From c4f8bef7f41aba5161fcc6ca40fe59743980a5ff Mon Sep 17 00:00:00 2001
From: Itay Amzaleg <itay.amzaleg@fiverr.com>
Date: Wed, 5 Jan 2022 20:44:12 +0200
Subject: [PATCH] Error extensions support

---
 Sources/GraphQL/Error/GraphQLError.swift      | 20 +++++++++++
 .../Extensions/Codable+Extensions.swift       | 35 +++++++++++++++++++
 .../GraphQL/Extensions/Error+Extensions.swift | 13 +++++++
 3 files changed, 68 insertions(+)
 create mode 100644 Sources/GraphQL/Extensions/Error+Extensions.swift

diff --git a/Sources/GraphQL/Error/GraphQLError.swift b/Sources/GraphQL/Error/GraphQLError.swift
index 125326f1..7cfad6f1 100644
--- a/Sources/GraphQL/Error/GraphQLError.swift
+++ b/Sources/GraphQL/Error/GraphQLError.swift
@@ -9,6 +9,7 @@ public struct GraphQLError : Error, Codable {
         case message
         case locations
         case path
+        case extensions
     }
 
     /**
@@ -29,6 +30,18 @@ public struct GraphQLError : Error, Codable {
      * Appears in the result of `description`.
      */
     public let locations: [SourceLocation]
+    
+    /**
+     * A dictionary containing original error reflection
+     * to supply additional data from error extensions.
+     *
+     * Will reflect only Codable objects.
+     *
+     * For more information about supported types look at `AnyCodable` - `init(from:)`
+     *
+     * Appears in the result of `description`.
+     */
+    public let extensions: [String: AnyCodable]?
 
     /**
      * An array describing the index path into the execution response which
@@ -92,6 +105,7 @@ public struct GraphQLError : Error, Codable {
 
         self.path = path
         self.originalError = originalError
+        self.extensions = originalError?.reflection
     }
     
     public init(
@@ -106,6 +120,7 @@ public struct GraphQLError : Error, Codable {
         self.source = nil
         self.positions = []
         self.originalError = nil
+        self.extensions = nil
     }
     
     public init(_ error: Error) {
@@ -120,6 +135,7 @@ public struct GraphQLError : Error, Codable {
         message = try container.decode(String.self, forKey: .message)
         locations = try container.decode([SourceLocation]?.self, forKey: .locations) ?? []
         path = try container.decode(IndexPath.self, forKey: .path)
+        extensions = try container.decodeIfPresent([String: AnyCodable].self, forKey: .extensions)
     }
     
     public func encode(to encoder: Encoder) throws {
@@ -132,6 +148,10 @@ public struct GraphQLError : Error, Codable {
         }
         
         try container.encode(path, forKey: .path)
+        
+        if let extensions = extensions {
+            try container.encode(extensions, forKey: .extensions)
+        }
     }
 }
 
diff --git a/Sources/GraphQL/Extensions/Codable+Extensions.swift b/Sources/GraphQL/Extensions/Codable+Extensions.swift
index 77501eda..5fbd7342 100644
--- a/Sources/GraphQL/Extensions/Codable+Extensions.swift
+++ b/Sources/GraphQL/Extensions/Codable+Extensions.swift
@@ -9,3 +9,38 @@ public class AnyEncodable : Encodable {
         return try self.encodable.encode(to: encoder)
     }
 }
+
+public class AnyCodable : Codable {
+    private let codable: Codable
+    
+    public init(_ codable: Codable) {
+        self.codable = codable
+    }
+    
+    public func encode(to encoder: Encoder) throws {
+        return try self.codable.encode(to: encoder)
+    }
+    
+    required public init(from decoder: Decoder) throws {
+        let container = try decoder.singleValueContainer()
+        if container.decodeNil() {
+            self.codable = "Null"
+        } else if let bool = try? container.decode(Bool.self) {
+            self.codable = bool
+        } else if let int = try? container.decode(Int.self) {
+            self.codable = int
+        } else if let uint = try? container.decode(UInt.self) {
+            self.codable = uint
+        } else if let double = try? container.decode(Double.self) {
+            self.codable = double
+        } else if let string = try? container.decode(String.self) {
+            self.codable = string
+        } else if let array = try? container.decode([AnyCodable].self) {
+            codable = array
+        } else if let dictionary = try? container.decode([String: AnyCodable].self) {
+            codable = dictionary
+        } else {
+            throw DecodingError.dataCorruptedError(in: container, debugDescription: "AnyCodable: can't decode value")
+        }
+    }
+}
diff --git a/Sources/GraphQL/Extensions/Error+Extensions.swift b/Sources/GraphQL/Extensions/Error+Extensions.swift
new file mode 100644
index 00000000..f9f5ecf1
--- /dev/null
+++ b/Sources/GraphQL/Extensions/Error+Extensions.swift
@@ -0,0 +1,13 @@
+public extension Error {
+    var reflection: [String: AnyCodable] {
+        let errorReflection: Mirror = Mirror(reflecting: self)
+        return Dictionary(uniqueKeysWithValues: errorReflection.children.lazy.map({ (label: String?, value: Any) -> (String, AnyCodable)? in
+            guard let key = label,
+                  let codableValue = value as? Codable else {
+                      return nil
+            }
+            
+            return (key, AnyCodable(codableValue))
+        }).compactMap { $0 })
+    }
+}