feat(config): version-to-version migrations, migration for the upcomi… (

#44)

* feat(config): version-to-version migrations, migration for the upcoming v0.3.0 release

app.go

@@ -34,6 +34,7 @@ func (a *App) shutdown(ctx context.Context) {
 }
 
 func (a *App) domReady(ctx context.Context) {
+	config.RunMigrations()
 	config.SelfUpdate(ctx)
 }
 

config/config.go

@@ -12,6 +12,9 @@ import (
 // Config is the singleton config instance.
 var Config config
 
+// firstLaunch is true if the application is being run for the first time.
+var firstLaunch bool
+
 type filterList struct {
 	Name    string `json:"name"`
 	Type    string `json:"type"`
@@ -199,6 +202,7 @@ func init() {
 		if err := os.WriteFile(configFile, configData, 0644); err != nil {
 			log.Fatalf("failed to write config file: %v", err)
 		}
+		firstLaunch = true
 	}
 
 	if err := json.Unmarshal(configData, &Config); err != nil {

config/migrations.go

@@ -0,0 +1,79 @@
+package config
+
+import (
+	"errors"
+	"log"
+	"os"
+	"path"
+
+	"github.com/blang/semver"
+)
+
+// migrations is a map of version to migration function.
+// Warning: RunMigration() runs the migrations in arbitrary order.
+var migrations = map[string]func() error{
+	"v0.3.0": func() error {
+		errStr := Config.AddFilterList(filterList{
+			Name:    "DandelionSprout's URL Shortener",
+			Type:    "privacy",
+			Url:     "https://raw.githubusercontent.com/DandelionSprout/adfilt/master/LegitimateURLShortener.txt",
+			Enabled: true,
+		})
+		if errStr != "" {
+			err := errors.New(errStr)
+			return err
+		}
+		return nil
+	},
+}
+
+// RunMigrations runs the version-to-version migrations.
+func RunMigrations() {
+	if Version == "development" {
+		log.Println("skipping migrations in development mode")
+		return
+	}
+
+	var lastMigration string
+	lastMigrationFile := path.Join(Config.ConfigDir, "last_migration")
+	if firstLaunch {
+		lastMigration = Version
+	} else {
+		if _, err := os.Stat(lastMigrationFile); !os.IsNotExist(err) {
+			lastMigrationData, err := os.ReadFile(lastMigrationFile)
+			if err != nil {
+				log.Fatalf("failed to read last migration file: %v", err)
+			}
+			lastMigration = string(lastMigrationData)
+		} else {
+			// Should trigger when updating from pre v0.3.0
+			lastMigration = "v0.0.0"
+		}
+	}
+
+	lastMigrationV, err := semver.ParseTolerant(lastMigration)
+	if err != nil {
+		log.Printf("error parsing last migration(%s): %v\n", lastMigration, err)
+		return
+	}
+
+	for version, migration := range migrations {
+		versionV, err := semver.ParseTolerant(version)
+		if err != nil {
+			log.Printf("error parsing migration version(%s): %v\n", version, err)
+			continue
+		}
+
+		if lastMigrationV.LT(versionV) {
+			if err := migration(); err != nil {
+				log.Printf("error running migration(%s): %v\n", version, err)
+			} else {
+				log.Printf("ran migration %s\n", version)
+			}
+		}
+	}
+
+	if err := os.WriteFile(lastMigrationFile, []byte(Version), 0644); err != nil {
+		log.Printf("error writing last migration file: %v\n", err)
+	}
+}