pub mod structs;
use std::{cmp::min};
use log::{error, warn};
use sdl3::{Sdl, pixels::Color, rect::Rect};
use structs::{Prefs, DisplayData};

use crate::renderer::structs::Screen;

const LINE_COUNT: i32 = 5;
const COLOR_LCD_AMBER   : Color = Color::RGB(0xf4, 0xcb, 0x60);
const COLOR_LCD_GREEN   : Color = Color::RGB(0xb3, 0xff, 0x00);
const COLOR_LCD_RED     : Color = Color::RGB(0xff, 0x3a, 0x4a);
const COLOR_BACKGROUND  : Color = Color::RGB(0x0,  0x0,  0x0 );
const COLOR_TEXT_BG     : Color = Color::RGBA(0x0, 0x0, 0x0, 0x0);
const TEXT_SIZE: f32 = 160.0;  // Size of the font in pixels

// Offsets of each part within a line
const XOFFSET_ROUTE: u32 = 24;
const XOFFSET_DESTINATION: u32 = 300;
const XOFFSEET_TIME_LEFT: u32 = 1606;
const INTER_LINE_OVERLAP: u32 = 15; 

impl Screen<'_> {

    pub fn get_context(&self) -> &Sdl {
        return &self.context;
    }

    fn color_for(&self, due_in: i32) -> Color {
        if due_in > 15 { return COLOR_LCD_GREEN };
        if due_in > 10 { return COLOR_LCD_AMBER };
        return  COLOR_LCD_RED;
    }

    fn format_due_for(&self, due_in: i32, departure_time: u32) -> String {
        if due_in < 60 {
            return String::from("due");
        }
        if due_in < 3600 {
            return ((due_in / 60) as i32).to_string() + "min";
        } 
        return format!("{:02}:{:02}", (departure_time / 3600) as i32, ((departure_time % 3600) / 60) as i32);
    }


    pub fn update_information(&mut self, display_data: &DisplayData) {
        self.do_clear();

        // Print status first
        if display_data.status.is_some() {
            // If the update has some information text, show it
            self.do_print_at(5, display_data.status.as_ref().unwrap(), 0);
        } else {
            // Display date and time otherwise
            self.do_print_at(5, &format!("TODO: DATE/TIME GOES HERE").to_string(), 0);
        }

        // Then data lines from the bottom up
        let num_arrivals: i32 = min(LINE_COUNT, display_data.lines.len() as i32);
        for index in 0..num_arrivals {
            let line: u32 = ((num_arrivals - 1) - index) as u32;
            // Compose a line of text with all the information 
            let entry = display_data.lines.get(line as usize).unwrap();
            let due_in_mins = (entry.departure_time / 60) as i32;
            let due_color: Color = self.color_for(due_in_mins);
            let due_text = self.format_due_for(due_in_mins, entry.departure_time);

            self.color = COLOR_LCD_AMBER;
            self.do_print_at(line, &entry.route, XOFFSET_ROUTE);
            self.do_print_at(line, &entry.destination, XOFFSET_DESTINATION);
            self.color = due_color;
            self.do_print_at(line, &due_text, XOFFSEET_TIME_LEFT);
        };
        self.do_update();
    }


    pub fn _print(&mut self, line: u32, text: &str) {
        self.do_print_at(line, text, 0);
        self.do_update();
    }


    fn do_print_at(&mut self, line: u32, text: &str, left: u32) {
        if  text.len() == 0 {
            warn!("do_print_at called with a 0-length string");
            return;  
        }

        let render_result = self.font.render(text).lcd(self.color, COLOR_BACKGROUND);

        if render_result.is_err() {
            error!("Error rendering text \"{}\": {:#?}", text, render_result.err());
            return;
        }

        let rendered_text = render_result.unwrap();
        let texture_creator = self.canvas.texture_creator();
        let texture = rendered_text.as_texture(&texture_creator);

        if texture.is_err() {
            error!("Error creating texture from rendered text: {:#?}", texture.err());
            return;
        }

        let _= self.canvas.copy(&texture.unwrap(), 
            Rect::new(0, 0, rendered_text.width(), rendered_text.height()), 
            Rect::new(left.try_into().unwrap(), (line * (rendered_text.height() - INTER_LINE_OVERLAP)).try_into().unwrap(), rendered_text.width(), rendered_text.height()));
    }


    pub fn clear(&mut self) {
        self.do_clear();
        self.do_update();
    }


    fn do_update (&mut self) {
        self.canvas.present();
    }


    fn do_clear(&mut self) {
        self.canvas.set_draw_color(COLOR_BACKGROUND);
        self.canvas.clear();
    }

    /// Initialize video, allocate buffers and load fonts
    /// Based on https://github.com/vhspace/sdl3-rs/blob/master/examples/ttf-demo.rs
    pub fn init(prefs: &Prefs) -> Screen<'_> {
        // Initialize the screen   
        let sdl_context = sdl3::init().unwrap();
        let video_subsys = sdl_context.video().unwrap();

        let window = video_subsys
        .window("Dublin Bus", prefs.screen_width, prefs.screen_height)
        .position_centered()
        .borderless()
        //.fullscreen()
        .build().unwrap();

        // Load font
        let ttf_context = sdl3::ttf::init().unwrap();
        let font = ttf_context.load_font(&prefs.font_path, TEXT_SIZE).unwrap();
        
        let mut screen: Screen = Screen {
            canvas:  Box::new(window.into_canvas()), 
            font: Box::new(font),
            color: COLOR_LCD_AMBER,
            context: Box::new(sdl_context),
        };

        screen.clear();
        return screen;
    }
}