use st7735::gfx::PrimitveGFX;

pub struct FontGlyph {
    pub bitmap_offset: usize, // Offset in glyph bitmap
    pub width: u8, // Size of glyph
    pub height: u8,
    pub x_advance: u8, // Distance to advance along x-axis
    pub x_offset: i8, // Distance to upper left coner from cursor pos
    pub y_offset: i8,
}


pub struct Font {
    pub bitmap: &'static [u8], // Glyph bitmaps, concatenated
    pub glyphs: &'static [FontGlyph], // Array of glyph metadata
    pub first: u8, // Start of ASCII extend
    pub last: u8, // End of ASCII extend
    pub y_advance: u8, // Line height
}


pub trait FontRenderer: PrimitveGFX {
    fn draw_glyph(&mut self, x: u8, y: u8, glyph: &FontGlyph, font: &Font, size: u8, color: u16) {
        if size == 0 {
            return;
        }

        // Any clipping should be done by draw_rect

        let x = x as i16;
        let y = y as i16;
        let size = size as i16;

        let mut bo = glyph.bitmap_offset;
        let mut set_pixels: i16 = 0;
        let mut bits: u8 = 0;
        let mut bit: u8 = 0;

        for cur_y in 0..(glyph.height as i16) {
            for cur_x in 0..(glyph.width as i16) {
                if bit == 0 {
                    bits = font.bitmap[bo];
                    bo += 1;
                    bit = 0x80;
                }

                if bit & bits != 0 {
                    set_pixels += 1;
                } else if set_pixels > 0 {
                    let start_x = (x + ((glyph.x_offset as i16) + cur_x - set_pixels) * size) as u8;
                    let start_y = (y + ((glyph.y_offset as i16) + cur_y) * size) as u8;
                    let w = (set_pixels * size) as u8;
                    let h = size as u8;
                    self.fill_rect(start_x, start_y, w, h, color);

                    set_pixels = 0;
                }
                bit >>= 1;
            }

            if set_pixels > 0 {
                let start_x = (x +
                               ((glyph.x_offset as i16) + (glyph.width as i16) -
                                set_pixels) * size) as u8;
                let start_y = (y + ((glyph.y_offset as i16) + cur_y) * size) as u8;
                let w = (set_pixels * size) as u8;
                let h = size as u8;
                self.fill_rect(start_x, start_y, w, h, color);

                set_pixels = 0;
            }
        }
    }

    fn draw_text(&mut self, x: u8, y: u8, text: &str, font: &Font, size: u8, color: u16) {
        let mut cursor_x = x;
        let mut cursor_y = y;

        for text_char in text.chars() {
            let c = if text_char.is_ascii() {
                text_char as u8
            }
            else {
                '?' as u8
            };

            if c == '\n' as u8 {
                cursor_x = x;
                cursor_y += font.y_advance * size;
            }
            else if c >= font.first && c <= font.last && c != '\r' as u8 {
                let pos = (c - font.first) as usize;
                let glyph = &font.glyphs[pos];
                self.draw_glyph(cursor_x, cursor_y, glyph, &font, size, color);
                cursor_x += glyph.x_advance * size;
            }

        }

    }
}