package main

import (
	"context"
	"database/sql"

	"github.com/heroiclabs/nakama-common/runtime"
)

// Interface for registering match handlers
type BattleRoyaleMatch struct{}

// In-memory game state
type BattleRoyaleMatchState struct {
	presences  map[string]runtime.Presence
	emptyTicks int
}

// Run on match start, initializes game state and sets tick rate
func (m *BattleRoyaleMatch) MatchInit(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, params map[string]interface{}) (interface{}, int, string) {
	state := &BattleRoyaleMatchState{
		presences:  map[string]runtime.Presence{},
		emptyTicks: 0,
	}
	tickRate := 1 // MatchLoop invocations per second
	label := ""
	return state, tickRate, label
}

// Run when a user attempts to join or rejoin a match. Responsible for deciding whether or not to let them in.
func (m *BattleRoyaleMatch) MatchJoinAttempt(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, dispatcher runtime.MatchDispatcher, tick int64, state interface{}, presence runtime.Presence, metadata map[string]string) (interface{}, bool, string) {
	lobbyState, ok := state.(*BattleRoyaleMatchState)
	if !ok {
		logger.Error("State is not a valid lobby state object for MatchJoin.")
		return nil, false, "Failed to join match: match does not exist."
	}
	accepted := true
	rejectedMessage := ""

	return lobbyState, accepted, rejectedMessage
}

// Run when a user successfully joins a match, registers their presence in the game state
func (m *BattleRoyaleMatch) MatchJoin(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, dispatcher runtime.MatchDispatcher, tick int64, state interface{}, presences []runtime.Presence) interface{} {
	lobbyState, ok := state.(*BattleRoyaleMatchState)
	if !ok {
		logger.Error("State is not a valid lobby state object for MatchJoin.")
		return nil
	}

	for i := 0; i < len(presences); i++ {
		lobbyState.presences[presences[i].GetSessionId()] = presences[i]
	}

	return lobbyState
}

// Run when a user successfully leaves a match, de-registers their presence in the game state
func (m *BattleRoyaleMatch) MatchLeave(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, dispatcher runtime.MatchDispatcher, tick int64, state interface{}, presences []runtime.Presence) interface{} {
	lobbyState, ok := state.(*BattleRoyaleMatchState)
	if !ok {
		logger.Error("State is not a valid lobby state object for MatchLeave.")
		return nil
	}

	for i := 0; i < len(presences); i++ {
		delete(lobbyState.presences, presences[i].GetSessionId())
	}

	return lobbyState
}

// Run when a match gets an arbitrary signal from the Nakama runtime (probably from the matchmaker/match lister APIs)
func (m *BattleRoyaleMatch) MatchSignal(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, dispatcher runtime.MatchDispatcher, tick int64, state interface{}, data string) (interface{}, string) {
	lobbyState, ok := state.(*BattleRoyaleMatchState)
	if !ok {
		logger.Error("State is not a valid lobby state object for MatchSignal.")
		return nil, "Failed to get valid state for return signal"
	}

	returnMessage := ""
	return lobbyState, returnMessage
}

// Run when the server enters the graceful shutdown flow. Gives the match a chance to shutdown cleanly within graceSeconds.
func (m *BattleRoyaleMatch) MatchTerminate(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, dispatcher runtime.MatchDispatcher, tick int64, state interface{}, graceSeconds int) interface{} {
	lobbyState, ok := state.(*BattleRoyaleMatchState)
	if !ok {
		logger.Error("State is not a valid lobby state object for MatchTerminate.")
		return nil
	}

	return lobbyState
}

// Main game loop, executed at tickRate per second specified in MatchInit
func (m *BattleRoyaleMatch) MatchLoop(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, dispatcher runtime.MatchDispatcher, tick int64, state interface{}, messages []runtime.MatchData) interface{} {
	lobbyState, ok := state.(*BattleRoyaleMatchState)
	if !ok {
		logger.Error("State is not a valid lobby state object for MatchLoop.")
		return nil
	}

	// If we have no presences in the match according to the match state, increment the empty ticks count
	if len(lobbyState.presences) == 0 {
		lobbyState.emptyTicks++
	}

	// If the match has been empty for more than 100 ticks, end the match by returning nil
	if lobbyState.emptyTicks > 100 {
		return nil
	}

	return lobbyState
}

// RPC for force-creating a match for debugging/development, separate from the matchmaking process
func ManualForceCreateBRMatchRPC(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, payload string) (string, error) {
	/*params := make(map[string]interface{})

	if err := json.Unmarshal([]byte(payload), &params); err != nil {
		return "", err
	}*/

	modulename := "battle-royale"

	if matchId, err := nk.MatchCreate(ctx, modulename, make(map[string]interface{})); err != nil {
		return "", err
	} else {
		return matchId, nil
	}
}

// main function for hooking into the nakama runtime, responsible for setting up all handlers
func InitModule(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, initializer runtime.Initializer) error {
	// Register handlers for match lifecycle
	if err := initializer.RegisterMatch("battle-royale", func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule) (runtime.Match, error) {
		return &BattleRoyaleMatch{}, nil
	}); err != nil {
		logger.Error("Unable to register match handler: %v", nil)
		return err
	}

	// Register RPCs
	if err := initializer.RegisterRpc("manual_force_create_br_match_rpc", ManualForceCreateBRMatchRPC); err != nil {
		logger.Error("Unable to register: %v", err)
		return err
	}

	return nil
}