acrookston · April 28, 2018 22:09 · Apr 28, 2018 · Apr 28, 2018 · Apr 28, 2018
diff --git a/MigrationCreateItems.swift b/MigrationCreateItems.swift
@@ -4,7 +4,7 @@
 //
 //  Created by Andrew C on 8/30/17.
 //  Copyright © 2017 Andrew Crookston. All rights reserved.
-//  Licence: MIT
+//  License: MIT
 //
 
 import Foundation

diff --git a/SQLiteMigration.swift b/SQLiteMigration.swift
@@ -4,7 +4,7 @@
 //
 //  Created by Andrew C on 8/30/17.
 //  Copyright © 2017 Andrew Crookston. All rights reserved.
-//  Licence: MIT
+//  License: MIT
 //
 
 import Foundation

diff --git a/MigrationCreateItems.swift b/MigrationCreateItems.swift
@@ -4,6 +4,7 @@
 //
 //  Created by Andrew C on 8/30/17.
 //  Copyright © 2017 Andrew Crookston. All rights reserved.
+//  Licence: MIT
 //
 
 import Foundation

diff --git a/SQLiteMigration.swift b/SQLiteMigration.swift
@@ -4,6 +4,7 @@
 //
 //  Created by Andrew C on 8/30/17.
 //  Copyright © 2017 Andrew Crookston. All rights reserved.
+//  Licence: MIT
 //
 
 import Foundation

diff --git a/MigrationCreateItems.swift b/MigrationCreateItems.swift
@@ -0,0 +1,31 @@
+//
+//  MigrationCreateItems.swift
+//  Stash
+//
+//  Created by Andrew C on 8/30/17.
+//  Copyright © 2017 Andrew Crookston. All rights reserved.
+//
+
+import Foundation
+import SQLite
+
+final class MigrationCreateItems: SQLiteMigration {
+    static let name: String = "create_items"
+
+    static func migrate(connection: Connection) -> Bool {
+        do {
+            try connection.run(Table(Item.tableName).create { t in
+                t.column(Expression<Int64>("id"), primaryKey: .autoincrement)
+                t.column(Expression<String>("uid"), unique: true)
+                t.column(Expression<Int64>("type"))
+                t.column(Expression<String>("content"))
+                t.column(Expression<String?>("notes"))
+                t.column(Expression<String?>("metadata"))
+            })
+            return true
+        } catch {
+            print("#DB MIGRATION ERROR: \(error)")
+            return false
+        }
+    }
+}
diff --git a/SQLiteMigration.swift b/SQLiteMigration.swift
@@ -0,0 +1,111 @@
+//
+//  SQLiteMigration.swift
+//  Stash
+//
+//  Created by Andrew C on 8/30/17.
+//  Copyright © 2017 Andrew Crookston. All rights reserved.
+//
+
+import Foundation
+import SQLite
+
+protocol SQLiteMigration {
+    static var name: String { get }
+    static func migrate(connection: Connection) -> Bool
+}
+
+final class SQLiteMigrator {
+
+    static func register(_ migration: SQLiteMigration.Type) {
+        sharedInstance.migrations.append(migration)
+    }
+
+    static func register(_ migrations: [SQLiteMigration.Type]) {
+        sharedInstance.migrations.append(contentsOf: migrations)
+    }
+
+    @discardableResult static func migrate(_ connection: Connection) -> Bool {
+        return sharedInstance.migrate(connection)
+    }
+
+    // MARK: - private
+
+    private static let schemaTable = Table("db_schema_migration")
+
+    private static let sharedInstance = SQLiteMigrator()
+
+    private var migrations = [SQLiteMigration.Type]()
+    private lazy var completed = [String]()
+
+
+    private init() {}
+
+    private func migrate(connection: Connection, migration: SQLiteMigration.Type) -> Bool {
+        print("#DB CHECKING MIGRATION: \(migration.name)")
+        if !hasMigrated(migration: migration) {
+            print("#DB MIGRATING: \(migration.name)")
+            if migration.migrate(connection: connection) {
+                completed(migration: migration, connection: connection)
+                return true
+            }
+            return true
+        }
+        return false
+    }
+
+    private func completed(migration: SQLiteMigration.Type, connection: Connection) {
+        completed.append(migration.name)
+
+        let name = Expression<String>("name")
+        do {
+            let insert = SQLiteMigrator.schemaTable.insert(name <- migration.self.name)
+            try connection.run(insert)
+        } catch {
+            print("#DB SAVE MIGRATED ERROR: \(error)")
+        }
+    }
+
+    private func hasMigrated(migration: SQLiteMigration.Type) -> Bool {
+        return completed.contains(migration.name)
+    }
+
+    private func setup(connection: Connection) {
+        createSchema(connection: connection)
+        completed = loadMigrations(connection: connection)
+    }
+
+    private func loadMigrations(connection: Connection) -> [String] {
+        var migrations = [String]()
+        let name = Expression<String>("name")
+        do {
+            for migration in try connection.prepare(SQLiteMigrator.schemaTable) {
+                migrations.append(migration[name])
+            }
+        } catch {
+            print("#DB LOAD MIGRATIONS ERROR: \(error)")
+        }
+        return migrations
+    }
+
+    @discardableResult private func createSchema(connection: Connection) -> Bool {
+        do {
+            try connection.run(SQLiteMigrator.schemaTable.create(ifNotExists: true) { t in
+                t.column(Expression<String>("name"), unique: true)
+            })
+            return true
+        } catch {
+            print("#DB MIGRATION ERROR: \(error)")
+            return false
+        }
+    }
+
+    private func migrate(_ connection: Connection) -> Bool {
+        setup(connection: connection)
+        for migration in migrations {
+            if !migrate(connection: connection, migration: migration) {
+                return false
+            }
+        }
+        return true
+    }
+}
diff --git a/usage.swift b/usage.swift
@@ -0,0 +1,3 @@
+// After creating a db connection:
+SQLiteMigrator.register(MigrationCreateItems.self)
+SQLiteMigrator.migrate(connection)
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