package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"os/exec"
	"path"
	"sort"
	"strings"
	"syscall"
	"time"

	"github.com/google/uuid"
	"gogs.inhome.blapointe.com/bel/pttodo/pttodo"
	"gopkg.in/yaml.v2"
)

func edit(config *config) error {
	if !config.edit {
		return nil
	}
	return _edit(func() []string { return config.Targets() })
}

func _edit(filepaths func() []string) error {
	editableDir, err := inEditableDirAsTodos(filepaths())
	if err != nil {
		return err
	}

	if err := modifyEditableDir(editableDir, func() error {
		files, err := listDir(editableDir)
		if err != nil {
			return err
		}
		for _, p := range files {
			if _, err := pttodo.NewTodosFromFile(p); err != nil {
				return err
			}
		}
		return nil
	}); err != nil {
		return err
	}

	editedFiles, err := listDir(editableDir)
	if err != nil {
		return err
	}

	for _, target := range editedFiles {
		r, err := filePathReader(path.Join(editableDir, path.Base(target)))
		if err != nil {
			return err
		}
		var newTodos []pttodo.Todo
		if err := yaml.NewDecoder(r).Decode(&newTodos); err != nil {
			return err
		}
		original := originals[target]

		newTodoIDs := map[string]struct{}{}
		for i := range newTodos {
			newTodoIDs[newTodos[i].ID()] = struct{}{}
		}

		for i := range original.Todo {
			if _, ok := newTodoIDs[original.Todo[i].ID()]; !ok {
				original.Todo[i].TS = pttodo.TS(time.Now().Unix())
				if string(original.Todo[i].Schedule) != "" && !original.Todo[i].Triggered() {
					original.Scheduled = append(original.Scheduled, original.Todo[i])
				}
				original.Done = append(original.Done, original.Todo[i])
			}
		}
		original.Todo = newTodos

		original.AutoMove()

		c, err := yaml.Marshal(original)
		if err != nil {
			return err
		}
		outputPath := target
		if info, _ := os.Stat(target); info != nil && info.ModTime() != lastModified[target] {
			outputPath = fmt.Sprintf("%s.%s.%s", outputPath, uuid.New().String(), path.Ext(outputPath))
		}
		if err := ioutil.WriteFile(outputPath, c, os.ModePerm); err != nil {
			return err
		}
	}
	return nil
}

func inEditableDirAsTodos(filepaths []string) (string, error) {
	tempDir, err := ioutil.TempDir(os.TempDir(), "edit-pttodo-*")
	if err != nil {
		return "", err
	}
	return tempDir, copyTodoToDir(tempDir, filepaths)
}

func copyTodoToDir(d string, filepaths []string) error {
	inboxes := []string{}
	for _, target := range filepaths {
		p := path.Join(d, path.Base(target))
		if strings.Contains(path.Base(target), ".todo.") {
			inboxes = append(inboxes, target)
			continue
		}
		if root, err := pttodo.NewRootFromFile(target); err != nil {
			return err
		} else if b, err := yaml.Marshal(root.Todo); err != nil {
			return err
		} else if err := os.WriteFile(p, b, os.ModePerm); err != nil {
			return err
		}
	}
	for _, inbox := range inboxes {
		target := path.Join(path.Dir(inbox), strings.Split(path.Base(inbox), ".todo.")[0])
		p := path.Join(d, path.Base(target))

		root, err := pttodo.NewRootFromFile(p)
		if err != nil {
			return err
		}
		subroot, err := pttodo.NewRootFromFile(inbox)
		if err != nil {
			return err
		}
		root.MergeIn(subroot)

		if b, err := yaml.Marshal(root.Todo); err != nil {
			return err
		} else if err := os.WriteFile(p, b, os.ModePerm); err != nil {
			return err
		}
	}
	return nil
}

func modifyEditableDir(d string, check func() error) error {
	for {
		if err := vimd(d); err != nil {
			return err
		}
		err := check()
		if err == nil {
			return nil
		}
		log.Printf("%s, press <Enter> to resume editing", err)
		b := make([]byte, 1)
		if _, err := os.Stdin.Read(b); err != nil {
			return err
		}
	}
}

func vimd(d string) error {
	bin := "vim"
	editorbin, err := exec.LookPath(bin)
	if err != nil {
		editorbin, err = exec.LookPath("vi")
	}
	if err != nil {
		return err
	}
	args := []string{editorbin, "-p"}
	files, err := listDir(d)
	if err != nil {
		return err
	}
	args = append(args, files...)
	cpid, err := syscall.ForkExec(
		editorbin,
		args,
		&syscall.ProcAttr{
			Dir:   d,
			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
}

func listDir(dname string) ([]string, error) {
	entries, err := os.ReadDir(dname)
	if err != nil {
		return nil, err
	}
	paths := make([]string, 0, len(entries))
	for i := range entries {
		if entries[i].IsDir() {
			continue
		}
		if strings.HasPrefix(path.Base(entries[i].Name()), ".") {
			continue
		}
		paths = append(paths, path.Join(dname, entries[i].Name()))
	}
	sort.Slice(paths, func(i, j int) bool {
		if path.Base(paths[i]) == "root.yaml" {
			return true
		}
		return paths[i] < paths[j]
	})
	return paths, nil
}