package events

import (
	"errors"
	"fmt"
	"strconv"

	"github.com/thrasher-/gocryptotrader/common"
	"github.com/thrasher-/gocryptotrader/communications"
	"github.com/thrasher-/gocryptotrader/communications/base"
	"github.com/thrasher-/gocryptotrader/config"
	"github.com/thrasher-/gocryptotrader/currency"
	"github.com/thrasher-/gocryptotrader/exchanges/ticker"
	log "github.com/thrasher-/gocryptotrader/logger"
)

const (
	itemPrice          = "PRICE"
	greaterThan        = ">"
	greaterThanOrEqual = ">="
	lessThan           = "<"
	lessThanOrEqual    = "<="
	isEqual            = "=="
	actionSMSNotify    = "SMS"
	actionConsolePrint = "CONSOLE_PRINT"
	actionTest         = "ACTION_TEST"
)

var (
	errInvalidItem      = errors.New("invalid item")
	errInvalidCondition = errors.New("invalid conditional option")
	errInvalidAction    = errors.New("invalid action")
	errExchangeDisabled = errors.New("desired exchange is disabled")

	// NOTE comms is an interim implementation
	comms *communications.Communications
)

// Event struct holds the event variables
type Event struct {
	ID        int
	Exchange  string
	Item      string
	Condition string
	Pair      currency.Pair
	Asset     string
	Action    string
	Executed  bool
}

// Events variable is a pointer array to the event structures that will be
// appended
var Events []*Event

// SetComms is an interim function that will support a median integration. This
// sets the current comms package.
func SetComms(commsP *communications.Communications) {
	comms = commsP
}

// AddEvent adds an event to the Events chain and returns an index/eventID
// and an error
func AddEvent(exchange, item, condition string, currencyPair currency.Pair, asset, action string) (int, error) {
	err := IsValidEvent(exchange, item, condition, action)
	if err != nil {
		return 0, err
	}

	evt := &Event{}

	if len(Events) == 0 {
		evt.ID = 0
	} else {
		evt.ID = len(Events) + 1
	}

	evt.Exchange = exchange
	evt.Item = item
	evt.Condition = condition
	evt.Pair = currencyPair
	evt.Asset = asset
	evt.Action = action
	evt.Executed = false
	Events = append(Events, evt)
	return evt.ID, nil
}

// RemoveEvent deletes and event by its ID
func RemoveEvent(eventID int) bool {
	for i, x := range Events {
		if x.ID == eventID {
			Events = append(Events[:i], Events[i+1:]...)
			return true
		}
	}
	return false
}

// GetEventCounter displays the emount of total events on the chain and the
// events that have been executed.
func GetEventCounter() (total, executed int) {
	total = len(Events)

	for _, x := range Events {
		if x.Executed {
			executed++
		}
	}
	return total, executed
}

// ExecuteAction will execute the action pending on the chain
func (e *Event) ExecuteAction() bool {
	if common.StringContains(e.Action, ",") {
		action := common.SplitStrings(e.Action, ",")
		if action[0] == actionSMSNotify {
			message := fmt.Sprintf("Event triggered: %s", e.String())
			if action[1] == "ALL" {
				comms.PushEvent(base.Event{TradeDetails: message})
			}
		}
	} else {
		log.Debugf("Event triggered: %s", e.String())
	}
	return true
}

// String turns the structure event into a string
func (e *Event) String() string {
	condition := common.SplitStrings(e.Condition, ",")
	return fmt.Sprintf(
		"If the %s%s [%s] %s on %s is %s then %s.", e.Pair.Base.String(),
		e.Pair.Quote.String(),
		e.Asset,
		e.Item,
		e.Exchange,
		condition[0]+" "+condition[1],
		e.Action,
	)
}

// CheckCondition will check the event structure to see if there is a condition
// met
func (e *Event) CheckCondition() bool {
	condition := common.SplitStrings(e.Condition, ",")
	targetPrice, _ := strconv.ParseFloat(condition[1], 64)

	t, err := ticker.GetTicker(e.Exchange, e.Pair, e.Asset)
	if err != nil {
		return false
	}

	lastPrice := t.Last

	if lastPrice == 0 {
		return false
	}

	switch condition[0] {
	case greaterThan:
		if lastPrice > targetPrice {
			return e.ExecuteAction()
		}
	case greaterThanOrEqual:
		if lastPrice >= targetPrice {
			return e.ExecuteAction()
		}
	case lessThan:
		if lastPrice < targetPrice {
			return e.ExecuteAction()
		}
	case lessThanOrEqual:
		if lastPrice <= targetPrice {
			return e.ExecuteAction()
		}
	case isEqual:
		if lastPrice == targetPrice {
			return e.ExecuteAction()
		}
	}
	return false
}

// IsValidEvent checks the actions to be taken and returns an error if incorrect
func IsValidEvent(exchange, item, condition, action string) error {
	exchange = common.StringToUpper(exchange)
	item = common.StringToUpper(item)
	action = common.StringToUpper(action)

	if !IsValidExchange(exchange) {
		return errExchangeDisabled
	}

	if !IsValidItem(item) {
		return errInvalidItem
	}

	if !common.StringContains(condition, ",") {
		return errInvalidCondition
	}

	c := common.SplitStrings(condition, ",")

	if !IsValidCondition(c[0]) || c[1] == "" {
		return errInvalidCondition
	}

	if common.StringContains(action, ",") {
		a := common.SplitStrings(action, ",")

		if a[0] != actionSMSNotify {
			return errInvalidAction
		}

		if a[1] != "ALL" {
			comms.PushEvent(base.Event{Type: a[1]})
		}
	} else if action != actionConsolePrint && action != actionTest {
		return errInvalidAction
	}

	return nil
}

// CheckEvents is the overarching routine that will iterate through the Events
// chain
func CheckEvents() {
	for {
		total, executed := GetEventCounter()
		if total > 0 && executed != total {
			for _, event := range Events {
				if !event.Executed {
					success := event.CheckCondition()
					if success {
						log.Debugf(
							"Event %d triggered on %s successfully.\n", event.ID,
							event.Exchange,
						)
						event.Executed = true
					}
				}
			}
		}
	}
}

// IsValidExchange validates the exchange
func IsValidExchange(exchange string) bool {
	exchange = common.StringToUpper(exchange)
	cfg := config.GetConfig()
	for x := range cfg.Exchanges {
		if cfg.Exchanges[x].Name == exchange && cfg.Exchanges[x].Enabled {
			return true
		}
	}
	return false
}

// IsValidCondition validates passed in condition
func IsValidCondition(condition string) bool {
	switch condition {
	case greaterThan, greaterThanOrEqual, lessThan, lessThanOrEqual, isEqual:
		return true
	}
	return false
}

// IsValidAction validates passed in action
func IsValidAction(action string) bool {
	action = common.StringToUpper(action)
	switch action {
	case actionSMSNotify, actionConsolePrint, actionTest:
		return true
	}
	return false
}

// IsValidItem validates passed in Item
func IsValidItem(item string) bool {
	item = common.StringToUpper(item)
	return (item == itemPrice)
}