package world

import (
	"fmt"
	"log"
	"math"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"sync"

	"gopkg.in/yaml.v3"
	"thehouseoficarus/internal/behavior"
)

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

	hazardMu        sync.Mutex
	hazardPathIndex map[string]string
	hazardDefs      map[string]*HazardDef
}

func New(dataDir string) *World {
	return &World{
		dataDir:       dataDir,
		roomPathIndex: behavior.BuildRoomIndex(filepath.Join(dataDir, "rooms")),
		groundItems:   make(map[int][]*groundEntry),
		seeded:        make(map[int]bool),
		objStates:     make(map[string]*ObjState),
		hazardDefs:    make(map[string]*HazardDef),
	}
}

func (w *World) LoadRoom(id int) (*Room, error) {
	w.mu.Lock()
	path, ok := w.roomPathIndex[id]
	w.mu.Unlock()
	if !ok {
		return nil, fmt.Errorf("read room %d: no such room", 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 comes from the filename (room.ID = id below); a mismatched
	// declared id: is silently ignored, so surface it rather than leave the
	// author believing their written id is in use.
	if room.ID != 0 && room.ID != id {
		log.Printf("room %d: file %s declares id %d but is loaded as room %d; the filename is authoritative and the declared id is ignored",
			id, path, room.ID, id)
	}
	room.ID = id
	if room.Exits == nil {
		room.Exits = make(map[ExitDir]ExitDef)
	}
	if room.ItemSpawns == nil {
		room.ItemSpawns = 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, Northeast, Northwest, Southeast, Southwest, Up, Down:
		return canon
	}
	return ""
}

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

	room, err := w.LoadRoom(roomID)
	if err != nil {
		// Do NOT mark a room seeded before it loads: a dangling exit (or a
		// not-yet-created room) would otherwise permanently disable its item
		// spawns even after the room is fixed/created.
		return
	}

	w.mu.Lock()
	defer w.mu.Unlock()
	// Re-check under the lock: a concurrent seed may have won the race while
	// this call was loading.
	if w.seeded[roomID] {
		return
	}
	w.seeded[roomID] = true

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

// spawnRespawnDelay converts a fractional respawn_ticks value to whole ticks.
// Truncating (the old int(v)) turned any 0 < v < 1 into a one-shot spawn that
// never returned; round instead and floor a positive value at one tick.
func spawnRespawnDelay(ticks float64) int {
	if ticks <= 0 {
		return 0
	}
	delay := int(math.Round(ticks))
	if delay < 1 {
		delay = 1
	}
	return delay
}

func (w *World) RoomIndex() map[int]bool {
	w.mu.Lock()
	defer w.mu.Unlock()
	ids := make(map[int]bool, len(w.roomPathIndex))
	for id := range w.roomPathIndex {
		ids[id] = true
	}
	return ids
}

func (w *World) RebuildRoomIndex(dataDir string) {
	w.mu.Lock()
	defer w.mu.Unlock()
	w.roomPathIndex = behavior.BuildRoomIndex(filepath.Join(dataDir, "rooms"))
}

func (w *World) AddRoomPath(id int, path string) {
	w.mu.Lock()
	defer w.mu.Unlock()
	w.roomPathIndex[id] = path
}

func (w *World) GetRoomPath(id int) (string, bool) {
	w.mu.Lock()
	defer w.mu.Unlock()
	path, ok := w.roomPathIndex[id]
	return path, ok
}

func (w *World) ClearHazardCache() {
	w.hazardMu.Lock()
	defer w.hazardMu.Unlock()
	w.hazardPathIndex = nil
	w.hazardDefs = make(map[string]*HazardDef)
}

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

func (w *World) ClearRoomState(roomID int) {
	w.mu.Lock()
	defer w.mu.Unlock()
	delete(w.groundItems, roomID)
	delete(w.seeded, roomID)
	prefix := fmt.Sprintf("%d:", roomID)
	for k := range w.objStates {
		if strings.HasPrefix(k, prefix) {
			delete(w.objStates, k)
		}
	}
}

// RekeyRooms remaps room-keyed runtime state per idMap (oldID -> newID):
// ground items, seeded markers, and object-state keys ("roomID:...").
// Uses delete-all-then-set-all so a swap cannot clobber an entry mid-rekey.
func (w *World) RekeyRooms(idMap map[int]int) {
	if len(idMap) == 0 {
		return
	}
	w.mu.Lock()
	defer w.mu.Unlock()
	movedGround := make(map[int][]*groundEntry, len(w.groundItems))
	for roomID, entries := range w.groundItems {
		if newID, ok := idMap[roomID]; ok && newID != roomID {
			movedGround[newID] = entries
			delete(w.groundItems, roomID)
		}
	}
	for newID, entries := range movedGround {
		w.groundItems[newID] = entries
	}
	movedSeeded := make(map[int]bool, len(w.seeded))
	for roomID := range w.seeded {
		if newID, ok := idMap[roomID]; ok && newID != roomID {
			movedSeeded[newID] = true
			delete(w.seeded, roomID)
		}
	}
	for newID := range movedSeeded {
		w.seeded[newID] = true
	}
	type objKeyMove struct {
		oldKey, newKey string
		st             *ObjState
		newID          int
	}
	var moves []objKeyMove
	for k, st := range w.objStates {
		roomStr, _, ok := strings.Cut(k, ":")
		if !ok {
			continue
		}
		roomID, err := strconv.Atoi(roomStr)
		if err != nil {
			continue
		}
		newID, ok := idMap[roomID]
		if !ok || newID == roomID {
			continue
		}
		newKey := fmt.Sprintf("%d:%s", newID, k[len(roomStr)+1:])
		moves = append(moves, objKeyMove{k, newKey, st, newID})
	}
	for _, m := range moves {
		delete(w.objStates, m.oldKey)
	}
	for _, m := range moves {
		// Keep the package invariant mapKey == ObjStateKey(st.RoomID, ...):
		// object lookups filter on st.RoomID while GetObjState looks up the
		// key, so a rekey that leaves RoomID stale makes the object vanish
		// from the renamed room (and TickObjWander then creates a second
		// entry for the same state). Remap wander rooms like MobStore does.
		m.st.RoomID = m.newID
		if mapped, ok := idMap[m.st.HomeRoomID]; ok && mapped != m.st.HomeRoomID {
			m.st.HomeRoomID = mapped
		}
		for i, room := range m.st.WanderRooms {
			if mapped, ok := idMap[room]; ok && mapped != room {
				m.st.WanderRooms[i] = mapped
			}
		}
		w.objStates[m.newKey] = m.st
	}
}