//
//  rhctl
//
//  Copyright (C) 2009-2016 Christian Pointner <equinox@helsinki.at>
//
//  This file is part of rhctl.
//
//  rhctl is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  any later version.
//
//  rhctl 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
//  along with rhctl. If not, see <http://www.gnu.org/licenses/>.
//

package main

import (
	"errors"
	"fmt"
	"time"

	"github.com/btittelbach/pubsub"
)

type Mood uint

const (
	MoodAwakening Mood = iota
	MoodSad
	MoodNervous
	MoodHappy
)

func (m Mood) String() string {
	switch m {
	case MoodAwakening:
		return "awakening"
	case MoodSad:
		return "sad"
	case MoodNervous:
		return "nervous"
	case MoodHappy:
		return "happy"
	}
	return "unknown"
}

type State struct {
	Mood         Mood
	Switch       SwitchState
	ActiveServer string
	Server       map[string]ServerState
	Settled      bool
}

type CommandType uint8

const (
	CmdState CommandType = iota
	CmdServer
	CmdSwitch
)

func (c CommandType) String() string {
	switch c {
	case CmdState:
		return "state"
	case CmdServer:
		return "server"
	case CmdSwitch:
		return "switch"
	}
	return "unknown"
}

type Command struct {
	Type     CommandType
	Args     []string
	Response chan<- interface{}
}

type SwitchControl struct {
	sw                       *AudioSwitch
	servers                  []*PlayoutServer
	state                    State
	settling                 *time.Timer
	Updates                  *pubsub.PubSub
	Commands                 chan *Command
	AwakeningSettlingTime    time.Duration // 30 * time.Second
	SelectServerSettlingTime time.Duration // 10 * time.Second
	UpdateStatesSettlingTime time.Duration //  3 * time.Second
	StaleStateCheckInterval  time.Duration //  1 * time.Minute
	StatesMaxAge             time.Duration //  2 * time.Hour
}

func (ctrl *SwitchControl) handleCommand(cmd *Command) {
	switch cmd.Type {
	case CmdState:
		if cmd.Response != nil {
			cmd.Response <- ctrl.state
		}
	case CmdServer:
		if len(cmd.Args) == 0 {
			if cmd.Response != nil {
				cmd.Response <- fmt.Errorf("no server specified")
			}
			return
		}
		result := ctrl.reconcile(cmd.Args[0])
		if cmd.Response != nil {
			cmd.Response <- result
		}
	case CmdSwitch:
		if len(cmd.Args) == 0 {
			if cmd.Response != nil {
				cmd.Response <- fmt.Errorf("no command specified")
			}
			return
		}
		c, err := NewSwitchCommandFromStrings(cmd.Args[0], cmd.Args[1:]...)
		if err != nil {
			if cmd.Response != nil {
				cmd.Response <- fmt.Errorf("switch command syntax error: %s", err.Error())
			}
			return
		}
		c.Response = cmd.Response
		ctrl.sw.Commands <- c
	}
}

func handleServer(sin <-chan ServerState, sout chan<- ServerState, cin <-chan Command, cout chan<- *Command) {
	for {
		select {
		case update := <-sin:
			sout <- update
		case cmd := <-cin:
			cout <- &cmd
		}
	}
}

func (ctrl *SwitchControl) checkMissingOrStaleStates(maxAge time.Duration) (isStale bool) {
	if time.Since(ctrl.state.Switch.AudioInputsUpdated) > maxAge {
		ctrl.sw.Commands <- &SwitchCommand{SwitchCmdStateAudio, nil, nil}
		isStale = true
	}
	if time.Since(ctrl.state.Switch.AudioSilenceUpdated) > maxAge {
		ctrl.sw.Commands <- &SwitchCommand{SwitchCmdStateSilence, nil, nil}
		isStale = true
	}
	if time.Since(ctrl.state.Switch.GPIUpdated) > maxAge {
		ctrl.sw.Commands <- &SwitchCommand{SwitchCmdStateGPIAll, nil, nil}
		isStale = true
	}
	if time.Since(ctrl.state.Switch.RelayUpdated) > maxAge {
		ctrl.sw.Commands <- &SwitchCommand{SwitchCmdStateRelay, nil, nil}
		isStale = true
	}
	if time.Since(ctrl.state.Switch.OCUpdated) > maxAge {
		ctrl.sw.Commands <- &SwitchCommand{SwitchCmdStateOC, nil, nil}
		isStale = true
	}

	for _, server := range ctrl.servers {
		s, exists := ctrl.state.Server[server.name]
		if !exists || time.Since(s.Updated) > maxAge {
			server.UpdateRequest <- true
			isStale = true
		}
	}
	return
}

func (ctrl *SwitchControl) getSwitchServerAssignment() (swsrv, swch string, err error) {
	activeInput := SwitchInputNum(0)
	cnt := 0
	for idx, in := range ctrl.state.Switch.Audio[0].Inputs {
		if in {
			activeInput = SwitchInputNum(idx + 1)
			cnt++
		}
	}
	if cnt != 1 || activeInput == SwitchInputNum(0) {
		return "", "", errors.New("no or more than one input is active")
	}

	return ctrl.sw.Inputs.GetServerAndChannel(activeInput)
}

func (ctrl *SwitchControl) selectServer(server string) bool {
	newIn, err := ctrl.sw.Inputs.GetNumber(server, ctrl.state.Server[server].Channel)
	if err != nil {
		rhdl.Printf("SwitchCTRL: no audio input configured for server/channel: '%s/%s'", server, ctrl.state.Server[server].Channel)
		return false
	}

	for idx, in := range ctrl.state.Switch.Audio[0].Inputs {
		if in && SwitchInputNum(idx+1) != newIn {
			ctrl.sw.Commands <- &SwitchCommand{SwitchCmdAudioFadeDownInput, []interface{}{SwitchInputNum(idx + 1)}, nil}
		}
	}
	ctrl.sw.Commands <- &SwitchCommand{SwitchCmdAudioFadeUpInput, []interface{}{newIn}, nil}
	ctrl.settling.Reset(ctrl.SelectServerSettlingTime)
	ctrl.state.Settled = false
	return true
}

func (ctrl *SwitchControl) checkAndSelectServer(server string) bool {
	if state, exists := ctrl.state.Server[server]; exists {
		if state.Health == ServerAlive && state.Channel != "" {
			return ctrl.selectServer(server)
		}
	}
	return false
}

func (ctrl *SwitchControl) selectNextValidServer() {
	for name, state := range ctrl.state.Server {
		if state.Health == ServerAlive && state.Channel != "" {
			if !ctrl.selectServer(name) {
				continue
			}
			ctrl.state.Mood = MoodNervous
			rhl.Printf("SwitchCTRL: found another valid server '%s' -> now in mood: %s", name, ctrl.state.Mood)
			return
		}
	}
	ctrl.state.Mood = MoodSad
	rhl.Printf("SwitchCTRL: found no alive/valid server -> now in mood: %s", ctrl.state.Mood)
}

func (ctrl *SwitchControl) reconcile(requestedServer string) (result bool) {
	if !ctrl.state.Settled {
		if requestedServer != "" {
			rhl.Printf("SwitchCTRL: ignoreing preferred server requests while settling")
		}
		return
	}
	if len(ctrl.servers) < 1 {
		ctrl.state.Mood = MoodHappy
		rhdl.Printf("SwitchCTRL: there are no servers configured -> now in mood: %s", ctrl.state.Mood)
		return
	}

	if ctrl.state.Mood == MoodAwakening && requestedServer != "" {
		rhl.Printf("SwitchCTRL: ignoreing preferred server requests while waking-up")
		return
	}
	reqSrvSuffix := ""
	if requestedServer != "" {
		reqSrvSuffix = " (requested server: '" + requestedServer + "')"
	}
	rhdl.Printf("SwitchCTRL: reconciling state...%s", reqSrvSuffix)

	swsrv, swch, err := ctrl.getSwitchServerAssignment()
	if err != nil {
		ctrl.state.Mood = MoodSad
		rhl.Printf("SwitchCTRL: switch input assignments are ambigious -> now in mood: %s", ctrl.state.Mood)
		return
	}
	rhl.Printf("SwitchCTRL: switch is set to server/channel: '%s/%s'", swsrv, swch)

	s, exists := ctrl.state.Server[swsrv]
	if !exists || s.Health != ServerAlive || s.Channel == "" {
		rhl.Printf("SwitchCTRL: server '%s' is unknown, dead or has invalid channel!", swsrv)
		if requestedServer != "" {
			if ctrl.checkAndSelectServer(requestedServer) {
				rhl.Printf("SwitchCTRL: switching to requested server '%s' ...", requestedServer)
				return true
			}
			rhl.Printf("SwitchCTRL: requested server '%s' is not selectable, ignoring request", requestedServer)
		}
		ctrl.selectNextValidServer()
		return
	}
	ctrl.state.ActiveServer = swsrv

	if requestedServer != "" {
		if ctrl.state.ActiveServer != requestedServer {
			if ctrl.checkAndSelectServer(requestedServer) {
				rhl.Printf("SwitchCTRL: switching to requested server '%s' ...", requestedServer)
				result = true
			} else {
				rhl.Printf("SwitchCTRL: requested server '%s' is not selectable, ignoring request", requestedServer)
			}
		} else {
			result = true
		}
	} else {
		if s.Channel != swch {
			// TODO: during normal operation switching server channels is expected and shouldn't lead to mood nervous?!?!?
			ctrl.state.Mood = MoodNervous
			rhl.Printf("SwitchCTRL: switch and server channel mismatch: '%s' != '%s' -> now in mood: %s", swch, s.Channel, ctrl.state.Mood)
			if !ctrl.selectServer(ctrl.state.ActiveServer) {
				ctrl.selectNextValidServer()
			}
			return
		}
	}

	for _, s := range ctrl.state.Server {
		if s.Health != ServerAlive {
			ctrl.state.Mood = MoodNervous
			rhl.Printf("SwitchCTRL: at least one configured server is dead -> now in mood: %s", ctrl.state.Mood)
			return
		}
	}
	ctrl.state.Mood = MoodHappy
	rhl.Printf("SwitchCTRL: all servers are alive -> now in mood: %s", ctrl.state.Mood)
	return
}

func (ctrl *SwitchControl) Run() {
	rhl.Printf("SwitchCTRL: starting up -> now in mood: %s", ctrl.state.Mood)

	ctrl.settling = time.NewTimer(ctrl.AwakeningSettlingTime)
	ctrl.state.Settled = false

	serverStateChanges := make(chan ServerState, 8)
	for _, srv := range ctrl.servers {
		go handleServer(srv.StateChanges, serverStateChanges, srv.Commands, ctrl.Commands)
	}

	// send out commands to switch and/or server to get missing infos
	ctrl.checkMissingOrStaleStates(0)
	staleTicker := time.NewTicker(ctrl.StaleStateCheckInterval)

	ctrl.reconcile("")
	for {
		select {
		case <-staleTicker.C:
			if ctrl.state.Settled { // better don't interfere with changes in progress
				if ctrl.checkMissingOrStaleStates(ctrl.StatesMaxAge) {
					ctrl.settling.Reset(ctrl.UpdateStatesSettlingTime)
					ctrl.state.Settled = false
				}
			}
		case <-ctrl.settling.C:
			ctrl.state.Settled = true
			ctrl.reconcile("")
			ctrl.Updates.Pub(ctrl.state, "state")
		case update := <-ctrl.sw.Updates:
			rhdl.Printf("got update from switch: %+v", update)
			for _, srv := range ctrl.servers {
				srv.SwitchUpdates <- update
			}
			ctrl.Updates.Pub(update, "switch:"+update.Type.String())
		case state := <-ctrl.sw.StateChanges:
			// rhdl.Printf("got switch state update: %+v", state)
			ctrl.Updates.Pub(state, "switch:state")
			ctrl.state.Switch = state
			ctrl.reconcile("")
			ctrl.Updates.Pub(ctrl.state, "state")
		case state := <-serverStateChanges:
			rhdl.Printf("got server state update: %+v", state)
			ctrl.Updates.Pub(state, "server:state")
			ctrl.state.Server[state.Name] = state
			ctrl.reconcile("")
			ctrl.Updates.Pub(ctrl.state, "state")
		case cmd := <-ctrl.Commands:
			ctrl.handleCommand(cmd)
		}
	}
}

func SwitchControlInit(conf *Config, sw *AudioSwitch, servers []*PlayoutServer) (ctrl *SwitchControl) {
	ctrl = &SwitchControl{}
	ctrl.sw = sw
	ctrl.servers = servers
	ctrl.state.Mood = MoodAwakening
	ctrl.state.Server = make(map[string]ServerState)
	ctrl.Updates = pubsub.NewNonBlocking(32)
	ctrl.Commands = make(chan *Command, 8)

	// TODO: get this from conf
	ctrl.AwakeningSettlingTime = 30 * time.Second
	ctrl.SelectServerSettlingTime = 10 * time.Second
	ctrl.UpdateStatesSettlingTime = 3 * time.Second
	ctrl.StaleStateCheckInterval = 1 * time.Minute
	ctrl.StatesMaxAge = 2 * time.Hour
	return
}