core: add screenshot utility

core/internal/screenshot/state.go

@@ -0,0 +1,65 @@
+package screenshot
+
+import (
+	"encoding/json"
+	"os"
+	"path"
+	"path/filepath"
+)
+
+type PersistentState struct {
+	LastRegion Region `json:"last_region"`
+}
+
+func getStateFilePath() string {
+	cacheDir, err := os.UserCacheDir()
+	if err != nil {
+		cacheDir = path.Join(os.Getenv("HOME"), ".cache")
+	}
+	return filepath.Join(cacheDir, "dms", "screenshot-state.json")
+}
+
+func LoadState() (*PersistentState, error) {
+	path := getStateFilePath()
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return &PersistentState{}, nil
+		}
+		return nil, err
+	}
+
+	var state PersistentState
+	if err := json.Unmarshal(data, &state); err != nil {
+		return &PersistentState{}, nil
+	}
+	return &state, nil
+}
+
+func SaveState(state *PersistentState) error {
+	path := getStateFilePath()
+	dir := filepath.Dir(path)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return err
+	}
+
+	data, err := json.MarshalIndent(state, "", "  ")
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(path, data, 0644)
+}
+
+func GetLastRegion() Region {
+	state, err := LoadState()
+	if err != nil {
+		return Region{}
+	}
+	return state.LastRegion
+}
+
+func SaveLastRegion(r Region) error {
+	state, _ := LoadState()
+	state.LastRegion = r
+	return SaveState(state)
+}