package apiv1

import (
	"context"
	"math/big"

	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/harmony-one/harmony/api/proto"
	nodeconfig "github.com/harmony-one/harmony/internal/configs/node"
	"github.com/harmony-one/harmony/internal/params"
	"github.com/harmony-one/harmony/shard"
)

// PublicHarmonyAPI provides an API to access Harmony related information.
// It offers only methods that operate on public data that is freely available to anyone.
type PublicHarmonyAPI struct {
	b Backend
}

// NewPublicHarmonyAPI ...
func NewPublicHarmonyAPI(b Backend) *PublicHarmonyAPI {
	return &PublicHarmonyAPI{b}
}

// ProtocolVersion returns the current Harmony protocol version this node supports
func (s *PublicHarmonyAPI) ProtocolVersion() hexutil.Uint {
	return hexutil.Uint(proto.ProtocolVersion)
}

// Syncing returns false in case the node is currently not syncing with the network. It can be up to date or has not
// yet received the latest block headers from its pears. In case it is synchronizing:
// - startingBlock: block number this node started to synchronise from
// - currentBlock:  block number this node is currently importing
// - highestBlock:  block number of the highest block header this node has received from peers
// - pulledStates:  number of state entries processed until now
// - knownStates:   number of known state entries that still need to be pulled
func (s *PublicHarmonyAPI) Syncing() (interface{}, error) {
	// TODO(ricl): find our Downloader module for syncing blocks
	return false, nil
}

// GasPrice returns a suggestion for a gas price.
func (s *PublicHarmonyAPI) GasPrice(ctx context.Context) (*hexutil.Big, error) {
	// TODO(ricl): add SuggestPrice API
	return (*hexutil.Big)(big.NewInt(1)), nil
}

// NodeMetadata captures select metadata of the RPC answering node
type NodeMetadata struct {
	BLSPublicKey   string             `json:"blskey"`
	Version        string             `json:"version"`
	NetworkType    string             `json:"network"`
	ChainConfig    params.ChainConfig `json:"chain-config"`
	IsLeader       bool               `json:"is-leader"`
	ShardID        uint32             `json:"shard-id"`
	CurrentEpoch   uint64             `json:"current-epoch"`
	BlocksPerEpoch *uint64            `json:"blocks-per-epoch,omitempty"`
	Role           string             `json:"role"`
	DNSZone        string             `json:"dns-zone"`
}

// GetNodeMetadata produces a NodeMetadata record, data is from the answering RPC node
func (s *PublicHarmonyAPI) GetNodeMetadata() NodeMetadata {
	cfg := nodeconfig.GetDefaultConfig()
	header := s.b.CurrentBlock().Header()
	var blockEpoch *uint64

	if header.ShardID() == shard.BeaconChainShardID {
		sched := shard.Schedule.InstanceForEpoch(header.Epoch())
		b := sched.BlocksPerEpoch()
		blockEpoch = &b
	}

	return NodeMetadata{
		cfg.ConsensusPubKey.SerializeToHexStr(),
		nodeconfig.GetVersion(),
		string(cfg.GetNetworkType()),
		*s.b.ChainConfig(),
		s.b.IsLeader(),
		s.b.GetShardID(),
		header.Epoch().Uint64(),
		blockEpoch,
		cfg.Role().String(),
		cfg.DNSZone,
	}
}