package main

import (
	"fmt"
	"runtime/cgo"
	"sync"
	"unsafe"

	"github.com/pion/webrtc/v3"
)

type DataChan struct {
	mu     sync.Mutex
	closed bool
	ch     *webrtc.DataChannel
	handle UintPtrT
}

// If you invoke this function, you *must* call Free,
// otherwise the channel will be leaked.
func NewDataChan(ch *webrtc.DataChannel) *DataChan {
	dataChan := new(DataChan)
	dataChan.ch = ch

	handle := UintPtrT(cgo.NewHandle(dataChan))
	dataChan.handle = handle

	ch.OnClose(func() {
		EmitEvent(
			TyDataChanOnClose,
			handle,
			0,
			0,
			0,
		)
	})

	ch.OnOpen(func() {
		EmitEvent(
			TyDataChanOnOpen,
			handle,
			0,
			0,
			0,
		)
	})

	ch.OnBufferedAmountLow(func() {
		EmitTrace(
			LvlTrace,
			fmt.Sprintf(
				"DataChannel(%v).OnBufferedAmountLow()",
				handle,
			),
		)
		EmitEvent(
			TyDataChanOnBufferedAmountLow,
			handle,
			0,
			0,
			0,
		)
	})

	ch.OnError(func(err error) {
		EmitTrace(
			LvlTrace,
			fmt.Sprintf(
				"DataChannel(%v).OnError(%v)",
				handle,
				err,
			),
		)

		// TODO - forward this to rust
	})

	ch.OnMessage(func(msg webrtc.DataChannelMessage) {
		buf := NewBuffer(msg.Data)
		EmitEvent(
			TyDataChanOnMessage,
			handle,
			buf.handle,
			0,
			0,
		)
	})

	return dataChan
}

func (dataChan *DataChan) Free() {
	dataChan.mu.Lock()
	defer dataChan.mu.Unlock()

	if dataChan.closed {
		return
	}

	dataChan.closed = true
	(cgo.Handle)(dataChan.handle).Delete()

	dataChan.ch.Close()
	dataChan.ch = nil
}

func CallDataChanFree(data_chan_id UintPtrT) {
	hnd := cgo.Handle(data_chan_id)
	dataChan := hnd.Value().(*DataChan)
	dataChan.Free()
}

func CallDataChanLabel(
	data_chan_id UintPtrT,
	response_cb MessageCb,
	response_usr unsafe.Pointer,
) {
	hnd := cgo.Handle(data_chan_id)
	dataChan := hnd.Value().(*DataChan)
	dataChan.mu.Lock()
	defer dataChan.mu.Unlock()

	if dataChan.closed {
		panic("DataChanClosed")
	}

	buf := NewBuffer([]byte(dataChan.ch.Label()))

	MessageCbInvoke(
		response_cb,
		response_usr,
		TyDataChanLabel,
		buf.handle,
		0,
		0,
		0,
	)
}

func CallDataChanReadyState(
	data_chan_id UintPtrT,
	response_cb MessageCb,
	response_usr unsafe.Pointer,
) {
	hnd := cgo.Handle(data_chan_id)
	dataChan := hnd.Value().(*DataChan)
	dataChan.mu.Lock()
	defer dataChan.mu.Unlock()

	if dataChan.closed {
		panic("DataChanClosed")
	}

	state := UintPtrT(dataChan.ch.ReadyState())

	MessageCbInvoke(
		response_cb,
		response_usr,
		TyDataChanReadyState,
		state,
		0,
		0,
		0,
	)
}

func CallDataChanSetBufferedAmountLowThreshold(
	data_chan_id UintPtrT,
	threshold UintPtrT,
	response_cb MessageCb,
	response_usr unsafe.Pointer,
) {
	hnd := cgo.Handle(data_chan_id)
	dataChan := hnd.Value().(*DataChan)
	dataChan.mu.Lock()
	defer dataChan.mu.Unlock()

	if dataChan.closed {
		panic("DataChanClosed")
	}

	dataChan.ch.SetBufferedAmountLowThreshold(uint64(threshold))

	buffered := dataChan.ch.BufferedAmount()

	MessageCbInvoke(
		response_cb,
		response_usr,
		TyDataChanSetBufferedAmountLowThreshold,
		UintPtrT(buffered),
		0,
		0,
		0,
	)
}

func CallDataChanBufferedAmount(
	data_chan_id UintPtrT,
	response_cb MessageCb,
	response_usr unsafe.Pointer,
) {
	hnd := cgo.Handle(data_chan_id)
	dataChan := hnd.Value().(*DataChan)
	dataChan.mu.Lock()
	defer dataChan.mu.Unlock()

	if dataChan.closed {
		panic("DataChanClosed")
	}

	buffered := dataChan.ch.BufferedAmount()

	MessageCbInvoke(
		response_cb,
		response_usr,
		TyDataChanBufferedAmount,
		UintPtrT(buffered),
		0,
		0,
		0,
	)
}

func CallDataChanSend(
	data_chan_id UintPtrT,
	buffer_id UintPtrT,
	response_cb MessageCb,
	response_usr unsafe.Pointer,
) {
	hnd := cgo.Handle(data_chan_id)
	dataChan := hnd.Value().(*DataChan)
	dataChan.mu.Lock()
	defer dataChan.mu.Unlock()

	if dataChan.closed {
		panic("DataChanClosed")
	}

	buf_hnd := cgo.Handle(buffer_id)
	buf := buf_hnd.Value().(*Buffer)
	buf.mu.Lock()
	defer buf.mu.Unlock()

	if buf.closed {
		panic("BufferClosed")
	}

	err := dataChan.ch.Send(buf.buf.Bytes())

	if err != nil {
		panic(err)
	}

	buffered := dataChan.ch.BufferedAmount()

	MessageCbInvoke(
		response_cb,
		response_usr,
		TyDataChanSend,
		UintPtrT(buffered),
		0,
		0,
		0,
	)
}