cpolis/cmd/data/articles.go

package data

import (
	"encoding/gob"
	"fmt"
	"os"
	"sync"
	"time"

	"github.com/google/uuid"
)

type Article struct {
	Title    string
	Author   string
	Created  time.Time
	Desc     string
	Content  string
	Tags     []string
	UUID     uuid.UUID
	AuthorID int64
}

type ArticleList struct {
	addCh    chan *Article
	delCh    chan uuid.UUID
	retCh    chan *Article
	getCh    chan []Article
	articles []*Article
	wg       sync.WaitGroup
}

type TagList struct {
	addCh chan string
	getCh chan []string
	tags  []string
	wg    sync.WaitGroup
}

func initArticleList() *ArticleList {
	return &ArticleList{
		addCh: make(chan *Article),
		delCh: make(chan uuid.UUID),
		retCh: make(chan *Article),
		getCh: make(chan []Article),
	}
}

func initTagList() *TagList {
	return &TagList{
		addCh: make(chan string),
		getCh: make(chan []string),
	}
}

func (al *ArticleList) start() {
	al.wg.Done()
	for {
		select {
		case article := <-al.addCh:
			al.articles = append(al.articles, article)
		case uuid := <-al.delCh:
			for i, article := range al.articles {
				if article.UUID == uuid {
					al.articles = append(al.articles[:i], al.articles[i+1:]...)
					al.retCh <- article
				}
			}
		case al.getCh <- func() []Article {
			var list []Article
			for _, article := range al.articles {
				list = append(list, *article)
			}
			return list
		}():
		}
	}
}

func (tl *TagList) start() {
	tl.wg.Done()
	for {
		select {
		case tag := <-tl.addCh:
			tl.tags = append(tl.tags, tag)
		case tl.getCh <- tl.tags:
		}
	}
}

func NewArticleList() *ArticleList {
	list := initArticleList()
	list.articles = []*Article{}

	list.wg.Add(1)
	go list.start()
	list.wg.Wait()

	return list
}

func (al *ArticleList) Add(a *Article) {
	al.addCh <- a
}

func (al *ArticleList) Release(uuid uuid.UUID) (*Article, bool) {
	al.delCh <- uuid
	article := <-al.retCh

	if article == nil {
		return nil, false
	}
	return article, true
}

func (al *ArticleList) Get() []Article {
	return <-al.getCh
}

func (al *ArticleList) Save(filename string) error {
	file, err := os.Create(filename)
	if err != nil {
		return fmt.Errorf("error creating key file: %v", err)
	}
	defer file.Close()

	articles := al.Get()
	if err = gob.NewEncoder(file).Encode(articles); err != nil {
		return fmt.Errorf("error ecoding key: %v", err)
	}

	return nil
}

func LoadArticleList(filename string) (*ArticleList, error) {
	file, err := os.Open(filename)
	if err != nil {
		return nil, fmt.Errorf("error opening key file: %v", err)
	}

	articleList := NewArticleList()
	if err = gob.NewDecoder(file).Decode(&articleList.articles); err != nil {
		return nil, fmt.Errorf("error decoding key: %v", err)
	}

	return articleList, nil
}

func NewTagList() *TagList {
	list := initTagList()
	list.tags = []string{}

	list.wg.Add(1)
	go list.start()
	list.wg.Wait()

	return list
}

func (tl *TagList) Add(tag string) {
	tl.addCh <- tag
}

func (tl *TagList) Get() []string {
	return <-tl.getCh
}

func (tl *TagList) Save(filename string) error {
	file, err := os.Create(filename)
	if err != nil {
		return fmt.Errorf("error creating key file: %v", err)
	}
	defer file.Close()

	tags := tl.Get()
	if err = gob.NewEncoder(file).Encode(tags); err != nil {
		return fmt.Errorf("error ecoding key: %v", err)
	}

	return nil
}

func LoadTagList(filename string) (*TagList, error) {
	file, err := os.Open(filename)
	if err != nil {
		return nil, fmt.Errorf("error opening key file: %v", err)
	}
	defer file.Close()

	tagList := NewTagList()
	if err = gob.NewDecoder(file).Decode(&tagList.tags); err != nil {
		return nil, fmt.Errorf("error decoding key: %v", err)
	}

	return tagList, nil
}