From 7106d5a6e7585dce5fdd552cca30063dd352dc23 Mon Sep 17 00:00:00 2001
From: René 'Necoro' Neumann <necoro@necoro.eu>
Date: Mon, 22 Feb 2021 22:54:43 +0100
Subject: Split cache and feed packages

---
 internal/feed/cache.go | 172 -------------------------------------------------
 1 file changed, 172 deletions(-)
 delete mode 100644 internal/feed/cache.go

(limited to 'internal/feed/cache.go')

diff --git a/internal/feed/cache.go b/internal/feed/cache.go
deleted file mode 100644
index 5f5c394..0000000
--- a/internal/feed/cache.go
+++ /dev/null
@@ -1,172 +0,0 @@
-package feed
-
-import (
-	"bufio"
-	"encoding/gob"
-	"errors"
-	"fmt"
-	"os"
-	"path/filepath"
-	"time"
-
-	"github.com/nightlyone/lockfile"
-
-	"github.com/Necoro/feed2imap-go/pkg/log"
-)
-
-type Version byte
-
-const (
-	currentVersion Version = 1
-)
-
-type CacheImpl interface {
-	findItem(*Feed) CachedFeed
-	Version() Version
-	Info() string
-	SpecificInfo(interface{}) string
-	transformToCurrent() (CacheImpl, error)
-}
-
-type Cache struct {
-	CacheImpl
-	lock   lockfile.Lockfile
-	locked bool
-}
-
-type CachedFeed interface {
-	Checked(withFailure bool)
-	Failures() int
-	Last() time.Time
-	ID() string
-	filterItems(items []item, ignoreHash bool, alwaysNew bool) []item
-	Commit()
-}
-
-func cacheForVersion(version Version) (CacheImpl, error) {
-	switch version {
-	case v1Version:
-		return newV1Cache(), nil
-	default:
-		return nil, fmt.Errorf("unknown cache version '%d'", version)
-	}
-}
-
-func lockName(fileName string) (string, error) {
-	return filepath.Abs(fileName + ".lck")
-}
-
-func lock(fileName string) (lock lockfile.Lockfile, err error) {
-	var lockFile string
-
-	if lockFile, err = lockName(fileName); err != nil {
-		return
-	}
-	log.Debugf("Handling lock file '%s'", lockFile)
-
-	if lock, err = lockfile.New(lockFile); err != nil {
-		err = fmt.Errorf("Creating lock file: %w", err)
-		return
-	}
-
-	if err = lock.TryLock(); err != nil {
-		err = fmt.Errorf("Locking cache: %w", err)
-		return
-	}
-
-	return
-}
-
-func (cache *Cache) store(fileName string) error {
-	if cache.CacheImpl == nil {
-		return fmt.Errorf("trying to store nil cache")
-	}
-	if cache.Version() != currentVersion {
-		return fmt.Errorf("trying to store cache with unsupported version '%d' (current: '%d')", cache.Version(), currentVersion)
-	}
-
-	f, err := os.Create(fileName)
-	if err != nil {
-		return fmt.Errorf("trying to store cache to '%s': %w", fileName, err)
-	}
-	defer f.Close()
-
-	writer := bufio.NewWriter(f)
-	if err = writer.WriteByte(byte(currentVersion)); err != nil {
-		return fmt.Errorf("writing to '%s': %w", fileName, err)
-	}
-
-	encoder := gob.NewEncoder(writer)
-	if err = encoder.Encode(cache.CacheImpl); err != nil {
-		return fmt.Errorf("encoding cache: %w", err)
-	}
-
-	writer.Flush()
-	log.Printf("Stored cache to '%s'.", fileName)
-
-	return cache.Unlock()
-}
-
-func (cache *Cache) Unlock() error {
-	if cache.locked {
-		if err := cache.lock.Unlock(); err != nil {
-			return fmt.Errorf("Unlocking cache: %w", err)
-		}
-	}
-	cache.locked = false
-	return nil
-}
-
-func newCache() (Cache, error) {
-	cache, err := cacheForVersion(currentVersion)
-	if err != nil {
-		return Cache{}, err
-	}
-	return Cache{
-		CacheImpl: cache,
-		locked:    false,
-	}, nil
-}
-
-func LoadCache(fileName string) (Cache, error) {
-	f, err := os.Open(fileName)
-	if err != nil {
-		if errors.Is(err, os.ErrNotExist) {
-			// no cache there yet -- make new
-			return newCache()
-		}
-		return Cache{}, fmt.Errorf("opening cache at '%s': %w", fileName, err)
-	}
-	defer f.Close()
-
-	lock, err := lock(fileName)
-	if err != nil {
-		return Cache{}, err
-	}
-
-	log.Printf("Loading cache from '%s'", fileName)
-
-	reader := bufio.NewReader(f)
-	version, err := reader.ReadByte()
-	if err != nil {
-		return Cache{}, fmt.Errorf("reading from '%s': %w", fileName, err)
-	}
-
-	cache, err := cacheForVersion(Version(version))
-	if err != nil {
-		return Cache{}, err
-	}
-
-	decoder := gob.NewDecoder(reader)
-	if err = decoder.Decode(cache); err != nil {
-		return Cache{}, fmt.Errorf("decoding for version '%d' from '%s': %w", version, fileName, err)
-	}
-
-	if cache, err = cache.transformToCurrent(); err != nil {
-		return Cache{}, fmt.Errorf("cannot transform from version %d to %d: %w", version, currentVersion, err)
-	}
-
-	log.Printf("Loaded cache (version %d), transformed to version %d.", version, currentVersion)
-
-	return Cache{cache, lock, true}, nil
-}
-- 
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