mod ffi;
pub mod parse;

use std::ffi::{CStr, CString};

use parse::QuickJSBinary;

pub fn compile(src: &[u8], filename: &str) -> QuickJSBinary {
    unsafe {
        let filename = CString::new(filename).unwrap();

        let rt = ffi::JS_NewRuntime();
        let ctx = ffi::JS_NewContext(rt);

        let obj = ffi::JS_Eval(
            ctx,
            src.as_ptr(),
            src.len(),
            filename.as_ptr().cast(),
            ffi::JS_EVAL_FLAG_COMPILE_ONLY | ffi::JS_EVAL_TYPE_MODULE,
        );

        assert!(obj.tag != ffi::JS_TAG_EXCEPTION, "{}", get_exception(ctx));

        let mut len = 0;
        let buf = ffi::JS_WriteObject(ctx, &mut len, obj, ffi::JS_WRITE_OBJ_BYTECODE);
        ffi::JS_FreeValue(ctx, obj);

        assert!(!buf.is_null());
        let bytes = std::slice::from_raw_parts(buf, len).to_vec();

        // TODO: Are we sure other cleanup is not necessary?
        ffi::JS_FreeContext(ctx);
        ffi::JS_FreeRuntime(rt);

        QuickJSBinary::parse(&bytes).unwrap().1
    }
}

fn get_exception(ctx: *mut ffi::JSContext) -> String {
    unsafe {
        let err = ffi::JS_GetException(ctx);
        let text = ffi::JS_ToCStringLen2(ctx, std::ptr::null_mut(), err, false);

        let message = if text.is_null() {
            "quickjs raised an exception it could not describe".to_string()
        } else {
            CStr::from_ptr(text).to_string_lossy().into_owned()
        };

        message
    }
}