package game

import (
	"fmt"
	"log"
	"regexp"
)

type PlayerNotificationType int

const (
	InvalidNotification PlayerNotificationType = iota
	DeclaredActionNotification
	ResolvedActionNotification
	PriorityNotification
	TargetSelectionPrompt
	DeclareTriggeredActionsPrompt
	DraftPickPrompt
	JoinedPlayerNotification
	ReadyPlayerNotification
	ConcededNotification
)

func (n PlayerNotificationType) String() string {
	switch n {
	case InvalidNotification:
		return "InvalidNotification"
	case DeclaredActionNotification:
		return "DeclaredActionNotification"
	case ResolvedActionNotification:
		return "ResolvedActionNotification"
	case PriorityNotification:
		return "PriorityNotification"
	case TargetSelectionPrompt:
		return "TargetSelectionPrompt"
	case DeclareTriggeredActionsPrompt:
		return "DeclareTriggeredActionsPrompt"
	case DraftPickPrompt:
		return "DraftPickPrompt"
	case JoinedPlayerNotification:
		return "JoinedPlayerNotification"
	case ReadyPlayerNotification:
		return "ReadyPlayerNotification"
	case ConcededNotification:
		return "ConcededNotification"
	default:
		log.Panicf("Unhandled notification %d", n)
		return ""
	}
}

func (n PlayerNotification) IsPriorityNotification() bool {
	return n.Notification == PriorityNotification
}

type PlayerNotification struct {
	Notification PlayerNotificationType
	Context      any
	Error        error
}

func (n PlayerNotification) String() string {
	if n.Error != nil {
		return fmt.Sprintf("error %v: %v", n.Notification, n.Error)
	}

	return fmt.Sprintf("%v: %v", n.Notification, n.Context)
}

func (n PlayerNotification) Valid() bool {
	return n.Notification != InvalidNotification
}

type TargetSelectionCtx struct {
	Action Action
	Prompt string
}

func newPriorityNotification() PlayerNotification {
	return PlayerNotification{PriorityNotification, nil, nil}
}

func newDeclaredActionNotification(a Action, err error) PlayerNotification {
	return PlayerNotification{DeclaredActionNotification, a, err}
}

func newResolvedActionNotification(a Action, err error) PlayerNotification {
	return PlayerNotification{ResolvedActionNotification, a, err}
}

func newTargetSelectionPrompt(a Action, desc string) PlayerNotification {
	return PlayerNotification{TargetSelectionPrompt, TargetSelectionCtx{a, desc}, nil}
}

func newUpkeepPrompt(p *Player) PlayerNotification {
	a := newUpkeepAction(p)
	return newTargetSelectionPrompt(a, "Select units to disband")
}

func newBuyPrompt(p *Player) PlayerNotification {
	a := newBuyAction(p)
	prompt := newTargetSelectionPrompt(a, "Select a card to buy")
	return prompt
}

func newHandCardSelectionPrompt(p *Player, min, max int) PlayerNotification {
	a := newHandCardSelection(p, min, max)
	desc := fmt.Sprintf("Select between %d and %d hand cards", min, max)
	return newTargetSelectionPrompt(a, desc)
}

func newAlliedUnitSelectionPrompt(p *Player, min, max int) PlayerNotification {
	a := newAlliedUnitSelection(p, min, max)
	desc := fmt.Sprintf("Select between %d and %d allied units", min, max)
	return newTargetSelectionPrompt(a, desc)
}

func newTileSelectionPrompt(p *Player, c TargetConstraintFunc, min, max int) PlayerNotification {
	a := newTileSelection(p, c, min, max)
	desc := fmt.Sprintf("Select between %d and %d tiles", min, max)
	return newTargetSelectionPrompt(a, desc)
}

func newDeclareTriggeredActionsPrompt(triggeredActions []*TriggeredAction) PlayerNotification {
	return PlayerNotification{DeclareTriggeredActionsPrompt, triggeredActions, nil}
}

func newDraftPickPrompt(pack PileOfCards) PlayerNotification {
	return PlayerNotification{DraftPickPrompt, pack, nil}
}

// Create a notification about a joined new player.
// The notification only contains the name since a full `game.Player` may not be
// reconstructable for clients without a game state (e.g. draft client).
func NewJoinedPlayerNotification(p *Player) PlayerNotification {
	return PlayerNotification{JoinedPlayerNotification, p.Name, nil}
}

// Create a notification about a player's readiness.
// The notification only contains the name since a full `game.Player` may not be
// reconstructable for clients without a game state (e.g. draft client).
func NewReadyPlayerNotification(p *Player) PlayerNotification {
	return PlayerNotification{ReadyPlayerNotification, p.Name, nil}
}

// newConcededNotification creates a notification about a player's concession.
func newConcededNotification(p *Player) PlayerNotification {
	return PlayerNotification{ConcededNotification, p, nil}
}

// Marshal marshals a PlayerNotification to plain text.
//
// The marshaled PlayerNotification has the form `!TYPE{CONTEXT}`.
func (n PlayerNotification) Marshal(s State) []byte {
	out := []byte{'!'}
	ctx := []byte{}
	switch n.Notification {
	case DraftPickPrompt:
		out = append(out, []byte("pick")...)
		ctx = []byte(n.Context.(PileOfCards).String())
	case PriorityNotification:
		out = append(out, []byte("priority")...)
	case DeclaredActionNotification:
		out = append(out, []byte("declared")...)
		ctx = MarshalAction(n.Context.(Action))
	case ResolvedActionNotification:
		out = append(out, []byte("resolved")...)
		if n.Error != nil {
			ctx = []byte(n.Error.Error())
		}
	case JoinedPlayerNotification:
		out = append(out, []byte("joined")...)
		ctx = []byte(n.Context.(string))
	case ReadyPlayerNotification:
		out = append(out, []byte("ready")...)
		ctx = []byte(n.Context.(string))
	case ConcededNotification:
		out = append(out, []byte("ready")...)
		ctx = []byte(n.Context.(*Player).Name)
	default:
		log.Fatalf("Marshal(%s) not implement\n", n)
	}
	out = fmt.Appendf(out, "{%s}", ctx)

	return out
}

var PlayerNotificationRegex = regexp.MustCompile(`!(.*)\{(.*)\}`)

type InvalidPlayerNotificationError struct {
	ErrorString string
}

func (err InvalidPlayerNotificationError) Error() string {
	return err.ErrorString
}

var (
	ErrBadFormat           = InvalidPlayerNotificationError{"bad format"}
	ErrUnknownNotification = InvalidPlayerNotificationError{"unknown notification"}
	ErrNoContextExpected   = InvalidPlayerNotificationError{"no context expected"}
)

// UnmarshalPlayerNotification creates a UnmarshalPlayerNotification from plain text.
// For the PlayerNotification plain text format see MarshalPlayerNotification.
func UnmarshalPlayerNotification(s State, in []byte) (n PlayerNotification, err error) {
	m := PlayerNotificationRegex.FindSubmatch(in)
	if len(m) != 3 {
		return n, ErrBadFormat
	}
	t := string(m[1])
	ctx := m[2]

	switch t {
	case "pick":
		pack := NewPileOfCards()
		err = pack.FromString(string(ctx))
		if err != nil {
			return
		}
		n = newDraftPickPrompt(pack)

	case "priority":
		if len(ctx) > 0 {
			err = ErrNoContextExpected
		}
		n = newPriorityNotification()

	case "resolved":
		var err error
		if len(ctx) > 0 {
			err = ErrNoContextExpected
		}
		n = newResolvedActionNotification(s.Stack().Actions[len(s.Stack().Actions)-1], err)

	case "joined":
		n = PlayerNotification{JoinedPlayerNotification, string(ctx), nil}

	case "ready":
		n = PlayerNotification{ReadyPlayerNotification, string(ctx), nil}

	case "conceded":
		p := s.PlayerByName(string(ctx))
		if p == nil {
			err = ErrUnknownPlayer
			return
		}
		n = newConcededNotification(p)

	default:
		return n, ErrUnknownNotification
	}
	return
}

type PlayerControl interface {
	Player() *Player
	// SendAction sends an Action and blocks until it is sent.
	SendAction(Action) error
	// RecvAction returns the next Action.
	// It blocks until the Action is received or an error occurs.
	RecvAction() (Action, error)
	// SendNotification sends an PlayerNotification and blocks until it is sent.
	SendNotification(PlayerNotification) error
	// RecvNotification returns a new PlayerNotification.
	// If no new notification is available an zero/invalid PlayerNotification is returned and err == nil.
	// RecvNotification never blocks.
	RecvNotification() (PlayerNotification, error)
	Close()
}

// ChanPlayerControl implements a PlayerControl using two go channels.
// Objects are transferred directly.
// Therefore ChanPlayerControl is only suitable for communication in the same process.
type ChanPlayerControl struct {
	player        *Player
	actions       chan Action
	notifications chan PlayerNotification
}

func (c *ChanPlayerControl) Player() *Player { return c.player }
func (c *ChanPlayerControl) SendAction(a Action) error {
	c.actions <- a
	return nil
}

func (c *ChanPlayerControl) RecvAction() (Action, error) {
	return <-c.actions, nil
}

func (c *ChanPlayerControl) SendNotification(n PlayerNotification) error {
	c.notifications <- n
	return nil
}

func (c *ChanPlayerControl) RecvNotification() (PlayerNotification, error) {
	var n PlayerNotification
	select {
	case n = <-c.notifications:
	default:
	}
	return n, nil
}

func (c *ChanPlayerControl) Close() {
	close(c.actions)
	close(c.notifications)
}

func NewChanPlayerControl(p *Player) *ChanPlayerControl {
	a := make(chan Action)
	n := make(chan PlayerNotification)
	return &ChanPlayerControl{p, a, n}
}

func prompt(ctrl PlayerControl, notification PlayerNotification) (Action, error) {
	ctrl.SendNotification(notification)
	return ctrl.RecvAction()
}

func promptBuy(ctrl PlayerControl) (Action, error) {
	return prompt(ctrl, newBuyPrompt(ctrl.Player()))
}

func promptAction(ctrl PlayerControl) (Action, error) {
	return prompt(ctrl, newPriorityNotification())
}