// cargo-deps: hsl, image, csv = "1.0.0-beta.4", serde, serde_derive

extern crate csv;
extern crate hsl;
extern crate image;
extern crate serde;
#[macro_use]
extern crate serde_derive;

use std::collections::BTreeSet;
use std::io;

#[derive(Debug, Deserialize)]
#[serde(rename_all = "camelCase")]
struct Tile {
    tile_x: usize,
    tile_y: usize,
    create_time: u64,
    modify_count: u64,
    modify_time: u64,
    access_count: u64,
    access_time: u64,
}

// Torus size (in tiles).
const TORUS_SZ: u32 = 512;

// Tile width/height (in pixels).
const TILE_W: u32 = 4;
const TILE_H: u32 = 1;

fn main() {
    // Read the `torus.csv` into a 2D array of `(access, modify)`.
    // Also track the values we see in `BTreeSet` (for ordering).
    let mut tiles = [[(0, 0); TORUS_SZ as usize]; TORUS_SZ as usize];
    let mut ord_a = BTreeSet::new();
    let mut ord_m = BTreeSet::new();
    for result in csv::Reader::from_reader(io::stdin()).deserialize() {
        let Tile {
            access_count: a,
            modify_count: m,
            tile_x: x,
            tile_y: y,
            ..
        } = result.unwrap();

        // HACK(eddyb) ignore 0,0 for analysis - too busy.
        if (x, y) != (0, 0) {
            ord_a.insert(a);
            ord_m.insert(m);
        }

        tiles[y][x] = (a, m);
    }

    // Extract the maximum values.
    // TODO(eddyb) chunk values for better representation.
    let max_a = ord_a.iter().next_back().cloned().unwrap_or(0) as f64;
    let max_m = ord_m.iter().next_back().cloned().unwrap_or(0) as f64;

    // Compose the heatmap image in-memory from the 2D array.
    let mut heatmap = image::ImageBuffer::new(TORUS_SZ * TILE_W, TORUS_SZ * TILE_H);
    let red = hsl::HSL::from_rgb(&[255, 0, 0]).h;
    // let green = hsl::HSL::from_rgb(&[0, 255, 0]).h;
    // let blue = hsl::HSL::from_rgb(&[0, 0, 255]).h;
    for y in 0..TORUS_SZ {
        for x in 0..TORUS_SZ {
            let (a, m) = tiles[y as usize][x as usize];
            let a = (a as f64 / max_a).min(1.0).powf(0.1);
            let m = (m as f64 / max_m).min(1.0).powf(0.1);

            // access => luminosity, modify => hue (green -> red)
            // let h = green * (1.0 - m) + red * m;
            // let s = 1.0;
            // let l = a.max(m) * 0.5;

            // access => luminosity, modify => saturation (grey -> red)
            let h = red;
            let s = m;
            let l = a * 0.5;

            let (r, g, b) = hsl::HSL { h, s, l }.to_rgb();
            let rgb = image::Rgb([r, g, b]);

            let coord = |x, dx, px| ((x * 2 + TORUS_SZ + 1) * px / 2 + dx) % (TORUS_SZ * px);
            for dy in 0..TILE_H {
                let y = coord(y, dy, TILE_H);
                for dx in 0..TILE_W {
                    let x = coord(x, dx, TILE_W);
                    heatmap.put_pixel(x, y, rgb);
                }
            }
        }
    }

    // Save the heatmap image.
    heatmap.save("heatmap.png").unwrap();
}