import os

const vexe = @VEXE
const tests_dir = os.dir(@FILE)
const v3_dir = os.dir(tests_dir)
const v3_src = os.join_path(v3_dir, 'v3.v')

fn build_v3() string {
    v3_bin := os.join_path(os.temp_dir(), 'v3_spawn_args_test')
    build := os.execute('${vexe} -o ${v3_bin} ${v3_src}')
    assert build.exit_code == 0, build.output
    return v3_bin
}

fn gen_c(v3_bin string, name string, src string) string {
    src_file := os.join_path(os.temp_dir(), '${name}.v')
    os.write_file(src_file, src) or { panic(err) }
    c_out := os.join_path(os.temp_dir(), '${name}.c')
    os.rm(c_out) or {}
    compile := os.execute('${v3_bin} ${src_file} -o ${c_out}')
    assert compile.exit_code == 0, compile.output
    return os.read_file(c_out) or { '' }
}

// A `spawn` of a free function with arguments must pack the arguments into a heap
// struct and run the real function through a wrapper, instead of emitting a
// `(void*)0` no-op that silently drops the call and its arguments.
fn test_spawn_free_function_with_arguments_packs_args() {
    v3_bin := build_v3()
    c_code := gen_c(v3_bin, 'v3_spawn_args_free', '
struct Counter {
mut:
    total int
}

fn add(mut c Counter, a int, b int) {
    c.total = a + b
}

fn main() {
    mut c := Counter{}
    _ := spawn add(mut c, 3, 4)
    println("ok")
}
')
    assert c_code.contains('add_thread_args'), c_code
    assert c_code.contains('pthread_create'), c_code
    assert c_code.contains('add(p->a0, p->a1, p->a2)'), c_code
}

// A `spawn` of a method with arguments must pack the receiver and arguments and
// dispatch the real method instead of dropping the call.
fn test_spawn_method_with_arguments_packs_receiver_and_args() {
    v3_bin := build_v3()
    c_code := gen_c(v3_bin, 'v3_spawn_args_method', '
struct Counter {
mut:
    total int
}

fn (mut c Counter) bump(x int) {
    c.total += x
}

fn main() {
    mut c := Counter{}
    _ := spawn c.bump(10)
    println("ok")
}
')
    assert c_code.contains('pthread_create'), c_code
    assert c_code.contains('Counter__bump(p->a0, p->a1)'), c_code
}

// A no-arg `spawn` of a by-value receiver method must copy the receiver into the
// heap arg struct; casting the void* thread argument straight to the struct type
// (`(Greeter)arg`) is invalid C.
fn test_spawn_value_receiver_copies_receiver() {
    v3_bin := build_v3()
    c_code := gen_c(v3_bin, 'v3_spawn_value_receiver', '
struct Greeter {
    name string
}

fn (g Greeter) greet() {
    println(g.name)
}

fn main() {
    g := Greeter{name: "world"}
    _ := spawn g.greet()
    println("ok")
}
')
    assert c_code.contains('pthread_create'), c_code
    assert c_code.contains('Greeter__greet(p->a0)'), c_code
    assert !c_code.contains('(Greeter)arg'), c_code
}