import FluentKit
import Foundation
import HummingbirdFluent

/// A `Sendable` snapshot of an ``ExampleRecord``, safe to return across concurrency boundaries.
///
/// Repositories return these value-type snapshots rather than FluentKit models, which are mutable reference
/// types that must not escape the database's execution context.
public struct Example: Sendable, Equatable {

    // MARK: Properties

    /// The record's primary key, or `nil` if it has never been saved.
    public let id: UUID?
    /// The record's name.
    public let name: String

}

/// Reads and writes ``ExampleRecord`` rows through the default database.
///
/// This is the shape every real repository takes: it holds the `Sendable` `Fluent` service, resolves the
/// default database per call, and maps FluentKit models to `Sendable` snapshots before returning — so no
/// model ever escapes across an async boundary. It is reference scaffolding paired with ``ExampleRecord``;
/// replace it with the first real repository once a domain model is defined.
public struct ExampleRepository: Sendable {

    // MARK: Properties

    /// The service providing the default database the repository reads and writes through.
    private let fluent: Fluent

    // MARK: Initializers

    /// Creates a repository backed by the given `Fluent` service.
    /// - Parameter fluent: the service whose default database the repository operates on.
    public init(fluent: Fluent) {
        self.fluent = fluent
    }

    // MARK: Methods

    /// Inserts a record with the given name.
    /// - Parameter name: the name of the record to insert.
    /// - Returns: a `Sendable` snapshot of the inserted record, including its assigned identifier.
    public func create(name: String) async throws -> Example {
        let record = ExampleRecord(name: name)

        try await record.save(on: fluent.db())

        return Example(id: record.id, name: record.name)
    }

    /// Fetches every record, ordered by name.
    /// - Returns: a `Sendable` snapshot of each record, sorted by name.
    public func all() async throws -> [Example] {
        try await ExampleRecord.query(on: fluent.db())
            .sort(\.$name)
            .all()
            .map { Example(id: $0.id, name: $0.name) }
    }

}