//! In-window Command line interface. Used for operations that are just easier than with GUI.
//!
//! Sometimes it is nice to have a GUI, for instance when a selection has to be made, things have to
//! be moved etc., however for operations like saving/loading and exporting, no such thing has to be
//! done and the GUI is really just slowing you down (at least in my opinion). For these operations,
//! it is much better to simply have a command do that specific thing. It is also much easier to
//! implement a new command, so features can be tested more quickly. For some things, there should
//! still be a GUI option. With the example of saving/loading, it is much easier to find some hidden
//! folder in a GUI, so that is definitely a consideration for the future.

pub mod cmd;
pub use self::cmd::*;

use crate::client::colours::DEFAULT_COLOURS;
use crate::client::input::{Button, Input};
use crate::client::Editor;
use crate::math::Vec2;
use raylib::drawing::{RaylibDraw, RaylibDrawHandle};
use std::sync::mpsc::Receiver;

/// The command line interface. Should be created only once per program instance.
pub struct CLI {
    text: String,
    char_pipe: Option<Receiver<char>>,
}

impl CLI {
    /// Create a CLI for this instance
    pub fn new(input: &mut Input) -> Self {
        input.add_global(Button::Text(':').into());

        Self {
            text: String::new(),
            char_pipe: None,
        }
    }

    /// Activates the CLI, which will now capture keyboard input and execute commands accordingly.
    pub fn try_activate(&mut self, input: &mut Input) {
        if !self.active() {
            self.char_pipe = input.try_capture_keyboard();

            if self.char_pipe.is_some() {
                self.text = ":".to_owned();
            }
        }
    }

    /// Deactivate the command line.
    pub fn deactivate(&mut self) {
        // Hang up, the input handler will get the message.
        self.char_pipe = None;
    }

    /// Checks if the CLI is currently active. This means input to other things should be ignored.
    pub fn active(&self) -> bool {
        self.char_pipe.is_some()
    }

    fn perform_command(&mut self, editor: &mut Editor) {
        match cmd::parse_command(&self.text[1..]) {
            Ok(cmd) => match cmd.process(editor) {
                Ok(res) => self.text = format!("SUCCESS: {}", res),
                Err(err) => self.text = format!("ERROR: {}", err),
            },
            Err(err) => self.text = format!("SYNTAX ERROR: {}", err),
        }
    }

    /// Handle input for the command line and perform any commands the user may want to run.
    pub fn update(&mut self, editor: &mut Editor, input: &mut Input) {
        /* Check if the CLI is currently active. If not and it should not be activated according to
         * keyboard input, there is nothing to do.
         */
        if !self.active() {
            if input.poll_global(&Button::Text(':').into()) {
                self.try_activate(input);
                if !self.active() {
                    return;
                }
            } else {
                return;
            }
        }

        let rx = self
            .char_pipe
            .as_mut()
            .expect("No character pipe eventhough CLI should be active");

        if let Ok(c) = rx.try_recv() {
            match c {
                '\x1B' => self.text.clear(), // Escape
                '\x7f' => {
                    self.text.pop();
                } // Backspace
                '\n' => {
                    self.perform_command(editor);
                    self.deactivate();
                }
                c => self.text.push(c),
            }
        }

        // When the text is empty, there is also no command marker, so set as inactive and leave.
        if self.text.is_empty() {
            self.deactivate()
        }
    }

    /// Draw the command line at the bottom of the window.
    pub fn draw(&self, rld: &mut RaylibDrawHandle) {
        let pos = Vec2::new(150., rld.get_screen_height() as f32 - 25.);

        rld.draw_rectangle_v(
            pos,
            Vec2::new(rld.get_screen_width() as f32 - pos.x, 25.),
            DEFAULT_COLOURS.cli_background,
        );
        rld.draw_text(
            &self.text,
            155,
            rld.get_screen_height() - 22,
            20,
            DEFAULT_COLOURS.cli_foreground,
        );
    }
}