refine field mapping ux and fix iso8601 fractional-second parsing

BulkHealthApp/Import/ImportModels.swift

@@ -12,6 +12,10 @@ struct TemplateField: Identifiable, Hashable {
 	let id: String
 	let title: String
 	let description: String
+	let targetExplanation: String
+	let targetExample: String
+	let targetFormat: String
+	let targetAllowedValues: String?
 	let type: FieldType
 	let isRequired: Bool
 }
@@ -31,6 +35,38 @@ struct ImportMapping: Equatable {
 	}
 }
 
+enum FieldFormatterType: String, CaseIterable, Identifiable {
+	case passthrough
+	case dateISO8601ToISO8601
+	case dateGermanDayMonthYearToISO8601
+	case dateGermanDayMonthYearHourMinuteToISO8601
+	case dateUnixSecondsToISO8601
+
+	var id: String { rawValue }
+}
+
+struct FieldFormatterConfig: Equatable {
+	var formatterType: FieldFormatterType
+
+	static func `default`(for fieldType: TemplateField.FieldType) -> FieldFormatterConfig {
+		if fieldType == .date {
+			return FieldFormatterConfig(formatterType: .dateISO8601ToISO8601)
+		}
+
+		return FieldFormatterConfig(formatterType: .passthrough)
+	}
+}
+
+struct FieldFormattingPreview {
+	let matched: Int
+	let total: Int
+	let examples: [String]
+
+	var isPartial: Bool {
+		total > 0 && matched < total
+	}
+}
+
 struct MoodwellPayload: Decodable {
 	let mymoods: [MoodwellEntry]
 }
@@ -57,7 +93,9 @@ struct MoodwellEntry: Decodable, Identifiable {
 			"arrayOfWeathers": .stringArray(arrayOfWeathers),
 			"createdAt": .string(createdAt),
 			"arrayOfActivities": .stringArray(arrayOfActivities),
-			"arrayOfGoodEmotions": .stringArray(arrayOfGoodEmotions)
+			"arrayOfGoodEmotions": .stringArray(arrayOfGoodEmotions),
+			"combinedEmotions": .stringArray(arrayOfGoodEmotions + arrayOfBadEmotions),
+			"combinedAssociations": .stringArray(arrayOfActivities + arrayOfWeathers.map { "weather:\($0)" })
 		]
 	}
 }
@@ -66,6 +104,7 @@ enum ImportValue: Hashable {
 	case string(String)
 	case number(Double)
 	case stringArray([String])
+	case date(Date)
 	case null
 
 	func asString() -> String? {
@@ -88,6 +127,87 @@ enum ImportValue: Hashable {
 		}
 		return nil
 	}
+
+	func asDate() -> Date? {
+		if case let .date(value) = self {
+			return value
+		}
+		return nil
+	}
+
+	func sourceString() -> String? {
+		switch self {
+		case let .string(value):
+			return value
+		case let .number(value):
+			if value.rounded() == value {
+				return String(Int(value))
+			}
+			return String(value)
+		case let .stringArray(value):
+			return value.joined(separator: ", ")
+		case let .date(value):
+			return value.formatted(date: .abbreviated, time: .shortened)
+		case .null:
+			return nil
+		}
+	}
+
+	func displayString() -> String {
+		sourceString() ?? "<null>"
+	}
+}
+
+enum ImportFieldFormatterEngine {
+	static func apply(sourceText: String, config: FieldFormatterConfig) -> String? {
+		switch config.formatterType {
+		case .passthrough:
+			return sourceText
+		case .dateISO8601ToISO8601:
+			guard let date = parseISO8601(sourceText.trimmingCharacters(in: .whitespacesAndNewlines)) else {
+				return nil
+			}
+			return iso8601String(from: date)
+		case .dateGermanDayMonthYearToISO8601:
+			return convertDate(sourceText, sourcePattern: "dd.MM.yyyy")
+		case .dateGermanDayMonthYearHourMinuteToISO8601:
+			return convertDate(sourceText, sourcePattern: "dd.MM.yyyy HH:mm")
+		case .dateUnixSecondsToISO8601:
+			guard let seconds = Double(sourceText.trimmingCharacters(in: .whitespacesAndNewlines)) else {
+				return nil
+			}
+			return iso8601String(from: Date(timeIntervalSince1970: seconds))
+		}
+	}
+
+	private static func convertDate(_ input: String, sourcePattern: String) -> String? {
+		let formatter = DateFormatter()
+		formatter.locale = Locale(identifier: "en_US_POSIX")
+		formatter.calendar = Calendar(identifier: .gregorian)
+		formatter.dateFormat = sourcePattern
+		guard let date = formatter.date(from: input.trimmingCharacters(in: .whitespacesAndNewlines)) else {
+			return nil
+		}
+		return iso8601String(from: date)
+	}
+
+	private static func iso8601String(from date: Date) -> String {
+		let output = ISO8601DateFormatter()
+		output.formatOptions = [.withInternetDateTime]
+		return output.string(from: date)
+	}
+
+	private static func parseISO8601(_ input: String) -> Date? {
+		let withFractional = ISO8601DateFormatter()
+		withFractional.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+		if let date = withFractional.date(from: input) {
+			return date
+		}
+
+		let plain = ISO8601DateFormatter()
+		plain.formatOptions = [.withInternetDateTime]
+		return plain.date(from: input)
+	}
 }
 
 struct StateOfMindDraft: Identifiable, Hashable {