use std::collections::HashMap;
use std::ffi::OsStr;
use std::fs;
use std::io;
use std::option::Option;
use std::path::PathBuf;

use imgui;
use rlua::Lua;
use serialport;

use crate::rusbtmc;

#[derive(Default, PartialEq)]
pub struct Test {
    pub path: PathBuf,
    text: Option<String>,
}

impl Test {
    pub fn new(path: PathBuf) -> Test {
        Test {
            path: path,
            text: None,
        }
    }

    pub fn read(&mut self) -> &str {
        if self.text.is_none() {
            self.text = Some(fs::read_to_string(&self.path).expect("Failed to read file"));
        }

        return self.text.as_ref().unwrap();
    }

    // pub fn text(&self) -> &str {
    //     return match &self.text {
    //         Some(text) => text,
    //         None => "",
    //     }
    // }
}

#[derive(Default)]
pub struct Bench {
    /* tests window */
    lua: Lua,
    tests: Vec<Test>,
    tests_path: PathBuf,
    /* devices window */
    selected_test: Option<usize>,
    selected_usb_dev: Option<usize>,
    usb_devices: HashMap<imgui::ImString, rusbtmc::Instrument<rusb::GlobalContext>>,
    selected_serial_dev: Option<usize>,
    // serial_devices: HashMap<imgui::ImString, (serialport::SerialPortBuilder, Option<serialport::SerialPort>>,
    lua_console: Vec<imgui::ImString>,
    instr_console: Vec<imgui::ImString>,
    instr_input: imgui::ImString,
}

impl Bench {
    pub fn new() -> Bench {
        /* Prepare lua environment */
        let lua = Lua::new();
        let lua_setup = lua.context(|context| -> rlua::Result<()> {
            use rlua::{String, Variadic};

            let globals = context.globals();

            let ui_table = context.create_table()?;
            let ui_print = context.create_function(|_, _strings: Variadic<String>| {
                // TODO
                // lua_console.push()
                Ok(())
            })?;

            ui_table.set("print", ui_print)?;
            globals.set("ui", ui_table)?;

            Ok(())
        });

        if let Err(_) = lua_setup {
            // TODO: handle errors
        }

        let mut b = Bench {
            lua: lua,
            tests: Vec::new(),
            tests_path: PathBuf::from("lua"),
            selected_test: None,
            selected_usb_dev: None,
            usb_devices: HashMap::new(),
            selected_serial_dev: None,
            lua_console: Vec::new(),
            instr_console: Vec::new(),
            instr_input: imgui::ImString::with_capacity(256),
            // scope: None,
        };

        // TODO: set graphically and use RV
        let _ = b.load_tests();

        return b;
    }

    /// Loads lua tests from tests_path
    pub fn load_tests(&mut self) -> io::Result<()> {
        let entries: Result<Vec<PathBuf>, io::Error> = fs::read_dir(&self.tests_path)?
            .into_iter()
            .map(|r| r.map(|f| f.path()))
            .collect();

        match entries {
            Ok(files) => {
                self.tests = files
                    .into_iter()
                    .filter(|f| f.is_file())
                    .filter(|f| f.extension().unwrap_or(OsStr::new("")) == "lua")
                    .map(|f| Test::new(f))
                    .collect();

                return Ok(());
            }
            Err(e) => return Err(e),
        }
    }

    fn get_selected_device<'a>(
        index: Option<usize>,
        list: &'a mut HashMap<imgui::ImString, rusbtmc::Instrument<rusb::GlobalContext>>,
    ) -> Option<&'a mut rusbtmc::Instrument<rusb::GlobalContext>> {
        let selected_index = match index {
            Some(i) => i,
            None => return None,
        };

        for (index, (_name, dev)) in list.iter_mut().enumerate() {
            if matches!(selected_index, i if i == index) {
                return Some(dev);
            }
        }

        return None;
    }

    /// draws the entire interface
    pub fn draw(&mut self, _: &mut bool, ui: &mut imgui::Ui) {
        use imgui::*;

        /* Testbench window */
        let tb_win = Window::new(im_str!("Testbench"))
            .size([400., 500.], Condition::Appearing)
            .position([20., 20.], Condition::Appearing);

        tb_win.build(&ui, || {
            for (index, test) in self.tests.iter().enumerate() {
                if let Some(test_name) = test.path.to_str() {
                    let test_name: ImString = test_name.to_string().into();
                    let selected = matches!(self.selected_test, Some(i) if i == index);

                    if Selectable::new(&test_name).selected(selected).build(ui) {
                        self.selected_test = Some(index)
                    }
                }
            }

            if let Some(index) = self.selected_test {
                ui.separator();
                if let Some(test_name) = self.tests[index].path.to_str() {
                    let imstr: ImString =
                        format!("Selected Test: {}", test_name).to_string().into();
                    ui.text_wrapped(&imstr);
                    ui.same_line(0.);
                    if ui.button(im_str!("Run"), [0., 0.]) {
                        self.run_test(index);
                    }

                    ui.same_line(0.);
                    if ui.button(im_str!("Show"), [0., 0.]) {
                        self.show_test(index);
                    }
                }
            }

            ui.separator();
            ChildWindow::new("lua console")
                .size([0., 0.])
                .scrollable(true)
                .build(&ui, || {
                    for line in &self.lua_console {
                        ui.text(line);
                    }
                });
        });

        /* devices window */
        let dev_win = Window::new(im_str!("Devices"))
            .size([400., 500.], Condition::Appearing)
            .position([520., 20.], Condition::Appearing);

        dev_win.build(&ui, || {
            /* usb devices */
            // buttons
            ui.text_wrapped(im_str!("USB Devices"));
            ui.same_line(0.);
            if ui.button(im_str!("Refresh"), [0., 0.]) {
                // TODO: do not remove open devices
                self.usb_devices.clear();
                self.selected_usb_dev = None;

                if let Ok(instruments) = rusbtmc::instruments() {
                    for instr in instruments {
                        let desc = match instr.device.device_descriptor() {
                            Ok(desc) => desc,
                            Err(_) => {
                                dbg!("failed to get descriptor");
                                continue;
                            }
                        };

                        let handle = match instr.device.open() {
                            Ok(handle) => handle,
                            Err(e) => {
                                dbg!("failed to get handle", e);
                                continue;
                            }
                        };

                        let prodstr = match handle.read_product_string_ascii(&desc) {
                            Ok(s) => s,
                            Err(_) => {
                                dbg!("failed to read product string");
                                continue;
                            }
                        };

                        let dev_name: ImString = prodstr.into();
                        self.usb_devices.insert(dev_name, instr);
                    }
                }
            }

            if let Some(instr) = Bench::get_selected_device(
                self.selected_usb_dev.clone(),
                &mut self.usb_devices
            ) {
                // TODO: handle errors
                ui.same_line(0.);
                if ui.button(im_str!("Open"), [0., 0.]) {
                    let _ = dbg!(instr.open());
                }

                ui.same_line(0.);
                if ui.button(im_str!("Close"), [0., 0.]) {
                    let _ = dbg!(instr.close());
                }

                ui.same_line(0.);
                if ui.button(im_str!("Pulse"), [0., 0.]) {
                    let _ = dbg!(instr.pulse());
                }
            }

            ui.separator();

            // device list
            for (index, (name, dev)) in self.usb_devices.iter().enumerate() {
                let selected = matches!(self.selected_usb_dev, Some(i) if i == index);
                let mut label = name.clone();
                if dev.is_connected() {
                    label.push_str(" (connected)");
                }

                if Selectable::new(&label).selected(selected).build(ui) {
                    self.selected_usb_dev = Some(index);
                }
            }

            ui.separator();

            // serial devices
            /*
            ui.text_wrapped(im_str!("Serial Devices"));
            ui.same_line(0.);
            if ui.button(im_str!("Refresh"), [0., 0.]) {
                if let Ok(ports) = serialport::available_ports() {
                    for port in ports {
                        
                    }
                }
            }

            ui.separator();
            */

            // interactive device console
            ui.input_text(im_str!("Device"), &mut self.instr_input)
                .build();
            ui.same_line(0.);

            if let Some(instr) = Bench::get_selected_device(
                self.selected_usb_dev,
                &mut self.usb_devices
            ) {
                if ui.button(im_str!("Send"), [0., 0.]) {
                    let _ = dbg!(instr.write(self.instr_input.to_str()));
                    self.instr_input.clear();
                }
            }

            ChildWindow::new("instrument console")
                .size([0., 0.])
                .scrollable(true)
                .build(&ui, || {
                    for line in &self.instr_console {
                        ui.text(line);
                    }
                });
        });
    }

    fn run_test(&mut self, index: usize) {
        if let Some(test) = self.tests.get_mut(index) {
            let text = test.read();
            let mut output = imgui::ImString::new("");

            self.lua.context(
                |context| match context.load(text).eval::<rlua::MultiValue>() {
                    Ok(values) => {
                        output.push_str(
                            &values
                                .iter()
                                .map(|value| format!("{:?}", value))
                                .collect::<Vec<_>>()
                                .join("\t"),
                        );
                    }
                    Err(e) => {
                        output.push_str(&e.to_string());
                    }
                },
            );

            self.lua_console.push(output);
        }
    }

    fn show_test(&self, _index: usize) {
        // TODO
    }
}