Implement fetching offerings from a PFI DID (#19)

Sources/tbDEX/HttpClient/GetOfferingsFilter.swift

@@ -0,0 +1,17 @@
+import Foundation
+
+public struct GetOfferingFilter: Codable {
+    let id: String?
+    let payinCurrency: String?
+    let payoutCurrency: String?
+
+    public init(
+        id: String? = nil,
+        payinCurrency: String? = nil,
+        payoutCurrency: String? = nil
+    ) {
+        self.id = id
+        self.payinCurrency = payinCurrency
+        self.payoutCurrency = payoutCurrency
+    }
+}

Sources/tbDEX/HttpClient/HttpClient.swift

@@ -0,0 +1,72 @@
+import Foundation
+
+public enum HttpClient {
+
+    public struct HttpClientError: Error {
+        let reason: String
+    }
+
+    static let session = URLSession(configuration: .default)
+
+    public struct GetOfferingsResponse: Codable {
+        public let data: [Offering]
+    }
+
+    /// Get `Offering`s from a PFI.
+    public static func getOfferings(
+        pfiDidUri: String,
+        filter: GetOfferingFilter? = nil
+    ) async -> Result<GetOfferingsResponse, HttpClientError> {
+        guard let pfiServiceEndpoint = await getPFIServiceEndpoint(pfiDidUri: pfiDidUri) else {
+            return .failure(.init(reason: "DID does not have service of type PFI"))
+        }
+
+        guard var components = URLComponents(string: "\(pfiServiceEndpoint)/offerings") else {
+            return .failure(.init(reason: "Could not create URLComponents from PFI service endpoint"))
+        }
+
+        components.queryItems = filter?.queryItems()
+
+        guard let url = components.url else {
+            return .failure(.init(reason: "Could not create URL from URLComponents"))
+        }
+
+        do {
+            let response = try await URLSession.shared.data(from: url)
+
+            // Set up the JSONDecoder with a custom date decoding strategy
+            let decoder = JSONDecoder()
+            decoder.dateDecodingStrategy = .custom({ (decoder) -> Date in
+                let container = try decoder.singleValueContainer()
+                let dateString = try container.decode(String.self)
+
+                // Create a custom ISO8601DateFormatter
+                let dateFormatter = ISO8601DateFormatter()
+                dateFormatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+
+                if let date = dateFormatter.date(from: dateString) {
+                    return date
+                } else {
+                    throw DecodingError.dataCorruptedError(
+                        in: container,
+                        debugDescription: "Invalid date: \(dateString)"
+                    )
+                }
+            })
+
+            let offerings = try decoder.decode(GetOfferingsResponse.self, from: response.0)
+            return .success(offerings)
+        } catch {
+            return .failure(.init(reason: "Error while fetching offerings: \(error)"))
+        }
+    }
+
+    private static func getPFIServiceEndpoint(pfiDidUri: String) async -> String? {
+        let resolutionResult = await DidResolver.resolve(didUri: pfiDidUri)
+        if let service = resolutionResult.didDocument?.service?.first(where: { $0.type == "PFI" }) {
+            return service.serviceEndpoint
+        } else {
+            return nil
+        }
+    }
+}

Sources/tbDEX/Utilities/Encodable+QueryItems.swift

@@ -0,0 +1,17 @@
+import Foundation
+
+extension Encodable {
+
+    /// Returns an array of `URLQueryItem` representing the `Encodable` object.
+    func queryItems() -> [URLQueryItem] {
+        let encoder = JSONEncoder()
+        guard let data = try? encoder.encode(self) else {
+            return []
+        }
+        guard let dictionary = try? JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] else {
+            return []
+        }
+        return dictionary.map { URLQueryItem(name: $0.key, value: "\($0.value)") }
+    }
+
+}

Tests/tbDEXTests/Dids/DidJwkTests.swift

@@ -78,12 +78,4 @@ final class DidJwkTests: XCTestCase {
         XCTAssertNil(resolutionResult.didResolutionMetadata.error)
     }
 
-    func test_resolveIon() async throws {
-        let didUri =
-            "did:ion:EiC8RWXbMYyFsqQ5hxP3k2GVvqPaeP8EAN6i9wQblzj__Q: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"
-
-        let resolutionResult = await DidIon.resolve(didUri: didUri)
-        XCTAssertNotNil(resolutionResult.didDocument)
-    }
-
 }