package controllers

import (
	"context"
	"log"
	"sync"
	"time"

	"git.joco.dk/sng/fermentord/internal/configuration"
	"git.joco.dk/sng/fermentord/pkg/temperature"
	"github.com/getsentry/sentry-go"
)

type ChamberState int

const (
	ChamberStateIdle ChamberState = iota
	ChamberStateCooling
	ChamberStateHeating
)

var ChamberStateMap = map[ChamberState]string{
	ChamberStateIdle:    "IDLE",
	ChamberStateCooling: "COOLING",
	ChamberStateHeating: "HEATING",
}

type ChamberController struct {
	ConfigUpdates chan configuration.Configuration
	config        configuration.Configuration

	// Current state.
	chamberState           ChamberState
	lastChamberStateChange time.Time
	lastCoolerStateChange  time.Time
	C                      chan ChamberState
	isPaused               bool

	// Current temperature readings.
	ambientTemperature float64
	chamberTemperature float64
	wortTemperature    float64

	chTemp  chan temperature.TemperatureReading
	chPause chan bool

	pid *PIDController
	hub *sentry.Hub
}

func NewChamberController(config configuration.Configuration) *ChamberController {
	return &ChamberController{
		C:             make(chan ChamberState),
		config:        config,
		pid:           NewPIDController(config.PID.Kp, config.PID.Ki, config.PID.Kd),
		chTemp:        make(chan temperature.TemperatureReading),
		chPause:       make(chan bool, 1),
		chamberState:  ChamberStateIdle,
		ConfigUpdates: make(chan configuration.Configuration, 1),
		hub:           sentry.CurrentHub().Clone(),
	}
}

func (p *ChamberController) Run(ctx context.Context, wg *sync.WaitGroup) {
	defer p.hub.Flush(10 * time.Second)
	defer wg.Done()

	ticker := time.NewTicker(1 * time.Second)

	for {
		select {
		case <-ticker.C:
			state := p.computeChamberState()
			p.setChamberState(state)

		case t := <-p.chTemp:
			p.ambientTemperature = t.Ambient
			p.chamberTemperature = t.Chamber
			p.wortTemperature = t.Wort

		case pause := <-p.chPause:
			p.setPause(pause)

		case c := <-p.ConfigUpdates:
			p.config = c

		case <-ctx.Done():
			ticker.Stop()
			p.isPaused = false
			// TODO Check if the line below blocks on shutdown
			//p.setChamberState(ChamberStateIdle)

			return
		}
	}
}

func (p *ChamberController) SetTemperature(t temperature.TemperatureReading) {
	p.chTemp <- t
}

// Pause is a thread-safe way to pause the controller.
func (p *ChamberController) Pause() {
	p.chPause <- true
}

// Resume is a thread-safe way to resume the controller.
func (p *ChamberController) Resume() {
	p.chPause <- false
}

func (p *ChamberController) setPause(pause bool) {
	if pause {
		p.setChamberState(ChamberStateIdle)
		p.isPaused = true
	} else {
		p.isPaused = false
		state := p.computeChamberState()
		p.setChamberState(state)
	}
}

func (p *ChamberController) setChamberState(state ChamberState) {
	if state == p.chamberState {
		return
	}

	if p.isPaused {
		return
	}

	log.Printf("State changed from %v to %v", p.chamberState, state)

	if p.chamberState == ChamberStateCooling || state == ChamberStateCooling {
		p.lastCoolerStateChange = time.Now()
	}

	p.chamberState = state
	p.lastChamberStateChange = time.Now()
	p.C <- state
}

func (p *ChamberController) computeChamberState() ChamberState {
	offset := p.pid.Compute(p.chamberTemperature, p.config.FermentationTemperature)
	chamberTargetTemp := p.config.FermentationTemperature + offset

	runtimeSecs := time.Since(p.lastChamberStateChange).Seconds()

	if p.chamberState == ChamberStateCooling {
		// Ensure compressor min. runtime
		if runtimeSecs < p.config.Limits.MinCoolerRuntimeSecs {
			return p.chamberState
		}

		// Limit compressor runtime
		if runtimeSecs > p.config.Limits.MaxCoolerRuntimeSecs {
			return ChamberStateIdle
		}

		// Limit chamber min. temp.
		if p.chamberTemperature < p.config.Limits.MinChamberTemperature {
			return ChamberStateIdle
		}

		// Limit chamber max. temp.
		if p.chamberTemperature > p.config.Limits.MaxChamberTemperature {
			return ChamberStateIdle
		}
	}

	var next ChamberState
	heater := p.chamberTemperature < p.config.FermentationTemperature-p.config.DeltaTemperatureHeat &&
		p.chamberTemperature < chamberTargetTemp-p.config.DeltaTemperatureHeat
	cooler := p.chamberTemperature > p.config.FermentationTemperature+p.config.DeltaTemperatureCool &&
		p.chamberTemperature > chamberTargetTemp+p.config.DeltaTemperatureCool

	if cooler && heater {
		// This should not happen!
		log.Print("Trying to set cooler and heater on at the same time. This should NOT happen! Setting IDLE mode.")
		p.hub.CaptureMessage("Trying to set cooler and heater on at the same time")
		next = ChamberStateIdle
	} else if !cooler && !heater {
		next = ChamberStateIdle
	} else if cooler {
		next = ChamberStateCooling
	} else if heater {
		next = ChamberStateHeating
	}

	// Ensure compressor cooldown
	if p.chamberState != ChamberStateCooling && next == ChamberStateCooling &&
		time.Since(p.lastCoolerStateChange).Seconds() < p.config.Limits.MinCoolerCooldownSecs {
		return ChamberStateIdle
	}

	// Ensure that heater wont run just after cooling cycle
	if p.chamberState != ChamberStateHeating && next == ChamberStateHeating && time.Since(p.lastCoolerStateChange).Seconds() < p.config.Limits.HeaterGraceTimeSecs {
		return ChamberStateIdle
	}

	return next
}