refactor: better project structure (#35)

This project is starting to grow, and I've seen flaws in the initial
project structure design
I think I'll restructure the entire project directory for better
scalability and also cleaner

internal/config/state.go

@@ -0,0 +1,68 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/BurntSushi/toml"
+)
+
+type UpdaterState struct {
+	LastCheckTime time.Time `toml:"last-check-time"`
+	SeenVersion   string    `toml:"seen-version"`
+}
+
+type State struct {
+	LastMode string       `toml:"last-mode"`
+	Updater  UpdaterState `toml:"updater"`
+}
+
+func LoadState() *State {
+	s := DefaultState()
+
+	path, err := StatePath()
+	if err != nil {
+		return s
+	}
+
+	if _, statErr := os.Stat(path); os.IsNotExist(statErr) {
+		return s
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return s
+	}
+
+	if _, err := toml.Decode(string(data), s); err != nil {
+		return s
+	}
+
+	return s
+}
+
+func SaveState(s *State) error {
+	path, err := StatePath()
+	if err != nil {
+		return err
+	}
+
+	err = os.MkdirAll(filepath.Dir(path), 0755)
+	if err != nil {
+		return err
+	}
+
+	file, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	enc := toml.NewEncoder(file)
+	if err := enc.Encode(s); err != nil {
+		return err
+	}
+
+	return nil
+}