muse/storage/entrylist.go

package storage

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
	"sort"
	"sync"
	"time"

	"github.com/gorilla/feeds"
)

type (
	EntryList struct {
		Filename string
		ModTime  time.Time
		v        []*Entry
		mu       sync.RWMutex
	}
)

func (list *EntryList) Len() int      { return len(list.v) }
func (list *EntryList) Swap(i, j int) { list.v[i], list.v[j] = list.v[j], list.v[i] }
func (list *EntryList) Less(i, j int) bool {
	return time.Time(list.v[i].Date).After(time.Time(list.v[j].Date))
}

func (list *EntryList) modified() (mod bool) {
	info, err := os.Stat(list.Filename)
	if err == nil {
		mod = list.ModTime.Before(info.ModTime())
		list.ModTime = info.ModTime()
	} else {
		mod = true
	}
	return
}

func (list *EntryList) write() (err error) {
	data, err := json.MarshalIndent(list.v, "", "    ")
	if err == nil {
		err = ioutil.WriteFile(list.Filename, data, 0644)
	}
	if err == nil {
		list.ModTime = time.Now()
	}
	return
}

func (list *EntryList) read() (err error) {
	if list.modified() {
		list.v = make([]*Entry, 0, len(list.v))
		if data, err := ioutil.ReadFile(list.Filename); err == nil {
			err = json.Unmarshal(data, &list.v)
		}
	}
	return
}

func (list *EntryList) GetEntries() (entry []*Entry, err error) {
	list.mu.RLock()
	defer list.mu.RUnlock()

	err = list.read()
	entry = list.v

	return
}

func (list *EntryList) AddEntry(entry *Entry) (err error) {
	list.mu.Lock()
	defer list.mu.Unlock()

	if err = list.read(); err == nil {
		list.v = append(list.v, entry)
		sort.Sort(list)
		err = list.write()
	}

	return
}

func (list *EntryList) ReadSliceList(oval int, nval int) (entries []*Entry, err error) {
	list.mu.RLock()
	defer list.mu.RUnlock()

	if nval <= 0 {
		nval = list.Len()
	}

	if oval <= 0 {
		oval = 0
	}

	err = list.read()
	if err == nil {
		if oval >= list.Len() {
			entries = nil
		} else if oval+nval >= list.Len() {
			entries = list.v[oval:]
		} else {
			entries = list.v[oval : oval+nval]
		}
	}

	return
}

func (list *EntryList) DeleteElement(pos int) (err error) {
	list.mu.Lock()
	defer list.mu.Unlock()

	if err = list.read(); err == nil {
		if pos >= 0 && pos < list.Len() {
			if pos == 0 {
				list.v = list.v[pos+1:]
			} else if pos == list.Len()-1 {
				list.v = list.v[:pos]
			} else {
				list.v = append(list.v[:pos], list.v[pos+1:]...)
			}

			err = list.write()
		}
	}

	return
}

// TODO rutas relativas
func (list *EntryList) GetFeed() (feed *feeds.Feed) {
	list.mu.RLock()
	defer list.mu.RUnlock()

	err := list.read()

	if err == nil {
		feed = &feeds.Feed{
			Title:       "danoloan.es muse",
			Link:        &feeds.Link{Href: "https://danoloan.es/muse"},
			Description: "bitácora musical de danoloan",
			Author:      &feeds.Author{Name: "danoloan", Email: "danolo@danoloan.es"},
		}

		feed.Items = make([]*feeds.Item, 0, list.Len())
		for _, elem := range list.v {
			item := &feeds.Item{
				Created: time.Time(elem.Date),
			}

			if elem.Track != "" {
				item.Title = elem.Track
			} else if elem.Album != "" {
				item.Title = elem.Album
			}

			item.Description = fmt.Sprintf("<p>%s - %s</p>\n", item.Title, elem.Artist)
			if elem.Cover != "" {
				item.Description = fmt.Sprintf("%s<img src=\"%s\"/>\n", item.Description, elem.Cover)
			}

			if elem.Linkto != "" {
				item.Link = &feeds.Link{Href: elem.Linkto}
			} else {
				item.Link = &feeds.Link{Href: "https://danoloan.es/muse"}
			}

			feed.Items = append(feed.Items, item)
		}
	}

	return
}