PackageGenerator.swift

import DangerShellExecutor
import Foundation
import Version

struct PackageGenerator {
    let folder: String
    let generatedFolder: String
    let packageListMaker: PackageListMaking
    let fileCreator: FileCreating
    private var masterPackageName: String { "PACKAGES" }

    init(folder: String,
         generatedFolder: String,
         packageListMaker: PackageListMaking? = nil,
         fileCreator: FileCreating = FileCreator()) {
        self.folder = folder
        self.generatedFolder = generatedFolder
        self.fileCreator = fileCreator
        if let packageListMaker = packageListMaker {
            self.packageListMaker = packageListMaker
        } else {
            self.packageListMaker = PackageListMaker(folder: folder, fileManager: .default, dataReader: FileReader())
        }
    }

    func generateMasterPackageDescription(forSwiftToolsVersion toolsVersion: Version,
                                          macOSVersion: Version) throws {
        let header = makePackageDescriptionHeader(forSwiftToolsVersion: toolsVersion)
        let packages = packageListMaker.makePackageList()
        let platform = makeSupportedPlatform(forMacOSVersion: macOSVersion)

        var description = "\(header)\n\n" +
            "import PackageDescription\n\n" +
            "let package = Package(\n" +
            "    name: \"\(masterPackageName)\",\n" +
            (platform.isEmpty ? "" : "    platforms: [\(platform)],\n") +
            "    products: [.executable(name: \"DangerDependencies\", " +
            "targets: [\"\(masterPackageName)\"])]," +
            "\n" +
            "    dependencies: [\n"

        for (index, package) in packages.enumerated() {
            if index > 0 {
                description += ",\n"
            }

            description.append("        \(package.dependencyString(forToolsVersion: toolsVersion))")
        }

        description.append("\n    ],\n")
        description.append("    targets: [.executableTarget(name: \"\(masterPackageName)\", dependencies: [")

        if !packages.isEmpty {
            description.append("\"")
            description.append(packages.map(\.name).joined(separator: "\", \""))
            description.append("\"")
        }

        description.append("])],\n")

        var versionString = String(toolsVersion.major)

        if toolsVersion == Version(major: 4, minor: 2, patch: 0) {
            versionString.append(".\(toolsVersion.minor)")
        }

        description.append("    swiftLanguageVersions: [.version(\"\(versionString)\")]\n)")

        fileCreator.createFile(atPath: generatedFolder.appendingPath("Package.swift"),
                               contents: Data(description.utf8))
    }

    func makePackageDescriptionHeader(forSwiftToolsVersion toolsVersion: Version) -> String {
        let swiftVersion = "\(toolsVersion.major).\(toolsVersion.minor)"
        let generationVersion = 3

        return "// swift-tools-version:\(swiftVersion)\n" +
            "// danger-dependency-generator-version:\(generationVersion)"
    }

    func makeSupportedPlatform(forMacOSVersion macOSVersion: Version) -> String {
        if case .null = macOSVersion { return "" }
        switch macOSVersion.major {
        case 10 where (10 ... 15).contains(macOSVersion.minor):
            return ".macOS(.v10_\(macOSVersion.minor))"
        case 11...:
            return ".macOS(.v\(macOSVersion.major))"
        default:
            return ""
        }
    }
}