Accept an iHateMoney project name where the id is expected

PayForMe.xcodeproj/project.pbxproj

@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		88E8E4370F88039587CB3E85 /* ProjectIdentifierTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 69E6AED117C0505EF274EA0B /* ProjectIdentifierTests.swift */; };
 		481FB4FB23E964C8003BD108 /* ProjectManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 481FB4FA23E964C8003BD108 /* ProjectManager.swift */; };
 		481FB4FD23EAD78F003BD108 /* AddProjectManualViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 481FB4FC23EAD78F003BD108 /* AddProjectManualViewModel.swift */; };
 		489995DA23F6EC6F008B7E38 /* OnboardingView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 489995D923F6EC6F008B7E38 /* OnboardingView.swift */; };
@@ -88,6 +89,7 @@
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXFileReference section */
+		69E6AED117C0505EF274EA0B /* ProjectIdentifierTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ProjectIdentifierTests.swift; sourceTree = "<group>"; };
 		0865D2DAF541B24078D1DC41 /* TestHelpers.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = TestHelpers.swift; sourceTree = "<group>"; };
 		143F41EE78329905894C8A29 /* BalanceCalculationTests.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = BalanceCalculationTests.swift; sourceTree = "<group>"; };
 		316FBA7C0CE4ABB51EC2A121 /* NetworkRequestTests.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = NetworkRequestTests.swift; sourceTree = "<group>"; };
@@ -228,6 +230,7 @@
 			isa = PBXGroup;
 			children = (
 				654754E32528B29F00A82EB6 /* AddProjectManuallyTests.swift */,
+				69E6AED117C0505EF274EA0B /* ProjectIdentifierTests.swift */,
 				654754E52528B29F00A82EB6 /* Info.plist */,
 				6523FC4B25580EEF00BCD843 /* UrlExtensionsTests.swift */,
 				0865D2DAF541B24078D1DC41 /* TestHelpers.swift */,
@@ -544,6 +547,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				654754E42528B29F00A82EB6 /* AddProjectManuallyTests.swift in Sources */,
+				88E8E4370F88039587CB3E85 /* ProjectIdentifierTests.swift in Sources */,
 				6523FC4C25580EEF00BCD843 /* UrlExtensionsTests.swift in Sources */,
 				57BC8D25B91CE40F4669650C /* TestHelpers.swift in Sources */,
 				D279295CFA25D9CC69C6F27C /* BillTests.swift in Sources */,

PayForMe/Model/Project.swift

@@ -97,6 +97,22 @@ enum ProjectBackend: Int, Codable {
     case cospend = 0
     case iHateMoney = 1
 
+    /// What the user typed into the add-project form, turned into the value the
+    /// API expects.
+    ///
+    /// iHateMoney addresses projects by an id derived from the name, and the id
+    /// is never shown in its web UI — so people type the name and the request
+    /// 404s. Cospend uses the share token exactly as entered and must not be
+    /// touched.
+    func projectIdentifier(fromUserInput input: String) -> String {
+        switch self {
+        case .iHateMoney:
+            return input.iHateMoneyProjectId
+        case .cospend:
+            return input
+        }
+    }
+
     var staticPath: String {
         switch self {
         case .cospend:

PayForMe/Util/Util.swift

@@ -57,6 +57,50 @@ extension String {
         return false
     }
 
+    /// The project id iHateMoney derives from a project's name: NFKD-normalised,
+    /// stripped of everything that is not a word character, whitespace or a
+    /// hyphen, lowercased, with runs of hyphens and whitespace collapsed into a
+    /// single hyphen.
+    ///
+    /// Users only ever see the name — the id is not shown anywhere in the web UI
+    /// — but the API is addressed by the id. A name typed into the add-project
+    /// form therefore has to be converted the same way the server converts it.
+    /// Mirrors `slugify()` in `ihatemoney/utils.py`.
+    var iHateMoneyProjectId: String {
+        let withoutPunctuation = decomposedStringWithCompatibilityMapping.unicodeScalars.filter { scalar in
+            switch scalar.properties.generalCategory {
+            case .nonspacingMark, .spacingMark, .enclosingMark:
+                // The diacritics NFKD just split off. Dropping them is what
+                // turns "Café" into "cafe" rather than "cafe\u{301}".
+                return false
+            default:
+                return CharacterSet.alphanumerics.contains(scalar)
+                    || scalar == "_"
+                    || scalar == "-"
+                    || CharacterSet.whitespacesAndNewlines.contains(scalar)
+            }
+        }
+
+        let normalised = String(String.UnicodeScalarView(withoutPunctuation))
+            .trimmingCharacters(in: .whitespacesAndNewlines)
+            .lowercased()
+
+        var result = ""
+        var lastWasSeparator = false
+        for character in normalised {
+            if character == "-" || character.isWhitespace {
+                if !lastWasSeparator {
+                    result.append("-")
+                }
+                lastWasSeparator = true
+            } else {
+                result.append(character)
+                lastWasSeparator = false
+            }
+        }
+        return result
+    }
+
     var isValidEmail: Bool {
         // here, `try!` will always succeed because the pattern is valid
         let regex = try! NSRegularExpression(pattern: "^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$", options: .caseInsensitive)

PayForMe/Views/Projects/Manual/AddProjectManualViewModel.swift

@@ -299,7 +299,11 @@ class AddProjectManualViewModel: ObservableObject {
                     guard !password.isEmpty else { return nil }
                     effectivePassword = password
                 }
-                return Project(name: token, password: effectivePassword, token: token, backend: server.0, url: url, projectId: self.projectName)
+                // iHateMoney is addressed by the project id, which it derives
+                // from the name. The name is all users ever see, so accept it
+                // and convert it the same way the server does.
+                let identifier = server.0.projectIdentifier(fromUserInput: token)
+                return Project(name: token, password: effectivePassword, token: identifier, backend: server.0, url: url, projectId: identifier)
             }
             .removeDuplicates()
             .share()

PayForMeTests/ProjectIdentifierTests.swift

@@ -0,0 +1,79 @@
+//
+//  ProjectIdentifierTests.swift
+//  PayForMeTests
+//
+//  iHateMoney addresses a project by an id it derives from the project's name.
+//  That id is not shown anywhere in its web UI, so people type the name they
+//  see, the request 404s, and the project stays blank — the subject of #53.
+//
+//  The expectations below mirror `slugify()` in `ihatemoney/utils.py`:
+//
+//      value = unicodedata.normalize("NFKD", value)
+//      value = str(re.sub(r"[^\w\s-]", "", value).strip().lower())
+//      return re.sub(r"[-\s]+", "-", value)
+//
+
+import XCTest
+@testable import PayForMe
+
+final class ProjectIdentifierTests: XCTestCase {
+
+    // MARK: The cases from the issue
+
+    /// "if I choose to enter in the form id: spongebob-house […] the bills and
+    /// users will load with name: Spongebob-house but not with: Spongebob house"
+    func testASpaceBecomesAHyphen() {
+        XCTAssertEqual("Spongebob house".iHateMoneyProjectId, "spongebob-house")
+    }
+
+    /// "special characters are omitted from project ids […]
+    /// `something + somethingelse` -> `something-somethingelse`"
+    func testPunctuationIsDroppedAndTheGapCollapses() {
+        XCTAssertEqual("something + somethingelse".iHateMoneyProjectId,
+                       "something-somethingelse")
+    }
+
+    // MARK: The rules
+
+    func testAnIdThatIsAlreadyCorrectIsUnchanged() {
+        XCTAssertEqual("spongebob-house".iHateMoneyProjectId, "spongebob-house",
+                       "users who do enter the real id must not be broken")
+    }
+
+    func testAccentsAreFolded() {
+        XCTAssertEqual("Café Ausflug".iHateMoneyProjectId, "cafe-ausflug")
+    }
+
+    func testRunsOfSeparatorsCollapse() {
+        XCTAssertEqual("Trip   2024".iHateMoneyProjectId, "trip-2024")
+        XCTAssertEqual("a --  b".iHateMoneyProjectId, "a-b")
+    }
+
+    func testSurroundingWhitespaceIsTrimmed() {
+        XCTAssertEqual("  Urlaub  ".iHateMoneyProjectId, "urlaub")
+    }
+
+    /// An underscore is a word character in the pattern and survives.
+    func testUnderscoresSurvive() {
+        XCTAssertEqual("Wohnung_WG".iHateMoneyProjectId, "wohnung_wg")
+    }
+
+    func testAStringWithNothingUsableBecomesEmpty() {
+        XCTAssertEqual("!?!".iHateMoneyProjectId, "")
+        XCTAssertEqual("".iHateMoneyProjectId, "")
+    }
+
+    // MARK: Backend dispatch
+
+    func testIHateMoneyInputIsNormalised() {
+        XCTAssertEqual(ProjectBackend.iHateMoney.projectIdentifier(fromUserInput: "Spongebob house"),
+                       "spongebob-house")
+    }
+
+    /// Cospend addresses projects by a share token, which is case-sensitive and
+    /// must survive untouched — normalising it would break every Cospend project.
+    func testCospendInputIsUntouched() {
+        let token = "9dA50e410157DC1ca63e594af022f3a2"
+        XCTAssertEqual(ProjectBackend.cospend.projectIdentifier(fromUserInput: token), token)
+    }
+}