// Copyright © 2023 Mastodon gGmbH. All rights reserved. import Foundation import MastodonSDK struct FollowersCountHistoryDay: Codable { let dstring: String let day: Int let count: Int func copy(count: Int) -> Self { FollowersCountHistoryDay(dstring: dstring, day: day, count: count) } } class FollowersCountHistory { static let shared = FollowersCountHistory() private let userDefaults = UserDefaults.standard private let calendar = Calendar.current private let followersCountCacheDateFormatter: DateFormatter = { let formatter = DateFormatter() formatter.dateFormat = "yyyyMMdd" return formatter }() private func elapsedFollowersCountDateStrings() -> [String] { (-7...0).map { elapsedDay in let date = calendar.date(byAdding: .day, value: elapsedDay, to: .now)! return followersCountCacheDateFormatter.string(from: date) } } private func userDefaultsKey(for account: FollowersEntryAccountable) -> String { if account.acct.contains("@") { return account.acct } return "\(account.acct)@\(account.domain)" } private func emptyHistoricDataForToday(for account: FollowersEntryAccountable) -> [FollowersCountHistoryDay] { elapsedFollowersCountDateStrings().enumerated().map { FollowersCountHistoryDay(dstring: $0.element, day: $0.offset, count: account.followersCount) } } private func followersHistorySorted(for account: FollowersEntryAccountable) -> [FollowersCountHistoryDay] { guard let jsonData = userDefaults.string(forKey: userDefaultsKey(for: account))?.data(using: .utf8), let jsonObject = try? JSONDecoder().decode([FollowersCountHistoryDay].self, from: jsonData) else { return emptyHistoricDataForToday(for: account) } return jsonObject } func updateFollowersTodayCount(account: FollowersEntryAccountable, count: Int) { let relevantDays = elapsedFollowersCountDateStrings() let existingHistory = followersHistorySorted(for: account) var newHistory = existingHistory /// first we're going to update the existing day and remove legacy days (older than 7) existingHistory.forEach { existingDay in if !relevantDays.contains(where: { $0 == existingDay.dstring }) { /// remove legacy data/ newHistory.removeAll(where: { $0.dstring == existingDay.dstring }) } } relevantDays.enumerated().forEach { index, day in if !newHistory.contains(where: { $0.dstring == day }) { newHistory.insert( FollowersCountHistoryDay(dstring: day, day: index, count: account.followersCount), at: index ) } } /// then we're going to update the history dataset with new value, if this is the first encounter if let last = newHistory.popLast()?.copy(count: count) { newHistory.append(last) } if let jsonData = try? JSONEncoder().encode(newHistory), let jsonString = String(data: jsonData, encoding: .utf8) { userDefaults.set(jsonString, forKey: userDefaultsKey(for: account)) } } func chartValues(for account: FollowersEntryAccountable) -> [Double] { followersHistorySorted(for: account).map { Double($0.count) } } func increaseCountString(for account: FollowersEntryAccountable) -> String? { let history = followersHistorySorted(for: account) let relevantDays = elapsedFollowersCountDateStrings() let today = relevantDays.last! let followersToday = history.first(where: { $0.dstring == today })?.count ?? account.followersCount let followersYesterday = history[safe: history.count-2]?.count ?? account.followersCount let followersChange = followersToday - followersYesterday switch followersChange { case ..<0: return "\(followersChange)" case 0: return nil default: return "+\(followersChange)" } } }