Add plain text and coloured logging to the Client

Logs websocket events (connect, message, error and close events)

adr/0003-logging-methods-vs-logger-class.md

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+# 3. Logging methods vs logger class
+
+Date: 2024-03-19
+
+## Status
+
+Accepted
+
+## Context
+
+I'm deciding between integrating logging directly into the main class or creating a dedicated logger class.
+
+### Option 1: Logging methods
+
+The first approach weaves logging actions into the operational code, resulting in a tight coupling of functionality and
+logging. Classes should be open for extension but closed for modification, and this strategy violates that principle.
+
+```ruby
+class Client
+  def connect(relay)
+    execute_within_an_em_thread do
+      client = build_websocket_client(relay.url)
+      parent_to_child_channel.subscribe do |msg|
+        client.send(msg)
+        emit(:send, msg)
+        log_send(msg) # <------ new code
+      end
+
+      client.on :open do
+        child_to_parent_channel.push(type: :open, relay:)
+        log_connection_opened(relay) # <------ new code
+      end
+
+      client.on :message do |event|
+        child_to_parent_channel.push(type: :message, data: event.data)
+        log_message_received(event.data) # <------ new code
+      end
+
+      client.on :error do |event|
+        child_to_parent_channel.push(type: :error, message: event.message)
+        log_error(event.message) # <------ new code
+      end
+
+      client.on :close do |event|
+        child_to_parent_channel.push(type: :close, code: event.code, reason: event.reason)
+        log_connection_closed(event.code, event.reason) # <------ new code
+      end
+    end
+
+    # ------ new code below ------
+
+    def log_send(msg)
+      logger.info("Message sent: #{msg}")
+    end
+
+    def log_connection_opened(relay)
+      logger.info("Connection opened to #{relay.url}")
+    end
+
+    def log_message_received(data)
+      logger.info("Message received: #{data}")
+    end
+
+    def log_error(message)
+      logger.error("Error: #{message}")
+    end
+
+    def log_connection_closed(code, reason)
+      logger.info("Connection closed with code: #{code}, reason: #{reason}")
+    end
+  end
+end
+```
+
+### Option 2: Logger class
+
+The second strategy separates logging into its own class, promoting cleaner code and adherence to the Single
+Responsibility Principle. Client already exposes events that can be tapped into, so the logger class can listen to these
+events and log accordingly.
+
+```ruby
+class ClientLogger
+  def attach_to(client)
+    logger_instance = self
+
+    client.on(:connect) { |relay| logger_instance.on_connect(relay) }
+    client.on(:message) { |message| logger_instance.on_message(message) }
+    client.on(:send) { |message| logger_instance.on_send(message) }
+    client.on(:error) { |message| logger_instance.on_error(message) }
+    client.on(:close) { |code, reason| logger_instance.on_close(code, reason) }
+  end
+
+  def on_connect(relay); end
+  def on_message(message); end
+  def on_send(message); end
+  def on_error(message); end
+  def on_close(code, reason); end
+end
+
+client = Nostr::Client.new
+logger = Nostr::ClientLogger.new
+logger.attach_to(client)
+```
+
+This approach decouples logging from the main class, making it easier to maintain and extend the logging system without
+affecting the core logic.
+
+## Decision
+
+I've chosen the dedicated logger class route. This choice is driven by a desire for extensibility in the logging system.
+With a separate logger, I can easily modify logging behavior—like changing formats, adjusting verbosity levels,
+switching colors, or altering output destinations (files, networks, etc.) — without needing to rewrite any of the main
+operational code.
+
+## Consequences
+
+Adopting a dedicated logger class offers greater flexibility and simplifies maintenance, making it straightforward to
+adjust how and what I log independently of the core logic. This separation of concerns means that any future changes
+to logging preferences or requirements can be implemented quickly and without risk to the main class's functionality.
+However, it's important to manage the integration carefully to avoid introducing complexity, such as handling
+dependencies and ensuring seamless communication between the main operations and the logging system.
+