pub mod theme;

use std::{
    collections::hash_map::HashMap,
    borrow::Borrow,
    mem::replace
};
use serde_derive::{Deserialize};
use serde_yaml;
use integral_geometry::{Point, Size, Rect};
use landgen::{
    outline_template::OutlineTemplate
};
use rand::{thread_rng, Rng};
use land2d::Land2D;
use vec2d::Vec2D;
use self::theme::Theme;

#[derive(Deserialize)]
struct PointDesc {
    x: u32,
    y: u32
}

#[derive(Deserialize)]
struct RectDesc {
    x: u32,
    y: u32,
    w: u32,
    h: u32
}

#[derive(Deserialize)]
struct TemplateDesc {
    width: usize,
    height: usize,
    can_flip: bool,
    can_invert: bool,
    can_mirror: bool,
    is_negative: bool,
    put_girders: bool,
    max_hedgehogs: u8,
    outline_points: Vec<Vec<RectDesc>>,
    fill_points: Vec<PointDesc>
}

#[derive(Deserialize)]
struct TemplateCollectionDesc {
    templates: Vec<TemplateDesc>,
    template_types: HashMap<String, Vec<usize>>
}

impl From<&TemplateDesc> for OutlineTemplate {
    fn from(desc: &TemplateDesc) -> Self {
        OutlineTemplate {
            islands: desc.outline_points.iter()
                .map(|v| v.iter()
                    .map(|r| Rect::from_size(
                        Point::new(r.x as i32, r.y as i32),
                        Size::new(r.w as usize, r.h as usize)))
                    .collect())
                .collect(),
            fill_points: desc.fill_points.iter()
                .map(|p| Point::new(p.x as i32, p.y as i32))
                .collect(),
            size: Size::new(desc.width, desc.height),
            can_flip: desc.can_flip,
            can_invert: desc.can_invert,
            can_mirror: desc.can_mirror,
            is_negative: desc.is_negative
        }
    }
}

#[derive(PartialEq, Eq, Hash, Clone, Debug)]
struct TemplateType(String);

impl Borrow<str> for TemplateType {
    fn borrow(&self) -> &str {
        self.0.as_str()
    }
}

#[derive(Debug)]
pub struct MapGenerator {
    pub(crate) templates: HashMap<TemplateType, Vec<OutlineTemplate>>
}

impl MapGenerator {
    pub fn new() -> Self {
        Self { templates: HashMap::new() }
    }

    pub fn import_yaml_templates(&mut self, text: &str) {
        let mut desc: TemplateCollectionDesc = serde_yaml::from_str(text).unwrap();
        let templates = replace(&mut desc.templates, vec![]);
        self.templates = desc.template_types.into_iter()
            .map(|(size, indices)|
                (TemplateType(size), indices.iter()
                    .map(|i| (&templates[*i]).into())
                    .collect()))
            .collect();
    }

    pub fn get_template(&self, template_type: &str) -> Option<&OutlineTemplate> {
        self.templates.get(template_type).and_then(|t| thread_rng().choose(t))
    }

    pub fn make_texture(&self, land: &Land2D<u8>, theme: &Theme) -> Vec2D<u32> {
        let mut texture = Vec2D::new(land.size(), 0);

        if let Some(land_sprite) = theme.land_texture() {
            for (row_index, (land_row, tex_row)) in land.rows()
                .zip(texture.rows_mut())
                .enumerate()
            {
                let sprite_row = land_sprite.get_row(row_index % land_sprite.height());
                let mut x_offset = 0;
                while sprite_row.len() < land.width() - x_offset {
                    let copy_range = x_offset..x_offset + sprite_row.len();
                    tex_row_copy(
                        &land_row[copy_range.clone()],
                        &mut tex_row[copy_range],
                        sprite_row
                    );

                    x_offset += land_sprite.width()
                }

                if x_offset < land.width() {
                    let final_range = x_offset..land.width();
                    tex_row_copy(
                        &land_row[final_range.clone()],
                        &mut tex_row[final_range],
                        &sprite_row[..land.width() - x_offset]
                    );
                }
            }
        }

        if let Some(border_sprite) = theme.border_texture() {
            assert!(border_sprite.height() <= 512);
            let border_width = (border_sprite.height() / 2) as u8;
            let border_sprite = border_sprite.to_tiled();

            let mut offsets = vec![255u8; land.width()];

            land_border_pass(
                land.rows().rev().zip(texture.rows_mut().rev()),
                &mut offsets,
                border_width,
                |x, y| border_sprite.get_pixel(
                    x % border_sprite.width(),
                    border_sprite.height() - 1 - y,
                )
            );

            offsets.iter_mut().for_each(|v| *v = 255);

            land_border_pass(
                land.rows().zip(texture.rows_mut()),
                &mut offsets,
                border_width,
                |x, y| border_sprite.get_pixel(
                    x % border_sprite.width(),
                    y,
                )
            );
        }

        texture
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Color(u32);

impl Color {
    #[inline]
    fn red(self) -> u8 {
        (self.0 >> 0 & 0xFF) as u8
    }

    #[inline]
    fn green(self) -> u8 {
        (self.0 >> 8 & 0xFF) as u8
    }

    #[inline]
    fn blue(self) -> u8 {
        (self.0 >> 16 & 0xFF) as u8
    }

    #[inline]
    fn alpha(self) -> u8 {
        (self.0 >> 24 & 0xFF) as u8
    }
}

#[inline]
fn lerp(from: u8, to: u8, coef: u8) -> u8 {
    ((from as u16 * (256 - coef as u16) + to as u16 * coef as u16) / 256) as u8
}

#[inline]
fn blend(source: u32, target: u32) -> u32 {
    let source = Color(source);
    let target = Color(target);
    let alpha = lerp(target.alpha(), 255, source.alpha());
    let red = lerp(target.red(), source.red(), source.alpha());
    let green = lerp(target.green(), source.green(), source.alpha());
    let blue = lerp(target.blue(), source.blue(), source.alpha());
    (red as u32) << 0 | (green as u32) << 8 | (blue as u32) << 16 | (alpha as u32) << 24
}

fn land_border_pass<'a, T, F>(rows: T, offsets: &mut [u8], border_width: u8, pixel_getter: F)
    where T: Iterator<Item = (&'a [u8], &'a mut [u32])>,
          F: (Fn(usize, usize) -> u32)
{
    for (land_row, tex_row) in rows {
        for (x, ((land_v, tex_v), offset_v)) in land_row.iter()
            .zip(tex_row.iter_mut())
            .zip(offsets.iter_mut())
            .enumerate()
        {
            *offset_v = if *land_v == 0 {
                if *offset_v < border_width {
                    *tex_v = blend(
                        pixel_getter(x, *offset_v as usize),
                        *tex_v,
                    )
                }
                offset_v.saturating_add(1)
            } else {
                0
            }
        }
    }
}

fn tex_row_copy(land_row: &[u8], tex_row: &mut [u32], sprite_row: &[u32]) {
    for ((land_v, tex_v), sprite_v) in
        land_row.iter().zip(tex_row.iter_mut()).zip(sprite_row)
    {
        *tex_v = if *land_v == 0 {
            *sprite_v
        } else {
            0
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::{
        MapGenerator,
        TemplateType
    };

    #[test]
    fn simple_load() {
        let text = r#"
# comment

templates:
  -
    width: 3072
    height: 1424
    can_flip: false
    can_invert: false
    can_mirror: true
    is_negative: false
    put_girders: true
    max_hedgehogs: 18
    outline_points:
      -
        - {x: 748, y: 1424, w: 1, h: 1}
        - {x: 636, y: 1252, w: 208, h: 72}
        - {x: 898, y: 1110, w: 308, h: 60}
        - {x: 1128, y: 1252, w: 434, h: 40}
        - {x: 1574, y: 1112, w: 332, h: 40}
        - {x: 1802, y: 1238, w: 226, h: 36}
        - {x: 1930, y: 1424, w: 1, h: 1}
    fill_points:
      - {x: 1023, y: 0}
      - {x: 1023, y: 0}

template_types:
    test: [0]
"#;

        let mut generator = MapGenerator::new();
        generator.import_yaml_templates(&text);

        assert!(generator.templates.contains_key(&TemplateType("test".to_string())));

        let template = generator.get_template("test").unwrap();

        assert_eq!(template.islands[0].len(), 7);
    }
}