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/migrate.go

@@ -0,0 +1,90 @@
+package config
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+type legacyState struct {
+	Mode string `json:"mode"`
+}
+
+type legacyUpdateState struct {
+	SeenVersion string `json:"seen_version"`
+	LastCheck   int64  `json:"last_check"`
+}
+
+func MigrateFromLegacyJSON() error {
+	statePath, err := StatePath()
+	if err != nil {
+		return err
+	}
+
+	if _, statErr := os.Stat(statePath); statErr == nil {
+		return nil
+	}
+
+	home, homeErr := os.UserHomeDir()
+	if homeErr != nil {
+		return homeErr
+	}
+
+	legacyDir := filepath.Join(home, ".iris")
+	legacyStatePath := filepath.Join(legacyDir, "state.json")
+	legacyUpdatePath := filepath.Join(legacyDir, "update_state.json")
+
+	hasLegacyState := false
+	if _, err := os.Stat(legacyStatePath); err == nil {
+		hasLegacyState = true
+	}
+	hasLegacyUpdate := false
+	if _, err := os.Stat(legacyUpdatePath); err == nil {
+		hasLegacyUpdate = true
+	}
+
+	if !hasLegacyState && !hasLegacyUpdate {
+		return nil
+	}
+
+	state := DefaultState()
+
+	if hasLegacyState {
+		data, err := os.ReadFile(legacyStatePath)
+		if err == nil {
+			var ls legacyState
+			if err := json.Unmarshal(data, &ls); err == nil {
+				if ls.Mode == "history" || ls.Mode == "spec" {
+					state.LastMode = ls.Mode
+				}
+			}
+		}
+	}
+
+	if hasLegacyUpdate {
+		data, err := os.ReadFile(legacyUpdatePath)
+		if err == nil {
+			var lu legacyUpdateState
+			if err := json.Unmarshal(data, &lu); err == nil {
+				state.Updater.SeenVersion = lu.SeenVersion
+				if lu.LastCheck > 0 {
+					state.Updater.LastCheckTime = time.Unix(lu.LastCheck, 0)
+				}
+			}
+		}
+	}
+
+	if err := SaveState(state); err != nil {
+		return err
+	}
+
+	if hasLegacyState {
+		_ = os.Rename(legacyStatePath, legacyStatePath+".bak")
+	}
+	if hasLegacyUpdate {
+		_ = os.Rename(legacyUpdatePath, legacyUpdatePath+".bak")
+	}
+
+	return nil
+}