Provide functionality for playing a .wav file (#20)

PBI: 27951
Task: 28656

* Refactor slash stripping method

* Refactor remove_leading_slashes()

* Add checking to see if file name ends with .wav

* Change displayed error to our error and provide meaningful error message

src/adafruit_circuitplayground/express.py

@@ -1,5 +1,7 @@
 import json
 import sys
+import os
+import simpleaudio as sa
 from .pixel import Pixel
 from . import utils
 
@@ -28,6 +30,8 @@ def __init__(self):
         }
 
         self.pixels = Pixel(self.__state)
+        self.__speaker_enabled = False
+        self.__abs_path_to_code_file = ''
 
     @property
     def button_a(self):
@@ -49,4 +53,23 @@ def red_led(self, value):
     def __show(self):
         utils.show(self.__state)
 
+    def play_file(self, file_name):
+        file_name = utils.remove_leading_slashes(file_name)
+        abs_path_parent_dir = os.path.abspath(os.path.join(self.__abs_path_to_code_file, os.pardir))
+        abs_path_wav_file = os.path.normpath(os.path.join(abs_path_parent_dir, file_name))
+
+        if sys.implementation.version[0] >= 3:
+            if file_name.endswith(".wav"):
+                wave_obj = sa.WaveObject.from_wave_file(abs_path_wav_file)
+                try:
+                    play_obj = wave_obj.play()
+                except:
+                    # TODO TASK: 29054 Verfication of a "valid" .wav file
+                    raise EnvironmentError("Your .wav file is not suitable for the Circuit Playground Express.")
+                play_obj.wait_done()
+            else:
+                raise TypeError(file_name + " is not a path to a .wav file.")
+        else:
+            raise NotImplementedError("Please use Python 3 or higher.")
+
 cpx = Express()

src/adafruit_circuitplayground/utils.py

@@ -2,5 +2,9 @@
 import json
 
 def show(state):
-    print(json.dumps(state) + '\0', end='')
-    sys.stdout.flush()
+    print(json.dumps(state) + '\0', end='', flush=True)
+
+def remove_leading_slashes(string):
+    string = string.lstrip('\\/')
+
+    return string

src/setup.py

@@ -3,11 +3,11 @@
 import json
 import threading
 import copy
+from adafruit_circuitplayground.express import cpx
 from pathlib import Path
 
 read_val = ""
 
-
 class UserInput(threading.Thread):
 
     def __init__(self):
@@ -39,9 +39,9 @@ def run(self):
 threads.append(user_input)
 user_input.start()
 
-
 # User code thread
 def execute_user_code(abs_path_to_code_file):
+    cpx._Express__abs_path_to_code_file = abs_path_to_code_file
     # Execute the user's code.py file
     with open(abs_path_to_code_file) as file:
         user_code = file.read()