module os

fn signal_str(signal Signal) string {
    mut result := signal.str().to_upper()
    result = 'SIG${result}'
    return result
}

fn signal_from_str(str JS.String) Signal {
    s := string(str)
    return match s {
        'SIGHUP' {
            Signal.hup
        }
        'SIGINT' {
            Signal.int
        }
        'SIGQUIT' {
            Signal.quit
        }
        'SIGILL' {
            Signal.ill
        }
        'SIGTRAP' {
            Signal.trap
        }
        'SIGABRT' {
            Signal.abrt
        }
        'SIGBUS' {
            Signal.bus
        }
        'SIGFPE' {
            Signal.fpe
        }
        'SIGKILL' {
            Signal.kill
        }
        'SIGUSR1' {
            Signal.usr1
        }
        'SIGSEGV' {
            Signal.segv
        }
        'SIGUSR2' {
            Signal.usr2
        }
        'SIGPIPE' {
            Signal.pipe
        }
        'SIGALRM' {
            Signal.alrm
        }
        'SIGTERM' {
            Signal.term
        }
        'SIGSTKFLT' {
            Signal.stkflt
        }
        'SIGCHLD' {
            Signal.chld
        }
        'SIGCONT' {
            Signal.cont
        }
        'SIGSTOP' {
            Signal.stop
        }
        'SIGTSTP' {
            Signal.tstp
        }
        'SIGTTIN' {
            Signal.ttin
        }
        'SIGTTOU' {
            Signal.ttou
        }
        'SIGURG' {
            Signal.urg
        }
        'SIGXCPU' {
            Signal.xcpu
        }
        'SIGXFSZ' {
            Signal.xfsz
        }
        'SIGVTALRM' {
            Signal.vtalrm
        }
        'SIGPROF' {
            Signal.prof
        }
        'SIGWINCH' {
            Signal.winch
        }
        'SIGPOLL' {
            Signal.poll
        }
        'SIGPWR' {
            Signal.pwr
        }
        'SIGSYS' {
            Signal.sys
        }
        else {
            panic('unknown signal: ${s}')
        }
    }
}

// signal will assign `handler` callback to be called when `signum` signal is received.
//
// # Behaviour on different backends:
// - NodeJS: Will use `process.on` and add `handler` to the listeners list for `signum` to happen
// - Browser: Will use `window.addEventListener` for handling signal
//
// TODO: Add signal events implementation for browser backend
pub fn signal_opt(signum Signal, handler SignalHandler) !SignalHandler {
    signame := signal_str(signum)
    _ := signame
    $if js_node {
        #$process.on(signame.str,function (sig) { handler(os__signal_from_str(sig));});

        return handler
    } $else $if js_browser {
        #let event = new CustomEvent(signame.str, {detail: signum});
        #window.addEventListener(signame.str, function (e) { handler(e.detail); });

        return handler
    } $else {
        return error('signal handlers are not supported on bare JS')
    }
}