/*
For each request type, define the following:

1. RpcRequest "To" method [message.go], which does basic validation and conversion to "Args" type via json.Decoder()
2. json.Decoder() calls "UnmarshalON" defined on each "Args" struct
3. EthereumApi method, taking the "Args" type and replying with an interface to be marshalled to ON

*/
package rpc

import (
	"fmt"
	"math/big"
	"strings"
	"sync"

	"github.com/ethereum/go-ethereum/core"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/ethereum/go-ethereum/ethutil"
	"github.com/ethereum/go-ethereum/event/filter"
	"github.com/ethereum/go-ethereum/state"
	"github.com/ethereum/go-ethereum/xeth"
)

const (
	defaultGasPrice = "10000000000000"
	defaultGas      = "10000"
)

type EthereumApi struct {
	xeth          *xeth.XEth
	filterManager *filter.FilterManager

	logMut sync.RWMutex
	logs   map[int]state.Logs

	messagesMut sync.RWMutex
	messages    map[int][]xeth.WhisperMessage
	// Register keeps a list of accounts and transaction data
	regmut   sync.Mutex
	register map[string][]*NewTxArgs

	db ethutil.Database
}

func NewEthereumApi(eth *xeth.XEth) *EthereumApi {
	db, _ := ethdb.NewLDBDatabase("dapps")
	api := &EthereumApi{
		xeth:          eth,
		filterManager: filter.NewFilterManager(eth.Backend().EventMux()),
		logs:          make(map[int]state.Logs),
		messages:      make(map[int][]xeth.WhisperMessage),
		db:            db,
	}
	go api.filterManager.Start()

	return api
}

func (self *EthereumApi) Register(args string, reply *interface{}) error {
	self.regmut.Lock()
	defer self.regmut.Unlock()

	if _, ok := self.register[args]; ok {
		self.register[args] = nil // register with empty
	}
	return nil
}

func (self *EthereumApi) Unregister(args string, reply *interface{}) error {
	self.regmut.Lock()
	defer self.regmut.Unlock()

	delete(self.register, args)

	return nil
}

func (self *EthereumApi) WatchTx(args string, reply *interface{}) error {
	self.regmut.Lock()
	defer self.regmut.Unlock()

	txs := self.register[args]
	self.register[args] = nil

	*reply = txs
	return nil
}

func (self *EthereumApi) NewFilter(args *FilterOptions, reply *interface{}) error {
	var id int
	filter := core.NewFilter(self.xeth.Backend())
	filter.SetOptions(toFilterOptions(args))
	filter.LogsCallback = func(logs state.Logs) {
		self.logMut.Lock()
		defer self.logMut.Unlock()

		self.logs[id] = append(self.logs[id], logs...)
	}
	id = self.filterManager.InstallFilter(filter)
	*reply = id

	return nil
}

func (self *EthereumApi) UninstallFilter(id int, reply *interface{}) error {
	delete(self.logs, id)
	self.filterManager.UninstallFilter(id)
	*reply = true
	return nil
}

func (self *EthereumApi) NewFilterString(args string, reply *interface{}) error {
	var id int
	filter := core.NewFilter(self.xeth.Backend())

	callback := func(block *types.Block) {
		self.logMut.Lock()
		defer self.logMut.Unlock()

		self.logs[id] = append(self.logs[id], &state.StateLog{})
	}
	if args == "pending" {
		filter.PendingCallback = callback
	} else if args == "chain" {
		filter.BlockCallback = callback
	}

	id = self.filterManager.InstallFilter(filter)
	*reply = id

	return nil
}

func (self *EthereumApi) FilterChanged(id int, reply *interface{}) error {
	self.logMut.Lock()
	defer self.logMut.Unlock()

	*reply = toLogs(self.logs[id])

	self.logs[id] = nil // empty the logs

	return nil
}

func (self *EthereumApi) Logs(id int, reply *interface{}) error {
	self.logMut.Lock()
	defer self.logMut.Unlock()

	filter := self.filterManager.GetFilter(id)
	if filter != nil {
		*reply = toLogs(filter.Find())
	}

	return nil
}

func (p *EthereumApi) GetBlock(args *GetBlockArgs, reply *interface{}) error {
	err := args.requirements()
	if err != nil {
		return err
	}

	if args.BlockNumber > 0 {
		*reply = p.xeth.BlockByNumber(args.BlockNumber)
	} else {
		*reply = p.xeth.BlockByHash(args.Hash)
	}
	return nil
}

func (p *EthereumApi) Transact(args *NewTxArgs, reply *interface{}) error {
	if len(args.Gas) == 0 {
		args.Gas = defaultGas
	}

	if len(args.GasPrice) == 0 {
		args.GasPrice = defaultGasPrice
	}

	// TODO if no_private_key then
	if _, exists := p.register[args.From]; exists {
		p.register[args.From] = append(p.register[args.From], args)
	} else {
		result, _ := p.xeth.Transact( /* TODO specify account */ args.To, args.Value, args.Gas, args.GasPrice, args.Data)
		*reply = result
	}
	return nil
}

func (p *EthereumApi) Call(args *NewTxArgs, reply *interface{}) error {
	result, err := p.xeth.Call( /* TODO specify account */ args.To, args.Value, args.Gas, args.GasPrice, args.Data)
	if err != nil {
		return err
	}

	*reply = result
	return nil
}

func (p *EthereumApi) PushTx(args *PushTxArgs, reply *interface{}) error {
	err := args.requirementsPushTx()
	if err != nil {
		return err
	}
	result, _ := p.xeth.PushTx(args.Tx)
	*reply = result
	return nil
}

func (p *EthereumApi) GetStateAt(args *GetStateArgs, reply *interface{}) error {
	err := args.requirements()
	if err != nil {
		return err
	}

	state := p.xeth.State().SafeGet(args.Address)

	value := state.StorageString(args.Key)
	var hx string
	if strings.Index(args.Key, "0x") == 0 {
		hx = string([]byte(args.Key)[2:])
	} else {
		// Convert the incoming string (which is a bigint) into hex
		i, _ := new(big.Int).SetString(args.Key, 10)
		hx = ethutil.Bytes2Hex(i.Bytes())
	}
	rpclogger.Debugf("GetStateAt(%s, %s)\n", args.Address, hx)
	*reply = map[string]string{args.Key: value.Str()}
	return nil
}

func (p *EthereumApi) GetStorageAt(args *GetStorageArgs, reply *interface{}) error {
	err := args.requirements()
	if err != nil {
		return err
	}

	*reply = p.xeth.State().SafeGet(args.Address).Storage()
	return nil
}

func (p *EthereumApi) GetPeerCount(reply *interface{}) error {
	*reply = p.xeth.PeerCount()
	return nil
}

func (p *EthereumApi) GetIsListening(reply *interface{}) error {
	*reply = p.xeth.IsListening()
	return nil
}

func (p *EthereumApi) GetCoinbase(reply *interface{}) error {
	*reply = p.xeth.Coinbase()
	return nil
}

func (p *EthereumApi) Accounts(reply *interface{}) error {
	*reply = p.xeth.Accounts()
	return nil
}

func (p *EthereumApi) GetIsMining(reply *interface{}) error {
	*reply = p.xeth.IsMining()
	return nil
}

func (p *EthereumApi) BlockNumber(reply *interface{}) error {
	*reply = p.xeth.Backend().ChainManager().CurrentBlock().Number()
	return nil
}

func (p *EthereumApi) GetTxCountAt(args *GetTxCountArgs, reply *interface{}) error {
	err := args.requirements()
	if err != nil {
		return err
	}
	*reply = p.xeth.TxCountAt(args.Address)
	return nil
}

func (p *EthereumApi) GetBalanceAt(args *GetBalanceArgs, reply *interface{}) error {
	err := args.requirements()
	if err != nil {
		return err
	}
	state := p.xeth.State().SafeGet(args.Address)
	*reply = toHex(state.Balance().Bytes())
	return nil
}

func (p *EthereumApi) GetCodeAt(args *GetCodeAtArgs, reply *interface{}) error {
	err := args.requirements()
	if err != nil {
		return err
	}
	*reply = p.xeth.CodeAt(args.Address)
	return nil
}

func (p *EthereumApi) Sha3(args *Sha3Args, reply *interface{}) error {
	*reply = toHex(crypto.Sha3(fromHex(args.Data)))
	return nil
}

func (p *EthereumApi) DbPut(args *DbArgs, reply *interface{}) error {
	err := args.requirements()
	if err != nil {
		return err
	}

	p.db.Put([]byte(args.Database+args.Key), []byte(args.Value))
	*reply = true
	return nil
}

func (p *EthereumApi) DbGet(args *DbArgs, reply *interface{}) error {
	err := args.requirements()
	if err != nil {
		return err
	}

	res, _ := p.db.Get([]byte(args.Database + args.Key))
	*reply = string(res)
	return nil
}

func (p *EthereumApi) NewWhisperIdentity(reply *interface{}) error {
	*reply = p.xeth.Whisper().NewIdentity()
	return nil
}

func (p *EthereumApi) NewWhisperFilter(args *xeth.Options, reply *interface{}) error {
	var id int
	args.Fn = func(msg xeth.WhisperMessage) {
		p.messagesMut.Lock()
		defer p.messagesMut.Unlock()
		p.messages[id] = append(p.messages[id], msg)
	}
	id = p.xeth.Whisper().Watch(args)
	*reply = id
	return nil
}

func (self *EthereumApi) MessagesChanged(id int, reply *interface{}) error {
	self.messagesMut.Lock()
	defer self.messagesMut.Unlock()

	*reply = self.messages[id]

	self.messages[id] = nil // empty the messages

	return nil
}

func (p *EthereumApi) WhisperPost(args *WhisperMessageArgs, reply *interface{}) error {
	err := p.xeth.Whisper().Post(args.Payload, args.To, args.From, args.Topics, args.Priority, args.Ttl)
	if err != nil {
		return err
	}

	*reply = true
	return nil
}

func (p *EthereumApi) HasWhisperIdentity(args string, reply *interface{}) error {
	*reply = p.xeth.Whisper().HasIdentity(args)
	return nil
}

func (p *EthereumApi) WhisperMessages(id int, reply *interface{}) error {
	*reply = p.xeth.Whisper().Messages(id)
	return nil
}

func (p *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) error {
	// Spec at https://github.com/ethereum/wiki/wiki/Generic-ON-RPC
	rpclogger.DebugDetailf("%T %s", req.Params, req.Params)
	switch req.Method {
	case "eth_coinbase":
		return p.GetCoinbase(reply)
	case "eth_listening":
		return p.GetIsListening(reply)
	case "eth_mining":
		return p.GetIsMining(reply)
	case "eth_peerCount":
		return p.GetPeerCount(reply)
	case "eth_number":
		return p.BlockNumber(reply)
	case "eth_accounts":
		return p.Accounts(reply)
	case "eth_countAt":
		args, err := req.ToGetTxCountArgs()
		if err != nil {
			return err
		}
		return p.GetTxCountAt(args, reply)
	case "eth_codeAt":
		args, err := req.ToGetCodeAtArgs()
		if err != nil {
			return err
		}
		return p.GetCodeAt(args, reply)
	case "eth_balanceAt":
		args, err := req.ToGetBalanceArgs()
		if err != nil {
			return err
		}
		return p.GetBalanceAt(args, reply)
	case "eth_stateAt":
		args, err := req.ToGetStateArgs()
		if err != nil {
			return err
		}
		return p.GetStateAt(args, reply)
	case "eth_storageAt":
		args, err := req.ToStorageAtArgs()
		if err != nil {
			return err
		}
		return p.GetStorageAt(args, reply)
	case "eth_blockByNumber", "eth_blockByHash":
		args, err := req.ToGetBlockArgs()
		if err != nil {
			return err
		}
		return p.GetBlock(args, reply)
	case "eth_transact":
		args, err := req.ToNewTxArgs()
		if err != nil {
			return err
		}
		return p.Transact(args, reply)
	case "eth_call":
		args, err := req.ToNewTxArgs()
		if err != nil {
			return err
		}
		return p.Call(args, reply)
	case "eth_newFilter":
		args, err := req.ToFilterArgs()
		if err != nil {
			return err
		}
		return p.NewFilter(args, reply)
	case "eth_newFilterString":
		args, err := req.ToFilterStringArgs()
		if err != nil {
			return err
		}
		return p.NewFilterString(args, reply)
	case "eth_uninstallFilter":
		args, err := req.ToUninstallFilterArgs()
		if err != nil {
			return err
		}
		return p.UninstallFilter(args, reply)
	case "eth_changed":
		args, err := req.ToFilterChangedArgs()
		if err != nil {
			return err
		}
		return p.FilterChanged(args, reply)
	case "eth_filterLogs":
		args, err := req.ToFilterChangedArgs()
		if err != nil {
			return err
		}
		return p.Logs(args, reply)
	case "eth_gasPrice":
		*reply = defaultGasPrice
		return nil
	case "eth_register":
		args, err := req.ToRegisterArgs()
		if err != nil {
			return err
		}
		return p.Register(args, reply)
	case "eth_unregister":
		args, err := req.ToRegisterArgs()
		if err != nil {
			return err
		}
		return p.Unregister(args, reply)
	case "eth_watchTx":
		args, err := req.ToWatchTxArgs()
		if err != nil {
			return err
		}
		return p.WatchTx(args, reply)
	case "web3_sha3":
		args, err := req.ToSha3Args()
		if err != nil {
			return err
		}
		return p.Sha3(args, reply)
	case "db_put":
		args, err := req.ToDbPutArgs()
		if err != nil {
			return err
		}
		return p.DbPut(args, reply)
	case "db_get":
		args, err := req.ToDbGetArgs()
		if err != nil {
			return err
		}
		return p.DbGet(args, reply)
	case "shh_newIdentity":
		return p.NewWhisperIdentity(reply)
	case "shh_newFilter":
		args, err := req.ToWhisperFilterArgs()
		if err != nil {
			return err
		}
		return p.NewWhisperFilter(args, reply)
	case "shh_changed":
		args, err := req.ToWhisperIdArgs()
		if err != nil {
			return err
		}
		return p.MessagesChanged(args, reply)
	case "shh_post":
		args, err := req.ToWhisperPostArgs()
		if err != nil {
			return err
		}
		return p.WhisperPost(args, reply)
	case "shh_haveIdentity":
		args, err := req.ToWhisperHasIdentityArgs()
		if err != nil {
			return err
		}
		return p.HasWhisperIdentity(args, reply)
	case "shh_getMessages":
		args, err := req.ToWhisperIdArgs()
		if err != nil {
			return err
		}
		return p.WhisperMessages(args, reply)
	default:
		return NewErrorResponse(fmt.Sprintf("%v %s", ErrorNotImplemented, req.Method))
	}

	rpclogger.DebugDetailf("Reply: %T %s", reply, reply)
	return nil
}