Initial GoWallpaper implementation

2026-07-31 21:25:56 +08:00
commit 1a4bb858f3
18 changed files with 1432 additions and 0 deletions
@@ -0,0 +1,177 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"time"
+)
+
+const cacheIndexFileName = "index.json"
+
+type CacheEntry struct {
+	FileName  string    `json:"file_name"`
+	CreatedAt time.Time `json:"created_at"`
+}
+
+type CacheIndex struct {
+	Entries  []CacheEntry `json:"entries"`
+	Current  int          `json:"current"`
+	cacheDir string
+}
+
+func loadCacheIndex(cacheDir string) (*CacheIndex, error) {
+	if err := os.MkdirAll(cacheDir, 0o755); err != nil {
+		return nil, fmt.Errorf("创建缓存目录: %w", err)
+	}
+	idx := &CacheIndex{Current: -1, cacheDir: cacheDir}
+	path := filepath.Join(cacheDir, cacheIndexFileName)
+	data, err := os.ReadFile(path)
+	if err == nil {
+		if err := json.Unmarshal(data, idx); err != nil {
+			return nil, fmt.Errorf("解析缓存索引: %w", err)
+		}
+	} else if !errors.Is(err, os.ErrNotExist) {
+		return nil, fmt.Errorf("读取缓存索引: %w", err)
+	}
+	idx.cacheDir = cacheDir
+	changed := idx.repair()
+	if errors.Is(err, os.ErrNotExist) || changed {
+		if err := idx.save(); err != nil {
+			return nil, err
+		}
+	}
+	return idx, nil
+}
+
+func (idx *CacheIndex) repair() bool {
+	changed := false
+	valid := make([]CacheEntry, 0, len(idx.Entries))
+	seen := make(map[string]bool)
+	for _, entry := range idx.Entries {
+		if entry.FileName == "" || filepath.Base(entry.FileName) != entry.FileName || seen[entry.FileName] {
+			changed = true
+			continue
+		}
+		if _, err := os.Stat(filepath.Join(idx.cacheDir, entry.FileName)); err != nil {
+			changed = true
+			continue
+		}
+		seen[entry.FileName] = true
+		valid = append(valid, entry)
+	}
+	idx.Entries = valid
+	if len(idx.Entries) == 0 {
+		if idx.Current != -1 {
+			changed = true
+		}
+		idx.Current = -1
+	} else if idx.Current < 0 || idx.Current >= len(idx.Entries) {
+		idx.Current = len(idx.Entries) - 1
+		changed = true
+	}
+	return changed
+}
+
+func (idx *CacheIndex) save() error {
+	data, err := json.MarshalIndent(struct {
+		Entries []CacheEntry `json:"entries"`
+		Current int          `json:"current"`
+	}{idx.Entries, idx.Current}, "", "  ")
+	if err != nil {
+		return err
+	}
+	data = append(data, '\n')
+	if err := atomicWriteFile(filepath.Join(idx.cacheDir, cacheIndexFileName), data, 0o644); err != nil {
+		return fmt.Errorf("保存缓存索引: %w", err)
+	}
+	return nil
+}
+
+func (idx *CacheIndex) add(path string, maxCount int) error {
+	oldEntries := append([]CacheEntry(nil), idx.Entries...)
+	oldCurrent := idx.Current
+	name := filepath.Base(path)
+	idx.Entries = append(idx.Entries, CacheEntry{FileName: name, CreatedAt: time.Now()})
+	idx.Current = len(idx.Entries) - 1
+	if err := idx.trim(maxCount); err != nil {
+		idx.Entries = oldEntries
+		idx.Current = oldCurrent
+		return err
+	}
+	return nil
+}
+
+func (idx *CacheIndex) trim(maxCount int) error {
+	if maxCount <= 0 || len(idx.Entries) <= maxCount {
+		return idx.save()
+	}
+	oldEntries := append([]CacheEntry(nil), idx.Entries...)
+	oldCurrent := idx.Current
+	removeCount := len(idx.Entries) - maxCount
+	removed := append([]CacheEntry(nil), idx.Entries[:removeCount]...)
+	idx.Entries = append([]CacheEntry(nil), idx.Entries[removeCount:]...)
+	idx.Current -= removeCount
+	if idx.Current < 0 && len(idx.Entries) > 0 {
+		idx.Current = 0
+	}
+	if err := idx.save(); err != nil {
+		idx.Entries = oldEntries
+		idx.Current = oldCurrent
+		return err
+	}
+	for _, entry := range removed {
+		_ = os.Remove(filepath.Join(idx.cacheDir, entry.FileName))
+	}
+	return nil
+}
+
+func (idx *CacheIndex) previous() (string, bool, error) {
+	if idx.Current <= 0 || len(idx.Entries) == 0 {
+		return "", false, nil
+	}
+	idx.Current--
+	if err := idx.save(); err != nil {
+		idx.Current++
+		return "", false, err
+	}
+	return filepath.Join(idx.cacheDir, idx.Entries[idx.Current].FileName), true, nil
+}
+
+func (idx *CacheIndex) next() (string, bool, error) {
+	if idx.Current < 0 || idx.Current >= len(idx.Entries)-1 {
+		return "", false, nil
+	}
+	idx.Current++
+	if err := idx.save(); err != nil {
+		idx.Current--
+		return "", false, err
+	}
+	return filepath.Join(idx.cacheDir, idx.Entries[idx.Current].FileName), true, nil
+}
+
+func uniqueCachePath(cacheDir string) string {
+	base := time.Now().Format("20060102_150405_000000000")
+	path := filepath.Join(cacheDir, base+".jpg")
+	if _, err := os.Stat(path); errors.Is(err, os.ErrNotExist) {
+		return path
+	}
+	for i := 1; ; i++ {
+		candidate := filepath.Join(cacheDir, fmt.Sprintf("%s_%d.jpg", base, i))
+		if _, err := os.Stat(candidate); errors.Is(err, os.ErrNotExist) {
+			return candidate
+		}
+	}
+}
+
+func cachedImageFiles(cacheDir string) ([]string, error) {
+	matches, err := filepath.Glob(filepath.Join(cacheDir, "*.jpg"))
+	if err != nil {
+		return nil, err
+	}
+	sort.Strings(matches)
+	return matches, nil
+}