package main

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

	"gopkg.in/yaml.v2"
)

const (
	DUMP_ALL       = "all"
	DUMP_TODO      = "todo"
	DUMP_SCHEDULED = "scheduled"
	DUMP_DONE      = "done"
)

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")
	filepathToMergeIn := flag.String("g", "", "path to yaml file to merge into -f")
	root := flag.String("root", DUMP_TODO, "path to pretty print ("+fmt.Sprint([]string{DUMP_ALL, DUMP_TODO, DUMP_SCHEDULED, DUMP_DONE})+")")
	tags := flag.String("tags", "", "csv of all tags to find, -tag to invert")
	search := flag.String("search", "", "fts case insensitive")
	e := flag.Bool("e", false, "edit file")
	dry := flag.Bool("dry", false, "dry run")
	flag.Parse()
	if *filepathToMergeIn != "" {
		if err := merge(*dry, *filepath, *filepathToMergeIn); err != nil {
			return err
		}
	}
	if *e {
		if err := edit(*dry, *filepath); err != nil {
			return err
		}
	}
	var tagslist []string
	if *tags != "" {
		tagslist = strings.Split(*tags, ",")
	}
	return dump(*dry, os.Stdout, *filepath, tagslist, *search, *root)
}

func verifyRoot(root pttodo.Root) error {
	f, err := ioutil.TempFile(os.TempDir(), "tmp")
	if err != nil {
		return err
	}
	f.Close()
	tempFile := f.Name()
	b, err := yaml.Marshal(root)
	if err != nil {
		return err
	}
	if err := ioutil.WriteFile(tempFile, b, os.ModePerm); err != nil {
		return err
	}
	defer os.Remove(tempFile)
	return verifyFile(tempFile)
}

func verifyFile(path string) error {
	return dump(true, io.Discard, path, nil, "", DUMP_ALL)
}

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() + ".yaml"
		return os.Rename(f.Name(), tempFile)
	}
	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}
		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 {
		return verifyFile(tempFile)
	}
	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 merge(dry bool, filepath string, mergeTargetFilePath string) error {
	baseReader, err := filePathReader(filepath)
	if err != nil {
		return err
	}
	baseB, err := ioutil.ReadAll(baseReader)
	if err != nil {
		return err
	}

	mergingReader, err := filePathReader(mergeTargetFilePath)
	if err != nil {
		return err
	}
	mergingB, err := ioutil.ReadAll(mergingReader)
	if err != nil {
		return err
	}

	var base, merging pttodo.Root
	if err := yaml.Unmarshal(baseB, &base); err != nil {
		return err
	}
	if err := yaml.Unmarshal(mergingB, &merging); err != nil {
		return err
	}

	base.MergeIn(merging)

	if err := verifyRoot(base); err != nil {
		return err
	}
	tmppath, err := marshalRootToTempFile(base)
	if err != nil {
		return err
	}
	if dry {
		log.Printf("would've moved %s to %s when adding %s", tmppath, filepath, mergeTargetFilePath)
		return nil
	}
	return os.Rename(tmppath, filepath)
}

func marshalRootToTempFile(root pttodo.Root) (string, error) {
	f, err := ioutil.TempFile(os.TempDir(), "tmp")
	if err != nil {
		return "", err
	}
	f.Close()
	os.Remove(f.Name())
	b, err := yaml.Marshal(root)
	if err != nil {
		return "", err
	}
	filepath := f.Name() + ".yaml"
	err = ioutil.WriteFile(filepath, b, os.ModePerm)
	return filepath, err
}

func dump(dry bool, writer io.Writer, filepath string, tags []string, search, rootDisplay string) error {
	reader, err := filePathReader(filepath)
	if err != nil {
		return err
	}

	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 rootDisplay {
	case DUMP_ALL:
	case DUMP_TODO:
		v = root.Todo
	case DUMP_SCHEDULED:
		v = root.Scheduled
	case DUMP_DONE:
		v = root.Done
	}
	if todos, ok := v.([]pttodo.Todo); ok {
		if len(tags) > 0 {
			result := make([]pttodo.Todo, 0, len(todos))
			for _, todo := range todos {
				skip := false
				for _, tag := range tags {
					positiveTag := strings.TrimLeft(tag, "-")
					hasTag := strings.Contains(todo.Tags, positiveTag)
					wantToHaveTag := !strings.HasPrefix(tag, "-")
					skip = skip || !(hasTag == wantToHaveTag)
				}
				if !skip {
					result = append(result, todo)
				}
			}
			todos = result
		}
		if len(search) > 0 {
			result := make([]pttodo.Todo, 0, len(todos))
			for _, todo := range todos {
				if strings.Contains(strings.ToLower(fmt.Sprint(todo)), strings.ToLower(search)) {
					result = append(result, todo)
				}
			}
			todos = result
		}
		v = todos
	}
	b2, err := yaml.Marshal(v)
	if err != nil {
		return err
	}
	fmt.Fprintf(writer, "%s\n", b2)

	if dry {
		return nil
	}

	b3, err := yaml.Marshal(root)
	if err != nil {
		return err
	}
	return os.WriteFile(filepath, b3, os.ModePerm)
}

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