use core::{
    ffi::{c_char, c_int},
    fmt::Write,
};

use printf_compat::{format, output};

/// Printf according to the format string, function will return the number of bytes written(including '\0')
pub unsafe extern "C" fn printf(w: &mut impl Write, str: *const c_char, mut args: ...) -> c_int {
    let bytes_written = format(str as _, args.as_va_list(), output::fmt_write(w));
    bytes_written + 1
}

struct TerminalOut;
impl Write for TerminalOut {
    fn write_str(&mut self, s: &str) -> core::fmt::Result {
        print!("{}", s);
        Ok(())
    }
}

/// See https://ebpf-docs.dylanreimerink.nl/linux/helper-function/bpf_trace_printk/
pub fn trace_printf(fmt_ptr: u64, _fmt_len: u64, arg3: u64, arg4: u64, arg5: u64) -> u64 {
    unsafe { printf(&mut TerminalOut, fmt_ptr as _, arg3, arg4, arg5) as u64 }
}