//===----------------------------------------------------------------------===//
// Copyright © 2026 Apple Inc. and the container project authors.
//
// 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 ArgumentParser
import ContainerAPIClient
import ContainerLog
import ContainerPersistence
import ContainerResource
import ContainerizationError
import ContainerizationOCI
import Foundation
import Logging
import SystemPackage

public struct ClusterLoadImage: AsyncParsableCommand {
    public init() {}

    private static let ctrPath = "/usr/local/bin/ctr"

    public static let configuration = CommandConfiguration(
        commandName: "load-image",
        abstract: "Load a container image into a cluster's containerd"
    )

    @Option(name: .long, help: "Cluster name")
    var name: String = ClusterHelper.defaultName

    @Argument(help: "Image reference to load (e.g. demo-api:latest)")
    var image: String

    @Option(
        help: "Platform of the image to load (format: os/arch[/variant], default: linux/arm64)"
    )
    var platform: String?

    @Option(name: .long, help: "Optionally load into specific nodes only")
    var node: [String] = []

    public func run() async throws {
        LoggingSystem.bootstrap { _ in StderrLogHandler() }
        let log = Logger(label: ClusterHelper.pluginName)

        let tmpFile = FilePath(FileManager.default.temporaryDirectory.path(percentEncoded: false))
            .appending("cluster-image-\(UUID().uuidString).tar")
        defer { try? FileManager.default.removeItem(atPath: tmpFile.string) }

        let containerSystemConfig: ContainerSystemConfig = try await ConfigurationLoader.load()

        let client = ContainerClient()

        // Guard: refuse to operate on a container not owned by this plugin.
        let container = try await client.get(id: name)
        guard container.configuration.labels[ResourceLabelKeys.plugin] == ClusterHelper.pluginName else {
            log.error("container is not a cluster, refusing image load", metadata: ["name": "\(name)"])
            throw ContainerizationError(.invalidArgument, message: "\(name) is not a cluster")
        }

        let workers = try await ClusterHelper.workerContainerNames(clusterName: name, client: client)
        let targets = try Self.resolveTargets(clusterName: name, nodes: node, workers: workers)

        log.info("Saving image", metadata: ["ref": "\(image)"])
        let fq = ClusterHelper.fqReference(image)
        let resolvedPlatform = try platform.map { try Platform(from: $0) } ?? Platform(from: "linux/\(Arch.hostArchitecture().rawValue)")
        try await ClientImage.save(references: [fq], out: tmpFile.string, platform: resolvedPlatform, containerSystemConfig: containerSystemConfig)

        var failures: [(node: String, error: Error)] = []
        for target in targets {
            do {
                try await Self.importImage(into: target, tarPath: tmpFile.string, client: client, log: log)
            } catch {
                log.error("Failed to load image", metadata: ["target": "\(target)", "error": "\(error)"])
                failures.append((node: target, error: error))
            }
        }

        guard failures.isEmpty else {
            let detail = failures.map { "\($0.node): \($0.error)" }.joined(separator: "; ")
            throw ContainerizationError(
                .internalError, message: "failed to load image into \(failures.count) node(s): \(detail)")
        }
    }

    /// Resolves which node containers to load the image into: `nodes` (each validated
    /// as the control plane or one of `workers`) if non-empty, otherwise the control
    /// plane plus every worker.
    static func resolveTargets(clusterName: String, nodes: [String], workers: [String]) throws -> [String] {
        guard !nodes.isEmpty else {
            return [clusterName] + workers
        }
        var seen = Set<String>()
        var targets: [String] = []
        for node in nodes {
            guard node == clusterName || workers.contains(node) else {
                throw ContainerizationError(
                    .invalidArgument, message: "\(node) is not a node of cluster \(clusterName)")
            }
            if seen.insert(node).inserted {
                targets.append(node)
            }
        }
        return targets
    }

    private static func importImage(
        into target: String, tarPath: String, client: ContainerClient, log: Logger
    ) async throws {
        log.info("Importing image into node", metadata: ["target": "\(target)"])
        guard let inputHandle = FileHandle(forReadingAtPath: tarPath) else {
            throw ContainerizationError(.internalError, message: "failed to open image tar: \(tarPath)")
        }
        defer { try? inputHandle.close() }

        let importConfig = ProcessConfiguration(
            executable: Self.ctrPath,
            arguments: ["--namespace", "k8s.io", "images", "import", "-"],
            environment: [],
            terminal: false
        )
        let importProc = try await client.createProcess(
            containerId: target,
            processId: UUID().uuidString.lowercased(),
            configuration: importConfig,
            stdio: [inputHandle, nil, nil]
        )
        try await importProc.start()
        let importCode = try await importProc.wait()
        guard importCode == 0 else {
            throw ContainerizationError(
                .internalError,
                message: "ctr import exited \(importCode) on \(target)")
        }
    }
}