//===----------------------------------------------------------------------===//
// Copyright © 2025 Apple Inc. and the container project authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//===----------------------------------------------------------------------===//

import ContainerClient
import ContainerXPC
import Containerization
import ContainerizationError
import Foundation
import Logging

struct KernelHarness {
    private let log: Logging.Logger
    private let service: KernelService

    init(service: KernelService, log: Logging.Logger) {
        self.log = log
        self.service = service
    }

    public func install(_ message: XPCMessage) async throws -> XPCMessage {
        let kernelFilePath = try message.kernelFilePath()
        let platform = try message.platform()

        guard let kernelTarUrl = try message.kernelTarURL() else {
            // We have been given a path to a kernel binary on disk
            guard let kernelFile = URL(string: kernelFilePath) else {
                throw ContainerizationError(.invalidArgument, message: "Invalid kernel file path: \(kernelFilePath)")
            }
            try await self.service.installKernel(kernelFile: kernelFile, platform: platform)
            return message.reply()
        }

        let progressUpdateService = ProgressUpdateService(message: message)
        try await self.service.installKernelFrom(tar: kernelTarUrl, kernelFilePath: kernelFilePath, platform: platform, progressUpdate: progressUpdateService?.handler)
        return message.reply()
    }

    public func getDefaultKernel(_ message: XPCMessage) async throws -> XPCMessage {
        guard let platformData = message.dataNoCopy(key: .systemPlatform) else {
            throw ContainerizationError(.invalidArgument, message: "Missing SystemPlatform")
        }
        let platform = try JSONDecoder().decode(SystemPlatform.self, from: platformData)
        let kernel = try await self.service.getDefaultKernel(platform: platform)
        let reply = message.reply()
        let data = try JSONEncoder().encode(kernel)
        reply.set(key: .kernel, value: data)
        return reply
    }
}

extension XPCMessage {
    fileprivate func platform() throws -> SystemPlatform {
        guard let platformData = self.dataNoCopy(key: .systemPlatform) else {
            throw ContainerizationError(.invalidArgument, message: "Missing SystemPlatform in XPC Message")
        }
        let platform = try JSONDecoder().decode(SystemPlatform.self, from: platformData)
        return platform
    }

    fileprivate func kernelFilePath() throws -> String {
        guard let kernelFilePath = self.string(key: .kernelFilePath) else {
            throw ContainerizationError(.invalidArgument, message: "Missing kernel file path in XPC Message")
        }
        return kernelFilePath
    }

    fileprivate func kernelTarURL() throws -> URL? {
        guard let kernelTarURLString = self.string(key: .kernelTarURL) else {
            return nil
        }
        guard let k = URL(string: kernelTarURLString) else {
            throw ContainerizationError(.invalidArgument, message: "Cannot parse URL from \(kernelTarURLString)")
        }
        return k
    }
}
