Improve Decodable implementation

Sources/Core/Spec+Context.swift

@@ -0,0 +1,51 @@
+//  Spec+Context.swift
+
+import Foundation
+
+extension Spec.Product {
+    func makeContext() -> [String: Any] {
+        [
+            "name": name,
+            "productType": productType.rawValue,
+            "targets": targets
+        ]
+    }
+}
+
+extension Spec.RemoteDependency {
+    func makeContext() -> [String: Any] {
+        var retVal = [
+            "name": name,
+            "url": url
+        ]
+        if let ref {
+            switch ref {
+            case .branch(let value):
+                retVal["branch"] = value
+            case .revision(let value):
+                retVal["revision"] = value
+            case .version(let value):
+                retVal["version"] = value
+            }
+        }
+        return retVal.compactMapValues { $0 }
+    }
+}
+
+extension Spec {
+    func makeContext() -> [String: Any] {
+        let values: [String: Any?] = [
+            "package_name": name,
+            "platforms": platforms,
+            "local_dependencies": localDependencies,
+            "remote_dependencies": remoteDependencies.map{ $0.makeContext() },
+            "products": products.map{ $0.makeContext() },
+            "targets": targets,
+            "local_binary_targets": localBinaryTargets,
+            "remote_binary_targets": remoteBinaryTargets,
+            "swift_tools_version": swiftToolsVersion,
+            "swift_versions": swiftLanguageVersions
+        ]
+        return values.compactMapValues { $0 }
+    }
+}

Sources/Core/SpecGenerator.swift

@@ -40,9 +40,7 @@ final class SpecGenerator {
                 return Spec.RemoteDependency(
                     name: dependency.name,
                     url: remoteDependency.url ?? dependency.url,
-                    version: remoteDependency.version ?? dependency.version,
-                    revision: remoteDependency.revision ?? dependency.revision,
-                    branch: remoteDependency.branch ?? dependency.branch
+                    ref: remoteDependency.ref ?? dependency.ref
                 )
             }
 

Sources/Models/Dependencies.swift

@@ -9,19 +9,23 @@ struct Dependencies: Decodable {
 struct Dependency: Decodable {
     let name: String
     let url: String
-    let version: String?
-    let revision: String?
-    let branch: String?
+    let ref: Ref
 
-    init(name: String, url: String, version: String?, revision: String?, branch: String?) {
-        guard version != nil || revision != nil || branch != nil else {
-            fatalError("You need to provide at least one of the following: version, revision or branch")
-        }
-
+    enum CodingKeys: String, CodingKey {
+        case name
+        case url
+    }
+
+    init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        self.name = try container.decode(String.self, forKey: .name)
+        self.url = try container.decode(String.self, forKey: .url)
+        self.ref = try Ref(from: decoder)
+    }
+
+    init(name: String, url: String, ref: Ref) {
         self.name = name
         self.url = url
-        self.version = version
-        self.revision = revision
-        self.branch = branch
+        self.ref = ref
     }
 }

Sources/Models/Ref.swift

@@ -0,0 +1,29 @@
+//  Ref.swift
+
+import Foundation
+
+enum Ref: Decodable {
+    case version(String)
+    case revision(String)
+    case branch(String)
+
+    enum CodingKeys: String, CodingKey {
+        case version
+        case revision
+        case branch
+    }
+
+    init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+
+        if let version = try container.decodeIfPresent(String.self, forKey: .version) {
+            self = .version(version)
+        } else if let revision = try container.decodeIfPresent(String.self, forKey: .revision) {
+            self = .revision(revision)
+        } else if let branch = try container.decodeIfPresent(String.self, forKey: .branch) {
+            self = .branch(branch)
+        } else {
+            throw DecodingError.dataCorruptedError(forKey: CodingKeys.version, in: container, debugDescription: "Expected one of version, revision, or branch to be present.")
+        }
+    }
+}

Sources/Models/Spec.swift

@@ -8,21 +8,14 @@ struct Spec: Decodable {
 
     struct Product: Decodable {
         let name: String
-        let productType: String
+        let productType: ProductType
         let targets: [String]
 
         enum CodingKeys: CodingKey {
             case name
             case productType
             case targets
         }
-
-        init(from decoder: Decoder) throws {
-            let container = try decoder.container(keyedBy: CodingKeys.self)
-            self.name = try container.decode(String.self, forKey: .name)
-            self.productType = try container.decode(ProductType.self, forKey: .productType).rawValue
-            self.targets = try container.decode([String].self, forKey: .targets)
-        }
     }
 
     enum ProductType: String, Decodable {
@@ -39,37 +32,24 @@ struct Spec: Decodable {
     struct RemoteDependency: Decodable {
         let name: String
         let url: String?
-        let version: String?
-        let revision: String?
-        let branch: String?
+        let ref: Ref?
 
         enum CodingKeys: CodingKey {
             case name
             case url
-            case version
-            case revision
-            case branch
         }
 
         init(from decoder: Decoder) throws {
             let container = try decoder.container(keyedBy: CodingKeys.self)
             self.name = try container.decode(String.self, forKey: .name)
             self.url = try container.decodeIfPresent(String.self, forKey: .url)
-            self.version = try container.decodeIfPresent(String.self, forKey: .version)
-            self.revision = try container.decodeIfPresent(String.self, forKey: .revision)
-            self.branch = try container.decodeIfPresent(String.self, forKey: .branch)
+            self.ref = (try? Ref(from: decoder)) ?? nil
         }
 
-        init(name: String, url: String, version: String?, revision: String?, branch: String?) {
-            guard version != nil || revision != nil || branch != nil else {
-                fatalError("You need to provide at least one of the following: version, revision or branch")
-            }
-
+        init(name: String, url: String, ref: Ref) {
             self.name = name
             self.url = url
-            self.version = version
-            self.revision = revision
-            self.branch = branch
+            self.ref = ref
         }
     }
 
@@ -181,21 +161,3 @@ struct Spec: Decodable {
         self.swiftLanguageVersions = swiftLanguageVersions
     }
 }
-
-extension Spec {
-    func makeContext() -> [String: Any] {
-        let values: [String: Any?] = [
-            "package_name": name,
-            "platforms": platforms,
-            "local_dependencies": localDependencies,
-            "remote_dependencies": remoteDependencies,
-            "products": products,
-            "targets": targets,
-            "local_binary_targets": localBinaryTargets,
-            "remote_binary_targets": remoteBinaryTargets,
-            "swift_tools_version": swiftToolsVersion,
-            "swift_versions": swiftLanguageVersions
-        ]
-        return values.compactMapValues { $0 }
-    }
-}