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use std::{
    collections::{BTreeMap, HashMap},
    io::Write,
    iter::Iterator,
};

use crossterm::{
    cursor, queue,
    style::{self, ContentStyle},
};

use super::{Canvas, Coord, Drawable, Pixel, Pixels, Rect, Style};

pub struct Buffer<S: Style> {
    pub width: u16,
    pub height: u16,
    pixels: Vec<Pixel<S>>,
    pub changes: BTreeMap<usize, Pixel<S>>,
    pub styles: HashMap<S, ContentStyle>,
}

impl<S: Style> Default for Buffer<S> {
    fn default() -> Self {
        Self {
            width: 0,
            height: 0,
            pixels: Vec::new(),
            changes: BTreeMap::new(),
            styles: HashMap::new(),
        }
    }
}

impl<S: Style> Buffer<S> {
    pub fn canvas<'a>(&'a mut self, frame: Rect) -> Canvas<'a, S> {
        Canvas::new(self, frame)
    }

    pub fn set_styles(&mut self, styles: HashMap<S, ContentStyle>) {
        self.styles = styles;
    }

    pub fn resize(&mut self, width: u16, height: u16) {
        self.width = width;
        self.height = height;
        self.pixels = (0..width * height).map(|_| Pixel::default()).collect();
    }

    pub fn draw_changes<W: Write>(&mut self, stdout: &mut W) -> Result<(), crossterm::ErrorKind> {
        let mut last_style = None;
        let mut last_coord = None;
        let mut text = "".to_string();

        for (k, v) in self.changes.iter() {
            if let Some(pixel) = self.pixels.get(*k) {
                if *pixel != *v {
                    self.pixels[*k] = *v;
                } else {
                    continue;
                }
            } else {
                continue;
            }

            if last_style != Some(v.style) || *k == 0 || last_coord != Some(*k - 1) {
                if !text.is_empty() {
                    let style = match self.styles.get(&last_style.unwrap()) {
                        Some(s) => *s,
                        None => ContentStyle::default(),
                    };
                    queue!(stdout, style::PrintStyledContent(style.apply(text)))?;
                }

                let coord = Coord::from_index(*k, self.width);
                queue!(stdout, cursor::MoveTo(coord.x, coord.y))?;

                text = v.text.unwrap_or(' ').to_string();
                last_style = Some(v.style);
            } else {
                text = format!("{}{}", text, v.text.unwrap_or(' '));
            }

            last_coord = Some(*k);
        }

        if !text.is_empty() {
            let style = match self.styles.get(&last_style.unwrap()) {
                Some(s) => *s,
                None => ContentStyle::default(),
            };

            queue!(stdout, style::PrintStyledContent(style.apply(text)))?;
        }

        self.changes.clear();

        stdout.flush()?;

        Ok(())
    }

    pub fn get_pixel(&self, x: u16, y: u16) -> Option<&Pixel<S>> {
        let index = Coord::from((x, y)).as_index(self.width);

        self.pixels.get(index)
    }
}

impl<S: Style> Drawable<S> for Buffer<S> {
    fn fill(&mut self, text: char, style: S) {
        self.rect(Rect::new(0, 0, self.width, self.height), text, style);
    }
    fn rect(&mut self, rect: Rect, text: char, style: S) {
        let text: String = (0..rect.width).map(|_| text).collect();
        for y in 0..rect.height {
            self.string(rect.x, rect.y + y, text.clone(), style);
        }
    }

    fn string(&mut self, x: u16, y: u16, text: String, style: S) {
        let index = Coord::from((x, y)).as_index(self.width);

        for (i, c) in text.chars().enumerate() {
            if i + index >= self.pixels.len() {
                break;
            }

            self.pixel_at_index(
                index + i,
                Pixel {
                    text: Some(c),
                    style,
                },
            );
        }
    }

    fn pixels(&mut self, x: u16, y: u16, pixels: &Pixels<S>) {
        let index = Coord::from((x, y)).as_index(self.width);

        for (i, p) in pixels.iter().enumerate() {
            if i + index >= self.pixels.len() {
                break;
            }

            self.pixel_at_index(index + i, *p);
        }
    }

    fn pixel(&mut self, x: u16, y: u16, pixel: Pixel<S>) {
        let index = Coord::from((x, y)).as_index(self.width);
        self.pixel_at_index(index, pixel);
    }

    fn pixel_at_index(&mut self, coord: usize, pixel: Pixel<S>) {
        if self.pixels[coord] != pixel {
            self.changes.insert(coord, pixel);
        } else {
            self.changes.remove(&coord);
        }
    }
}