package drops

import (
	"dk/internal/store"
	"fmt"
	"sort"
	"sync"
)

// Drop represents a drop item in the game
type Drop struct {
	ID    int    `json:"id"`
	Name  string `json:"name"`
	Level int    `json:"level"`
	Type  int    `json:"type"`
	Att   string `json:"att"`
}

func (d *Drop) Save() error {
	dropStore := GetStore()
	dropStore.UpdateDrop(d)
	return nil
}

func (d *Drop) Delete() error {
	dropStore := GetStore()
	dropStore.RemoveDrop(d.ID)
	return nil
}

// Creates a new Drop with sensible defaults
func New() *Drop {
	return &Drop{
		Name:  "",
		Level: 1,              // Default minimum level
		Type:  TypeConsumable, // Default to consumable
		Att:   "",
	}
}

// Validate checks if drop has valid values
func (d *Drop) Validate() error {
	if d.Name == "" {
		return fmt.Errorf("drop name cannot be empty")
	}
	if d.Level < 1 {
		return fmt.Errorf("drop Level must be at least 1")
	}
	if d.Type < TypeConsumable {
		return fmt.Errorf("invalid drop type: %d", d.Type)
	}
	return nil
}

// DropType constants for drop types
const (
	TypeConsumable = 1
)

// DropStore provides in-memory storage with O(1) lookups and drop-specific indices
type DropStore struct {
	*store.BaseStore[Drop]               // Embedded generic store
	byLevel                map[int][]int // Level -> []ID
	byType                 map[int][]int // Type -> []ID
	allByID                []int         // All IDs sorted by ID
	mu                     sync.RWMutex  // Protects indices
}

// Global in-memory store
var dropStore *DropStore
var storeOnce sync.Once

// Initialize the in-memory store
func initStore() {
	dropStore = &DropStore{
		BaseStore: store.NewBaseStore[Drop](),
		byLevel:   make(map[int][]int),
		byType:    make(map[int][]int),
		allByID:   make([]int, 0),
	}
}

// GetStore returns the global drop store
func GetStore() *DropStore {
	storeOnce.Do(initStore)
	return dropStore
}

// AddDrop adds a drop to the in-memory store and updates all indices
func (ds *DropStore) AddDrop(drop *Drop) {
	ds.mu.Lock()
	defer ds.mu.Unlock()

	// Validate drop
	if err := drop.Validate(); err != nil {
		return
	}

	// Add to base store
	ds.Add(drop.ID, drop)

	// Rebuild indices
	ds.rebuildIndicesUnsafe()
}

// RemoveDrop removes a drop from the store and updates indices
func (ds *DropStore) RemoveDrop(id int) {
	ds.mu.Lock()
	defer ds.mu.Unlock()

	// Remove from base store
	ds.Remove(id)

	// Rebuild indices
	ds.rebuildIndicesUnsafe()
}

// UpdateDrop updates a drop efficiently
func (ds *DropStore) UpdateDrop(drop *Drop) {
	ds.mu.Lock()
	defer ds.mu.Unlock()

	// Validate drop
	if err := drop.Validate(); err != nil {
		return
	}

	// Update base store
	ds.Add(drop.ID, drop)

	// Rebuild indices
	ds.rebuildIndicesUnsafe()
}

// LoadData loads drop data from JSON file, or starts with empty store
func LoadData(dataPath string) error {
	ds := GetStore()

	// Load from base store, which handles JSON loading
	if err := ds.BaseStore.LoadData(dataPath); err != nil {
		return err
	}

	// Rebuild indices from loaded data
	ds.rebuildIndices()
	return nil
}

// SaveData saves drop data to JSON file
func SaveData(dataPath string) error {
	ds := GetStore()
	return ds.BaseStore.SaveData(dataPath)
}

// rebuildIndicesUnsafe rebuilds all indices from base store data (caller must hold lock)
func (ds *DropStore) rebuildIndicesUnsafe() {
	// Clear indices
	ds.byLevel = make(map[int][]int)
	ds.byType = make(map[int][]int)
	ds.allByID = make([]int, 0)

	// Collect all drops and build indices
	allDrops := ds.GetAll()

	for id, drop := range allDrops {
		// Level index
		ds.byLevel[drop.Level] = append(ds.byLevel[drop.Level], id)

		// Type index
		ds.byType[drop.Type] = append(ds.byType[drop.Type], id)

		// All IDs
		ds.allByID = append(ds.allByID, id)
	}

	// Sort allByID by ID
	sort.Ints(ds.allByID)

	// Sort level indices by ID
	for level := range ds.byLevel {
		sort.Ints(ds.byLevel[level])
	}

	// Sort type indices by level, then ID
	for dropType := range ds.byType {
		sort.Slice(ds.byType[dropType], func(i, j int) bool {
			dropI, _ := ds.GetByID(ds.byType[dropType][i])
			dropJ, _ := ds.GetByID(ds.byType[dropType][j])
			if dropI.Level != dropJ.Level {
				return dropI.Level < dropJ.Level
			}
			return ds.byType[dropType][i] < ds.byType[dropType][j]
		})
	}
}

// rebuildIndices rebuilds all drop-specific indices from base store data
func (ds *DropStore) rebuildIndices() {
	ds.mu.Lock()
	defer ds.mu.Unlock()
	ds.rebuildIndicesUnsafe()
}

// Retrieves a drop by ID
func Find(id int) (*Drop, error) {
	ds := GetStore()
	drop, exists := ds.GetByID(id)
	if !exists {
		return nil, fmt.Errorf("drop with ID %d not found", id)
	}
	return drop, nil
}

// Retrieves all drops
func All() ([]*Drop, error) {
	ds := GetStore()
	ds.mu.RLock()
	defer ds.mu.RUnlock()

	result := make([]*Drop, 0, len(ds.allByID))
	for _, id := range ds.allByID {
		if drop, exists := ds.GetByID(id); exists {
			result = append(result, drop)
		}
	}
	return result, nil
}

// Retrieves drops by minimum level requirement
func ByLevel(minLevel int) ([]*Drop, error) {
	ds := GetStore()
	ds.mu.RLock()
	defer ds.mu.RUnlock()

	var result []*Drop
	for level := 1; level <= minLevel; level++ {
		if ids, exists := ds.byLevel[level]; exists {
			for _, id := range ids {
				if drop, exists := ds.GetByID(id); exists {
					result = append(result, drop)
				}
			}
		}
	}
	return result, nil
}

// Retrieves drops by type
func ByType(dropType int) ([]*Drop, error) {
	ds := GetStore()
	ds.mu.RLock()
	defer ds.mu.RUnlock()

	ids, exists := ds.byType[dropType]
	if !exists {
		return []*Drop{}, nil
	}

	result := make([]*Drop, 0, len(ids))
	for _, id := range ids {
		if drop, exists := ds.GetByID(id); exists {
			result = append(result, drop)
		}
	}
	return result, nil
}

// Saves a new drop to the in-memory store and sets the ID
func (d *Drop) Insert() error {
	ds := GetStore()

	// Validate before insertion
	if err := d.Validate(); err != nil {
		return fmt.Errorf("validation failed: %w", err)
	}

	// Assign new ID if not set
	if d.ID == 0 {
		d.ID = ds.GetNextID()
	}

	// Add to store
	ds.AddDrop(d)
	return nil
}

// Returns true if the drop is a consumable item
func (d *Drop) IsConsumable() bool {
	return d.Type == TypeConsumable
}

// Returns the string representation of the drop type
func (d *Drop) TypeName() string {
	switch d.Type {
	case TypeConsumable:
		return "Consumable"
	default:
		return "Unknown"
	}
}