(rpc.BlockNumberOrHash)
	// Try to unmarshal bNrOrHash
	if err := bnOrHash.UnmarshalJSON(data); err == nil {
		sb.BlockNumberOrHash = bnOrHash
		return nil
	}
	// Try to unmarshal RLP
	var input string
	if err := json.Unmarshal(data, &input); err != nil {
		return err
	}
	blob, err := hexutil.Decode(input)
	if err != nil {
		return err
	}
	sb.RLP = blob
	return nil
}

// GetSigner returns the signer for a specific oasys block.
// Can be called with either a blocknumber, blockhash or an rlp encoded blob.
// The RLP encoded blob can either be a block or a header.
func (api *API) GetSigner(rlpOrBlockNr *blockNumberOrHashOrRLP) (common.Address, error) {
	if len(rlpOrBlockNr.RLP) == 0 {
		blockNrOrHash := rlpOrBlockNr.BlockNumberOrHash
		var header *types.Header
		if blockNrOrHash == nil {
			header = api.chain.CurrentHeader()
		} else if hash, ok := blockNrOrHash.Hash(); ok {
			header = api.chain.GetHeaderByHash(hash)
		} else if number, ok := blockNrOrHash.Number(); ok {
			header = api.chain.GetHeaderByNumber(uint64(number.Int64()))
		}
		if header == nil {
			return common.Address{}, fmt.Errorf("missing block %v", blockNrOrHash.String())
		}
		return api.oasys.Author(header)
	}
	block := new(types.Block)
	if err := rlp.DecodeBytes(rlpOrBlockNr.RLP, block); err == nil {
		return api.oasys.Author(block.Header())
	}
	header := new(types.Header)
	if err := rlp.DecodeBytes(rlpOrBlockNr.RLP, header); err != nil {
		return common.Address{}, err
	}
	return api.oasys.Author(header)
}
