From 8dd032393ec2e9093020d65b67944f5575d102c4 Mon Sep 17 00:00:00 2001
From: mykola2312 <49044616+mykola2312@users.noreply.github.com>
Date: Sun, 17 Nov 2024 22:04:42 +0200
Subject: [PATCH] implement small migrations tool

---
 db/db.go                | 84 ++++++++++++++++++++++++++++++++++++++---
 go.mod                  |  3 +-
 go.sum                  |  4 ++
 main.go                 |  9 +----
 migrations/000_init.sql |  4 ++
 migrations/001_test.sql |  4 ++
 6 files changed, 95 insertions(+), 13 deletions(-)
 create mode 100644 migrations/000_init.sql
 create mode 100644 migrations/001_test.sql

diff --git a/db/db.go b/db/db.go
index 46afc2d..29ff235 100644
--- a/db/db.go
+++ b/db/db.go
@@ -4,8 +4,13 @@ import (
 	"database/sql"
 	"log"
 	"os"
+	"path"
+	"strconv"
+	"strings"
 
 	_ "github.com/mattn/go-sqlite3"
+	"github.com/umpc/go-sortedmap"
+	"github.com/umpc/go-sortedmap/asc"
 )
 
 type DBConfig struct {
@@ -22,7 +27,6 @@ func Init(_config *DBConfig) {
 func checkConfig() {
 	if config == nil {
 		log.Fatal("DBConfig not initialized! Call db.Init!")
-		os.Exit(1)
 	}
 }
 
@@ -35,14 +39,12 @@ func open(dbPath string) (*sql.DB, error) {
 	/* if database is empty. we must create
 	'_migration` table and apply all releveant migrations
 	*/
-	_, err = db.Query("SELECT id FROM `_migration` LIMIT 1;")
+	_, err = db.Query("SELECT `_seq` FROM `_migration` LIMIT 1;")
 	if err != nil {
 		// create table
 		_, err = db.Exec(`
 		CREATE TABLE _migration (
-			id		INTEGER PRIMARY KEY AUTOINCREMENT,
-			seq		INTEGER	NOT NULL UNIQUE,
-			name	TEXT	NOT NULL UNIQUE
+			_seq	INTEGER PRIMARY KEY UNIQUE
 		);`)
 		// can't create migration table - fatal
 		if err != nil {
@@ -52,6 +54,77 @@ func open(dbPath string) (*sql.DB, error) {
 	return db, nil
 }
 
+func applyMigrations(db *sql.DB) {
+	entries, err := os.ReadDir(config.MigrationsPath)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// load migrations from directory
+	migrations := sortedmap.New(len(entries), asc.Int)
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+
+		name := entry.Name()
+		split := strings.Split(name, "_")
+		if len(split) < 2 {
+			log.Printf("%s does not follow 000_name.sql convention\n", name)
+			continue
+		}
+
+		seq, err := strconv.Atoi(split[0])
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		migrations.Insert(name, seq)
+	}
+
+	if migrations.Len() == 0 {
+		log.Fatal("no migrations!")
+	}
+
+	// detect last database migration
+	var seq int = -1
+	row := db.QueryRow("SELECT `_seq` FROM `_migration` ORDER BY `_seq` DESC LIMIT 1;")
+	if row.Err() == nil {
+		row.Scan(&seq)
+	}
+
+	// apply migrations starting from seq
+	iter, err := migrations.BoundedIterCh(false, seq+1, nil)
+	if err != nil {
+		// no migrations to apply
+		return
+	}
+	defer iter.Close()
+
+	for m := range iter.Records() {
+		path := path.Join(config.MigrationsPath, m.Key.(string))
+		bytes, err := os.ReadFile(path)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		sql := string(bytes[:])
+		_, err = db.Exec(sql)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		// successfuly applied migration, so bump seq and insert in table
+		seq = m.Val.(int)
+		_, err = db.Exec("INSERT INTO `_migration` (_seq) VALUES (?);", seq)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		log.Printf("Applied migration %d\n", seq)
+	}
+}
+
 func Open() (*sql.DB, error) {
 	checkConfig()
 
@@ -59,6 +132,7 @@ func Open() (*sql.DB, error) {
 	if err != nil {
 		return nil, err
 	}
+	applyMigrations(db)
 
 	return db, nil
 }
diff --git a/go.mod b/go.mod
index b64cfc1..7b870ef 100644
--- a/go.mod
+++ b/go.mod
@@ -3,5 +3,6 @@ module wargh
 go 1.23.2
 
 require (
-	github.com/mattn/go-sqlite3 v1.14.24 // indirect
+	github.com/mattn/go-sqlite3 v1.14.24
+	github.com/umpc/go-sortedmap v0.0.0-20180422175548-64ab94c482f4
 )
diff --git a/go.sum b/go.sum
index 0de2071..b6e0fcc 100644
--- a/go.sum
+++ b/go.sum
@@ -1,4 +1,8 @@
+github.com/elliotchance/orderedmap/v2 v2.4.0 h1:6tUmMwD9F998FNpwFxA5E6NQvSpk2PVw7RKsVq3+2Cw=
+github.com/elliotchance/orderedmap/v2 v2.4.0/go.mod h1:85lZyVbpGaGvHvnKa7Qhx7zncAdBIBq6u56Hb1PRU5Q=
 github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/mattn/go-sqlite3 v1.14.24 h1:tpSp2G2KyMnnQu99ngJ47EIkWVmliIizyZBfPrBWDRM=
 github.com/mattn/go-sqlite3 v1.14.24/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=
+github.com/umpc/go-sortedmap v0.0.0-20180422175548-64ab94c482f4 h1:qk1XyC6UGfPa51PGmsTQJavyhfMLScqw97pEV3sFClI=
+github.com/umpc/go-sortedmap v0.0.0-20180422175548-64ab94c482f4/go.mod h1:X6iKjXCleSyo/LZzKZ9zDF/ZB2L9gC36I5gLMf32w3M=
diff --git a/main.go b/main.go
index c12892b..36b4070 100644
--- a/main.go
+++ b/main.go
@@ -6,12 +6,10 @@ import (
 	"wargh/db"
 )
 
-const DB_PATH = "wargh.db"
-
 func main() {
 	db.Init(&db.DBConfig{
-		DBPath:         DB_PATH,
-		MigrationsPath: "",
+		DBPath:         "wargh.db",
+		MigrationsPath: "migrations",
 	})
 
 	DB, err := db.Open()
@@ -20,7 +18,4 @@ func main() {
 		os.Exit(1)
 	}
 	defer DB.Close()
-
-	_, err = DB.Exec("CREATE TABLE test (id INTEGER PRIMARY KEY AUTOINCREMENT, value TEXT NOT NULL);")
-	log.Fatal(err)
 }
diff --git a/migrations/000_init.sql b/migrations/000_init.sql
new file mode 100644
index 0000000..0bb8bd3
--- /dev/null
+++ b/migrations/000_init.sql
@@ -0,0 +1,4 @@
+CREATE TABLE test (
+    id      INTEGER PRIMARY KEY AUTOINCREMENT,
+    test    TEXT    NOT NULL UNIQUE
+);
\ No newline at end of file
diff --git a/migrations/001_test.sql b/migrations/001_test.sql
new file mode 100644
index 0000000..888a230
--- /dev/null
+++ b/migrations/001_test.sql
@@ -0,0 +1,4 @@
+CREATE TABLE test2 (
+    id      INTEGER PRIMARY KEY AUTOINCREMENT,
+    test2   TEXT    NOT NULL UNIQUE
+);
\ No newline at end of file