// This is a simplified go-reimplementation of the gst-launch-<version> cli tool.
// It has no own parameters and simply parses the cli arguments as launch syntax.
// When the parsing succeeded, the pipeline is run until the stream ends or an error happens.
package main

import (
	"context"
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/go-gst/go-gst/pkg/gst"
)

func main() {
	gst.Init()

	// Let GStreamer create a pipeline from the parsed launch syntax on the cli.
	res, err := gst.ParseLaunch(strings.Join(os.Args[1:], " "))
	if err != nil {
		fmt.Printf("Parse error: %v", err)
		return
	}

	pipeline := res.(gst.Pipeline)

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	go func() {
		for msg := range pipeline.GetBus().Messages(ctx) {
			switch msg.Type() {
			case gst.MessageEOS: // When end-of-stream is received stop the main loop
				fmt.Println("End-of-stream received")
				cancel()
			case gst.MessageError: // Error messages are always fatal
				debug, err := msg.ParseError()
				fmt.Println("ERROR:", err.Error())
				if debug != "" {
					fmt.Println("DEBUG:", debug)
				}
				cancel()

			case gst.MessageAny:
			case gst.MessageApplication:
			case gst.MessageAsyncDone:
			case gst.MessageAsyncStart:
			case gst.MessageBuffering:
			case gst.MessageClockLost:
			case gst.MessageClockProvide:
			case gst.MessageDeviceAdded:
			case gst.MessageDeviceChanged:
			case gst.MessageDeviceRemoved:
			case gst.MessageDurationChanged:
			case gst.MessageElement:
			case gst.MessageExtended:
			case gst.MessageHaveContext:
			case gst.MessageInfo:
			case gst.MessageInstantRateRequest:
			case gst.MessageLatency:
			case gst.MessageNeedContext:
			case gst.MessageNewClock:
			case gst.MessageProgress:
			case gst.MessagePropertyNotify:
			case gst.MessageQos:
			case gst.MessageRedirect:
			case gst.MessageRequestState:
			case gst.MessageResetTime:
			case gst.MessageSegmentDone:
			case gst.MessageSegmentStart:
			case gst.MessageStateChanged:
				old, state, pending := msg.ParseStateChanged()

				fmt.Printf("State changed: %s => %s (%s)\n", old, state, pending)
			case gst.MessageStateDirty:
			case gst.MessageStepDone:
			case gst.MessageStepStart:
			case gst.MessageStreamCollection:
			case gst.MessageStreamStart:
			case gst.MessageStreamStatus:
			case gst.MessageStreamsSelected:
			case gst.MessageStructureChange:
			case gst.MessageTag:
			case gst.MessageToc:
			case gst.MessageUnknown:
			case gst.MessageWarning:
			default:
				panic("unexpected gst.MessageType")
			}
		}
	}()

	// Start the pipeline
	pipeline.SetState(gst.StatePlaying)

	<-ctx.Done()
	pipeline.BlockSetState(gst.StateNull, gst.ClockTime(time.Second))
}