use gtk;
use gtk::prelude::*;
use std::cell::RefCell;
use portaudio as pa;
use std::rc::Rc;
use std::sync::Arc;
use std::io;
use std::io::Write;
use std::thread;
use std::sync::mpsc::*;

const GUI_XML: &'static str = r#"
<interface>
  <object class="GtkWindow" id="window">
    <property name="title">Rusty Microphone</property>
    <child>
      <object class="GtkComboBoxText" id="dropdown">
      </object>
    </child>
  </object>
</interface>
"#;

struct ApplicationState {
    pa: pa::PortAudio,
    pa_stream: Option<pa::Stream<pa::NonBlocking, pa::Input<f32>>>
}

pub fn start_gui() -> Result<(), String> {
    let pa = try!(::audio::init().map_err(|e| e.to_string()));
    let microphones = try!(::audio::get_device_list(&pa).map_err(|e| e.to_string()));

    let (mic_sender, mic_receiver) = channel();
    let state = Rc::new(RefCell::new(ApplicationState {
        pa: pa,
        pa_stream: None
    }));
    
    try!(gtk::init().map_err(|_| "Failed to initialize GTK."));

    let gtk_builder = try!(create_window(microphones));

    {
        let state_for_dropdown = state.clone();
        
        let dropdown: gtk::ComboBoxText = try!(
            gtk_builder.get_object("dropdown").ok_or("GUI does not contain an object with id 'dropdown'")
        );
        dropdown.connect_changed(move |dropdown: &gtk::ComboBoxText| {
            match state_for_dropdown.borrow_mut().pa_stream {
                Some(ref mut stream) => {stream.stop().ok();},
                _ => {}
            }
            let selected_mic = dropdown.get_active_id().and_then(|id| id.parse().ok()).expect("Dropdown did not change to a valid value");
            let stream = ::audio::start_listening(&state_for_dropdown.borrow().pa, selected_mic, mic_sender.clone()).ok();
            if stream.is_none() {
                writeln!(io::stderr(), "Failed to open audio channel").ok();
            }
            state_for_dropdown.borrow_mut().pa_stream = stream;
        });
    }

    let async_thread = thread::spawn(move || {
        for samples in mic_receiver {
            let frequency_domain = ::transforms::fft(samples, 44100.0);
            
            let max_frequency = frequency_domain.iter()
                .fold(None as Option<::transforms::FrequencyBucket>, |max, next|
                      if max.is_none() || max.clone().unwrap().intensity < next.intensity { Some(next.clone()) } else { max }
                ).unwrap().max_freq;
            println!("{}Hz", max_frequency.floor());
        }
    });

    gtk::main();
    Ok(())
}

fn create_window(microphones: Vec<(u32, String)>) -> Result<gtk::Builder, String> {
    let gtk_builder = gtk::Builder::new_from_string(GUI_XML);
    let window: gtk::Window = try!(
        gtk_builder.get_object("window")
                   .ok_or("GUI does not contain an object with id 'window'")
    );
    window.set_default_size(300, 300);
    window.connect_delete_event(|_, _| {
        gtk::main_quit();
        Inhibit(false)
    });
    window.show_all();

    let dropdown: gtk::ComboBoxText = try!(
        gtk_builder.get_object("dropdown")
                   .ok_or("GUI does not contain an object with id 'dropdown'")
    );
    set_dropdown_items(&dropdown, microphones);

    Ok(gtk_builder)
}

fn set_dropdown_items(dropdown: &gtk::ComboBoxText, microphones: Vec<(u32, String)>) {
    for (index, name) in microphones {
        dropdown.append(Some(format!("{}", index).as_ref()), name.as_ref());
    }
}