/*
DESCRIPTION
  inputs.go contains code for interfacing with various revid inputs to obtain
  input data streams.

AUTHORS
  Saxon A. Nelson-Milton <saxon@ausocean.org>
  Alan Noble <alan@ausocean.org>
  Dan Kortschak <dan@ausocean.org>
  Trek Hopton <trek@ausocean.org>

LICENSE
  revid is Copyright (C) 2017-2019 the Australian Ocean Lab (AusOcean)

  It is free software: you can redistribute it and/or modify them
  under the terms of the GNU General Public License as published by the
  Free Software Foundation, either version 3 of the License, or (at your
  option) any later version.

  It is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  for more details.

  You should have received a copy of the GNU General Public License
  in gpl.txt.  If not, see http://www.gnu.org/licenses.
*/

package revid

import (
	"errors"
	"fmt"
	"io"
	"net"
	"os"
	"os/exec"
	"strconv"
	"strings"
	"time"

	"bitbucket.org/ausocean/av/codec/codecutil"
	"bitbucket.org/ausocean/av/input/gvctrl"
	"bitbucket.org/ausocean/av/protocol/rtcp"
	"bitbucket.org/ausocean/av/protocol/rtp"
	"bitbucket.org/ausocean/av/protocol/rtsp"
	"bitbucket.org/ausocean/utils/logger"
)

// TODO: remove this when gvctrl has configurable user and pass.
const (
	ipCamUser = "admin"
	ipCamPass = "admin"
)

// AVDevice describes a configurable audio or video device from which media data
// can be obtained. AVDevice implements io.Reader.
type AVDevice interface {
	io.Reader

	// Set allows for configuration of the AVDevice using a Config struct. All,
	// some or none of the fields of the Config struct may be used for configuration
	// by an implementation. An implementation should specify what fields are
	// considered.
	Set(c Config) error

	// Start will start the AVDevice capturing media data; after which the Read
	// method may be called to obtain the data. The format of the data may differ
	// and should be specified by the implementation.
	Start() error

	// Stop will stop the AVDevice from capturing media data. From this point
	// Reads will no longer be successful.
	Stop() error
}

// multiError implements the built in error interface. multiError is used here
// to collect multi errors during validation of configruation parameters for o
// AVDevices.
type multiError []error

func (me multiError) Error() string {
	return fmt.Sprintf("%v", me)
}

// startRaspivid sets up things for input from raspivid i.e. starts
// a raspivid process and pipes it's data output.
func (r *Revid) startRaspivid() (func() error, error) {
	r.config.Logger.Log(logger.Info, pkg+"starting raspivid")

	const disabled = "0"
	args := []string{
		"--output", "-",
		"--nopreview",
		"--timeout", disabled,
		"--width", fmt.Sprint(r.config.Width),
		"--height", fmt.Sprint(r.config.Height),
		"--bitrate", fmt.Sprint(r.config.Bitrate * 1000), // Convert from kbps to bps.
		"--framerate", fmt.Sprint(r.config.FrameRate),
		"--rotation", fmt.Sprint(r.config.Rotation),
		"--brightness", fmt.Sprint(r.config.Brightness),
		"--saturation", fmt.Sprint(r.config.Saturation),
		"--exposure", fmt.Sprint(r.config.Exposure),
		"--awb", fmt.Sprint(r.config.AutoWhiteBalance),
	}

	if r.config.FlipHorizontal {
		args = append(args, "--hflip")
	}

	if r.config.FlipVertical {
		args = append(args, "--vflip")
	}
	if r.config.FlipHorizontal {
		args = append(args, "--hflip")
	}

	switch r.config.InputCodec {
	default:
		return nil, fmt.Errorf("revid: invalid input codec: %v", r.config.InputCodec)
	case codecutil.H264:
		args = append(args,
			"--codec", "H264",
			"--inline",
			"--intra", fmt.Sprint(r.config.MinFrames),
		)
		if r.config.VBR {
			args = append(args, "-qp", fmt.Sprint(r.config.Quantization))
		}
	case codecutil.MJPEG:
		args = append(args, "--codec", "MJPEG")
	}
	r.config.Logger.Log(logger.Info, pkg+"raspivid args", "raspividArgs", strings.Join(args, " "))
	r.cmd = exec.Command("raspivid", args...)

	stdout, err := r.cmd.StdoutPipe()
	if err != nil {
		return nil, err
	}
	err = r.cmd.Start()
	if err != nil {
		return nil, fmt.Errorf("could not start raspivid command: %w", err)
	}

	r.wg.Add(1)
	go r.processFrom(stdout, 0)
	return nil, nil
}

// startV4l sets up webcam input and starts the revid.processFrom routine.
func (r *Revid) startV4L() (func() error, error) {
	const defaultVideo = "/dev/video0"

	r.config.Logger.Log(logger.Info, pkg+"starting webcam")
	if r.config.InputPath == "" {
		r.config.Logger.Log(logger.Info, pkg+"using default video device", "device", defaultVideo)
		r.config.InputPath = defaultVideo
	}

	args := []string{
		"-i", r.config.InputPath,
		"-f", "h264",
		"-r", fmt.Sprint(r.config.FrameRate),
	}

	br := r.config.Bitrate * 1000
	args = append(args,
		"-b:v", fmt.Sprint(br),
		"-maxrate", fmt.Sprint(br),
		"-bufsize", fmt.Sprint(br/2),
		"-s", fmt.Sprintf("%dx%d", r.config.Width, r.config.Height),
		"-",
	)

	r.config.Logger.Log(logger.Info, pkg+"ffmpeg args", "args", strings.Join(args, " "))
	r.cmd = exec.Command("ffmpeg", args...)

	stdout, err := r.cmd.StdoutPipe()
	if err != nil {
		return nil, nil
	}

	err = r.cmd.Start()
	if err != nil {
		r.config.Logger.Log(logger.Fatal, pkg+"cannot start webcam", "error", err.Error())
		return nil, nil
	}

	r.wg.Add(1)
	go r.processFrom(stdout, time.Duration(0))
	return nil, nil
}

// setupInputForFile sets up input from file and starts the revid.processFrom
// routine.
func (r *Revid) setupInputForFile() (func() error, error) {
	f, err := os.Open(r.config.InputPath)
	if err != nil {
		r.config.Logger.Log(logger.Error, err.Error())
		r.Stop()
		return nil, err
	}

	// TODO(kortschak): Maybe we want a context.Context-aware parser that we can stop.
	r.wg.Add(1)
	go r.processFrom(f, 0)
	return func() error { return f.Close() }, nil
}

// startRTSPCamera uses RTSP to request an RTP stream from an IP camera. An RTP
// client is created from which RTP packets containing either h264/h265 can be
// read by the selected lexer.
//
// TODO(saxon): this function should really be startGeoVision. It's much too
// specific to be called startRTSPCamera.
func (r *Revid) startRTSPCamera() (func() error, error) {
	r.config.Logger.Log(logger.Info, pkg+"starting geovision...")

	err := gvctrl.Set(
		r.config.CameraIP,
		gvctrl.Channel(r.config.CameraChan),
		gvctrl.CodecOut(
			map[uint8]gvctrl.Codec{
				codecutil.H264:  gvctrl.CodecH264,
				codecutil.H265:  gvctrl.CodecH265,
				codecutil.MJPEG: gvctrl.CodecMJPEG,
			}[r.config.InputCodec],
		),
		gvctrl.Height(int(r.config.Height)),
		gvctrl.FrameRate(int(r.config.FrameRate)),
		gvctrl.VariableBitrate(r.config.VBR),
		gvctrl.VBRQuality(
			map[quality]gvctrl.Quality{
				qualityStandard:  gvctrl.QualityStandard,
				qualityFair:      gvctrl.QualityFair,
				qualityGood:      gvctrl.QualityGood,
				qualityGreat:     gvctrl.QualityGreat,
				qualityExcellent: gvctrl.QualityExcellent,
			}[r.config.VBRQuality],
		),
		gvctrl.VBRBitrate(r.config.VBRBitrate),
		gvctrl.CBRBitrate(int(r.config.Bitrate)),
		gvctrl.Refresh(float64(r.config.MinFrames)/float64(r.config.FrameRate)),
	)
	if err != nil {
		return nil, fmt.Errorf("could not set IPCamera settings: %w", err)
	}

	r.config.Logger.Log(logger.Info, pkg+"completed geovision configuration")

	time.Sleep(5 * time.Second)

	rtspClt, local, remote, err := rtsp.NewClient("rtsp://" + ipCamUser + ":" + ipCamPass + "@" + r.config.CameraIP + ":8554/" + "CH002.sdp")
	if err != nil {
		return nil, err
	}

	r.config.Logger.Log(logger.Info, pkg+"created RTSP client")

	resp, err := rtspClt.Options()
	if err != nil {
		return nil, err
	}
	r.config.Logger.Log(logger.Debug, pkg+"RTSP OPTIONS response", "response", resp.String())

	resp, err = rtspClt.Describe()
	if err != nil {
		return nil, err
	}
	r.config.Logger.Log(logger.Debug, pkg+"RTSP DESCRIBE response", "response", resp.String())

	resp, err = rtspClt.Setup("track1", fmt.Sprintf("RTP/AVP;unicast;client_port=%d-%d", rtpPort, rtcpPort))
	if err != nil {
		return nil, err
	}
	r.config.Logger.Log(logger.Debug, pkg+"RTSP SETUP response", "response", resp.String())

	rtpCltAddr, rtcpCltAddr, rtcpSvrAddr, err := formAddrs(local, remote, *resp)
	if err != nil {
		return nil, err
	}

	r.config.Logger.Log(logger.Info, pkg+"RTSP session setup complete")

	rtpClt, err := rtp.NewClient(rtpCltAddr)
	if err != nil {
		return nil, err
	}

	rtcpClt, err := rtcp.NewClient(rtcpCltAddr, rtcpSvrAddr, rtpClt, r.config.Logger.Log)
	if err != nil {
		return nil, err
	}

	r.config.Logger.Log(logger.Info, pkg+"RTCP and RTP clients created")

	// Check errors from RTCP client until it has stopped running.
	go func() {
		for {
			err, ok := <-rtcpClt.Err()
			if ok {
				r.config.Logger.Log(logger.Warning, pkg+"RTCP error", "error", err.Error())
			} else {
				return
			}
		}
	}()

	// Start the RTCP client.
	rtcpClt.Start()

	r.config.Logger.Log(logger.Info, pkg+"RTCP client started")

	// Start reading data from the RTP client.
	r.wg.Add(1)
	go r.processFrom(rtpClt, time.Second/time.Duration(r.config.FrameRate))

	r.config.Logger.Log(logger.Info, pkg+"started input processor")

	resp, err = rtspClt.Play()
	if err != nil {
		return nil, err
	}
	r.config.Logger.Log(logger.Debug, pkg+"RTSP server PLAY response", "response", resp.String())
	r.config.Logger.Log(logger.Info, pkg+"play requested, now receiving stream")

	return func() error {
		err := rtpClt.Close()
		if err != nil {
			return fmt.Errorf("could not close RTP client: %w", err)
		}

		err = rtspClt.Close()
		if err != nil {
			return fmt.Errorf("could not close RTSP client: %w", err)
		}

		rtcpClt.Stop()

		r.config.Logger.Log(logger.Info, pkg+"RTP, RTSP and RTCP clients stopped and closed")
		return nil
	}, nil
}

// formAddrs is a helper function to form the addresses for the RTP client,
// RTCP client, and the RTSP server's RTCP addr using the local, remote addresses
// of the RTSP conn, and the SETUP method response.
func formAddrs(local, remote *net.TCPAddr, setupResp rtsp.Response) (rtpCltAddr, rtcpCltAddr, rtcpSvrAddr string, err error) {
	svrRTCPPort, err := parseSvrRTCPPort(setupResp)
	if err != nil {
		return "", "", "", err
	}
	rtpCltAddr = strings.Split(local.String(), ":")[0] + ":" + strconv.Itoa(rtpPort)
	rtcpCltAddr = strings.Split(local.String(), ":")[0] + ":" + strconv.Itoa(rtcpPort)
	rtcpSvrAddr = strings.Split(remote.String(), ":")[0] + ":" + strconv.Itoa(svrRTCPPort)
	return
}

// parseServerRTCPPort is a helper function to get the RTSP server's RTCP port.
func parseSvrRTCPPort(resp rtsp.Response) (int, error) {
	transport := resp.Header.Get("Transport")
	for _, p := range strings.Split(transport, ";") {
		if strings.Contains(p, "server_port") {
			port, err := strconv.Atoi(strings.Split(p, "-")[1])
			if err != nil {
				return 0, err
			}
			return port, nil
		}
	}
	return 0, errors.New("SETUP response did not provide RTCP port")
}

// processFrom is run as a routine to read from a input data source, lex and
// then send individual access units to revid's encoders.
func (r *Revid) processFrom(read io.Reader, delay time.Duration) {
	r.err <- r.lexTo(r.encoders, read, delay)
	r.config.Logger.Log(logger.Info, pkg+"finished lexing")
	r.wg.Done()
}