package world

import (
	"fmt"
	"math/rand"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"sync"

	"gopkg.in/yaml.v3"
)

const DropDespawnTicks = 1000
const ReserveTicks = 100

type GroundItemInfo struct {
	ItemID       string
	Quantity     int
	ReservedFor  string
	ReserveTimer int
}

type groundEntry struct {
	itemID       string
	quantity     int
	isSpawn      bool
	respawnTimer int // >0 = counting down to respawn
	respawnQty   int
	respawnDelay int
	despawnTimer int // >0 = counting down to despawn (dropped items)
	reservedFor  string
	reserveTimer int // >0 = counting down reservation
}

type World struct {
	dataDir     string
	mu          sync.Mutex
	groundItems map[int][]*groundEntry
	seeded      map[int]bool
	objStates   map[string]*ObjState
	objMoves    []ObjMove
}

type ObjMove struct {
	DefID     string
	Name      string
	FromRoom  int
	ToRoom    int
}

type ObjState struct {
	Depleted      bool
	DepleteTimer  int
	DefID         string
	Name          string
	Index         int
	RoomID        int
	JustRespawned bool
	WanderRooms   []int
	WanderInterval int
	WanderCounter int
	SharedMax     int
	SharedTimer   int
}

func (w *World) ObjStateKey(roomID int, defID string, index int) string {
	return fmt.Sprintf("%d:%s:%d", roomID, defID, index)
}

func (w *World) objStateKey(roomID int, defID string, index int) string {
	return w.ObjStateKey(roomID, defID, index)
}

func (w *World) EnsureObjectStates(roomID int, defIDs []string) {
	w.mu.Lock()
	defer w.mu.Unlock()
	if w.objStates == nil {
		w.objStates = make(map[string]*ObjState)
	}
	counts := make(map[string]int)
	for _, defID := range defIDs {
		idx := counts[defID]
		counts[defID]++
		key := w.objStateKey(roomID, defID, idx)
		if _, exists := w.objStates[key]; !exists {
			w.objStates[key] = &ObjState{
				DefID:  defID,
				Name:   defID,
				Index:  idx,
				RoomID: roomID,
			}
		}
	}
}

func (w *World) GetObjState(roomID int, defID string, index int) *ObjState {
	w.mu.Lock()
	defer w.mu.Unlock()
	if w.objStates == nil {
		return nil
	}
	return w.objStates[w.objStateKey(roomID, defID, index)]
}

func (w *World) GetObjStateByKey(key string) *ObjState {
	w.mu.Lock()
	defer w.mu.Unlock()
	if w.objStates == nil {
		return nil
	}
	return w.objStates[key]
}

func (w *World) AllObjInstances(roomID int) []ObjState {
	w.mu.Lock()
	defer w.mu.Unlock()
	var out []ObjState
	for _, st := range w.objStates {
		if st.RoomID == roomID {
			out = append(out, *st)
		}
	}
	sort.Slice(out, func(i, j int) bool {
		if out[i].DefID != out[j].DefID {
			return out[i].DefID < out[j].DefID
		}
		return out[i].Index < out[j].Index
	})
	return out
}

func (w *World) FindObjInstances(roomID int, name string) []ObjState {
	w.mu.Lock()
	defer w.mu.Unlock()
	var out []ObjState
	lower := strings.ToLower(name)
	for key, st := range w.objStates {
		if st.RoomID != roomID {
			continue
		}
		if !wordMatchesObj(lower, st.DefID, st.Name) {
			continue
		}
		out = append(out, ObjState{
			DefID:        st.DefID,
			Name:         st.Name,
			Index:        st.Index,
			RoomID:       st.RoomID,
			Depleted:     st.Depleted,
			DepleteTimer: st.DepleteTimer,
			SharedMax:    st.SharedMax,
			SharedTimer:  st.SharedTimer,
		})
		_ = key
	}
	sort.Slice(out, func(i, j int) bool {
		if out[i].DefID != out[j].DefID {
			return out[i].DefID < out[j].DefID
		}
		return out[i].Index < out[j].Index
	})
	return out
}

func wordMatchesObj(lower, defID, objName string) bool {
	if WordPrefixMatch(lower, objName) {
		return true
	}
	nameWords := strings.Fields(strings.ToLower(objName))
	inputWords := strings.Fields(strings.ToLower(lower))

	// Check defID as whole (bidirectional)
	if strings.HasPrefix(strings.ToLower(defID), lower) || strings.HasPrefix(lower, strings.ToLower(defID)) {
		return true
	}
	// Check each defID part (split by underscore) against each input word (bidirectional)
	for _, part := range strings.Split(defID, "_") {
		for _, iw := range inputWords {
			pl := strings.ToLower(part)
			if strings.HasPrefix(pl, iw) || strings.HasPrefix(iw, pl) {
				return true
			}
		}
	}
	_ = nameWords
	return false
}

func (w *World) SetObjName(roomID int, defID string, name string) {
	w.mu.Lock()
	defer w.mu.Unlock()
	for key, st := range w.objStates {
		if st.RoomID == roomID && st.DefID == defID {
			st.Name = name
		}
		_ = key
	}
}

func (w *World) SetObjWander(roomID int, defID string, rooms []int, interval int) {
	w.mu.Lock()
	defer w.mu.Unlock()
	for key, st := range w.objStates {
		if st.RoomID == roomID && st.DefID == defID {
			st.WanderRooms = rooms
			st.WanderInterval = interval
		}
		_ = key
	}
}

func (w *World) SetObjSharedDeplete(roomID int, defID string, max int) {
	w.mu.Lock()
	defer w.mu.Unlock()
	for key, st := range w.objStates {
		if st.RoomID == roomID && st.DefID == defID && st.SharedMax == 0 {
			st.SharedMax = max
			st.SharedTimer = max
		}
		_ = key
	}
}

func (w *World) AllSharedObjStates() []*ObjState {
	w.mu.Lock()
	defer w.mu.Unlock()
	var out []*ObjState
	for _, st := range w.objStates {
		if st.SharedMax > 0 {
			out = append(out, st)
		}
	}
	return out
}

func (w *World) SetObjDepleted(roomID int, defID string, index int, delay int) {
	w.mu.Lock()
	defer w.mu.Unlock()
	key := w.objStateKey(roomID, defID, index)
	if st, ok := w.objStates[key]; ok {
		st.Depleted = true
		st.DepleteTimer = delay
	}
}

func New(dataDir string) *World {
	return &World{
		dataDir:     dataDir,
		groundItems: make(map[int][]*groundEntry),
		seeded:      make(map[int]bool),
		objStates:   make(map[string]*ObjState),
	}
}

func (w *World) LoadRoom(id int) (*Room, error) {
	path := filepath.Join(w.dataDir, "rooms", fmt.Sprintf("%d.yaml", id))
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read room %d: %w", id, err)
	}
	var room Room
	if err := yaml.Unmarshal(data, &room); err != nil {
		return nil, fmt.Errorf("parse room %d: %w", id, err)
	}
	room.ID = id
	if room.Exits == nil {
		room.Exits = make(map[ExitDir]ExitDef)
	}
	if room.Spawns == nil {
		room.Spawns = make([]SpawnDef, 0)
	}
	if room.Mobs == nil {
		room.Mobs = make([]RoomMob, 0)
	}
	return &room, nil
}

func (w *World) ResolveExit(input string) ExitDir {
	if dir, ok := ExitAliases[strings.ToLower(input)]; ok {
		return dir
	}
	canon := ExitDir(strings.ToLower(input))
	switch canon {
	case North, South, East, West, Up, Down:
		return canon
	}
	return ""
}

func (w *World) GroundItemsDetailed(roomID int) []GroundItemInfo {
	w.mu.Lock()
	defer w.mu.Unlock()
	var out []GroundItemInfo
	for _, e := range w.groundItems[roomID] {
		if e.quantity <= 0 {
			continue
		}
		info := GroundItemInfo{
			ItemID:   e.itemID,
			Quantity: e.quantity,
		}
		if e.reserveTimer > 0 && e.reservedFor != "" {
			info.ReservedFor = e.reservedFor
			info.ReserveTimer = e.reserveTimer
		}
		out = append(out, info)
	}
	return out
}

func (w *World) GroundItems(roomID int) map[string]int {
	w.mu.Lock()
	defer w.mu.Unlock()
	out := make(map[string]int)
	for _, e := range w.groundItems[roomID] {
		if e.quantity > 0 {
			out[e.itemID] += e.quantity
		}
	}
	return out
}

func (w *World) AddReservedGroundItem(roomID int, itemID string, qty int, owner string) {
	w.mu.Lock()
	defer w.mu.Unlock()
	e := &groundEntry{
		itemID:       itemID,
		quantity:     qty,
		despawnTimer: DropDespawnTicks,
		reservedFor:  owner,
		reserveTimer: ReserveTicks,
	}
	w.groundItems[roomID] = append(w.groundItems[roomID], e)
}

func (w *World) AddGroundItem(roomID int, itemID string, qty int) {
	w.mu.Lock()
	defer w.mu.Unlock()
	for _, e := range w.groundItems[roomID] {
		if e.quantity > 0 && strings.EqualFold(e.itemID, itemID) &&
			(e.reserveTimer <= 0 || e.reservedFor == "") {
			e.quantity += qty
			e.despawnTimer = DropDespawnTicks
			return
		}
	}
	e := &groundEntry{
		itemID:       itemID,
		quantity:     qty,
		despawnTimer: DropDespawnTicks,
	}
	w.groundItems[roomID] = append(w.groundItems[roomID], e)
}

func (w *World) RemoveReservedGroundItem(roomID int, itemID string, qty int, owner string) (int, bool) {
	w.mu.Lock()
	defer w.mu.Unlock()
	removed := 0
	remaining := qty
	for _, e := range w.groundItems[roomID] {
		if remaining <= 0 {
			break
		}
		if !strings.EqualFold(e.itemID, itemID) {
			continue
		}
		if e.quantity <= 0 {
			continue
		}
		if e.reserveTimer > 0 && e.reservedFor != "" && e.reservedFor != owner {
			return removed, false
		}
		take := e.quantity
		if take > remaining {
			take = remaining
		}
		e.quantity -= take
		removed += take
		remaining -= take
		if e.isSpawn && e.quantity <= 0 && e.respawnDelay > 0 {
			e.respawnTimer = e.respawnDelay
		}
	}
	return removed, true
}

func (w *World) RemoveGroundItem(roomID int, itemID string, qty int) int {
	w.mu.Lock()
	defer w.mu.Unlock()

	removed := 0
	remaining := qty

	for _, e := range w.groundItems[roomID] {
		if remaining <= 0 {
			break
		}
		if !strings.EqualFold(e.itemID, itemID) {
			continue
		}
		if e.quantity <= 0 {
			continue
		}
		take := e.quantity
		if take > remaining {
			take = remaining
		}
		e.quantity -= take
		removed += take
		remaining -= take

		if e.isSpawn && e.quantity <= 0 && e.respawnDelay > 0 {
			e.respawnTimer = e.respawnDelay
		}
	}
	return removed
}

func (w *World) SeedGroundItems(roomID int) {
	w.mu.Lock()
	if w.seeded[roomID] {
		w.mu.Unlock()
		return
	}
	w.seeded[roomID] = true
	w.mu.Unlock()

	room, err := w.LoadRoom(roomID)
	if err != nil {
		return
	}

	w.mu.Lock()
	defer w.mu.Unlock()

	for _, s := range room.Spawns {
		merged := false
		for _, e := range w.groundItems[roomID] {
			if e.quantity > 0 && strings.EqualFold(e.itemID, s.ItemID) &&
				(e.reserveTimer <= 0 || e.reservedFor == "") {
				e.quantity += s.Quantity
				e.respawnQty += s.Quantity
				e.isSpawn = true
				e.respawnDelay = s.RespawnTicks
				merged = true
				break
			}
		}
		if !merged {
			e := &groundEntry{
				itemID:       s.ItemID,
				quantity:     s.Quantity,
				isSpawn:      true,
				respawnDelay: s.RespawnTicks,
				respawnQty:   s.Quantity,
			}
			w.groundItems[roomID] = append(w.groundItems[roomID], e)
		}
	}
}

func (w *World) Tick() {
	w.mu.Lock()
	defer w.mu.Unlock()

	for _, entries := range w.groundItems {
		for _, e := range entries {
		if e.respawnTimer > 0 {
			e.respawnTimer--
			if e.respawnTimer <= 0 {
				e.quantity = e.respawnQty
				for _, other := range entries {
					if other != e && other.quantity > 0 && strings.EqualFold(other.itemID, e.itemID) &&
						(other.reserveTimer <= 0 || other.reservedFor == "") {
						e.quantity += other.quantity
						other.quantity = 0
					}
				}
			}
		}
			if e.despawnTimer > 0 {
				e.despawnTimer--
				if e.despawnTimer <= 0 {
					e.quantity = 0
				}
			}
			if e.reserveTimer > 0 {
				e.reserveTimer--
				if e.reserveTimer <= 0 {
					e.reservedFor = ""
				}
			}
		}
	}

	for _, st := range w.objStates {
		if st.Depleted && st.DepleteTimer > 0 {
			st.DepleteTimer--
			if st.DepleteTimer <= 0 {
				st.Depleted = false
				st.JustRespawned = true
				if st.SharedMax > 0 {
					st.SharedTimer = st.SharedMax
				}
			}
		}
	}
}

func (w *World) FlushObjRespawns() []ObjState {
	w.mu.Lock()
	defer w.mu.Unlock()
	var out []ObjState
	for _, st := range w.objStates {
		if st.JustRespawned {
			out = append(out, *st)
			st.JustRespawned = false
		}
	}
	return out
}

func (w *World) TickObjWander() {
	w.mu.Lock()
	defer w.mu.Unlock()
	var moves []struct {
		st     *ObjState
		toRoom int
	}
	for _, st := range w.objStates {
		if len(st.WanderRooms) == 0 || st.WanderInterval <= 0 {
			continue
		}
		st.WanderCounter++
		if st.WanderCounter >= st.WanderInterval {
			st.WanderCounter = 0
			toRoom := st.WanderRooms[rand.Intn(len(st.WanderRooms))]
			if toRoom == st.RoomID {
				continue
			}
			moves = append(moves, struct {
				st     *ObjState
				toRoom int
			}{st, toRoom})
		}
	}
	for _, m := range moves {
		oldKey := w.objStateKey(m.st.RoomID, m.st.DefID, m.st.Index)
		fromRoom := m.st.RoomID
		m.st.RoomID = m.toRoom
		newKey := w.objStateKey(m.st.RoomID, m.st.DefID, m.st.Index)
		delete(w.objStates, oldKey)
		w.objStates[newKey] = m.st
		w.objMoves = append(w.objMoves, ObjMove{
			DefID:    m.st.DefID,
			Name:     m.st.Name,
			FromRoom: fromRoom,
			ToRoom:   m.toRoom,
		})
	}
}

func (w *World) FlushObjMoves() []ObjMove {
	w.mu.Lock()
	defer w.mu.Unlock()
	out := w.objMoves
	w.objMoves = nil
	return out
}