package main

// A note on the origin of the name.
// http://en.wikipedia.org/wiki/Barak
// TODO: Nonrepudiable command log

import (
	"errors"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"os"
	"reflect"
	"sync"
	"time"

	"github.com/tendermint/tendermint/binary"
	. "github.com/tendermint/tendermint/cmd/barak/types"
	. "github.com/tendermint/tendermint/common"
	pcm "github.com/tendermint/tendermint/process"
	"github.com/tendermint/tendermint/rpc"
)

var Routes = map[string]*rpc.RPCFunc{
	"status": rpc.NewRPCFunc(Status, []string{}),
	"run":    rpc.NewRPCFunc(Run, []string{"auth_command"}),
	// NOTE: also, two special non-JSONRPC routes called "download" and "upload"
}

type Options struct {
	Validators    []Validator
	ListenAddress string
	StartNonce    uint64
	Registries    []string
}

// Global instance
var barak = struct {
	mtx        sync.Mutex
	pid        int
	nonce      uint64
	processes  map[string]*pcm.Process
	validators []Validator
	rootDir    string
	registries []string
}{
	mtx:        sync.Mutex{},
	pid:        os.Getpid(),
	nonce:      0,
	processes:  make(map[string]*pcm.Process),
	validators: nil,
	rootDir:    "",
	registries: nil,
}

func main() {
	fmt.Printf("New Barak Process (PID: %d)\n", os.Getpid())

	// read flags to change options file.
	var optionsBytes []byte
	var optionsFile string
	var err error
	flag.StringVar(&optionsFile, "options-file", "", "Read options from file instead of stdin")
	flag.Parse()
	if optionsFile != "" {
		optionsBytes, err = ioutil.ReadFile(optionsFile)
	} else {
		optionsBytes, err = ioutil.ReadAll(os.Stdin)
	}
	if err != nil {
		panic(Fmt("Error reading input: %v", err))
	}
	options := binary.ReadJSON(&Options{}, optionsBytes, &err).(*Options)
	if err != nil {
		panic(Fmt("Error parsing input: %v", err))
	}
	barak.nonce = options.StartNonce
	barak.validators = options.Validators
	barak.rootDir = os.Getenv("BRKROOT")
	if barak.rootDir == "" {
		barak.rootDir = os.Getenv("HOME") + "/.barak"
	}
	err = EnsureDir(barak.rootDir)
	if err != nil {
		panic(Fmt("Error creating barak rootDir: %v", err))
	}
	barak.registries = options.Registries

	// Write pid to file.
	err = AtomicWriteFile(barak.rootDir+"/pidfile", []byte(Fmt("%v", barak.pid)))
	if err != nil {
		panic(Fmt("Error writing pidfile: %v", err))
	}

	// Debug.
	fmt.Printf("Options: %v\n", options)
	fmt.Printf("Barak: %v\n", barak)

	// Start rpc server.
	mux := http.NewServeMux()
	mux.HandleFunc("/download", ServeFile)
	mux.HandleFunc("/register", Register)
	// TODO: mux.HandleFunc("/upload", UploadFile)
	rpc.RegisterRPCFuncs(mux, Routes)
	rpc.StartHTTPServer(options.ListenAddress, mux)

	// Register this barak with central listener
	for _, registry := range barak.registries {
		go func(registry string) {
			resp, err := http.Get(registry + "/register")
			if err != nil {
				fmt.Printf("Error registering to registry %v:\n  %v\n", registry, err)
				return
			}
			body, _ := ioutil.ReadAll(resp.Body)
			fmt.Printf("Successfully registered with registry %v\n  %v\n", registry, string(body))
		}(registry)
	}

	TrapSignal(func() {
		fmt.Println("Barak shutting down")
	})
}

//------------------------------------------------------------------------------
// RPC functions

func Status() (*ResponseStatus, error) {
	barak.mtx.Lock()
	pid := barak.pid
	nonce := barak.nonce
	validators := barak.validators
	barak.mtx.Unlock()

	return &ResponseStatus{
		Pid:        pid,
		Nonce:      nonce,
		Validators: validators,
	}, nil
}

func Run(authCommand AuthCommand) (interface{}, error) {
	command, err := parseValidateCommand(authCommand)
	if err != nil {
		return nil, err
	}
	log.Info(Fmt("Run() received command %v:\n%v", reflect.TypeOf(command), command))
	// Issue command
	switch c := command.(type) {
	case CommandRunProcess:
		return RunProcess(c.Wait, c.Label, c.ExecPath, c.Args, c.Input)
	case CommandStopProcess:
		return StopProcess(c.Label, c.Kill)
	case CommandListProcesses:
		return ListProcesses()
	default:
		return nil, errors.New("Invalid endpoint for command")
	}
}

func parseValidateCommandStr(authCommandStr string) (Command, error) {
	var err error
	authCommand := binary.ReadJSON(AuthCommand{}, []byte(authCommandStr), &err).(AuthCommand)
	if err != nil {
		fmt.Printf("Failed to parse auth_command")
		return nil, errors.New("AuthCommand parse error")
	}
	return parseValidateCommand(authCommand)
}

func parseValidateCommand(authCommand AuthCommand) (Command, error) {
	commandJSONStr := authCommand.CommandJSONStr
	signatures := authCommand.Signatures
	// Validate commandJSONStr
	if !validate([]byte(commandJSONStr), barak.validators, signatures) {
		fmt.Printf("Failed validation attempt")
		return nil, errors.New("Validation error")
	}
	// Parse command
	var err error
	command := binary.ReadJSON(NoncedCommand{}, []byte(commandJSONStr), &err).(NoncedCommand)
	if err != nil {
		fmt.Printf("Failed to parse command")
		return nil, errors.New("Command parse error")
	}
	// Prevent replays
	if barak.nonce+1 != command.Nonce {
		return nil, errors.New("Replay error")
	} else {
		barak.nonce += 1
	}
	return command.Command, nil
}

//------------------------------------------------------------------------------
// RPC base commands
// WARNING Not validated, do not export to routes.

func RunProcess(wait bool, label string, execPath string, args []string, input string) (*ResponseRunProcess, error) {
	barak.mtx.Lock()

	// First, see if there already is a process labeled 'label'
	existing := barak.processes[label]
	if existing != nil && existing.EndTime.IsZero() {
		barak.mtx.Unlock()
		return nil, fmt.Errorf("Process already exists: %v", label)
	}

	// Otherwise, create one.
	err := EnsureDir(barak.rootDir + "/outputs")
	if err != nil {
		return nil, fmt.Errorf("Failed to create outputs dir: %v", err)
	}
	outPath := Fmt("%v/outputs/%v_%v.out", barak.rootDir, label, time.Now().Format("2006_01_02_15_04_05_MST"))
	proc, err := pcm.Create(pcm.ProcessModeDaemon, label, execPath, args, input, outPath)
	if err == nil {
		barak.processes[label] = proc
	}
	barak.mtx.Unlock()
	if err != nil {
		return nil, err
	}

	if wait {
		<-proc.WaitCh
		output := pcm.ReadOutput(proc)
		fmt.Println("Read output", output)
		if proc.ExitState == nil {
			return &ResponseRunProcess{
				Success: true,
				Output:  output,
			}, nil
		} else {
			return &ResponseRunProcess{
				Success: proc.ExitState.Success(), // Would be always false?
				Output:  output,
			}, nil
		}
	} else {
		return &ResponseRunProcess{
			Success: true,
			Output:  "",
		}, nil
	}
}

func StopProcess(label string, kill bool) (*ResponseStopProcess, error) {
	barak.mtx.Lock()
	proc := barak.processes[label]
	barak.mtx.Unlock()

	if proc == nil {
		return nil, fmt.Errorf("Process does not exist: %v", label)
	}

	err := pcm.Stop(proc, kill)
	return &ResponseStopProcess{}, err
}

func ListProcesses() (*ResponseListProcesses, error) {
	var procs = []*pcm.Process{}
	barak.mtx.Lock()
	fmt.Println("Processes: %v", barak.processes)
	for _, proc := range barak.processes {
		procs = append(procs, proc)
	}
	barak.mtx.Unlock()

	return &ResponseListProcesses{
		Processes: procs,
	}, nil
}

// Another barak instance registering its external
// address to a remote barak.
func Register(w http.ResponseWriter, req *http.Request) {
	registry, err := os.OpenFile(barak.rootDir+"/registry.log", os.O_RDWR|os.O_APPEND, 0x600)
	if err != nil {
		http.Error(w, "Could not open registry file. Please contact the administrator", 500)
		return
	}
	// TODO: Also check the X-FORWARDED-FOR or whatever it's called.
	registry.Write([]byte(Fmt("++ %v\n", req.RemoteAddr)))
	registry.Close()
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(200)
	w.Write([]byte("Noted!"))
}

func ServeFile(w http.ResponseWriter, req *http.Request) {
	authCommandStr := req.FormValue("auth_command")
	command, err := parseValidateCommandStr(authCommandStr)
	if err != nil {
		http.Error(w, Fmt("Invalid command: %v", err), 400)
	}
	serveCommand, ok := command.(CommandServeFile)
	if !ok {
		http.Error(w, "Invalid command", 400)
	}
	path := serveCommand.Path
	if path == "" {
		http.Error(w, "Must specify path", 400)
		return
	}
	file, err := os.Open(path)
	if err != nil {
		http.Error(w, Fmt("Error opening file: %v. %v", path, err), 400)
		return
	}
	_, err = io.Copy(w, file)
	if err != nil {
		fmt.Fprintf(os.Stderr, Fmt("Error serving file: %v. %v", path, err))
		return
	}
}