Implement Messages feature

[pritam-bs]

• Provided NStackMessageWidget for the user to get and show messages from NStack
• The user can use either the default dialog provided by the SDK or override the dialog and implement the UI as per the requirements.

[hassan-saleh-ml]

@pritam-bs let's wait for @nivisi to review before merging

[nivisi]

Edit: two changes requested on the nstack.dart must actually be on the .txt file, jfyi 😄

[nivisi]

Since dart 3 we have new class modifiers that allow us to put restrictions on who and how can inherit from our classes (Official docs). My suggestion would be to follow the new rules:

1. Make the parent NStackMessageOptions a sealed class, meaning it can only be inherited within our library. It will allow us to use a switch statement in the _onMessage callback. Refer to my message below.
2. Make two subclasses final to prevent subtyping outside of this NStack library.

Suggested change

	abstract class NStackMessageOptions {}
	class DefaultNstackMessageOptions implements NStackMessageOptions {
	/// Title of the OK button.
	final String? okButtonTitle;
	/// Title of the Open URL button.
	final String? openUrlButtonTitle;
	/// Title of the dialog.
	final String? dialogTitle;
	DefaultNstackMessageOptions({
	this.okButtonTitle,
	this.openUrlButtonTitle,
	this.dialogTitle,
	});
	}
	class CustomNstackMessageOptions implements NStackMessageOptions {
	sealed class NStackMessageOptions {}
	final class DefaultNstackMessageOptions implements NStackMessageOptions {
	/// Title of the OK button.
	final String? okButtonTitle;
	/// Title of the Open URL button.
	final String? openUrlButtonTitle;
	/// Title of the dialog.
	final String? dialogTitle;
	DefaultNstackMessageOptions({
	this.okButtonTitle,
	this.openUrlButtonTitle,
	this.dialogTitle,
	});
	}
	final class CustomNstackMessageOptions implements NStackMessageOptions {

[nivisi]

If we'll use a sealed base class, we'll be able to do:

Suggested change

	void _onMessage(Message message) {
	if (widget.messageOptions is CustomNstackMessageOptions) {
	(widget.messageOptions as CustomNstackMessageOptions)
	.onMessage
	.call(message);
	} else {
	final messageOptions =
	widget.messageOptions as DefaultNstackMessageOptions;
	NStackMessageDialog.show(
	context,
	message: message,
	okButtonTitle: messageOptions.okButtonTitle,
	openUrlButtonTitle: messageOptions.openUrlButtonTitle,
	dialogTitle: messageOptions.dialogTitle,
	);
	}
	}
	void _onMessage(Message message) {
	final messageOptions = widget.messageOptions;
	switch (messageOptions) {
	case CustomNstackMessageOptions():
	messageOptions.onMessage(message);
	break;
	case DefaultNstackMessageOptions():
	NStackMessageDialog.show(
	context,
	message: message,
	okButtonTitle: messageOptions.okButtonTitle,
	openUrlButtonTitle: messageOptions.openUrlButtonTitle,
	dialogTitle: messageOptions.dialogTitle,
	);
	break;
	}
	}

[nivisi]

Suggested change

	Future<void> setMessageViewed(int messageId) async {
	try {
	if (_appOpenData != null) {
	await _repository.postMessageSeen(
	appOpenData: _appOpenData!,
	messageId: messageId,
	);
	} else {
	LogUtil.log('NStack --> Could not post message seen.');
	}
	} catch (e) {
	LogUtil.log('NStack --> Could not post message seen.');
	}
	}
	Future<void> setMessageViewed(int messageId) async {
	final appOpenData = _appOpenData;
	if (appOpenData == null) {
	LogUtil.log('NStack --> Could not post message seen.');
	return;
	}
	try {
	await _repository.postMessageSeen(
	appOpenData: appOpenData,
	messageId: messageId,
	);
	} catch (e) {
	LogUtil.log('NStack --> Could not post message seen.');
	}
	}

[nivisi]

LGTM

[nivisi]

If we use square brackets, you'll be able to navigate to the references classes (basically anything referenced: methods, fields etc) easier by holding the CMND (or whatever) button.

Suggested change

	/// It can be either `DefaultNstackHandlerConfiguration` or `CustomNstackHandlerConfiguration`.
	/// It can be either [DefaultNstackHandlerConfiguration] or [CustomNstackHandlerConfiguration].