From e68ded1b3c48e866df9a8fb05d6d061eaa35042a Mon Sep 17 00:00:00 2001
From: Marc Cataford <mcat@riseup.net>
Date: Thu, 11 Jul 2024 00:09:24 -0400
Subject: [PATCH] refactor: isolate db handler

---
 cobble.go       | 11 +++--------
 database.go     | 45 +++++++++++++++++++++++++++++++++++++++++++++
 migrate.go      | 11 ++---------
 migrate_test.go |  8 ++++----
 models.go       | 14 +-------------
 5 files changed, 55 insertions(+), 34 deletions(-)
 create mode 100644 database.go

diff --git a/cobble.go b/cobble.go
index 700054b..9991768 100644
--- a/cobble.go
+++ b/cobble.go
@@ -18,13 +18,8 @@ var up = &cobra.Command{
 	Run: func(cmd *cobra.Command, args []string) {
 		dbPort, _ := strconv.Atoi(os.Getenv("DB_PORT"))
 
-		dbConnection, err := ConnectToDatabase(DatabaseConfiguration{
-			User:         os.Getenv("DB_APP_USER"),
-			Password:     os.Getenv("DB_APP_PASSWORD"),
-			DatabaseName: os.Getenv("DB_NAME"),
-			Host:         os.Getenv("DB_HOST"),
-			Port:         dbPort,
-		})
+		db := NewDatabase(os.Getenv("DB_HOST"), dbPort)
+		err := db.Connect(os.Getenv("DB_APP_USER"), os.Getenv("DB_APP_PASSWORD"), os.Getenv("DB_NAME"))
 
 		if err != nil {
 			log.Printf("Failed to connect to the database: %s", err)
@@ -36,7 +31,7 @@ var up = &cobra.Command{
 
 		for _, migration := range migrationHistory {
 			log.Printf("%s", migration.Name)
-			if err = migrate(dbConnection, migration.Path); err != nil {
+			if err = migrate(db, migration.Path); err != nil {
 				os.Exit(1)
 			}
 		}
diff --git a/database.go b/database.go
new file mode 100644
index 0000000..9f8126b
--- /dev/null
+++ b/database.go
@@ -0,0 +1,45 @@
+package main
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+	_ "github.com/lib/pq"
+)
+
+type Database struct {
+	Host       string
+	Port       int
+	connection *sql.DB
+}
+
+func NewDatabase(host string, port int) Database {
+	return Database{
+		Host: host,
+		Port: port,
+	}
+}
+
+func (d *Database) Connect(user string, password string, dbname string) error {
+	connectionString := fmt.Sprintf("postgresql://%s:%s@%s:%d?sslmode=disable", user, password, d.Host, d.Port)
+
+	conn, err := sql.Open(dbname, connectionString)
+
+	if err != nil {
+		return err
+	}
+
+	d.connection = conn
+
+	return nil
+}
+
+func (d Database) Execute(sql string) error {
+	if d.connection == nil {
+		return errors.New("Cannot execute SQL without being connected to a database.")
+	}
+
+	_, err := d.connection.Exec(sql)
+
+	return err
+}
diff --git a/migrate.go b/migrate.go
index c37492b..784a331 100644
--- a/migrate.go
+++ b/migrate.go
@@ -8,9 +8,7 @@ package main
 import (
 	"bufio"
 	"bytes"
-	"database/sql"
-	"fmt"
-	_ "github.com/lib/pq"
+
 	"log"
 	"os"
 	"path/filepath"
@@ -41,7 +39,7 @@ func migrate(db DB, migrationPath string) error {
 
 	log.Printf("SQL: %s", migrationSql)
 
-	_, err = db.Exec(migrationSql)
+	err = db.Execute(migrationSql)
 
 	if err != nil {
 		log.Printf("Failed to run %s: %s", migrationPath, err)
@@ -126,8 +124,3 @@ func getMigrations(migrationsRoot string) ([]Migration, error) {
 
 	return migrationGraph.GetLinearHistory()
 }
-
-func ConnectToDatabase(config DatabaseConfiguration) (*sql.DB, error) {
-	connectionString := fmt.Sprintf("postgresql://%s:%s@%s:%d?sslmode=disable", config.User, config.Password, config.Host, config.Port)
-	return sql.Open(config.DatabaseName, connectionString)
-}
diff --git a/migrate_test.go b/migrate_test.go
index da15370..01f68d2 100644
--- a/migrate_test.go
+++ b/migrate_test.go
@@ -19,18 +19,18 @@ type MockResult struct {
 	sql.Result
 }
 
-func (m *MockSqlDB) Exec(sql string, args ...any) (sql.Result, error) {
+func (m *MockSqlDB) Execute(sql string) error {
 	m.queries = append(m.queries, sql)
 
 	if m.mockedError != nil {
-		return MockResult{}, m.mockedError
+		return m.mockedError
 	}
 
 	if m.mockedResult != nil {
-		return m.mockedResult, nil
+		return nil
 	}
 
-	return MockResult{}, nil
+	return nil
 }
 
 func TestGetMigrationsGathersSqlFiles(t *testing.T) {
diff --git a/models.go b/models.go
index e93e9a1..16489ec 100644
--- a/models.go
+++ b/models.go
@@ -1,9 +1,5 @@
 package main
 
-import (
-	"database/sql"
-)
-
 type MigrationHeaders struct {
 	Requirements []string
 }
@@ -15,14 +11,6 @@ type Migration struct {
 	Run      bool
 }
 
-type DatabaseConfiguration struct {
-	Host         string
-	User         string
-	Password     string
-	DatabaseName string
-	Port         int
-}
-
 type MigrationGraph struct {
 	// Reference to the root of the graph.
 	Root *Migration
@@ -33,5 +21,5 @@ type MigrationGraph struct {
 }
 
 type DB interface {
-	Exec(sql string, args ...any) (sql.Result, error)
+	Execute(sql string) error
 }