package main

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

	"gopkg.in/yaml.v2"
)

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

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

func edit(dry bool, filepath string) error {
	var tempFile string
	cp := func() error {
		f, err := ioutil.TempFile(os.TempDir(), path.Base(filepath))
		if err != nil {
			return err
		}
		if _, err := os.Stat(filepath); err == nil {
			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 {
		bin := "vim"
		if editor := os.Getenv("EDITOR"); editor != "" {
			bin = editor
		}
		editorbin, err := exec.LookPath(bin)
		if err != nil {
			editorbin, err = exec.LookPath("vi")
		}
		if err != nil {
			return err
		}
		args := []string{editorbin, tempFile}
		vimrc := path.Join(os.Getenv("HOME"), ".vimrc")
		if _, err := os.Stat(vimrc); err == nil {
			args = append(args, "-u", vimrc)
		}
		cpid, err := syscall.ForkExec(
			editorbin,
			args,
			&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 {
		if err := dump(true, io.Discard, tempFile); err != nil {
			return fmt.Errorf("failed to verify %s: %v", tempFile, err)
		}
		return nil
	}
	save := func() error {
		if dry {
			log.Printf("would've saved %s as %s", tempFile, filepath)
			return nil
		}
		return os.Rename(tempFile, filepath)
	}

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

	return nil
}

func dump(dry bool, 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()

	var v interface{} = root
	switch flag.Arg(0) {
	case "":
	case "todo":
		v = root.Todo
	case "scheduled":
		v = root.Scheduled
	case "done":
		v = root.Done
	}
	b2, err := yaml.Marshal(v)
	if err != nil {
		return err
	}
	fmt.Fprintf(writer, "%s\n", b2)

	if dry {
		return nil
	}

	return os.WriteFile(filepath, b2, os.ModePerm)
}