//===----------------------------------------------------------------------===//
// Copyright © 2025-2026 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 ContainerPersistence
import ContainerPlugin
import ContainerResource
import Containerization
import ContainerizationError
import ContainerizationOCI
import Foundation

extension Application {
    public struct ImageList: AsyncLoggableCommand {
        public init() {}
        public static let configuration = CommandConfiguration(
            commandName: "list",
            abstract: "List images",
            aliases: ["ls"])

        @Option(name: .long, help: "Format of the output")
        var format: ListFormat = .table

        @Flag(name: .shortAndLong, help: "Only output the image name")
        var quiet = false

        @Flag(name: .shortAndLong, help: "Verbose output")
        var verbose = false

        @OptionGroup
        public var logOptions: Flags.Logging

        public mutating func run() async throws {
            let containerSystemConfig: ContainerSystemConfig = try await Application.loadContainerSystemConfig()
            try Self.validate(quiet: quiet, verbose: verbose)

            var images = try await ClientImage.list().filter { img in
                !Utility.isInfraImage(name: img.reference, builderImage: containerSystemConfig.build.image, initImage: containerSystemConfig.vminit.image)
            }
            images.sort { $0.reference < $1.reference }

            // Quiet mode prints references directly and skips the more expensive
            // per-image manifest resolution.
            if quiet && format == .table {
                for image in images {
                    let processedReferenceString = try ClientImage.denormalizeReference(image.reference, containerSystemConfig: containerSystemConfig)
                    print(processedReferenceString)
                }
                return
            }

            try await Self.renderImages(
                images: images,
                format: format,
                verbose: verbose,
                resolve: { image in
                    try await image.toImageResource(containerSystemConfig: containerSystemConfig)
                },
                onError: { image, error in
                    log.warning(
                        "skipping unreadable image",
                        metadata: ["image": "\(image.reference)", "error": "\(error)"]
                    )
                },
                emit: Output.emit
            )
        }

        private static func validate(quiet: Bool, verbose: Bool) throws {
            if quiet && verbose {
                throw ContainerizationError(.invalidArgument, message: "cannot use flag --quiet and --verbose together")
            }
        }

        /// Renders readable images before reporting any skipped entries as a
        /// command failure, so callers can use the partial output without
        /// mistaking it for a complete listing.
        static func renderImages(
            images: [ClientImage],
            format: ListFormat,
            verbose: Bool,
            resolve: (ClientImage) async throws -> ImageResource,
            onError: (ClientImage, any Error) -> Void,
            emit: (String) -> Void
        ) async throws {
            var resources: [ImageResource] = []
            var skipped = 0
            for image in images {
                do {
                    resources.append(try await resolve(image))
                } catch {
                    guard isUnreadableImageError(error) else {
                        throw error
                    }
                    onError(image, error)
                    skipped += 1
                }
            }

            try Output.render(payload: resources, format: format, emit: emit) {
                if verbose {
                    return Output.renderTable(resources.flatMap { VerboseImageRow.rows(for: $0) })
                }
                return Output.renderTable(resources)
            }

            if skipped > 0 {
                throw ContainerizationError(.invalidState, message: "failed to read \(skipped) image(s)")
            }
        }

        private static func isUnreadableImageError(_ error: any Error) -> Bool {
            if let error = error as? ContainerizationError {
                return error.isCode(.notFound)
            }
            return error is DecodingError
        }
    }
}

/// A single row of the verbose image listing — one per platform variant.
private struct VerboseImageRow: ListDisplayable {
    let name: String
    let tag: String
    let indexDigest: String
    let os: String
    let arch: String
    let variant: String
    let fullSize: String
    let created: String
    let manifestDigest: String

    static var tableHeader: [String] {
        ["NAME", "TAG", "INDEX DIGEST", "OS", "ARCH", "VARIANT", "FULL SIZE", "CREATED", "MANIFEST DIGEST"]
    }

    var tableRow: [String] {
        [name, tag, indexDigest, os, arch, variant, fullSize, created, manifestDigest]
    }

    var quietValue: String {
        name
    }

    /// Flattens an ImageResource into one verbose image row entry per platform variant.
    static func rows(for resource: ImageResource) -> [VerboseImageRow] {
        let formatter = ByteCountFormatter()
        let reference = try? ContainerizationOCI.Reference.parse(resource.displayReference)
        let name = reference?.name ?? resource.displayReference
        let tag = reference?.tag ?? "<none>"
        let indexDigest = Utility.trimDigest(digest: resource.configuration.descriptor.digest)
        return
            resource.variants
            // Skip attestation manifests, which use the `unknown/unknown` platform.
            .filter { !($0.platform.os == "unknown" && $0.platform.architecture == "unknown") }
            .map { variant in
                VerboseImageRow(
                    name: name,
                    tag: tag,
                    indexDigest: indexDigest,
                    os: variant.platform.os,
                    arch: variant.platform.architecture,
                    variant: variant.platform.variant ?? "",
                    fullSize: formatter.string(fromByteCount: variant.size),
                    created: variant.config.created ?? "",
                    manifestDigest: Utility.trimDigest(digest: variant.digest)
                )
            }
    }
}