From 82ec1208715c26d23867742232b055d3a4d39dca Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Sun, 15 Dec 2024 13:27:09 -0500
Subject: [PATCH] Include rate limit reset date in error message

Closes #548
---
 .../Pachyderm/Sources/Pachyderm/Client.swift  | 33 ++++++++++++++-----
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/Packages/Pachyderm/Sources/Pachyderm/Client.swift b/Packages/Pachyderm/Sources/Pachyderm/Client.swift
index 906cf2eed..6065e8419 100644
--- a/Packages/Pachyderm/Sources/Pachyderm/Client.swift
+++ b/Packages/Pachyderm/Sources/Pachyderm/Client.swift
@@ -25,27 +25,30 @@ public struct Client: Sendable {
     
     public var timeoutInterval: TimeInterval = 60
     
-    static let decoder: JSONDecoder = {
-        let decoder = JSONDecoder()
-        
+    private static let dateFormatter: DateFormatter = {
         let formatter = DateFormatter()
         formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SZ"
         formatter.timeZone = TimeZone(abbreviation: "UTC")
         formatter.locale = Locale(identifier: "en_US_POSIX")
-        let iso8601 = ISO8601DateFormatter()
+        return formatter
+    }()
+    private static let iso8601Formatter = ISO8601DateFormatter()
+    private static func decodeDate(string: String) -> Date? {
+        // for the next time mastodon accidentally changes date formats >.>
+        return dateFormatter.date(from: string) ?? iso8601Formatter.date(from: string)
+    }
+    
+    static let decoder: JSONDecoder = {
+        let decoder = JSONDecoder()
         decoder.dateDecodingStrategy = .custom({ (decoder) in
             let container = try decoder.singleValueContainer()
             let str = try container.decode(String.self)
-            // for the next time mastodon accidentally changes date formats >.>
-            if let date = formatter.date(from: str) {
-                return date
-            } else if let date = iso8601.date(from: str) {
+            if let date = Self.decodeDate(string: str) {
                 return date
             } else {
                 throw DecodingError.typeMismatch(Date.self, .init(codingPath: container.codingPath, debugDescription: "unexpected date format: \(str)"))
             }
         })
-        
         return decoder
     }()
     
@@ -105,6 +108,15 @@ public struct Client: Sendable {
         return task
     }
     
+    private func error(from response: HTTPURLResponse) -> ErrorType {
+        if response.statusCode == 429,
+           let date = response.value(forHTTPHeaderField: "X-RateLimit-Reset").flatMap(Self.decodeDate) {
+            return .rateLimited(date)
+        } else {
+            return .unexpectedStatus(response.statusCode)
+        }
+    }
+    
     @discardableResult
     public func run<Result: Sendable>(_ request: Request<Result>) async throws -> (Result, Pagination?) {
         return try await withCheckedThrowingContinuation { continuation in
@@ -575,6 +587,8 @@ extension Client {
                 return "Invalid Model"
             case .mastodonError(let code, let error):
                 return "Server Error (\(code)): \(error)"
+            case .rateLimited(let reset):
+                return "Rate Limited Until \(reset.formatted(date: .omitted, time: .standard))"
             }
         }
     }
@@ -585,6 +599,7 @@ extension Client {
         case invalidResponse
         case invalidModel(Swift.Error)
         case mastodonError(Int, String)
+        case rateLimited(Date)
     }
     
     enum NodeInfoError: LocalizedError {