package main

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

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

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

func _edit(filepaths []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
	}

	edits := map[string]string{}
	for _, editedFile := range editedFiles {
		edits[path.Base(editedFile)] = editedFile

		edited, err := pttodo.NewTodosFromFile(editedFile)
		if err != nil {
			return err
		}
		original, err := pttodo.NewRootFromFile(func() string {
			for _, f := range filepaths {
				if path.Base(f) == path.Base(editedFile) {
					return f
				}
			}
			return "/dev/null"
		}())
		if err != nil {
			return err
		}

		editedIDs := map[string]int{}
		for i := range edited {
			editedIDs[edited[i].ID()] = 1
		}
		for i := range original.Todo {
			if _, ok := editedIDs[original.Todo[i].ID()]; ok {
				continue
			}
			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 = edited
		original.AutoMove()

		if err := func() error {
			f, err := os.Create(editedFile)
			if err != nil {
				return err
			}
			defer f.Close()

			return yaml.NewEncoder(f).Encode(original)
		}(); err != nil {
			return err
		}
	}

	dir := ""
	for _, f := range filepaths {
		if edited, ok := edits[path.Base(f)]; ok {
			if err := rename(edited, f); err != nil {
				return err
			}
			delete(edits, path.Base(f))
		} else if err := os.Remove(f); err != nil {
			return err
		}
		dir = path.Dir(f)
	}

	for base, editedFile := range edits {
		f := path.Join(dir, base)
		if _, err := os.Stat(f); err == nil {
			f = fmt.Sprintf("%s.todo.%s", f, uuid.New().String())
		}
		if err := rename(editedFile, f); 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 := map[string][]string{}
	for _, target := range filepaths {
		p := path.Join(d, path.Base(target))
		if strings.Contains(path.Base(target), ".todo.") {
			p := path.Join(d, strings.Split(path.Base(p), ".todo")[0])
			inboxes[p] = append(inboxes[p], 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 p, inboxes := range inboxes {
		inboxRoot := pttodo.Root{}
		for _, inbox := range inboxes {
			subInboxRoot, err := pttodo.NewRootFromFile(inbox)
			if err != nil {
				return err
			}
			inboxRoot.MergeIn(pttodo.Root{Todo: subInboxRoot.Todo})
			inboxRoot.MergeIn(pttodo.Root{Todo: subInboxRoot.Scheduled})
		}

		root, err := pttodo.NewRootFromFile(p)
		if err != nil {
			return err
		}
		root.MergeIn(pttodo.Root{Todo: inboxRoot.Todo})
		root.MergeIn(pttodo.Root{Todo: inboxRoot.Scheduled})

		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
}