app.go

package main

import (
	"fmt"
	"log"
	"net"
	"os"
	"os/exec"
	"strconv"
	"strings"
	"unicode"

	"github.com/nsf/termbox-go"
)

type App struct {
	ui   *UI
	nav  *Nav
	quit chan bool
}

func newApp() *App {
	ui := newUI()
	nav := newNav(ui.wins[0].h)
	quit := make(chan bool)

	return &App{
		ui:   ui,
		nav:  nav,
		quit: quit,
	}
}

func waitKey() error {
	// TODO: this should be done with termbox somehow

	c := `echo
	      echo -n 'Press any key to continue'
	      old=$(stty -g)
	      stty raw -echo
	      eval "ignore=\$(dd bs=1 count=1 2> /dev/null)"
	      stty $old
	      echo`

	cmd := exec.Command(gOpts.shell, "-c", c)

	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	if err := cmd.Run(); err != nil {
		return fmt.Errorf("waiting key: %s", err)
	}

	return nil
}

// This function is used to read expressions on the client side. Prompting
// commands (e.g. "read") are recognized and evaluated while being read here.
// Digits are interpreted as command counts but this is only done for digits
// preceding any non-digit characters (e.g. "42y2k" as 42 times "y2k").
func (app *App) readExpr() chan MultiExpr {
	ch := make(chan MultiExpr)

	renew := &CallExpr{"renew", nil}
	count := 1

	var acc []rune
	var cnt []rune

	go func() {
		for {
			switch ev := app.ui.pollEvent(); ev.Type {
			case termbox.EventKey:
				if ev.Ch != 0 {
					switch {
					case ev.Ch == '<':
						acc = append(acc, '<', 'l', 't', '>')
					case ev.Ch == '>':
						acc = append(acc, '<', 'g', 't', '>')
					case unicode.IsDigit(ev.Ch) && len(acc) == 0:
						cnt = append(cnt, ev.Ch)
					default:
						acc = append(acc, ev.Ch)
					}
				} else {
					val := gKeyVal[ev.Key]
					if string(val) == "<esc>" {
						ch <- MultiExpr{renew, 1}
						acc = nil
						cnt = nil
					}
					acc = append(acc, val...)
				}

				binds, ok := findBinds(gOpts.keys, string(acc))

				switch len(binds) {
				case 0:
					app.ui.message = fmt.Sprintf("unknown mapping: %s", string(acc))
					ch <- MultiExpr{renew, 1}
					acc = nil
					cnt = nil
				case 1:
					if ok {
						if len(cnt) > 0 {
							c, err := strconv.Atoi(string(cnt))
							if err != nil {
								log.Printf("converting command count: %s", err)
							}
							count = c
						} else {
							count = 1
						}
						expr := gOpts.keys[string(acc)]
						switch expr.(type) {
						case *CallExpr:
							switch expr.(*CallExpr).name {
							case "read",
								"read-shell",
								"read-shell-wait",
								"read-shell-async",
								"push":
								expr.eval(app, nil)
								app.ui.draw(app.nav)
							default:
								ch <- MultiExpr{expr, count}
							}
						default:
							ch <- MultiExpr{expr, count}
						}
						acc = nil
						cnt = nil
					}
					if len(acc) > 0 {
						app.ui.listBinds(binds)
					}
				default:
					if ok {
						// TODO: use a delay
						if len(cnt) > 0 {
							c, err := strconv.Atoi(string(cnt))
							if err != nil {
								log.Printf("converting command count: %s", err)
							}
							count = c
						} else {
							count = 1
						}
						expr := gOpts.keys[string(acc)]
						switch expr.(type) {
						case *CallExpr:
							switch expr.(*CallExpr).name {
							case "read",
								"read-shell",
								"read-shell-wait",
								"read-shell-async",
								"push":
								expr.eval(app, nil)
								app.ui.draw(app.nav)
							default:
								ch <- MultiExpr{expr, count}
							}
						default:
							ch <- MultiExpr{expr, count}
						}
						acc = nil
						cnt = nil
					}
					if len(acc) > 0 {
						app.ui.listBinds(binds)
					}
				}
			case termbox.EventResize:
				ch <- MultiExpr{renew, 1}
			default:
				// TODO: handle other events
			}
		}
	}()

	return ch
}

// This is the main event loop of the application. There are two channels to
// read expressions from client and server. Reading and evaluation are done on
// different goroutines except for prompting commands (e.g. "read"). Quitting
// commands should create separate goroutines to prevent deadlock here.
func (app *App) handleInp() {
	clientChan := app.readExpr()

	var serverChan chan Expr

	c, err := net.Dial("unix", gSocketPath)
	if err != nil {
		msg := fmt.Sprintf("connecting server: %s", err)
		app.ui.message = msg
		log.Printf(msg)
	} else {
		serverChan = readExpr(c)
	}

	for {
		select {
		case <-app.quit:
			log.Print("bye!")

			if gLastDirPath != "" {
				f, err := os.Create(gLastDirPath)
				if err != nil {
					log.Printf("opening last dir file: %s", err)
				}
				defer f.Close()

				dir := app.nav.currDir()

				_, err = f.WriteString(dir.path)
				if err != nil {
					log.Printf("writing last dir file: %s", err)
				}
			}

			return
		case e := <-clientChan:
			for i := 0; i < e.count; i++ {
				e.expr.eval(app, nil)
			}
			app.ui.draw(app.nav)
		case e := <-serverChan:
			e.eval(app, nil)
			app.ui.draw(app.nav)
		}
	}
}

func (app *App) exportVars() {
	var envFile string
	if f, err := app.nav.currFile(); err == nil {
		envFile = f.Path
	}

	marks := app.nav.currMarks()

	envFiles := strings.Join(marks, ":")

	os.Setenv("f", envFile)
	os.Setenv("fs", envFiles)

	if len(marks) == 0 {
		os.Setenv("fx", envFile)
	} else {
		os.Setenv("fx", envFiles)
	}

	os.Setenv("id", strconv.Itoa(gClientId))
}

// This function is used to run a command in shell. Following modes are used:
//
// Prefix  Wait  Async  Stdin/Stdout/Stderr  UI action
// $       No    No     Yes                  Pause and then resume
// !       Yes   No     Yes                  Pause and then resume
// &       No    Yes    No                   Do nothing
//
// Waiting async commands are not used for now.
func (app *App) runShell(s string, args []string, wait bool, async bool) {
	app.exportVars()

	if len(gOpts.ifs) != 0 {
		s = fmt.Sprintf("IFS='%s'; %s", gOpts.ifs, s)
	}

	args = append([]string{"-c", s, "--"}, args...)
	cmd := exec.Command(gOpts.shell, args...)

	if !async {
		cmd.Stdin = os.Stdin
		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr

		app.ui.pause()
		defer app.ui.resume()
		defer app.nav.renew(app.ui.wins[0].h)
	}

	var err error
	if async {
		err = cmd.Start()
	} else {
		err = cmd.Run()
	}

	if err != nil {
		msg := fmt.Sprintf("running shell: %s", err)
		app.ui.message = msg
		log.Print(msg)
	}

	if wait {
		if err := waitKey(); err != nil {
			msg := fmt.Sprintf("waiting shell: %s", err)
			app.ui.message = msg
			log.Print(msg)
		}
	}
}