Anviking · Anviking · Sep 19, 2016 · Sep 19, 2016
diff --git a/Decodable.xcodeproj/project.pbxproj b/Decodable.xcodeproj/project.pbxproj
@@ -59,6 +59,10 @@
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 		8F956D1F1B4D6FF700243072 /* Operators.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8F956D1E1B4D6FF700243072 /* Operators.swift */; };
 		8FA733591D328D13003A90A7 /* Header.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8F3E45AF1D32853F00FB71FC /* Header.swift */; };
+		8FA8B0601D90A4A3008E5728 /* ErrorFormatter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8FA8B05F1D90A4A3008E5728 /* ErrorFormatter.swift */; };
+		8FA8B0611D90A4A3008E5728 /* ErrorFormatter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8FA8B05F1D90A4A3008E5728 /* ErrorFormatter.swift */; };
+		8FA8B0621D90A4A3008E5728 /* ErrorFormatter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8FA8B05F1D90A4A3008E5728 /* ErrorFormatter.swift */; };
+		8FA8B0631D90A4A3008E5728 /* ErrorFormatter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8FA8B05F1D90A4A3008E5728 /* ErrorFormatter.swift */; };
 		8FB48ECA1D306C4700BC50A1 /* KeyPath.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8FB48EC91D306C4700BC50A1 /* KeyPath.swift */; };
 		8FB48ECB1D306C4700BC50A1 /* KeyPath.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8FB48EC91D306C4700BC50A1 /* KeyPath.swift */; };
 		8FB48ECC1D306C4700BC50A1 /* KeyPath.swift in Sources */ = {isa = PBXBuildFile; fileRef = 8FB48EC91D306C4700BC50A1 /* KeyPath.swift */; };
@@ -139,6 +143,7 @@
 		8F87BCBA1B580CE200E53A8C /* ErrorPathTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ErrorPathTests.swift; sourceTree = "<group>"; };
 		8F87BCC31B592F0E00E53A8C /* DecodingError.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DecodingError.swift; sourceTree = "<group>"; };
 		8F956D1E1B4D6FF700243072 /* Operators.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Operators.swift; sourceTree = "<group>"; };
+		8FA8B05F1D90A4A3008E5728 /* ErrorFormatter.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ErrorFormatter.swift; sourceTree = "<group>"; };
 		8FB48EC91D306C4700BC50A1 /* KeyPath.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = KeyPath.swift; sourceTree = "<group>"; };
 		8FD3D92E1C270A2D00D1AF4E /* MissingKeyOperatorTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MissingKeyOperatorTests.swift; sourceTree = "<group>"; };
 		8FE7B5621B4C9FB900837609 /* Decodable.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Decodable.framework; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -261,6 +266,7 @@
 				8F72DC551C3CB8C500A39E10 /* NSValueCastable.swift */,
 				8F3E45A31D327E4500FB71FC /* Decoders.swift */,
 				8FB48EC91D306C4700BC50A1 /* KeyPath.swift */,
+				8FA8B05F1D90A4A3008E5728 /* ErrorFormatter.swift */,
 				8F3E45991D31362B00FB71FC /* OptionalKeyPath.swift */,
 				8F956D1E1B4D6FF700243072 /* Operators.swift */,
 				8F00623E1C81EF61007BCF48 /* Overloads.swift */,
@@ -624,6 +630,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				8F87BCC51B592F0E00E53A8C /* DecodingError.swift in Sources */,
+				8FA8B0611D90A4A3008E5728 /* ErrorFormatter.swift in Sources */,
 				8FFAB8131B7CFA9500E2D724 /* Parse.swift in Sources */,
 				8F012EF61BB5A920007D0B5C /* Castable.swift in Sources */,
 				8FB48ECB1D306C4700BC50A1 /* KeyPath.swift in Sources */,
@@ -664,6 +671,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				57FCDE5B1BA283C900130C48 /* DecodingError.swift in Sources */,
+				8FA8B0631D90A4A3008E5728 /* ErrorFormatter.swift in Sources */,
 				57FCDE5C1BA283C900130C48 /* Parse.swift in Sources */,
 				8F012EF81BB5A928007D0B5C /* Castable.swift in Sources */,
 				8FB48ECD1D306C4700BC50A1 /* KeyPath.swift in Sources */,
@@ -688,6 +696,7 @@
 				8FB48ECA1D306C4700BC50A1 /* KeyPath.swift in Sources */,
 				8FE7B57E1B4CA01400837609 /* Decodable.swift in Sources */,
 				8F72DC561C3CB8C500A39E10 /* NSValueCastable.swift in Sources */,
+				8FA8B0601D90A4A3008E5728 /* ErrorFormatter.swift in Sources */,
 				8F3E459A1D31362B00FB71FC /* OptionalKeyPath.swift in Sources */,
 				8F00623F1C81EF61007BCF48 /* Overloads.swift in Sources */,
 				8F3E45B81D32884700FB71FC /* Documentation.swift in Sources */,
@@ -724,6 +733,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				D0DC547A1B78150900F79CB0 /* DecodingError.swift in Sources */,
+				8FA8B0621D90A4A3008E5728 /* ErrorFormatter.swift in Sources */,
 				8FFAB8141B7CFA9500E2D724 /* Parse.swift in Sources */,
 				8F012EF71BB5A920007D0B5C /* Castable.swift in Sources */,
 				8FB48ECC1D306C4700BC50A1 /* KeyPath.swift in Sources */,

diff --git a/Sources/DecodingError.swift b/Sources/DecodingError.swift
@@ -99,6 +99,30 @@ public enum DecodingError: Error, Equatable {
 
 }
 
+extension DecodingError: CustomStringConvertible {
+
+    private var errorMessage: String {
+        switch self {
+        case let .typeMismatch(expected, actual, _):
+            return "TypeMismatch: expected \(expected), not \(actual)"
+        case let .missingKey(key, _):
+            return "MissingKey: \(key)"
+        case .rawRepresentableInitializationError(_, _):
+            return "RawRepresentableInitializationError: could not be used to initialize \("TYPE").)" // FIXME
+        case let .other(error, _):
+            return "\(error)"
+        }
+    }
+
+    public var description: String {
+        var formatter = JSONErrorFormatter(path: metadata.path, message: errorMessage)
+        guard let rootObject = metadata.rootObject else {
+            return debugDescription // FIXME: Don't do this
+        }
+        return formatter.format(json: rootObject)
+    }
+}
+
 
 // Allow types to be used in pattern matching
 // E.g case typeMismatchError(NSNull.self, _, _) but be careful

diff --git a/Sources/ErrorFormatter.swift b/Sources/ErrorFormatter.swift
@@ -0,0 +1,171 @@
+//
+//  ErrorFormatter.swift
+//  Decodable
+//
+//  Created by Johannes Lund on 2016-09-20.
+//  Copyright © 2016 anviking. All rights reserved.
+//
+
+import Foundation
+
+extension String {
+    var indented: String {
+        return "  " + self.replacingOccurrences(of: "\n", with: "\n  ")
+    }
+
+    func replaceNewline(with string: String) -> String {
+        return replacingOccurrences(of: "\n", with: string)
+    }
+}
+
+/* TODO: Propagate errors through arrays
+enum DebugKey {
+
+    /// Dictionary/Object key
+    case key(String)
+
+    /// Array index
+    case index(Int)
+
+    var key: String? {
+        switch self {
+        case .key(let key):
+            return key
+        default:
+            return nil
+        }
+    }
+
+    var index: Int? {
+        switch self {
+        case .index(let index):
+            return index
+        default:
+            return nil
+        }
+    }
+}
+
+extension DebugKey: ExpressibleByStringLiteral {
+    public init(stringLiteral value: String) {
+        self = .key(value)
+    }
+
+    public init(extendedGraphemeClusterLiteral value: String) {
+        self = .key(value)
+    }
+
+    public init(unicodeScalarLiteral value: String) {
+        self = .key(value)
+    }
+}
+
+extension DebugKey: ExpressibleByIntegerLiteral {
+    public init(integerLiteral value: Int) {
+        self = .index(value)
+    }
+
+}
+*/
+/// Sorry. /Past me
+struct JSONErrorFormatter {
+    var path: [String]
+    let message: String
+
+    mutating func format(json: Any) -> String {
+        var result = ""
+        switch json {
+        case let json as NSDictionary:
+
+            for (key, value) in json {
+                result.append("\n")
+
+                // Check if key matches first item in `path`.
+                var highlightMatch = false
+                var isFinalKey = false
+                //if let a = (key as? String), let b = path.first?.key, a == b {
+                if let a = (key as? String), let b = path.first, a == b {
+                    highlightMatch = true
+                    path.removeFirst()
+                }
+
+                if path.count == 0 && highlightMatch {
+                    isFinalKey = true
+                }
+
+                var formattedValue = format(json: value)
+                let formattedKey = "\(key)"
+
+                switch (highlightMatch, formattedValue.contains("\n")) {
+                case (true, true):
+                    formattedValue = formattedValue.replaceNewline(with: "\n | ")
+                case (false, true):
+                    formattedValue = formattedValue.replaceNewline(with: "\n   ")
+                default:
+                    break
+                }
+
+                if isFinalKey {
+                    var lines = formattedValue.components(separatedBy: "\n")
+                    if lines.count > 0 {
+                        lines[0] = lines[0] + " <<<<---- \(message)"
+                    }
+                    formattedValue = lines.joined(separator: "\n")
+                }
+
+                result.append("\(formattedKey): \(formattedValue)")
+
+
+            }
+
+        case let json as [Any]:
+
+            var items: [String] = []
+            result.append("\n")
+            for (index, value) in json.enumerated() {
+
+                print(index)
+                // Check if key matches first item in `path`.
+                /*
+                var highlightMatch = false
+                var isFinalKey = false
+
+                if let i = path.first?.index, index == i {
+                    highlightMatch = true
+                    path.removeFirst()
+                }
+
+                if path.count == 0 && highlightMatch {
+                    isFinalKey = true
+                }
+                 */
+                var formattedValue = format(json: value)
+                /*
+
+
+                if isFinalKey {
+                    var lines = formattedValue.components(separatedBy: "\n")
+                    if lines.count > 0 {
+                        lines[0] = lines[0] + " <<<<---- \(message)"
+                    }
+                    formattedValue = lines.joined(separator: "\n")
+                }
+                */
+                formattedValue = formattedValue.indented
+                 /*
+                if highlightMatch {
+                    formattedValue = formattedValue.replacingOccurrences(of: "\n", with: "\n |")
+                }
+                */
+                items.append("[\(index)] \(formattedValue)")
+            }
+            result.append(items.joined(separator: "\n"))
+        case let json as String:
+            return "\"\(json)\""
+        default:
+            result += "\(json)"
+        }
+
+        return result
+    }
+}
diff --git a/Tests/ErrorPathTests.swift b/Tests/ErrorPathTests.swift
@@ -49,6 +49,17 @@ class ErrorPathTests: XCTestCase {
         }
     }
 
+    func testErrorDescription() {
+        // Actually there is no test here...
+        let dict: NSDictionary = ["object": ["repo": ["owner": ["id" : 1, "login": "anviking"]]]]
+
+        do {
+            _ = try dict => "object" => "repo" => "owner" => "oops" as String
+        } catch  {
+            print(error)
+        }
+    }
+
     // FIXME: #
     func testNestedUnexpectedNSNull() {
         let dict: NSDictionary = ["id": 1, "color": ["name": NSNull()]]