package gst

/*
#cgo pkg-config: gstreamer-1.0
#cgo CFLAGS: -Wno-deprecated-declarations -g -Wall
#include <gst/gst.h>
*/
import "C"
import (
	"errors"
	"unsafe"
)

// Init runs `gst_init`. It currently does not support arguments. This should
// be called before building any pipelines.
func Init() {
	C.gst_init(nil, nil)
}

// gobool provides an easy type conversion between C.gboolean and a go bool.
func gobool(b C.gboolean) bool {
	return b != 0
}

// gboolean converts a go bool to a C.gboolean.
func gboolean(b bool) C.gboolean {
	if b {
		return C.gboolean(1)
	}
	return C.gboolean(0)
}

// structureToGoMap converts a GstStructure into a Go map of strings.
func structureToGoMap(st *C.GstStructure) map[string]string {
	goDetails := make(map[string]string)
	numFields := int(C.gst_structure_n_fields((*C.GstStructure)(st)))
	for i := 0; i < numFields-1; i++ {
		fieldName := C.gst_structure_nth_field_name((*C.GstStructure)(st), (C.guint)(i))
		fieldValue := C.gst_structure_get_value((*C.GstStructure)(st), (*C.gchar)(fieldName))
		strValueDup := C.g_strdup_value_contents((*C.GValue)(fieldValue))
		goDetails[C.GoString(fieldName)] = C.GoString(strValueDup)
	}
	return goDetails
}

// MessageType is an alias to the C equivalent of GstMessageType.
type MessageType C.GstMessageType

// Type casting of GstMessageTypes
const (
	MessageAny          MessageType = C.GST_MESSAGE_ANY
	MessageStreamStart              = C.GST_MESSAGE_STREAM_START
	MessageEOS                      = C.GST_MESSAGE_EOS
	MessageInfo                     = C.GST_MESSAGE_INFO
	MessageWarning                  = C.GST_MESSAGE_WARNING
	MessageError                    = C.GST_MESSAGE_ERROR
	MessageStateChanged             = C.GST_MESSAGE_STATE_CHANGED
	MessageElement                  = C.GST_MESSAGE_ELEMENT
	MessageStreamStatus             = C.GST_MESSAGE_STREAM_STATUS
	MessageBuffering                = C.GST_MESSAGE_BUFFERING
	MessageLatency                  = C.GST_MESSAGE_LATENCY
	MessageNewClock                 = C.GST_MESSAGE_NEW_CLOCK
	MessageAsyncDone                = C.GST_MESSAGE_ASYNC_DONE
	MessageTag                      = C.GST_MESSAGE_TAG
)

func iteratorToElementSlice(iterator *C.GstIterator) ([]*Element, error) {
	elems := make([]*Element, 0)
	gval := new(C.GValue)

	for {
		switch C.gst_iterator_next((*C.GstIterator)(iterator), (*C.GValue)(unsafe.Pointer(gval))) {
		case C.GST_ITERATOR_DONE:
			C.gst_iterator_free((*C.GstIterator)(iterator))
			return elems, nil
		case C.GST_ITERATOR_RESYNC:
			C.gst_iterator_resync((*C.GstIterator)(iterator))
		case C.GST_ITERATOR_OK:
			cElemVoid := C.g_value_get_object((*C.GValue)(gval))
			cElem := (*C.GstElement)(cElemVoid)
			elems = append(elems, wrapElement(cElem))
			C.g_value_reset((*C.GValue)(gval))
		default:
			return nil, errors.New("Element iterator failed")
		}
	}
}

func goStrings(argc C.int, argv **C.gchar) []string {
	length := int(argc)
	tmpslice := (*[1 << 30]*C.gchar)(unsafe.Pointer(argv))[:length:length]
	gostrings := make([]string, length)
	for i, s := range tmpslice {
		gostrings[i] = C.GoString(s)
	}
	return gostrings
}