from __future__ import unicode_literals  # So that `print` can print Unicode characters in names
import logging
import sys

logger = logging.getLogger(__name__)


def get_microphones(audio):
    """
    Get audio devices which have input channels.

    :param audio: An instance of PyAudio to use.
    :type audio: pyaudio.PyAudio

    :return: An interator of PaAudio dicts containing information about the microphone devices.
    :rtype: Iterator[dict]
    """
    for i in range(audio.get_device_count()):
        device = audio.get_device_info_by_index(i)
        if device["maxInputChannels"] > 0:
            yield device


def choose_mic_interactive(audio):
    """
    Choose a microphone to use, interactively in the CLI.

    :param audio: An instance of PyAudio to use.
    :type audio: pyaudio.PyAudio

    :return: A dictionary from PyAudio containing information about the microphone to use, or None
        if there is no microphone.
    :rtype: dict | None
    """
    microphones = list(get_microphones(audio))
    if len(microphones) == 0: return None

    print("Found {} microphones:".format(len(microphones)))
    for i, mic in enumerate(microphones):
        print("- {}: {}".format(i, mic["name"]))

    chosen_microphone = None
    while chosen_microphone is None:
        chosen = raw_input("Which device would you like to use?\n> ")
        try:
            chosen = int(chosen)
            if chosen < 0 or chosen >= len(microphones): raise ValueError()
            chosen_microphone = microphones[chosen]
        except ValueError:
            print("Please enter a number between 0 and {}".format(len(microphones)-1))

    logger.info("Chose microphone \"{}\"".format(chosen_microphone["name"]))
    return chosen_microphone


def choose_mic_default(audio):
    """
    Get the system's default microphone to use.

    :param audio: An instance of PyAudio to use.
    :type audio: pyaudio.PyAudio

    :return: A dictionary from PyAudio containing information about the microphone to use, or None
        if there is no microphone.
    :rtype: dict | None
    """
    try:
        return audio.get_default_input_device_info()
    except IOError:
        return None


def choose_mic_arguments(audio):
    """
    Get a microphone to use from command line arguments.

    :param audio: An instance of PyAudio to use.
    :type audio: pyaudio.PyAudio

    :return: A dictionary from PyAudio containing information about the microphone to use, or None
        if there is no microphone satisfied by the arguments.
    :rtype: dict | None
    """
    microphone_name = None
    for i, arg in enumerate(sys.argv):
        if arg == "--microphone" and len(sys.argv) > i+1:
            microphone_name = sys.argv[i+1].strip()
        if arg.startswith("--microphone="):
            pre_fix_len = len("--microphone=")
            microphone_name = arg[pre_fix_len:].strip()

    if not microphone_name: return None

    available_mics = list(get_microphones(audio))
    for mic in available_mics:
        if mic["name"] == microphone_name:
            return mic

    available_mic_names = [mic["name"] for mic in available_mics]
    logger.warning("Microphone \"{}\" not found. Choose one of {}"
                   .format(microphone_name, available_mic_names))

    return None


def choose_mic(audio):
    """
    Get a microphone to use. Firstly, tries to see if there's an application argument specifying the
    microphone to use. If not, get the default microphone.

    :param audio: An instance of PyAudio to use.
    :type audio: pyaudio.PyAudio

    :return: A dictionary from PyAudio containing information about the microphone to use, or None
        if there is no microphone.
    :rtype: dict | None
    """
    chosen_mic = choose_mic_arguments(audio)
    if chosen_mic: return chosen_mic

    return choose_mic_default(audio)