package world

import (
	"strings"
)

const DropDespawnTicks = 1000
const ReserveTicks = 100

type GroundItemInfo struct {
	ItemID       string
	Quantity     int
	ReservedFor  string
	ReserveTimer int
	DespawnTimer int
	IsSpawn      bool
}

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
}

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,
			DespawnTimer: e.despawnTimer,
			IsSpawn:      e.isSpawn,
		}
		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) AddReservedItem(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()
	e := &groundEntry{
		itemID:       itemID,
		quantity:     qty,
		despawnTimer: DropDespawnTicks,
	}
	w.groundItems[roomID] = append(w.groundItems[roomID], e)
}

// RemoveReservedItem removes up to qty of itemID from the room's ground,
// refusing entries reserved for another player. It is ALL-OR-NOTHING:
// when any part of the quantity is unobtainable (a reserved-for-others
// entry, or too little accessible stock) nothing is taken and (0, false)
// is returned. Callers must never lose already-removed items to a failed
// pickup, so the removal is verified before any state is touched.
func (w *World) RemoveReservedItem(roomID int, itemID string, qty int, owner string) (int, bool) {
	w.mu.Lock()
	defer w.mu.Unlock()
	entries := w.groundItems[roomID]

	// Pass 1: verify the full quantity is takable by this owner without
	// mutating anything, so a blocked pickup can never leave the ground
	// half-emptied with nothing delivered.
	available := 0
	for _, e := range entries {
		if available >= qty {
			break
		}
		if e.quantity <= 0 || !strings.EqualFold(e.itemID, itemID) {
			continue
		}
		if e.reserveTimer > 0 && e.reservedFor != "" && e.reservedFor != owner {
			continue
		}
		available += e.quantity
	}
	if available < qty {
		return 0, false
	}

	// Pass 2: take. Every entry reachable here is takeable, so no
	// mid-loop abort is possible.
	removed := 0
	remaining := qty
	for _, e := range entries {
		if remaining <= 0 {
			break
		}
		if e.quantity <= 0 || !strings.EqualFold(e.itemID, itemID) {
			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, true
}

// AccessibleGround returns the ground items in roomID this owner may take:
// entries reserved for another player are excluded. Pickup flows use this
// to size requests and match names against takeable stock only.
func (w *World) AccessibleGround(roomID int, owner string) 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 {
			continue
		}
		if e.reserveTimer > 0 && e.reservedFor != "" && e.reservedFor != owner {
			continue
		}
		out[e.itemID] += e.quantity
	}
	return out
}

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) tickGroundItems() {
	for _, entries := range w.groundItems {
		for _, e := range entries {
			if e.respawnTimer > 0 {
				e.respawnTimer--
				if e.respawnTimer <= 0 {
					e.quantity = e.respawnQty
					w.mergeNearbyItems(entries, e)
				}
			}
			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 = ""
				}
			}
		}
	}
}

func (w *World) mergeNearbyItems(entries []*groundEntry, target *groundEntry) {
	for _, other := range entries {
		if other != target && other.quantity > 0 && strings.EqualFold(other.itemID, target.itemID) &&
			(other.reserveTimer <= 0 || other.reservedFor == "") &&
			other.despawnTimer <= 0 {
			target.quantity += other.quantity
			other.quantity = 0
		}
	}
}