Change drafts to store which accounts was used to create them

When loading a draft:

If the draft was created from a different account than the current one:
    If the draft was in reply to a status, don't allow it to be loaded.
    If the draft was not in reply to a status, prompt the user whether
    or not to load the draft.
If the draft was in reply to a different status than the current one:
    Prompt the user whether or not to load the draft.
Otherwise, load the draft.

Draft replies created from other accounts can't be loaded from different
accounts because the status for inReplyToID of the draft will have a
different instance-local ID if the two accounts are on different
instances.

See #16

Tusker/DraftsManager.swift

@@ -39,8 +39,8 @@ class DraftsManager: Codable {
         return drafts.sorted(by: { $0.lastModified > $1.lastModified })
     }
     
-    func create(text: String, contentWarning: String?, inReplyToID: String?, attachments: [DraftAttachment]) -> Draft {
+    func create(accountID: String, text: String, contentWarning: String?, inReplyToID: String?, attachments: [DraftAttachment]) -> Draft {
-        let draft = Draft(text: text, contentWarning: contentWarning, inReplyToID: inReplyToID, attachments: attachments)
+        let draft = Draft(accountID: accountID, text: text, contentWarning: contentWarning, inReplyToID: inReplyToID, attachments: attachments)
         drafts.append(draft)
         return draft
     }
@@ -55,14 +55,16 @@ class DraftsManager: Codable {
 extension DraftsManager {
     class Draft: Codable, Equatable {
         let id: UUID
+        private(set) var accountID: String
         private(set) var text: String
         private(set) var contentWarning: String?
         private(set) var attachments: [DraftAttachment]
         private(set) var inReplyToID: String?
         private(set) var lastModified: Date
         
-        init(text: String, contentWarning: String?, inReplyToID: String?, attachments: [DraftAttachment], lastModified: Date = Date()) {
+        init(accountID: String, text: String, contentWarning: String?, inReplyToID: String?, attachments: [DraftAttachment], lastModified: Date = Date()) {
             self.id = UUID()
+            self.accountID = accountID
             self.text = text
             self.contentWarning = contentWarning
             self.inReplyToID = inReplyToID
@@ -70,7 +72,8 @@ extension DraftsManager {
             self.lastModified = lastModified
         }
         
-        func update(text: String, contentWarning: String?, attachments: [DraftAttachment]) {
+        func update(accountID: String, text: String, contentWarning: String?, attachments: [DraftAttachment]) {
+            self.accountID = accountID
             self.text = text
             self.contentWarning = contentWarning
             self.lastModified = Date()

Tusker/LocalData.swift

@@ -101,6 +101,10 @@ class LocalData: ObservableObject {
         accounts.removeAll(where: { $0.id == info.id })
     }
     
+    func getAccount(id: String) -> UserAccountInfo? {
+        return accounts.first(where: { $0.id == id })
+    }
+    
     func getMostRecentAccount() -> UserAccountInfo? {
         guard onboardingComplete else { return nil }
         let mostRecent: UserAccountInfo?

Tusker/Screens/Compose/ComposeViewController.swift

@@ -368,10 +368,11 @@ class ComposeViewController: UIViewController {
             attachments.append(.init(attachment: attachment, description: description))
         }
         let cw = contentWarningEnabled ? contentWarningTextField.text : nil
+        let account = mastodonController.accountInfo!
         if let currentDraft = self.currentDraft {
-            currentDraft.update(text: self.statusTextView.text, contentWarning: cw, attachments: attachments)
+            currentDraft.update(accountID: account.id, text: self.statusTextView.text, contentWarning: cw, attachments: attachments)
         } else {
-            self.currentDraft = DraftsManager.shared.create(text: self.statusTextView.text, contentWarning: cw, inReplyToID: inReplyToID, attachments: attachments)
+            self.currentDraft = DraftsManager.shared.create(accountID: account.id, text: self.statusTextView.text, contentWarning: cw, inReplyToID: inReplyToID, attachments: attachments)
         }
         DraftsManager.save()
     }
@@ -622,8 +623,46 @@ extension ComposeViewController: DraftsTableViewControllerDelegate {
     }
     
     func shouldSelectDraft(_ draft: DraftsManager.Draft, completion: @escaping (Bool) -> Void) {
-        if draft.inReplyToID != self.inReplyToID {
+        if draft.accountID != mastodonController.accountInfo!.id {
-            // todo: better text for this
+            let currentAccount = mastodonController.accountInfo!
+            let currentAcct = "\(currentAccount.username)@\(currentAccount.instanceURL.host!)"
+            let otherAccount = LocalData.shared.getAccount(id: draft.accountID)
+            let otherAcct: String!
+            if let otherAccount = otherAccount {
+                otherAcct = "\(otherAccount.username)@\(otherAccount.instanceURL.host!)"
+            } else {
+                otherAcct = nil
+            }
+            
+            if draft.inReplyToID != nil {
+                let message: String
+                if otherAccount != nil {
+                    message = "The selected draft is a reply from a different account, it cannot be loaded from this account. To use it, switch accounts to \(otherAcct!)"
+                } else {
+                    message = "The selected draft is a reply from an account that has been logged-out of. It cannot be loaded."
+                }
+                let alertController = UIAlertController(title: "Reply from Different Account", message: message, preferredStyle: .alert)
+                alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: { (_) in
+                    completion(false)
+                }))
+                presentedViewController!.present(alertController, animated: true)
+            } else {
+                let message: String
+                if otherAccount != nil {
+                    message = "The selected draft is from a different account (\(otherAcct!)) than your currently active account (\(currentAcct)). Do you wish to load it anyway?"
+                } else {
+                    message = "The selected draft from an account that has been logged-out of."
+                }
+                let alertController = UIAlertController(title: "Draft from Different Account", message: message, preferredStyle: .alert)
+                alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { (_) in
+                    completion(false)
+                }))
+                alertController.addAction(UIAlertAction(title: "Load Draft", style: .default, handler: { (_) in
+                    completion(true)
+                }))
+                presentedViewController!.present(alertController, animated: true)
+            }
+        } else if draft.inReplyToID != self.inReplyToID {
             let alertController = UIAlertController(title: "Different Reply", message: "The selected draft is a reply to a different status, do you wish to use it?", preferredStyle: .alert)
             alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { (_) in
                 completion(false)