dezoomify-rs 2.18.1

use std::io::Write;

use base64::{Engine, engine::general_purpose::URL_SAFE_NO_PAD};
use hmac::{KeyInit, Mac, SimpleHmac};
use sha1::Sha1;

use super::PageInfo;
use std::ops::Deref;

type HmacSha1 = SimpleHmac<Sha1>;

pub fn compute_url(page: &PageInfo, x: u32, y: u32, z: usize) -> String {
    let mut url = format!("{}=x{}-y{}-z{}-t", page.base_url, x, y, z);

    let mut sign_path: Vec<u8> = Vec::new();
    sign_path.extend_from_slice(page.path().as_bytes());
    write!(sign_path, "=x{x}-y{y}-z{z}-t").unwrap();
    sign_path.extend_from_slice(page.token.as_bytes());

    let digest = mac_digest(&sign_path);
    url.push_str(&custom_base64(&digest));
    url
}

fn custom_base64(digest: &[u8]) -> String {
    URL_SAFE_NO_PAD.encode(digest).replace('-', "_")
}

fn mac_digest(b: &[u8]) -> impl Deref<Target = [u8]> {
    let key = &[123, 43, 78, 35, 222, 44, 197, 197];
    let mut mac = HmacSha1::new_from_slice(key).expect("HMac keys can have any length");
    mac.update(b);
    mac.finalize().into_bytes()
}

#[test]
fn test_compute_url() {
    let path = "https://lh3.googleusercontent.com/wGcDNN8L-2COcm9toX5BTp6HPxpMPPPuxrMU-ZL-W-nDHW8I_L4R5vlBJ6ITtlmONQ".into();
    let token = "KwCgJ1QIfgprHn0a93x7Q-HhJ04".into();
    assert_eq!(
        compute_url(
            &PageInfo {
                base_url: path,
                token,
                name: String::new()
            },
            0,
            0,
            7
        ),
        "https://lh3.googleusercontent.com/wGcDNN8L-2COcm9toX5BTp6HPxpMPPPuxrMU-ZL-W-nDHW8I_L4R5vlBJ6ITtlmONQ=x0-y0-z7-tHeJ3xylnSyyHPGwMZimI4EV3JP8"
    );
}

#[test]
fn test_compute_url_flowers() {
    // From https://artsandculture.google.com/asset/wildflower-painting-of-red-grevillea/wwEzEHEBAqxv4w
    let path =
        "https://lh5.ggpht.com/D0sqZ0sJbzoQeYFoySoXLJqgLMfXhi8-gGVGRqD_UEYUqkqk9Eqdxx5NNaw".into();
    let token = "mcOPEQJmk1514hP_dJkpwVwIhPU".into();
    assert_eq!(
        compute_url(
            &PageInfo {
                base_url: path,
                token,
                name: String::new()
            },
            0,
            0,
            7
        ),
        "https://lh5.ggpht.com/D0sqZ0sJbzoQeYFoySoXLJqgLMfXhi8-gGVGRqD_UEYUqkqk9Eqdxx5NNaw=x0-y0-z7-tBJ_NeDnzAKjz3ZbOzN_uFRRIbS0"
    );
}