//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#if FOUNDATION_FRAMEWORK
// for CFXPreferences call
internal import _ForSwiftFoundation
#endif

/// Holds user preferences about `Locale`, retrieved from user defaults. It is only used when creating the `current` Locale. Fixed-identifier locales never have preferences.
package struct LocalePreferences: Hashable, Sendable {
    package enum MeasurementUnit {
        case centimeters
        case inches

        /// Init with the value of a user defaults string
        init?(_ string: String?) {
            guard let string else { return nil }
            if string == "Centimeters" { self = .centimeters }
            else if string == "Inches" { self = .inches }
            else { return nil }
        }

        /// Get the value as a user defaults string
        var userDefaultString: String {
            switch self {
            case .centimeters: return "Centimeters"
            case .inches: return "Inches"
            }
        }
    }

    package enum TemperatureUnit {
        case fahrenheit
        case celsius

        /// Init with the value of a user defaults string
        init?(_ string: String?) {
            guard let string else { return nil }
            if string == "Celsius" { self = .celsius }
            else if string == "Fahrenheit" { self = .fahrenheit }
            else { return nil }
        }

        /// Get the value as a user defaults string
        var userDefaultString: String {
            switch self {
            case .celsius: return "Celsius"
            case .fahrenheit: return "Fahrenheit"
            }
        }
    }

    package var metricUnits: Bool?
    package var languages: [String]?
    package var locale: String?
    package var collationOrder: String?
    package var firstWeekday: [Calendar.Identifier : Int]?
    package var minDaysInFirstWeek: [Calendar.Identifier : Int]?
#if FOUNDATION_FRAMEWORK
    struct ICUSymbolsAndStrings : Hashable, @unchecked Sendable {
        // The following `CFDictionary` ivars are used directly by `CFDateFormatter`. Keep them as `CFDictionary` to avoid bridging them into and out of Swift. We don't need to access them from Swift at all.
        
        package var icuDateTimeSymbols: CFDictionary?
        package var icuDateFormatStrings: CFDictionary?
        package var icuTimeFormatStrings: CFDictionary?
        
        // The OS no longer writes out this preference, but we keep it here for compatibility with CFDateFormatter behavior.
        package var icuNumberFormatStrings: CFDictionary?
        package var icuNumberSymbols: CFDictionary?
    }
    
    var icuSymbolsAndStrings = ICUSymbolsAndStrings()
    
#if !NO_FORMATTERS
    package var dateFormats: [Date.FormatStyle.DateStyle: String]? // Bridged version of `icuDateFormatStrings`
#endif
#endif
    package var numberSymbols: [UInt32 : String]? // Bridged version of `icuNumberSymbols`

    package var country: String?
    package var measurementUnits: MeasurementUnit?
    package var temperatureUnit: TemperatureUnit?
    package var force24Hour: Bool?
    package var force12Hour: Bool?

    package init() { }
    
#if FOUNDATION_FRAMEWORK && canImport(_FoundationICU)
    // The framework init supports customized dateFormats
    package init(metricUnits: Bool? = nil,
         languages: [String]? = nil,
         locale: String? = nil,
         collationOrder: String? = nil,
         firstWeekday: [Calendar.Identifier : Int]? = nil,
         minDaysInFirstWeek: [Calendar.Identifier : Int]? = nil,
         country: String? = nil,
         measurementUnits: MeasurementUnit? = nil,
         temperatureUnit: TemperatureUnit? = nil,
         force24Hour: Bool? = nil,
         force12Hour: Bool? = nil,
         numberSymbols: [UInt32 : String]? = nil,
         dateFormats: [Date.FormatStyle.DateStyle: String]? = nil) {

        self.metricUnits = metricUnits
        self.languages = languages
        self.locale = locale
        self.collationOrder = collationOrder
        self.firstWeekday = firstWeekday
        self.minDaysInFirstWeek = minDaysInFirstWeek
        self.country = country
        self.measurementUnits = measurementUnits
        self.temperatureUnit = temperatureUnit
        self.force24Hour = force24Hour
        self.force12Hour = force12Hour
        self.numberSymbols = numberSymbols
        self.dateFormats = dateFormats
    }
#else
    package init(metricUnits: Bool? = nil,
         languages: [String]? = nil,
         locale: String? = nil,
         collationOrder: String? = nil,
         firstWeekday: [Calendar.Identifier : Int]? = nil,
         minDaysInFirstWeek: [Calendar.Identifier : Int]? = nil,
         country: String? = nil,
         measurementUnits: MeasurementUnit? = nil,
         temperatureUnit: TemperatureUnit? = nil,
         force24Hour: Bool? = nil,
         force12Hour: Bool? = nil,
         numberSymbols: [UInt32 : String]? = nil) {

        self.metricUnits = metricUnits
        self.languages = languages
        self.locale = locale
        self.collationOrder = collationOrder
        self.firstWeekday = firstWeekday
        self.minDaysInFirstWeek = minDaysInFirstWeek
        self.country = country
        self.measurementUnits = measurementUnits
        self.temperatureUnit = temperatureUnit
        self.force24Hour = force24Hour
        self.force12Hour = force12Hour
        self.numberSymbols = numberSymbols
    }
#endif

#if FOUNDATION_FRAMEWORK && !NO_CFPREFERENCES
    /// Interpret a dictionary (from user defaults) according to a predefined set of strings and convert it into the more strongly-typed `LocalePreferences` values.
    /// Several dictionaries may need to be applied to the same instance, which is why this is structured as a mutating setter rather than an initializer.
    /// Why use a `CFDictionary` instead of a Swift dictionary here? The input prefs may be a complete copy of the user's prefs, and we don't want to bridge a ton of unrelated data into Swift just to extract a few keys. Keeping it as a `CFDictionary` avoids that overhead, and we call into small CF helper functions to get the data we need, if it is there.
    package mutating func apply(_ prefs: CFDictionary) {
        var exists: DarwinBoolean = false
        
        guard CFDictionaryGetCount(prefs) > 0 else { return }
        
        if let langs = __CFLocalePrefsCopyAppleLanguages(prefs)?.takeRetainedValue() as? [String] {
            self.languages = langs
        }
        if let locale = __CFLocalePrefsCopyAppleLocale(prefs)?.takeRetainedValue() as? String {
            self.locale = locale
        }
        
        let isMetric = __CFLocalePrefsAppleMetricUnitsIsMetric(prefs, &exists)
        if exists.boolValue {
            self.metricUnits = isMetric
        }

        let isCentimeters = __CFLocalePrefsAppleMeasurementUnitsIsCm(prefs, &exists)
        if exists.boolValue {
            self.measurementUnits = isCentimeters ? .centimeters : .inches
        }

        let isCelsius = __CFLocalePrefsAppleTemperatureUnitIsC(prefs, &exists)
        if exists.boolValue {
            self.temperatureUnit = isCelsius ? .celsius : .fahrenheit
        }

        let is24Hour = __CFLocalePrefsAppleForce24HourTime(prefs, &exists)
        if exists.boolValue {
            self.force24Hour = is24Hour
        }
        
        let is12Hour = __CFLocalePrefsAppleForce12HourTime(prefs, &exists)
        if exists.boolValue {
            self.force12Hour = is12Hour
        }
        
        if let collationOrder = __CFLocalePrefsCopyAppleCollationOrder(prefs)?.takeRetainedValue() as? String {
            self.collationOrder = collationOrder
        }

        if let country = __CFLocalePrefsCopyCountry(prefs)?.takeRetainedValue() as? String {
            self.country = country
        }

        if let icuDateTimeSymbols = __CFLocalePrefsCopyAppleICUDateTimeSymbols(prefs)?.takeRetainedValue() {
            self.icuSymbolsAndStrings.icuDateTimeSymbols = icuDateTimeSymbols
        }

        if let icuDateFormatStrings = __CFLocalePrefsCopyAppleICUDateFormatStrings(prefs)?.takeRetainedValue() {
            self.icuSymbolsAndStrings.icuDateFormatStrings = icuDateFormatStrings
            // Bridge the mapping for Locale's usage
            if let dateFormatPrefs = icuDateFormatStrings as? [String: String] {
                var mapped: [Date.FormatStyle.DateStyle : String] = [:]
                for (key, value) in dateFormatPrefs {
                    if let k = UInt(key) {
                        mapped[Date.FormatStyle.DateStyle(rawValue: k)] = value
                    }
                }
                self.dateFormats = mapped
            }
        }
        
        if let icuTimeFormatStrings = __CFLocalePrefsCopyAppleICUTimeFormatStrings(prefs)?.takeRetainedValue() {
            self.icuSymbolsAndStrings.icuTimeFormatStrings = icuTimeFormatStrings
        }
        
        if let icuNumberFormatStrings = __CFLocalePrefsCopyAppleICUNumberFormatStrings(prefs)?.takeRetainedValue() {
            self.icuSymbolsAndStrings.icuNumberFormatStrings = icuNumberFormatStrings
        }
        
        if let icuNumberSymbols = __CFLocalePrefsCopyAppleICUNumberSymbols(prefs)?.takeRetainedValue() {
            // Store the CFDictionary for passing back to CFDateFormatter
            self.icuSymbolsAndStrings.icuNumberSymbols = icuNumberSymbols
            
            // And bridge the mapping for our own usage in Locale
            if let numberSymbolsPrefs = icuNumberSymbols as? [String: String] {
                var mapped: [UInt32 : String] = [:]
                for (key, value) in numberSymbolsPrefs {
                    if let symbol = UInt32(key) {
                        mapped[symbol] = value
                    }
                }
                
                if !mapped.isEmpty {
                    self.numberSymbols = mapped
                }
            }
        }
        

        if let firstWeekdaysPrefs = __CFLocalePrefsCopyAppleFirstWeekday(prefs)?.takeRetainedValue() as? [String: Int] {
            var mapped: [Calendar.Identifier : Int] = [:]
            for (key, value) in firstWeekdaysPrefs {
                if let id = Calendar.Identifier(identifierString: key) {
                    mapped[id] = value
                }
            }

            if !mapped.isEmpty {
                self.firstWeekday = mapped
            }
        }

        if let minDaysPrefs = __CFLocalePrefsCopyAppleMinDaysInFirstWeek(prefs)?.takeRetainedValue() as? [String: Int] {
            var mapped: [Calendar.Identifier : Int] = [:]
            for (key, value) in minDaysPrefs {
                if let id = Calendar.Identifier(identifierString: key) {
                    mapped[id] = value
                }
            }

            if !mapped.isEmpty {
                self.minDaysInFirstWeek = mapped
            }
        }
    }
#endif // FOUNDATION_FRAMEWORK
    
    /// For testing purposes, merge a set of override prefs into this one.
    package mutating func apply(_ prefs: LocalePreferences) {
        if let other = prefs.metricUnits { self.metricUnits = other }
        if let other = prefs.languages { self.languages = other }
        if let other = prefs.locale { self.locale = other }
        if let other = prefs.collationOrder { self.collationOrder = other }
        if let other = prefs.firstWeekday { self.firstWeekday = other }
        if let other = prefs.minDaysInFirstWeek { self.minDaysInFirstWeek = other }
        if let other = prefs.numberSymbols { self.numberSymbols = other }
#if FOUNDATION_FRAMEWORK
        if let other = prefs.icuSymbolsAndStrings.icuDateTimeSymbols { self.icuSymbolsAndStrings.icuDateTimeSymbols = other }
        if let other = prefs.icuSymbolsAndStrings.icuDateFormatStrings { self.icuSymbolsAndStrings.icuDateFormatStrings = other }
        if let other = prefs.icuSymbolsAndStrings.icuTimeFormatStrings { self.icuSymbolsAndStrings.icuTimeFormatStrings = other }
        if let other = prefs.icuSymbolsAndStrings.icuNumberFormatStrings { self.icuSymbolsAndStrings.icuNumberFormatStrings = other }
        if let other = prefs.icuSymbolsAndStrings.icuNumberSymbols { self.icuSymbolsAndStrings.icuNumberSymbols = other }
#if !NO_FORMATTERS
        if let other = prefs.dateFormats { self.dateFormats = other }
#endif // !NO_FORMATTERS
#endif // FOUNDATION_FRAMEWORK
        if let other = prefs.country { self.country = other }
        if let other = prefs.measurementUnits { self.measurementUnits = other }
        if let other = prefs.temperatureUnit { self.temperatureUnit = other }
        if let other = prefs.force24Hour { self.force24Hour = other }
        if let other = prefs.force12Hour { self.force12Hour = other }
    }

    package var measurementSystem: Locale.MeasurementSystem? {
        let metricPref = metricUnits
        let measurementPref = measurementUnits

        if metricPref == nil && measurementPref == nil {
            return nil
        } else if let metricPref, metricPref == true, let measurementPref, measurementPref == .inches {
            return Locale.MeasurementSystem.uk
        } else if let metricPref, metricPref == false {
            return Locale.MeasurementSystem.us
        } else if let measurementPref, measurementPref == .centimeters {
            return Locale.MeasurementSystem.metric
        } else {
            // There isn't enough info
            return nil
        }
    }

    package var hourCycle: Locale.HourCycle? {
        if let setForce24Hour = force24Hour, setForce24Hour  {
        // Respect 24-hour override if both force24hour and force12hour are true
            return .zeroToTwentyThree
        } else if let setForce12Hour = force12Hour, setForce12Hour {
            return .oneToTwelve
        } else {
            return nil
        }
    }
}