#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Image {
    pub pixels: Vec<u8>, // 64 for SD, 256 for HD
}

impl Image {
    /// flip image vertically
    fn flip(&mut self) {
        let mut pixels = Vec::with_capacity(64);

        for row in self.pixels.chunks(8).rev() {
            for pixel in row {
                pixels.push(*pixel);
            }
        }

        self.pixels = pixels;
    }

    /// mirror image horizontally
    fn mirror(&mut self) {
        let mut pixels = Vec::with_capacity(64);

        for row in self.pixels.chunks(8) {
            for i in (0..8).rev() {
                pixels.push(row[i]);
            }
        }

        self.pixels = pixels;
    }

    /// rotate image 90° clockwise
    fn rotate(&mut self) {
        let mut pixels = Vec::with_capacity(64);

        // start from bottom-left corner, work upward in that column,
        // then work on the next column to the right
        for x in 0..8 {
            for y in (0..8).rev() {
                pixels.push(self.pixels[(y * 8) + x]);
            }
        }

        self.pixels = pixels;
    }
}

impl From<String> for Image {
    fn from(string: String) -> Image {
        let string = string.replace("NaN", "0");
        let string = string.trim();
        let lines: Vec<&str> = string.lines().collect();
        let dimension = lines.len();
        let mut pixels: Vec<u8> = Vec::new();

        for line in lines {
            let line = &line[..dimension];
            for char in line.chars().into_iter() {
                pixels.push(match char {'1' => 1, _ => 0});
            }
        }

        Image { pixels }
    }
}

impl ToString for Image {
    fn to_string(&self) -> String {
        let mut string = String::new();

        let sqrt = (self.pixels.len() as f64).sqrt() as usize; // 8 for SD, 16 for HD
        for line in self.pixels.chunks(sqrt) {
            for pixel in line {
                string.push_str(&format!("{}", *pixel));
            }
            string.push('\n');
        }

        string.pop(); // remove trailing newline

        string
    }
}

pub(crate) fn animation_frames_from_string(string: String) -> Vec<Image> {
    let frames: Vec<&str> = string.split(">").collect();

    frames.iter().map(|&frame| Image::from(frame.to_string())).collect()
}

#[cfg(test)]
mod test {
    use crate::image::{Image, animation_frames_from_string};
    use crate::mock;

    #[test]
    fn test_image_from_string() {
        let output = Image::from(
            include_str!("test-resources/image").to_string()
        );

        let expected = Image {
            pixels: vec![
                1, 1, 1, 1, 1, 1, 1, 1,
                1, 1, 0, 0, 1, 1, 1, 1,
                1, 0, 1, 1, 1, 1, 1, 1,
                1, 1, 1, 1, 1, 1, 1, 1,
                1, 1, 1, 1, 1, 1, 1, 1,
                1, 1, 1, 1, 1, 1, 1, 1,
                1, 1, 1, 1, 1, 1, 1, 1,
                1, 1, 1, 1, 1, 1, 1, 1,
            ],
        };

        assert_eq!(output, expected);
    }

    #[test]
    fn test_image_to_string() {
        let output = mock::image::chequers_1().to_string();
        let expected = include_str!("test-resources/image-chequers-1").to_string();
        assert_eq!(output, expected);
    }

    #[test]
    fn test_animation_frames_from_string() {
        let output = animation_frames_from_string(
            include_str!("test-resources/animation_frames").to_string()
        );

        let expected = mock::image::animation_frames();

        assert_eq!(output, expected);
    }

    /// lots of Bitsy games have editor errors where pixels can be placed out of bounds
    /// check that these extraneous pixels are stripped out
    #[test]
    fn test_image_out_of_bounds() {
        let output = Image::from(
            include_str!("test-resources/image-oob").to_string()
        );
        
        let expected = Image {
            pixels: vec![
                1,1,1,1,1,1,1,1,
                1,1,0,0,1,1,1,1,
                1,0,1,1,1,1,1,1,
                1,1,1,1,1,1,1,1,
                1,1,1,1,1,1,1,1,
                1,1,1,1,1,1,1,1,
                1,1,1,1,1,1,1,1,
                0,0,0,0,0,0,0,0,
            ]
        };
        
        assert_eq!(output, expected);
    }

    #[test]
    fn flip() {
        let mut image = crate::mock::image::asymmetrical();
        image.flip();

        let flipped = Image { pixels: vec![
            0,0,0,1,0,0,0,0,
            0,0,1,0,0,0,0,0,
            0,1,0,0,0,0,0,0,
            1,0,0,0,0,0,0,0,
            1,0,0,0,0,0,0,0,
            0,1,0,0,0,0,0,0,
            0,0,0,0,0,0,0,0,
            0,0,0,0,0,0,0,0,
        ]};

        assert_eq!(image, flipped);
    }

    #[test]
    fn mirror() {
        let mut image = crate::mock::image::asymmetrical();
        image.mirror();

        let mirrored = Image { pixels: vec![
            0,0,0,0,0,0,0,0,
            0,0,0,0,0,0,0,0,
            0,0,0,0,0,0,1,0,
            0,0,0,0,0,0,0,1,
            0,0,0,0,0,0,0,1,
            0,0,0,0,0,0,1,0,
            0,0,0,0,0,1,0,0,
            0,0,0,0,1,0,0,0,
        ]};

        assert_eq!(image, mirrored);
    }

    #[test]
    fn rotate() {
        let mut image = crate::mock::image::asymmetrical();
        image.rotate();

        let rotated = Image { pixels: vec![
            0,0,0,1,1,0,0,0,
            0,0,1,0,0,1,0,0,
            0,1,0,0,0,0,0,0,
            1,0,0,0,0,0,0,0,
            0,0,0,0,0,0,0,0,
            0,0,0,0,0,0,0,0,
            0,0,0,0,0,0,0,0,
            0,0,0,0,0,0,0,0,
        ]};

        assert_eq!(image, rotated);
    }
}