module main

import v.debug

// vtest vflags: -d callstack

struct Test {}

fn (t Test) test_method() {
    fn_test4()
}

fn Test.test_static_method() {
    fn_test3()
}

fn fn_test2() ? {
    a := 1
    // debug.dump_callstack()
    print(a)
    assert debug.callstack(1)?.line == 43
    assert debug.callstack(0)?.line == 51
}

fn fn_test3() ? {
    // debug.dump_callstack()
    assert debug.callstack(3)?.line == 8
    assert debug.callstack(1)?.line == 41
    assert debug.callstack(0)?.line == 51
    return
}

fn fn_test4() ? {
    // debug.dump_callstack()
    assert debug.callstack(1)?.line == 10
}

fn fn_test_anon(cb fn ()) {
    cb()
}

fn fn_test() ? {
    fn_test2()
    print('enter')
    fn_test3()
    assert debug.callstack(0)?.line == 51
}

fn main() {
    print(12)
    fn_test()
    // debug.dump_callstack()
    // dump(debug.callstack(0))
    mut ret := debug.callstack(0)
    Test{}.test_method()
    Test.test_static_method()
    fn_test_anon(fn () {
        // debug.dump_callstack()
        ret := debug.callstack(3) or { return }
        res := ret.name.starts_with('anon_fn')
        assert res
    })

    ret = debug.callstack(0)
    assert ret == none
    assert fn_test_unnamed_fn_var(fn (a int, b int) bool {
        return a < b
    })
}

fn fn_test_unnamed_fn_var(cb fn (int, int) bool) bool {
    return cb(1, 2)
}