// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: 2023 The Ebitengine Authors

package purego_test

import (
	"fmt"
	"runtime"
	"testing"
	"unsafe"

	"github.com/ebitengine/purego"
)

// This is an internal OS-dependent function for getting the handle to a library
//
//go:linkname openLibrary openLibrary
func openLibrary(name string) (uintptr, error)

func getSystemLibrary() (string, error) {
	switch runtime.GOOS {
	case "darwin":
		return "/usr/lib/libSystem.B.dylib", nil
	case "linux":
		return "libc.so.6", nil
	case "freebsd":
		return "libc.so.7", nil
	case "windows":
		return "ucrtbase.dll", nil
	default:
		return "", fmt.Errorf("GOOS=%s is not supported", runtime.GOOS)
	}
}

func TestRegisterFunc(t *testing.T) {
	library, err := getSystemLibrary()
	if err != nil {
		t.Fatalf("couldn't get system library: %s", err)
	}
	libc, err := openLibrary(library)
	if err != nil {
		t.Fatalf("failed to dlopen: %s", err)
	}
	var puts func(string)
	purego.RegisterLibFunc(&puts, libc, "puts")
	puts("Calling C from from Go without Cgo!")
}

func ExampleNewCallback() {
	cb := purego.NewCallback(func(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15 int) int {
		fmt.Println(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15)
		return a1 + a2 + a3 + a4 + a5 + a6 + a7 + a8 + a9 + a10 + a11 + a12 + a13 + a14 + a15
	})

	var fn func(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15 int) int
	purego.RegisterFunc(&fn, cb)

	ret := fn(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
	fmt.Println(ret)

	// Output: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
	// 120
}

func Test_qsort(t *testing.T) {
	library, err := getSystemLibrary()
	if err != nil {
		t.Fatalf("couldn't get system library: %s", err)
	}
	libc, err := openLibrary(library)
	if err != nil {
		t.Fatalf("failed to dlopen: %s", err)
	}

	data := []int{88, 56, 100, 2, 25}
	sorted := []int{2, 25, 56, 88, 100}
	compare := func(a, b *int) int {
		return *a - *b
	}
	var qsort func(data []int, nitms uintptr, size uintptr, compar func(a, b *int) int)
	purego.RegisterLibFunc(&qsort, libc, "qsort")
	qsort(data, uintptr(len(data)), unsafe.Sizeof(int(0)), compare)
	for i := range data {
		if data[i] != sorted[i] {
			t.Errorf("got %d wanted %d at %d", data[i], sorted[i], i)
		}
	}
}

func TestRegisterFunc_Floats(t *testing.T) {
	library, err := getSystemLibrary()
	if err != nil {
		t.Fatalf("couldn't get system library: %s", err)
	}
	libc, err := openLibrary(library)
	if err != nil {
		t.Fatalf("failed to dlopen: %s", err)
	}
	{
		var strtof func(arg string) float32
		purego.RegisterLibFunc(&strtof, libc, "strtof")
		const (
			arg = "2"
		)
		got := strtof(arg)
		expected := float32(2)
		if got != expected {
			t.Errorf("strtof failed. got %f but wanted %f", got, expected)
		}
	}
	{
		var strtod func(arg string, ptr **byte) float64
		purego.RegisterLibFunc(&strtod, libc, "strtod")
		const (
			arg = "1"
		)
		got := strtod(arg, nil)
		expected := float64(1)
		if got != expected {
			t.Errorf("strtod failed. got %f but wanted %f", got, expected)
		}
	}
}

func TestRegisterLibFunc_Bool(t *testing.T) {
	// this callback recreates the state where the return register
	// contains other information but the least significant byte is false
	cbFalse := purego.NewCallback(func() uintptr {
		return 0x7F5948AE9A00
	})
	var runFalse func() bool
	purego.RegisterFunc(&runFalse, cbFalse)
	expected := false
	if got := runFalse(); got != expected {
		t.Errorf("runFalse failed. got %t but wanted %t", got, expected)
	}
}