package main

import (
	"bytes"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"local/pt-todo-server/pttodo"
	"os"
	"os/exec"
	"path"
	"syscall"

	"gopkg.in/yaml.v2"
)

func main() {
	if err := _main(); err != nil {
		panic(err)
	}
}

func _main() error {
	filepath := flag.String("f", "-", "path to yaml file")
	e := flag.Bool("e", false, "edit file")
	flag.Parse()
	if *e {
		if err := edit(*filepath); err != nil {
			return err
		}
	}
	return dump(os.Stdout, *filepath)
}

func edit(filepath string) error {
	var tempFile string
	cp := func() error {
		f, err := ioutil.TempFile(os.TempDir(), path.Base(filepath))
		if err != nil {
			return err
		}
		g, err := os.Open(filepath)
		if err != nil {
			return err
		}
		if _, err := io.Copy(f, g); err != nil {
			return err
		}
		g.Close()
		f.Close()
		tempFile = f.Name()
		return nil
	}
	vi := func() error {
		vibin, err := exec.LookPath("vi")
		if err != nil {
			return err
		}
		cpid, err := syscall.ForkExec(
			vibin,
			[]string{vibin, tempFile},
			&syscall.ProcAttr{
				Dir:   "",
				Env:   os.Environ(),
				Files: []uintptr{os.Stdin.Fd(), os.Stdout.Fd(), os.Stderr.Fd()},
				Sys:   nil,
			},
		)
		if err != nil {
			return err
		}
		proc, err := os.FindProcess(cpid)
		if err != nil {
			return err
		}
		state, err := proc.Wait()
		if err != nil {
			return err
		}
		if exitCode := state.ExitCode(); exitCode != 0 {
			return fmt.Errorf("bad exit code on vim: %d, state: %+v", exitCode, state)
		}
		return nil
	}
	verify := func() error {
		return dump(io.Discard, tempFile)
	}
	save := func() error {
		return os.Rename(tempFile, filepath)
	}

	for _, foo := range []func() error{cp, vi, verify, save} {
		if err := foo(); err != nil {
			if tempFile != "" {
				os.Remove(tempFile)
			}
			return err
		}
	}

	return nil
}

func dump(writer io.Writer, filepath string) error {
	var reader io.Reader
	if filepath == "-" {
		reader = os.Stdin
	} else {
		b, err := ioutil.ReadFile(filepath)
		if err != nil {
			return err
		}
		reader = bytes.NewReader(b)
	}

	b, err := ioutil.ReadAll(reader)
	if err != nil {
		return err
	}

	var root pttodo.Root
	if err := yaml.Unmarshal(b, &root); err != nil {
		return err
	}
	root.MoveScheduledToTodo()

	b2, err := yaml.Marshal(root)
	if err != nil {
		return err
	}
	fmt.Fprintf(writer, "%s\n", b2)
	return nil
}