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package feed
import (
"crypto/sha256"
"fmt"
"strconv"
"time"
"github.com/Necoro/feed2imap-go/pkg/log"
"github.com/Necoro/feed2imap-go/pkg/util"
)
const (
v1Version Version = 1
startFeedId uint64 = 1
)
type feedId uint64
func (id feedId) String() string {
return strconv.FormatUint(uint64(id), 16)
}
type v1Cache struct {
Ids map[feedDescriptor]feedId
NextId uint64
Feeds map[feedId]*cachedFeed
}
type cachedFeed struct {
id feedId // not saved, has to be set on loading
LastCheck time.Time
currentCheck time.Time
NumFailures int // can't be named `Failures` b/c it'll collide with the interface
Items []cachedItem
newItems []cachedItem
}
type itemHash [sha256.Size]byte
type cachedItem struct {
Guid string
Title string
Link string
PublishedDate time.Time
UpdatedDate time.Time
UpdatedCache time.Time
Hash itemHash
ID string
}
func (item cachedItem) String() string {
return fmt.Sprintf(`{
Title: %q
Guid: %q
Link: %q
Published: %s
Updated: %s
}`, item.Title, item.Guid, item.Link, util.TimeFormat(item.PublishedDate), util.TimeFormat(item.UpdatedDate))
}
func (cf *cachedFeed) Checked(withFailure bool) {
cf.currentCheck = time.Now()
if withFailure {
cf.NumFailures++
} else {
cf.NumFailures = 0
}
}
func (cf *cachedFeed) Commit() {
cf.Items = cf.newItems
cf.newItems = nil
cf.LastCheck = cf.currentCheck
}
func (cf *cachedFeed) Failures() int {
return cf.NumFailures
}
func (cf *cachedFeed) Last() time.Time {
return cf.LastCheck
}
func (cf *cachedFeed) ID() string {
return cf.id.String()
}
func (cache *v1Cache) Version() Version {
return v1Version
}
func newV1Cache() *v1Cache {
cache := v1Cache{
Ids: map[feedDescriptor]feedId{},
Feeds: map[feedId]*cachedFeed{},
NextId: startFeedId,
}
return &cache
}
func (cache *v1Cache) transformToCurrent() (Cache, error) {
return cache, nil
}
func (cache *v1Cache) getItem(id feedId) CachedFeed {
feed, ok := cache.Feeds[id]
if !ok {
feed = &cachedFeed{}
cache.Feeds[id] = feed
}
feed.id = id
return feed
}
func (cache *v1Cache) findItem(feed *Feed) CachedFeed {
if feed.cached != nil {
return feed.cached.(*cachedFeed)
}
fDescr := feed.descriptor()
id, ok := cache.Ids[fDescr]
if !ok {
var otherId feedDescriptor
changed := false
for otherId, id = range cache.Ids {
if otherId.Name == fDescr.Name {
log.Warnf("Feed %s seems to have changed URLs: new '%s', old '%s'. Updating.",
fDescr.Name, fDescr.Url, otherId.Url)
changed = true
break
} else if otherId.Url == fDescr.Url {
log.Warnf("Feed with URL '%s' seems to have changed its name: new '%s', old '%s'. Updating.",
fDescr.Url, fDescr.Name, otherId.Name)
changed = true
break
}
}
if changed {
delete(cache.Ids, otherId)
} else {
id = feedId(cache.NextId)
cache.NextId++
}
cache.Ids[fDescr] = id
}
item := cache.getItem(id)
feed.cached = item
return item
}
func (item *item) newCachedItem() cachedItem {
var ci cachedItem
ci.ID = item.itemId
ci.Title = item.Item.Title
ci.Link = item.Item.Link
if item.Item.PublishedParsed != nil {
ci.PublishedDate = *item.Item.PublishedParsed
}
if item.Item.UpdatedParsed != nil && !item.Item.UpdatedParsed.Equal(ci.PublishedDate) {
ci.UpdatedDate = *item.Item.UpdatedParsed
}
ci.Guid = item.Item.GUID
contentByte := []byte(item.Item.Description + item.Item.Content)
ci.Hash = sha256.Sum256(contentByte)
return ci
}
func (item *cachedItem) similarTo(other *cachedItem, ignoreHash bool) bool {
return other.Title == item.Title &&
other.Link == item.Link &&
other.PublishedDate.Equal(item.PublishedDate) &&
(ignoreHash || other.Hash == item.Hash)
}
func (cf *cachedFeed) deleteItem(index int) {
copy(cf.Items[index:], cf.Items[index+1:])
cf.Items[len(cf.Items)-1] = cachedItem{}
cf.Items = cf.Items[:len(cf.Items)-1]
}
func (cf *cachedFeed) filterItems(items []item, ignoreHash, alwaysNew bool) []item {
if len(items) == 0 {
return items
}
cacheItems := make(map[cachedItem]*item, len(items))
for idx := range items {
// remove complete duplicates on the go
cacheItems[items[idx].newCachedItem()] = &items[idx]
}
log.Debugf("%d items after deduplication", len(cacheItems))
filtered := make([]item, 0, len(items))
cacheadd := make([]cachedItem, 0, len(items))
app := func(item *item, ci cachedItem, oldIdx *int) {
if oldIdx != nil {
item.updateOnly = true
prevId := cf.Items[*oldIdx].ID
ci.ID = prevId
item.itemId = prevId
cf.deleteItem(*oldIdx)
}
filtered = append(filtered, *item)
cacheadd = append(cacheadd, ci)
}
CACHE_ITEMS:
for ci, item := range cacheItems {
log.Debugf("Now checking %s", ci)
if cf.LastCheck.IsZero() || ci.PublishedDate.After(cf.LastCheck) {
log.Debug("Newer than last check, including.")
item.addReason("time")
app(item, ci, nil)
continue
}
if ci.Guid != "" {
for idx, oldItem := range cf.Items {
if oldItem.Guid == ci.Guid {
log.Debugf("Guid matches with: %s", oldItem)
if !oldItem.similarTo(&ci, ignoreHash) {
item.addReason("guid (upd)")
app(item, ci, &idx)
} else {
log.Debugf("Similar, ignoring")
}
continue CACHE_ITEMS
}
}
log.Debug("Found no matching GUID, including.")
item.addReason("guid")
app(item, ci, nil)
continue
}
for idx, oldItem := range cf.Items {
if oldItem.similarTo(&ci, ignoreHash) {
log.Debugf("Similarity matches, ignoring: %s", oldItem)
continue CACHE_ITEMS
}
if oldItem.Link == ci.Link {
if alwaysNew {
log.Debugf("Link matches, but `always-new`.")
item.addReason("always-new")
continue
}
log.Debugf("Link matches, updating: %s", oldItem)
item.addReason("link (upd)")
app(item, ci, &idx)
continue CACHE_ITEMS
}
}
log.Debugf("No match found, inserting.")
item.addReason("new")
app(item, ci, nil)
}
log.Debugf("%d items after filtering", len(filtered))
cf.newItems = append(cacheadd, cf.Items...)
return filtered
}
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