The MishkaInstaller.Event.Hook module provides a set of functionalities to manage event hooks within the Mishka Installer system.

It leverages GenServer to handle asynchronous event-driven operations and offers a set of macros and functions for registering, starting, stopping, and managing hooks dynamically.

In addition to being one of the most significant modules of the MishkaInstaller library, the Hook module gives you the ability to make the library as a whole, as well as the projects that make use of this library, more modular.

It is essential to comprehend that you may treat any action performed independently as an event and register an unlimited number of plugins for that event.

You can do this by considering that action to be done separately. Each plugin has the potential to have its own individual inputs and outputs, and depending on the architecture of the area that you want to use Hook in, you may even be able to change the output and send it to other plugins.

Throughout all of the many parts that have been built for this module, it has been attempted to have a flexible approach to dealing with errors and to provide the programmer with a wide variety of options.

With the additional functions at her disposal, the programmer can actually create a gateway in their projects, where the data flow must pass through several gates, whether it changes or remains unchanged, and a series of operations are performed.

For illustration's sake, let's suppose you want the registration system to allow users to sign up for social networks on Twitter and Google.

When you use this library, it is conceivable that you can quickly display HTML or even operate in the background before registering after registering.

This is a significant improvement over the standard practice, in which you are required to modify the primary codes of your project. Create a separate plugin.

It is interesting to notice that these facilities are quite basic and convenient for the admin user.

If this opportunity is provided, the management can manage its own plugins in different ways if it has a dashboard.

It is crucial to highlight that each plugin is its own GenServer; in addition, it is dynamically supervised, and the information is stored in the database as well as in Mnesia.

Furthermore, this section is very useful even if the programmer wants to perform many tasks that are not associated with Perform defined functions.

The fact that the programmers have to introduce each plugin to the system based on a specific behavior is one of the exciting aspects of using this section. Additionally, the system has prepared some default behaviors to force the programmers to introduce the plugins in the order specified by the system.

The use of custom behaviors on the part of the programmer and MishkaInstaller itself makes debugging easier; however, this library does not leave the programmer to fend for themselves in this significant matter; rather, a straightforward error storage system is prepared based on the particular activities being performed.

Should prevent any unpredictable behavior at any costs.

Build purpose

Imagine you are going to make an application that will have many plugins built for it in the future. But the fact that many manipulations will be made on your source code makes it difficult to maintain the application.

For example, you present a content management system for your users, and now they need to activate a section for registration and SMS; the system allows you to present your desired input/output absolutely plugin oriented to your users and makes it possible for the developers to write their required applications beyond the core source code.

The library categorizes your whole software design structure into many parts; and has an appropriate dependency that is optional with GenServer; it considers a monitoring branch for each of your plugins, which results in fewer errors and downtime.

The considered part:

1. Behaviors and events
2. Recalling or Hook with priority
3. State management and links to the database (Mnesia support)

Most of the sections mentioned can be fully customized to suit your needs. This library offers a range of predefined strategies for public use, which might be sufficient for your requirements.

In Mishka Elixir Plugin Management Library, a series of action or hook functions are given to the developer of the main plugin or software, which helps build plugins outside the system and convert software sections into separate events.

Some of the functions of this module include the following:

• config/0 - Retrieves the merged configuration for the hook module.
• config/1 - Retrieves a specific configuration value by key.
• register/0 - Register a plugin for a specific event.
• start/0 - Start a plugin of a specific event.
• restart/0 - Restart a plugin of a specific event.
• stop/0 - Stop a plugin of a specific event.
• unregister/0 - Unregister a plugin of a specific event.
• get/0 - Retrieves a Plugin GenServer state.

Example:

defmodule RegisterEmailSender do
  use MishkaInstaller.Event.Hook, event: "after_success_login"

  def call(entries) do
    {:reply, entries}
  end
end

If you want to change a series of default information, do this:

use MishkaInstaller.Event.Hook,
  event: "after_success_login",
  initial: %{depends: [SomeEvent], priority: 20}

There should be one main functions in each plugin, namely call. In this function, whenever the action function calls this special event for which the plugin is written, based on priority. This plugin is also called. But what is important is the final output of the call function. This output may be the input of other plugins with higher priorities. The order of the plugins is from small to large, and if several plugins are registered for a number, it is sorted by name in the second parameter. And it should be noted that in any case, if you did not want this state to go to other plugins and the last output is returned in the same plugin, and you can replace {:reply, :halt, new_state} with {:reply, new_state}.

Note: If you want your plugin to execute automatically, all you need to do is send the name of the module in which you utilized the MishkaInstaller.Event.Hook to the Application module.*

children = [
  ...
  RegisterEmailSender
]

...
opts = [strategy: :one_for_one, name: SomeModule.Supervisor]
Supervisor.start_link(children, opts)

You can call all plugins of an event:

alias MishkaInstaller.Event.Hook

# Normal call an event plugins
Hook.call("after_success_login", params)

# If you want certain entries not to change
Hook.call("after_success_login", params, [private: something_based_on_your_data])

# If you want the initial entry to be displayed at the end
Hook.call("after_success_login", params, [return: true])

Use cases information

Module MishkaInstaller.Event.Event has all of the preset functionalities, and it is simple for you to build and implement your own strategy because of this.

You can override these functions: register: 0, start: 0, restart: 0, stop: 0, unregister: 0, get: 0

Consideration:

It should be brought to your attention that the output of the call function has a few trade-offs. These trade-offs do not restrict your ability to customize the outcome of the call function; nevertheless, they do cause you to move away from the foreseen and planned structure that is the approach that this library takes.

In situations when you have access to a :private key, it is preferable for your data to be in the form of a Map or a Keyword. This allows you to perform an accurate match prior to the output of the data. With the exception of these two circumstances, we do not collect any other data.

The list below is all the outputs that are checked in the form of different wrist patterns:

{:ok, data} when is_list(data) # It can be merged with the `:private` key
{:ok, data} when is_map(data) # It can be merged with the `:private` key
# If you have :private, we do not recommend to use this pattern
{:ok, data} # It can not be merged with the `:private` key
{:error, _errors} # It does not need to be merged
data when is_list(data) # It can be merged with the `:private` key
data when is_map(data) # It can be merged with the `:private` key

For example:

We do not recommend these the data or error data; they should have Map or Keyword format.

def call(entries) do
  {:reply, :halt, {:ok, "Message is sent!"}}
end

def call(entries) do
  {:reply, entries}
end

But it is recommended to use these.

def call(entries) do
  {:reply, :halt, {:ok, %{name: "mishka"}}
end

def call(entries) do
  {:reply, {:ok, [name: "mishka"]}
end

def call(entries) do
  {:reply, {:error, any_data}
end

Use cases information

Take note that you have the ability to set the queue of a plugin to false while you are defining it. This will ensure that the implementation and build of the event state module are not queued.

For projects that require a significant amount of time to compile their events module, this possibility has been implemented. Additionally, these projects may have created a series of conditions in order to avoid race conditions from occurring within their system.

It is true by default and recommend to set false till you get some problem.

Example:

use MishkaInstaller.Event.Hook, event: "after_success_login", queue: false