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|
package thumbnail
import (
"encoding/json"
"errors"
"fmt"
"os"
"path/filepath"
"sync"
"time"
)
type entry struct {
VideoPath string `json:"video_path"`
Thumbnail string `json:"thumbnail"`
ModTime time.Time `json:"mod_time"`
Timestamp time.Time `json:"timestamp"`
}
type Cache struct {
entries map[string]entry
mu sync.RWMutex
path string
}
func NewCache(root string) *Cache {
return newCache(root)
}
func newCache(root string) *Cache {
path := filepath.Join(root, cacheFilename)
return &Cache{
entries: make(map[string]entry),
path: path,
}
}
func (c *Cache) Load() error {
c.mu.Lock()
defer c.mu.Unlock()
data, err := os.ReadFile(c.path)
if err != nil {
if errors.Is(err, os.ErrNotExist) {
return nil
}
return fmt.Errorf("read cache file: %w", err)
}
var loaded []entry
if err := json.Unmarshal(data, &loaded); err != nil {
return fmt.Errorf("unmarshal cache: %w", err)
}
c.entries = make(map[string]entry, len(loaded))
for _, e := range loaded {
c.entries[e.VideoPath] = e
}
return nil
}
func (c *Cache) Lookup(videoPath string, modTime time.Time) (string, bool) {
c.mu.RLock()
defer c.mu.RUnlock()
e, ok := c.entries[videoPath]
if !ok {
return "", false
}
if !e.ModTime.Equal(modTime) {
return "", false
}
if _, err := os.Stat(e.Thumbnail); err != nil {
return "", false
}
return e.Thumbnail, true
}
func (c *Cache) Store(videoPath string, modTime time.Time, thumbnailPath string) error {
c.mu.Lock()
defer c.mu.Unlock()
c.entries[videoPath] = entry{
VideoPath: videoPath,
Thumbnail: thumbnailPath,
ModTime: modTime,
Timestamp: time.Now(),
}
return c.flush()
}
func (c *Cache) Remove(videoPath string) error {
c.mu.Lock()
defer c.mu.Unlock()
delete(c.entries, videoPath)
return c.flush()
}
func (c *Cache) flush() error {
loaded := make([]entry, 0, len(c.entries))
for _, e := range c.entries {
loaded = append(loaded, e)
}
data, err := json.MarshalIndent(loaded, "", " ")
if err != nil {
return fmt.Errorf("marshal cache: %w", err)
}
if err := os.WriteFile(c.path, data, 0o644); err != nil {
return fmt.Errorf("write cache file: %w", err)
}
return nil
}
|
