package dnfbridge

import (
	"context"
	"encoding/binary"
	"fmt"
	"strconv"
	"strings"
	"time"

	"longheng.io/server/internal/modules/dnf/dnfenum"
	dnfproto "longheng.io/server/internal/modules/dnf/protocol"
	dnfrepo "longheng.io/server/internal/modules/dnf/repository"
)

// The current EXE sends op237 (ENUM_CMDPACKET_TELEPORT) when a teleport
// potion is used. Body layout (86JP TownHandler.Handle_ENUM_CMDPACKET_TELEPORT
// and the current-EXE S2C op237 reader contract):
//
//	i16 potionSlot, i32 itemCode, u8 reserved, u8 townID, u8 areaID,
//	i16le positionX, i16le positionY
//
// The live current-client body is exactly 13 bytes.  It already contains the
// target selected in the teleport UI; do not replace it with a town gate.
// On success the server adapts that target into the same op36/op24 transport
// chain used by personal (aura) teleport, consumes one potion, refreshes the
// bag, and returns the op237 ACK {01, i16 slot, i32 code}. The failure ACK
// {00, 23} shows the client's text 36288 (current-EXE op237 error branch).
type currentTeleportPotionRequest struct {
	PotionSlotIndex int16
	ItemCode        int32
	Reserved        byte
	TownID          byte
	AreaID          byte
	PositionX       int16
	PositionY       int16
}

const currentTeleportPotionErrorUnsupported byte = 23
const currentTeleportPotionRequestWireSize = 13

func parseCurrentTeleportPotionRequest(body []byte) (currentTeleportPotionRequest, error) {
	if len(body) != currentTeleportPotionRequestWireSize {
		return currentTeleportPotionRequest{}, fmt.Errorf("current teleport potion body length %d, want %d", len(body), currentTeleportPotionRequestWireSize)
	}
	return currentTeleportPotionRequest{
		PotionSlotIndex: int16(binary.LittleEndian.Uint16(body[0:2])),
		ItemCode:        int32(binary.LittleEndian.Uint32(body[2:6])),
		Reserved:        body[6],
		TownID:          body[7],
		AreaID:          body[8],
		PositionX:       int16(binary.LittleEndian.Uint16(body[9:11])),
		PositionY:       int16(binary.LittleEndian.Uint16(body[11:13])),
	}, nil
}

func (s *Service) handleTeleportPotion(session *gameSession, body []byte) error {
	if session == nil {
		return nil
	}
	request, err := parseCurrentTeleportPotionRequest(body)
	if err != nil {
		s.logGameEvent(session, "game-town-teleport-potion-blocked",
			"body_len", len(body),
			"reason", "current_exe_op237_writer_boundary_mismatch",
			"error", err)
		return nil
	}
	if session.selectedCharacterID == 0 {
		return s.sendCurrentTeleportPotionFailure(session, request, "selected_character_missing")
	}
	catalog, err := s.currentPVFItemCatalog()
	if err != nil || catalog == nil {
		return s.sendCurrentTeleportPotionFailure(session, request, "runtime_pvf_catalog_unavailable")
	}
	if !currentTeleportPotionIsValid(catalog, request.ItemCode) {
		return s.sendCurrentTeleportPotionFailure(session, request, "item_is_not_a_pvf_teleport_potion")
	}
	repositories, ok := s.repositoryGroup()
	if !ok || repositories.CharacterItems == nil || repositories.Character == nil {
		return s.sendCurrentTeleportPotionFailure(session, request, "character_item_repository_unavailable")
	}

	ctx, cancel := context.WithTimeout(context.Background(), currentConsumableWriteTimeout)
	defer cancel()
	characterID := strconv.FormatUint(uint64(session.selectedCharacterID), 10)
	character, found, err := repositories.Character.Load(ctx, characterID)
	if err != nil {
		return err
	}
	if !found || character.Stats == nil {
		return s.sendCurrentTeleportPotionFailure(session, request, "selected_character_location_missing")
	}
	currentTown, ok := character.Stats["town_id"]
	if !ok || currentTown < 0 {
		return s.sendCurrentTeleportPotionFailure(session, request, "selected_character_town_id_missing")
	}
	potionKey, err := currentTeleportPotionSlot(ctx, repositories, characterID, request)
	if err != nil {
		return s.sendCurrentTeleportPotionFailure(session, request, "teleport_potion_missing_from_main_inventory")
	}

	// Reuse the exact personal/aura transport adapter.  Both features carry a
	// client-selected town area and coordinates, and the op36 owner validates
	// the route against the PVF before it emits the op24 transition and commits
	// the new location.
	transport := currentSoloTeleportRequest{
		TownID:    request.TownID,
		AreaID:    request.AreaID,
		PositionX: request.PositionX,
		PositionY: request.PositionY,
	}
	if err := s.handleTownSetUserArea(session, buildCurrentSoloTeleportMoveBody(transport, uint16(currentTown))); err != nil {
		return err
	}
	moved, found, err := repositories.Character.Load(ctx, characterID)
	if err != nil {
		return err
	}
	if !found || moved.Stats["town_id"] != int64(request.TownID) ||
		moved.Stats["area_id"] != int64(request.AreaID) ||
		moved.Stats["pos_x"] != int64(request.PositionX) ||
		moved.Stats["pos_y"] != int64(request.PositionY) {
		return s.sendCurrentTeleportPotionFailure(session, request, "town_transition_not_committed")
	}
	consumeCtx, consumeCancel := context.WithTimeout(context.Background(), currentConsumableWriteTimeout)
	defer consumeCancel()
	if err := consumeCurrentTeleportPotion(consumeCtx, repositories, characterID, potionKey); err != nil {
		return err
	}
	if err := s.sendSelectedCurrentContainerListsWithRefresh(session, "current_exe_op237_teleport_potion_consumed_after_op24", true); err != nil {
		return err
	}
	s.logGameEvent(session, "game-town-teleport-potion-committed",
		"char_id", session.selectedCharacterID,
		"item_code", request.ItemCode,
		"potion_slot", potionKey,
		"town_id", request.TownID,
		"area_id", request.AreaID,
		"position_x", request.PositionX,
		"position_y", request.PositionY)
	return s.sendGameUpperRawClass(session, uint16(dnfenum.CmdPacketTeleport), buildCurrentTeleportPotionSuccessAck(request), dnfproto.DefaultChannelClassification)
}

func currentTeleportPotionIsValid(catalog *pvfDungeonDropCatalog, itemCode int32) bool {
	if catalog == nil || itemCode <= 0 {
		return false
	}
	definition, err := catalog.ResolveItem(uint32(itemCode))
	if err != nil || definition.Kind != dungeonDropItemStackable {
		return false
	}
	return strings.EqualFold(strings.TrimSpace(definition.StackableType), "[teleport potion]")
}

// currentTeleportPotionSlot verifies the claimed slot first, then falls back
// to an id-based scan, matching the 86JP slot-mismatch fallback.
func currentTeleportPotionSlot(ctx context.Context, repositories dnfrepo.Group, characterID string, request currentTeleportPotionRequest) (string, error) {
	var matched string
	err := func() error {
		record, found, err := repositories.Inventory.Load(ctx, characterID)
		if err != nil {
			return err
		}
		if !found {
			return fmt.Errorf("inventory record missing: %s", characterID)
		}
		claimed := fmt.Sprintf("0:%d", request.PotionSlotIndex)
		if stack, ok := record.Slots[claimed]; ok && stack.Count > 0 && stack.ItemID == int64(request.ItemCode) {
			matched = claimed
			return nil
		}
		keys := make([]string, 0, len(record.Slots))
		for key, stack := range record.Slots {
			if strings.HasPrefix(key, "0:") && stack.ItemID == int64(request.ItemCode) && stack.Count > 0 {
				keys = append(keys, key)
			}
		}
		if len(keys) == 0 {
			return fmt.Errorf("teleport potion %d not found", request.ItemCode)
		}
		for _, key := range keys {
			if matched == "" || key < matched {
				matched = key
			}
		}
		return nil
	}()
	return matched, err
}

func consumeCurrentTeleportPotion(ctx context.Context, repositories dnfrepo.Group, characterID string, potionKey string) error {
	return dnfrepo.WithinCharacterItemsScoped(ctx, repositories.CharacterItems, characterID, func(inventory dnfrepo.InventoryRepository, _ dnfrepo.EquipmentRepository) error {
		record, found, err := inventory.Load(ctx, characterID)
		if err != nil {
			return err
		}
		if !found {
			return fmt.Errorf("inventory record missing: %s", characterID)
		}
		record = dnfrepo.CloneInventory(record)
		stack, ok := record.Slots[potionKey]
		if !ok || stack.Count <= 0 {
			return fmt.Errorf("teleport potion slot %s empty", potionKey)
		}
		stack.Count--
		if stack.Count <= 0 {
			delete(record.Slots, potionKey)
		} else {
			if stack.Extra == nil {
				stack.Extra = make(map[string]string, 4)
			}
			stack.Extra["amount_or_count"] = strconv.FormatInt(stack.Count, 10)
			stack.Extra["amount"] = strconv.FormatInt(stack.Count, 10)
			if len(stack.RawEntry) == currentItemListEntryWireSize {
				stack.RawEntry = append([]byte(nil), stack.RawEntry...)
				value := uint32(stack.Count)
				stack.RawEntry[0x06] = byte(value)
				stack.RawEntry[0x07] = byte(value >> 8)
				stack.RawEntry[0x08] = byte(value >> 16)
				stack.RawEntry[0x09] = byte(value >> 24)
			}
			record.Slots[potionKey] = stack
		}
		record.UpdatedAt = time.Now().UTC()
		return dnfrepo.SaveInventoryFields(ctx, inventory, record, dnfrepo.InventoryFieldSlots)
	})
}

func buildCurrentTeleportPotionSuccessAck(request currentTeleportPotionRequest) []byte {
	return []byte{
		1,
		byte(request.PotionSlotIndex), byte(request.PotionSlotIndex >> 8),
		byte(request.ItemCode), byte(request.ItemCode >> 8), byte(request.ItemCode >> 16), byte(request.ItemCode >> 24),
	}
}

func (s *Service) sendCurrentTeleportPotionFailure(session *gameSession, request currentTeleportPotionRequest, reason string) error {
	s.logGameEvent(session, "game-town-teleport-potion-blocked",
		"char_id", session.selectedCharacterID,
		"item_code", request.ItemCode,
		"town_id", request.TownID,
		"reason", reason)
	return s.sendGameUpperRawClass(session, uint16(dnfenum.CmdPacketTeleport), []byte{0, currentTeleportPotionErrorUnsupported}, dnfproto.DefaultChannelClassification)
}