| 1 | import SQLiteNIO |
| 2 | |
| 3 | /// One todo item as the page shows it. |
| 4 | public struct Todo: Sendable, Equatable { |
| 5 | public var id: Int |
| 6 | public var title: String |
| 7 | public var completed: Bool |
| 8 | } |
| 9 | |
| 10 | /// The app's SQLite database: one file, WAL mode, one connection. |
| 11 | /// |
| 12 | /// SQLiteNIO runs every call on its thread pool, and the one connection |
| 13 | /// serialises them. Each write below is a single SQL statement, so two |
| 14 | /// requests can never interleave half a change, and no transaction has to |
| 15 | /// span an `await`. |
| 16 | public final class Store: Sendable { |
| 17 | let db: SQLiteConnection |
| 18 | |
| 19 | /// Schema changes, in order. Only ever append to this list; never edit |
| 20 | /// or remove an entry, and never drop or rewrite data. |
| 21 | /// `PRAGMA user_version` records how many have run. |
| 22 | static let migrations: [String] = [ |
| 23 | """ |
| 24 | CREATE TABLE lists ( |
| 25 | id INTEGER PRIMARY KEY, |
| 26 | token TEXT NOT NULL UNIQUE, |
| 27 | created_at INTEGER NOT NULL DEFAULT (unixepoch()) |
| 28 | ); |
| 29 | CREATE TABLE todos ( |
| 30 | id INTEGER PRIMARY KEY AUTOINCREMENT, |
| 31 | list_id INTEGER NOT NULL REFERENCES lists(id), |
| 32 | title TEXT NOT NULL, |
| 33 | completed INTEGER NOT NULL DEFAULT 0, |
| 34 | created_at INTEGER NOT NULL DEFAULT (unixepoch()) |
| 35 | ); |
| 36 | CREATE INDEX todos_by_list ON todos(list_id, id); |
| 37 | """, |
| 38 | ] |
| 39 | |
| 40 | init(db: SQLiteConnection) { |
| 41 | self.db = db |
| 42 | } |
| 43 | |
| 44 | /// Opens (creating if needed) the database at `path` and brings its |
| 45 | /// schema up to date. |
| 46 | public static func open(path: String) async throws -> Store { |
| 47 | let db = try await SQLiteConnection.open(storage: .file(path: path)) |
| 48 | let store = Store(db: db) |
| 49 | do { |
| 50 | try await store.prepare() |
| 51 | } catch { |
| 52 | try? await db.close() |
| 53 | throw error |
| 54 | } |
| 55 | return store |
| 56 | } |
| 57 | |
| 58 | func prepare() async throws { |
| 59 | _ = try await db.query("PRAGMA journal_mode = WAL") |
| 60 | _ = try await db.query("PRAGMA synchronous = NORMAL") |
| 61 | _ = try await db.query("PRAGMA busy_timeout = 5000") |
| 62 | _ = try await db.query("PRAGMA foreign_keys = ON") |
| 63 | let version = try await db.query("PRAGMA user_version").first?.column("user_version")?.integer ?? 0 |
| 64 | for (index, sql) in Self.migrations.enumerated() where index >= version { |
| 65 | // The migration and its version bump commit together, or not at all. |
| 66 | try await db.withConnection { conn in |
| 67 | _ = try await conn.query("BEGIN IMMEDIATE") |
| 68 | do { |
| 69 | for statement in sql.split(separator: ";").map({ $0.trimmingWhitespace() }) where !statement.isEmpty { |
| 70 | _ = try await conn.query(String(statement)) |
| 71 | } |
| 72 | _ = try await conn.query("PRAGMA user_version = \(index + 1)") |
| 73 | _ = try await conn.query("COMMIT") |
| 74 | } catch { |
| 75 | _ = try? await conn.query("ROLLBACK") |
| 76 | throw error |
| 77 | } |
| 78 | } |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | public func close() async throws { |
| 83 | try await db.close() |
| 84 | } |
| 85 | |
| 86 | // MARK: Lists |
| 87 | |
| 88 | /// The list a cookie token names, if the app ever issued it. |
| 89 | public func list(token: String) async throws -> Int? { |
| 90 | try await db.query("SELECT id FROM lists WHERE token = ?", [.text(token)]) |
| 91 | .first?.column("id")?.integer |
| 92 | } |
| 93 | |
| 94 | /// Records a new, empty list under `token` and returns its id. |
| 95 | public func createList(token: String) async throws -> Int { |
| 96 | let rows = try await db.query("INSERT INTO lists (token) VALUES (?) RETURNING id", [.text(token)]) |
| 97 | guard let id = rows.first?.column("id")?.integer else { throw StoreError.noRowReturned } |
| 98 | return id |
| 99 | } |
| 100 | |
| 101 | // MARK: Todos |
| 102 | |
| 103 | public func todos(list: Int) async throws -> [Todo] { |
| 104 | try await db.query( |
| 105 | "SELECT id, title, completed FROM todos WHERE list_id = ? ORDER BY id", |
| 106 | [.integer(list)] |
| 107 | ).map { row in |
| 108 | Todo( |
| 109 | id: row.column("id")?.integer ?? 0, |
| 110 | title: row.column("title")?.string ?? "", |
| 111 | completed: row.column("completed")?.bool ?? false |
| 112 | ) |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | public func add(list: Int, title: String) async throws { |
| 117 | _ = try await db.query("INSERT INTO todos (list_id, title) VALUES (?, ?)", [.integer(list), .text(title)]) |
| 118 | } |
| 119 | |
| 120 | /// Flips one item. False if the list has no such item. |
| 121 | public func toggle(list: Int, id: Int) async throws -> Bool { |
| 122 | try await changed( |
| 123 | "UPDATE todos SET completed = 1 - completed WHERE id = ? AND list_id = ? RETURNING id", |
| 124 | [.integer(id), .integer(list)] |
| 125 | ) |
| 126 | } |
| 127 | |
| 128 | /// Renames one item. False if the list has no such item. |
| 129 | public func rename(list: Int, id: Int, title: String) async throws -> Bool { |
| 130 | try await changed( |
| 131 | "UPDATE todos SET title = ? WHERE id = ? AND list_id = ? RETURNING id", |
| 132 | [.text(title), .integer(id), .integer(list)] |
| 133 | ) |
| 134 | } |
| 135 | |
| 136 | /// Deletes one item. False if the list has no such item. |
| 137 | public func destroy(list: Int, id: Int) async throws -> Bool { |
| 138 | try await changed( |
| 139 | "DELETE FROM todos WHERE id = ? AND list_id = ? RETURNING id", |
| 140 | [.integer(id), .integer(list)] |
| 141 | ) |
| 142 | } |
| 143 | |
| 144 | /// Completes every item, or, if every item already is, reopens them all. |
| 145 | public func toggleAll(list: Int) async throws { |
| 146 | _ = try await db.query( |
| 147 | """ |
| 148 | UPDATE todos |
| 149 | SET completed = EXISTS (SELECT 1 FROM todos WHERE list_id = ?1 AND completed = 0) |
| 150 | WHERE list_id = ?1 |
| 151 | """, |
| 152 | [.integer(list)] |
| 153 | ) |
| 154 | } |
| 155 | |
| 156 | public func clearCompleted(list: Int) async throws { |
| 157 | _ = try await db.query("DELETE FROM todos WHERE list_id = ? AND completed = 1", [.integer(list)]) |
| 158 | } |
| 159 | |
| 160 | private func changed(_ sql: String, _ binds: [SQLiteData]) async throws -> Bool { |
| 161 | try await !db.query(sql, binds).isEmpty |
| 162 | } |
| 163 | } |
| 164 | |
| 165 | enum StoreError: Error { |
| 166 | case noRowReturned |
| 167 | } |
| 168 | |
| 169 | extension Substring { |
| 170 | func trimmingWhitespace() -> Substring { |
| 171 | var s = self |
| 172 | while let c = s.first, c.isWhitespace { s.removeFirst() } |
| 173 | while let c = s.last, c.isWhitespace { s.removeLast() } |
| 174 | return s |
| 175 | } |
| 176 | } |
| 177 | |
amadan