use std::env;
use std::fs;
use std::path::Path;

const HIGHLIGHT_STYLE_URL_TEMPLATE: &str =
    "https://cdnjs.cloudflare.com/ajax/libs/highlight.js/{VERSION}/styles/atom-one-dark.min.css";
const HIGHLIGHT_SCRIPT_URL_TEMPLATE: &str =
    "https://cdnjs.cloudflare.com/ajax/libs/highlight.js/{VERSION}/highlight.min.js";
const MERMAID_SCRIPT_URL_TEMPLATE: &str =
    "https://cdn.jsdelivr.net/npm/mermaid@{VERSION}/dist/mermaid.min.js";

const ASSETS_DIR: &str = "assets";

fn main() {
    let out_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
    let assets_path = Path::new(&out_dir).join(ASSETS_DIR);
    fs::create_dir_all(&assets_path).expect("Fail to create directory");

    let highlight_version = match env::var("HIGHLIGHT_VERSION") {
        Ok(var) => var,
        Err(_) => "11.9.0".to_string(),
    };

    let mermaid_version = match env::var("MERMAID_VERSION") {
        Ok(var) => var,
        Err(_) => "10".to_string(),
    };

    download(
        HIGHLIGHT_STYLE_URL_TEMPLATE,
        &highlight_version,
        &assets_path.join("highlight.css"),
    );
    download(
        HIGHLIGHT_SCRIPT_URL_TEMPLATE,
        &highlight_version,
        &assets_path.join("highlight.js"),
    );
    download(
        MERMAID_SCRIPT_URL_TEMPLATE,
        &mermaid_version,
        &assets_path.join("mermaid.js"),
    );
}

fn download(url: &str, version: &str, dest_path: &Path) {
    if !should_download(dest_path) {
        println!(
            "cargo:warning=✅ {} actual, skip downloading",
            dest_path.to_string_lossy()
        );
        return;
    }

    println!(
        "cargo:warning=📥 Downloading {}...",
        dest_path.to_string_lossy()
    );

    let response = reqwest::blocking::get(url.replace("{VERSION}", version))
        .expect("Fail to download sources")
        .error_for_status()
        .expect("Fail to download sources: non-2xx status code");

    let content = response.text().expect("Fail to read answer");
    fs::write(dest_path, &content).expect("Fail to write file");
}

fn should_download(path: &Path) -> bool {
    if env::var("FORCE_DEPS_DOWNLOAD").is_ok() {
        return true;
    }

    if path.exists() {
        return false;
    }

    true
}