package bimg

/*
#cgo pkg-config: vips
#include "vips.h"
*/
import "C"

import (
	"errors"
	"runtime"
	"strings"
	"sync"
	"unsafe"
)

var (
	m           sync.Mutex
	initialized bool = false
)

func init() {
	if C.VIPS_MAJOR_VERSION <= 7 && C.VIPS_MINOR_VERSION < 40 {
		panic("unsupported old vips version!")
	}

	Initialize()
}

// Explicit thread-safe start of libvips.
// You should only call this function if you previously shutdown libvips
func Initialize() {
	m.Lock()
	runtime.LockOSThread()
	defer m.Unlock()
	defer runtime.UnlockOSThread()

	err := C.vips_init(C.CString("bimg"))
	if err != 0 {
		Shutdown()
		panic("unable to start vips!")
	}

	C.vips_concurrency_set(0)                   // default
	C.vips_cache_set_max_mem(100 * 1024 * 1024) // 100 MB
	C.vips_cache_set_max(500)                   // 500 operations
	initialized = true
}

// Explicit thread-safe libvips shutdown. Call this to drop caches.
// If libvips was already initialized, the function is no-op
func Shutdown() {
	m.Lock()
	defer m.Unlock()

	if initialized == true {
		C.vips_shutdown()
		initialized = false
	}
}

// Output to stdout collected data for debugging purposes
func VipsDebug() {
	C.im__print_all()
}

func vipsRotate(image *C.struct__VipsImage, angle Angle) (*C.struct__VipsImage, error) {
	var out *C.struct__VipsImage
	defer C.g_object_unref(C.gpointer(image))

	err := C.vips_rotate(image, &out, C.int(angle))
	if err != 0 {
		return nil, catchVipsError()
	}

	return out, nil
}

func vipsFlip(image *C.struct__VipsImage, direction Direction) (*C.struct__VipsImage, error) {
	var out *C.struct__VipsImage
	defer C.g_object_unref(C.gpointer(image))

	err := C.vips_flip_bridge(image, &out, C.int(direction))
	if err != 0 {
		return nil, catchVipsError()
	}

	return out, nil
}

func vipsRead(buf []byte) (*C.struct__VipsImage, ImageType, error) {
	var image *C.struct__VipsImage
	imageType := vipsImageType(buf)

	if imageType == UNKNOWN {
		return nil, UNKNOWN, errors.New("Input buffer contains unsupported image format")
	}

	// feed it
	length := C.size_t(len(buf))
	imageBuf := unsafe.Pointer(&buf[0])
	imageTypeC := C.int(imageType)

	err := C.vips_init_image(imageBuf, length, imageTypeC, &image)
	if err != 0 {
		return nil, UNKNOWN, catchVipsError()
	}

	return image, imageType, nil
}

func vipsExtract(image *C.struct__VipsImage, left, top, width, height int) (*C.struct__VipsImage, error) {
	var buf *C.struct__VipsImage
	defer C.g_object_unref(C.gpointer(image))

	if width > MAX_SIZE || height > MAX_SIZE {
		return nil, errors.New("Maximum image size exceeded")
	}

	err := C.vips_extract_area_bridge(image, &buf, C.int(left), C.int(top), C.int(width), C.int(height))
	if err != 0 {
		return nil, catchVipsError()
	}

	return buf, nil
}

func vipsShrinkJpeg(buf []byte, input *C.struct__VipsImage, shrink int) (*C.struct__VipsImage, error) {
	var image *C.struct__VipsImage
	defer C.g_object_unref(C.gpointer(input))

	err := C.vips_jpegload_buffer_shrink(unsafe.Pointer(&buf[0]), C.size_t(len(buf)), &image, C.int(shrink))
	if err != 0 {
		return nil, catchVipsError()
	}

	return image, nil
}

func vipsShrink(input *C.struct__VipsImage, shrink int) (*C.struct__VipsImage, error) {
	var image *C.struct__VipsImage
	defer C.g_object_unref(C.gpointer(input))

	err := C.vips_shrink_0(input, &image, C.double(float64(shrink)), C.double(float64(shrink)))
	if err != 0 {
		return nil, catchVipsError()
	}

	return image, nil
}

func vipsEmbed(input *C.struct__VipsImage, left, top, width, height, extend int) (*C.struct__VipsImage, error) {
	var image *C.struct__VipsImage
	defer C.g_object_unref(C.gpointer(input))

	err := C.vips_embed_bridge(input, &image, C.int(left), C.int(top), C.int(width), C.int(height), C.int(extend))
	if err != 0 {
		return nil, catchVipsError()
	}

	return image, nil
}

func vipsAffine(input *C.struct__VipsImage, residual float64, i Interpolator) (*C.struct__VipsImage, error) {
	var image *C.struct__VipsImage

	istring := C.CString(i.String())
	interpolator := C.vips_interpolate_new(istring)

	defer C.free(unsafe.Pointer(istring))
	defer C.g_object_unref(C.gpointer(input))

	// Perform affine transformation
	err := C.vips_affine_interpolator(input, &image, C.double(residual), 0, 0, C.double(residual), interpolator)
	if err != 0 {
		return nil, catchVipsError()
	}

	return image, nil
}

func vipsImageType(buf []byte) ImageType {
	imageType := UNKNOWN

	length := C.size_t(len(buf))
	imageBuf := unsafe.Pointer(&buf[0])
	bufferType := C.GoString(C.vips_foreign_find_load_buffer(imageBuf, length))

	switch {
	case strings.HasSuffix(bufferType, "JpegBuffer"):
		imageType = JPEG
		break
	case strings.HasSuffix(bufferType, "PngBuffer"):
		imageType = PNG
		break
	case strings.HasSuffix(bufferType, "TiffBuffer"):
		imageType = TIFF
		break
	case strings.HasSuffix(bufferType, "WebpBuffer"):
		imageType = WEBP
		break
	case strings.HasSuffix(bufferType, "MagickBuffer"):
		imageType = MAGICK
		break
	}

	return imageType
}

type vipsSaveOptions struct {
	Quality     int
	Compression int
	Type        ImageType
}

func vipsSave(image *C.struct__VipsImage, o vipsSaveOptions) ([]byte, error) {
	var ptr unsafe.Pointer
	length := C.size_t(0)
	err := C.int(0)

	defer C.g_object_unref(C.gpointer(image))

	switch {
	case o.Type == PNG:
		err = C.vips_pngsave_bridge(image, &ptr, &length, 1, C.int(o.Compression), C.int(o.Quality), 0)
		break
	case o.Type == WEBP:
		err = C.vips_webpsave_bridge(image, &ptr, &length, 1, C.int(o.Quality), 0)
		break
	default:
		err = C.vips_jpegsave_bridge(image, &ptr, &length, 1, C.int(o.Quality), 0)
		break
	}

	if int(err) != 0 {
		return nil, catchVipsError()
	}

	buf := C.GoBytes(ptr, C.int(length))

	// Cleanup
	C.g_free(C.gpointer(ptr))
	C.vips_error_clear()

	return buf, nil
}

func vipsExifOrientation(image *C.struct__VipsImage) int {
	return int(C.vips_exif_orientation(image))
}

func vipsHasAlpha(image *C.struct__VipsImage) bool {
	return int(C.has_alpha_channel(image)) > 0
}

func vipsHasProfile(image *C.struct__VipsImage) bool {
	return int(C.has_profile_embed(image)) > 0
}

func vipsWindowSize(name string) float64 {
	return float64(C.interpolator_window_size(C.CString(name)))
}

func vipsSpace(image *C.struct__VipsImage) string {
	return C.GoString(C.vips_enum_nick_bridge(image))
}

func catchVipsError() error {
	s := C.GoString(C.vips_error_buffer())
	C.vips_error_clear()
	C.vips_thread_shutdown()
	// clean image memory buffer?
	return errors.New(s)
}