package main

import (
	"errors"
	"io/ioutil"
	"os"
	"time"

	yaml "gopkg.in/yaml.v2"
)

type Tree struct {
	path string
}

type Branch struct {
	Title   string
	Deleted bool
	Updated time.Time
	PID     string
}

func NewTree(path string) *Tree {
	return &Tree{
		path: path,
	}
}

func (tree *Tree) Get() (map[string]Branch, error) {
	b, err := ioutil.ReadFile(tree.path)
	if os.IsNotExist(err) {
		return map[string]Branch{}, nil
	}
	if err != nil {
		return nil, err
	}
	var m map[string]Branch
	err = yaml.Unmarshal(b, &m)
	return m, err
}

func (tree *Tree) Set(m map[string]Branch) error {
	b, err := yaml.Marshal(m)
	if err != nil {
		return err
	}
	return ioutil.WriteFile(tree.path, b, os.ModePerm)
}

func (tree *Tree) Del(id string) error {
	m, err := tree.Get()
	if err != nil {
		return err
	}
	branch, ok := m[id]
	if !ok {
		return nil
	}
	branch.Updated = time.Now().UTC()
	branch.Deleted = true
	m[id] = branch
	return tree.Set(m)
}

func (tree *Tree) Put(id string, branch Branch) error {
	branch.Updated = time.Now().UTC()
	if branch.Title == "" {
		branch.Title = "Untitled (" + time.Now().UTC().String() + ")"
	}
	m, err := tree.Get()
	if err != nil {
		return err
	}
	if _, ok := m[branch.PID]; !ok && branch.PID != "" {
		return errors.New("PID does not exist")
	}
	m[id] = branch
	return tree.Set(m)
}