package jail

import (
	"encoding/json"
	"errors"
	"fmt"
	"sync"

	"github.com/robertkrimen/otto"
	"github.com/status-im/status-go/geth/common"
	"github.com/status-im/status-go/geth/jail/internal/vm"
	"github.com/status-im/status-go/geth/log"
	"github.com/status-im/status-go/static"
)

var (
	// FIXME(tiabc): Get rid of this global variable. Move it to a constructor or initialization.
	web3JSCode = static.MustAsset("scripts/web3.js")

	//ErrInvalidJail - error jail init env
	ErrInvalidJail = errors.New("jail environment is not properly initialized")
)

// Jail represents jailed environment inside of which we hold multiple cells.
// Each cell is a separate JavaScript VM.
type Jail struct {
	nodeManager common.NodeManager
	baseJSCode  string // JavaScript used to initialize all new cells with

	cellsMx sync.RWMutex
	cells   map[string]*Cell // jail supports running many isolated instances of jailed runtime

	vm *vm.VM // vm for internal otto related tasks (see Send method)
}

// New returns new Jail environment with the associated NodeManager.
// It's caller responsibility to call jail.Stop() when jail is not needed.
func New(nodeManager common.NodeManager) *Jail {
	return &Jail{
		nodeManager: nodeManager,
		cells:       make(map[string]*Cell),
		vm:          vm.New(otto.New()),
	}
}

// BaseJS allows to setup initial JavaScript to be loaded on each jail.Parse().
func (jail *Jail) BaseJS(js string) {
	jail.baseJSCode = js
}

// NewCell initializes and returns a new jail cell.
func (jail *Jail) NewCell(chatID string) (common.JailCell, error) {
	if jail == nil {
		return nil, ErrInvalidJail
	}

	cellVM := otto.New()

	cell, err := newCell(chatID, cellVM)
	if err != nil {
		return nil, err
	}

	jail.cellsMx.Lock()
	jail.cells[chatID] = cell
	jail.cellsMx.Unlock()

	return cell, nil
}

// Stop stops jail and all assosiacted cells.
func (jail *Jail) Stop() {
	jail.cellsMx.Lock()
	defer jail.cellsMx.Unlock()

	for _, cell := range jail.cells {
		cell.Stop()
	}
	// TODO(tiabc): Move this initialisation to a proper place.
	jail.cells = make(map[string]*Cell)
}

// Cell returns the existing instance of Cell.
func (jail *Jail) Cell(chatID string) (common.JailCell, error) {
	jail.cellsMx.RLock()
	defer jail.cellsMx.RUnlock()

	cell, ok := jail.cells[chatID]
	if !ok {
		return nil, fmt.Errorf("cell[%s] doesn't exist", chatID)
	}

	return cell, nil
}

// Parse creates a new jail cell context, with the given chatID as identifier.
// New context executes provided JavaScript code, right after the initialization.
func (jail *Jail) Parse(chatID, js string) string {
	if jail == nil {
		return makeError(ErrInvalidJail.Error())
	}

	cell, err := jail.Cell(chatID)
	if err != nil {
		if _, mkerr := jail.NewCell(chatID); mkerr != nil {
			return makeError(mkerr.Error())
		}

		cell, _ = jail.Cell(chatID)
	}

	// init jeth and its handlers
	if err = cell.Set("jeth", struct{}{}); err != nil {
		return makeError(err.Error())
	}

	if err = registerHandlers(jail, cell, chatID); err != nil {
		return makeError(err.Error())
	}

	initJs := jail.baseJSCode + ";"
	if _, err = cell.Run(initJs); err != nil {
		return makeError(err.Error())
	}

	jjs := string(web3JSCode) + `
	var Web3 = require('web3');
	var web3 = new Web3(jeth);
	var Bignumber = require("bignumber.js");
        function bn(val){
            return new Bignumber(val);
        }
	` + js + "; var catalog = JSON.stringify(_status_catalog);"
	if _, err = cell.Run(jjs); err != nil {
		return makeError(err.Error())
	}

	res, err := cell.Get("catalog")
	if err != nil {
		return makeError(err.Error())
	}

	return makeResult(res.String(), err)
}

// Call executes the `call` function w/i a jail cell context identified by the chatID.
func (jail *Jail) Call(chatID, this, args string) string {
	cell, err := jail.Cell(chatID)
	if err != nil {
		return makeError(err.Error())
	}

	res, err := cell.Call("call", nil, this, args)

	return makeResult(res.String(), err)
}

// Send is a wrapper for executing RPC calls from within Otto VM.
// It uses own jail's VM instance instead of cell's one to
// increase safety of cell's vm usage.
// TODO(divan): investigate if it's possible to do conversions
// withouth involving otto code at all.
// nolint: errcheck, unparam
func (jail *Jail) Send(call otto.FunctionCall) otto.Value {
	request, err := jail.vm.Call("JSON.stringify", nil, call.Argument(0))
	if err != nil {
		throwJSException(err)
	}

	rpc := jail.nodeManager.RPCClient()
	// TODO(divan): remove this check as soon as jail cells have
	// proper cancellation mechanism implemented.
	if rpc == nil {
		throwJSException(fmt.Errorf("Error getting RPC client. Node stopped?"))
	}
	response := rpc.CallRaw(request.String())

	// unmarshal response to pass to otto
	var resp interface{}
	err = json.Unmarshal([]byte(response), &resp)
	if err != nil {
		throwJSException(fmt.Errorf("Error unmarshalling result: %s", err))
	}
	respValue, err := jail.vm.ToValue(resp)
	if err != nil {
		throwJSException(fmt.Errorf("Error converting result to Otto's value: %s", err))
	}

	return respValue
}

func newErrorResponse(msg string, id interface{}) map[string]interface{} {
	// Bundle the error into a JSON RPC call response
	return map[string]interface{}{
		"jsonrpc": "2.0",
		"id":      id,
		"error": map[string]interface{}{
			"code":    -32603, // Internal JSON-RPC Error, see http://www.jsonrpc.org/specification#error_object
			"message": msg,
		},
	}
}

func newErrorResponseOtto(vm *vm.VM, msg string, id interface{}) otto.Value {
	// TODO(tiabc): Handle errors.
	errResp, _ := json.Marshal(newErrorResponse(msg, id))
	errRespVal, _ := vm.Run("(" + string(errResp) + ")")
	return errRespVal
}

func newResultResponse(vm *otto.Otto, result interface{}) otto.Value {
	resp, _ := vm.Object(`({"jsonrpc":"2.0"})`)
	resp.Set("result", result) // nolint: errcheck

	return resp.Value()
}

// throwJSException panics on an otto.Value. The Otto VM will recover from the
// Go panic and throw msg as a JavaScript error.
// nolint: unparam
func throwJSException(msg error) otto.Value {
	val, err := otto.ToValue(msg.Error())
	if err != nil {
		log.Error(fmt.Sprintf("Failed to serialize JavaScript exception %v: %v", msg.Error(), err))
	}
	panic(val)
}

// JSONError is wrapper around errors, that are sent upwards
type JSONError struct {
	Error string `json:"error"`
}

func makeError(error string) string {
	str := JSONError{
		Error: error,
	}
	outBytes, _ := json.Marshal(&str)
	return string(outBytes)
}

func makeResult(res string, err error) string {
	var out string
	if err != nil {
		out = makeError(err.Error())
	} else {
		if "undefined" == res {
			res = "null"
		}
		out = fmt.Sprintf(`{"result": %s}`, res)
	}

	return out
}