extern crate serde_json;

use std::io::prelude::*;

fn main() {
    println!("cargo:rerun-if-changed=config.json");
    // Load theme name from config.json and output code to load the theme via include_dir!
    let config: serde_json::Value = 
        serde_json::from_str(&std::fs::read_to_string("./config.json").unwrap()).unwrap();

    generate_theme_loader(&config);
    generate_hljs_loader(&config);
}

fn generate_theme_loader(config: &serde_json::Value) {
    let theme_name = match config.get("theme") {
        Some(name) => name,
        None => panic!("Please define `theme` in `config.json`")
    };
    let theme_load_code = format!("const THEME_DIR: Dir = include_dir!(\"theme/{}\");", theme_name.as_str().unwrap());
    let out_path = std::path::PathBuf::from(std::env::var("OUT_DIR").unwrap());
    let mut out_file = std::fs::File::create(out_path.join("load_theme.rs")).unwrap();
    out_file.write_all(theme_load_code.as_bytes()).unwrap();
    out_file.sync_data().unwrap();
}

fn generate_hljs_loader(config: &serde_json::Value) {
    println!("cargo:rerun-if-changed=src/hljs_tpl.rs");
    
    let highlight_lang = match config.get("hljs") {
        Some(val) => val,
        None => panic!("Please specify what language for hljs to support in `config.json` with `hljs`")
    };

    if !highlight_lang.is_array() {
        panic!("`hljs` is not an array");
    }

    let highlight_lang = highlight_lang.as_array().unwrap().into_iter().map(|lang| {
        let lang = lang.as_str().unwrap();
        // Require only the needed language definition files
        format!("hljs.registerLanguage('{}', require('highlight.js/lib/languages/{}'));\n", lang, lang)
    }).collect::<String>();

    let js_code = format!(
        "const hljs = require(\\\"highlight.js/lib/highlight.js\\\");\n{}module.exports = hljs;",
        highlight_lang);
    let rs_code = std::fs::read_to_string("./src/hljs_tpl.rs").unwrap();
    let rs_code = format!("#[wasm_bindgen(inline_js = \"{}\")]\n{}", js_code, rs_code);
    let out_path = std::path::PathBuf::from(std::env::var("OUT_DIR").unwrap());
    let mut out_file = std::fs::File::create(out_path.join("load_hljs.rs")).unwrap();
    out_file.write_all(rs_code.as_bytes()).unwrap();
    out_file.sync_data().unwrap();
}