// ===----------------------------------------------------------------------===
//
// This source file is part of the Hummingbird DocC Middleware open source project
//
// Copyright (c) 2025 Röck+Cöde VoF. and the Hummingbird DocC Middleware project authors
// Licensed under the EUPL 1.2 or later.
//
// See LICENSE for license information
// See CONTRIBUTORS for the list of Hummingbird DocC Middleware project authors
//
// ===----------------------------------------------------------------------===

import Hummingbird

import struct Logging.Logger

/// A middleware that proxies requests to `DocC` documentation containers within a hosting app.
public struct DocCMiddleware {
    
    // MARK: Properties
    
    /// A type that contains the parameters to configure the middleware.
    let configuration: Configuration
    
    /// A protocol that defines file system interactions.
    let fileProvider: any FileProvider
    
    /// A type that interacts with the logging system.
    let logger: Logger
    
    /// A use case that checks whether a received URI could be processed or not.
    private let checkURI: CheckURIUseCase = .init()
    
    // MARK: Initializers
    
    /// Initializes this middleware with the root path to the `DocC` documentation containers in the file system.
    /// - Parameters:
    ///   - configuration: A type that contains the parameters to configure the middleware.
    ///   - logger: A type that interacts with the logging system.
    ///   - fileProvider: A type that conforms to the protocol that defines file system interactions, if any.
    init(
        configuration: Configuration,
        logger: Logger,
        fileProvider: (any FileProvider)? = nil
    ) {
        self.configuration = configuration
        self.fileProvider = if let fileProvider {
            fileProvider
        } else {
            LocalFileSystem(
                rootFolder: configuration.folderRoot,
                threadPool: configuration.threadPool,
                logger: logger
            )
        }
        self.logger = logger
    }
    
}

// MARK: - RouterMiddleware

extension DocCMiddleware: RouterMiddleware {
    
    // MARK: Type aliases
    
    public typealias Context = RequestContext
    public typealias Input = Request
    public typealias Output = Response
    
    // MARK: Functions
    
    public func handle(
        _ input: Input,
        context: any Context,
        next: (Input, any Context) async throws -> Output
    ) async throws -> Output {
        guard let uri = checkURI(input.uri) else {
            return try await next(input, context)
        }

        return try await next(input, context)
    }
    
}