package world

import (
	"strings"
)

const DropDespawnTicks = 1000
const ReserveTicks = 100

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

type groundEntry struct {
	itemID       string
	quantity     int
	quality      int
	maxQuality   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,
			Quality:      e.quality,
			MaxQuality:   e.maxQuality,
			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.AddReservedItemQ(roomID, itemID, qty, owner, 0, 0)
}

// AddReservedItemQ is AddReservedItem with the item's quality preserved (a
// non-stackable max_quality item dropped on death/trigger keeps its charge).
func (w *World) AddReservedItemQ(roomID int, itemID string, qty int, owner string, quality, maxQuality int) {
	w.mu.Lock()
	defer w.mu.Unlock()
	e := &groundEntry{
		itemID:       itemID,
		quantity:     qty,
		quality:      quality,
		maxQuality:   maxQuality,
		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.AddGroundItemQ(roomID, itemID, qty, 0, 0)
}

// AddGroundItemQ is AddGroundItem with the item's quality preserved. A
// dropped partially-used max_quality item must not come back full on pickup.
func (w *World) AddGroundItemQ(roomID int, itemID string, qty, quality, maxQuality int) {
	w.mu.Lock()
	defer w.mu.Unlock()
	e := &groundEntry{
		itemID:       itemID,
		quantity:     qty,
		quality:      quality,
		maxQuality:   maxQuality,
		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) {
	removed, _, _, ok := w.removeReservedItem(roomID, itemID, qty, owner)
	return removed, ok
}

// RemoveReservedItemQ is RemoveReservedItem that also reports the quality of
// the entry the pickup actually came from, so a partially-used non-stackable
// item keeps its charge through a drop/pickup round trip.
func (w *World) RemoveReservedItemQ(roomID int, itemID string, qty int, owner string) (removed, quality, maxQuality int, ok bool) {
	return w.removeReservedItem(roomID, itemID, qty, owner)
}

func (w *World) removeReservedItem(roomID int, itemID string, qty int, owner string) (removed, quality, maxQuality int, ok 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, 0, 0, false
	}

	// Pass 2: take. Every entry reachable here is takeable, so no
	// mid-loop abort is possible. The ownership check MUST match pass 1:
	// without it a player could consume a stack reserved for someone else
	// when a public stack and a reserved stack coexist (the reserved entry
	// comes first in the slice, so the take loop would drain it first).
	remaining := qty
	tookQuality, tookMaxQuality := 0, 0
	tookFromEntry := false
	for _, e := range entries {
		if remaining <= 0 {
			break
		}
		if e.quantity <= 0 || !strings.EqualFold(e.itemID, itemID) {
			continue
		}
		if e.reserveTimer > 0 && e.reservedFor != "" && e.reservedFor != owner {
			continue
		}
		take := e.quantity
		if take > remaining {
			take = remaining
		}
		if !tookFromEntry {
			tookQuality, tookMaxQuality = e.quality, e.maxQuality
			tookFromEntry = true
		}
		e.quantity -= take
		removed += take
		remaining -= take
		if e.isSpawn && e.quantity <= 0 && e.respawnDelay > 0 {
			e.respawnTimer = e.respawnDelay
		}
	}
	return removed, tookQuality, tookMaxQuality, true
}

// AccessibleGroundQuality reports the quality of the first ground entry this
// owner may take, so a pickup can stamp the item it is about to create. The
// boolean is false when no accessible entry exists.
func (w *World) AccessibleGroundQuality(roomID int, itemID, owner string) (quality, maxQuality int, ok bool) {
	w.mu.Lock()
	defer w.mu.Unlock()
	for _, e := range w.groundItems[roomID] {
		if e.quantity <= 0 || !strings.EqualFold(e.itemID, itemID) {
			continue
		}
		if e.reserveTimer > 0 && e.reservedFor != "" && e.reservedFor != owner {
			continue
		}
		return e.quality, e.maxQuality, true
	}
	return 0, 0, false
}

// RemoveAvailableItem removes up to maxQty of itemID from the room's
// ground, skipping entries reserved for another player, and returns the
// quantity actually removed. Unlike RemoveReservedItem it is not
// all-or-nothing: callers pass a generous upper bound (credit pickups use
// a sentinel far above any possible stock) and take whatever is accessible
// at the moment, so a request larger than the available stock still
// succeeds.
func (w *World) RemoveAvailableItem(roomID int, itemID string, maxQty int, owner string) int {
	w.mu.Lock()
	defer w.mu.Unlock()
	removed := 0
	remaining := maxQty
	for _, e := range w.groundItems[roomID] {
		if remaining <= 0 {
			break
		}
		if e.quantity <= 0 || !strings.EqualFold(e.itemID, itemID) {
			continue
		}
		if e.reserveTimer > 0 && e.reservedFor != "" && e.reservedFor != owner {
			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
}

// 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
		}
		// This helper has no owner, so it must not consume another player's
		// reserved entry (its siblings are reservation-aware).
		if e.reserveTimer > 0 && e.reservedFor != "" {
			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 roomID, 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 = ""
				}
			}
		}
		// Prune dead entries: without this every drop/loot/firemaking action
		// appends an entry that lives for the process lifetime and is scanned
		// on every tick and pickup. A spawn entry awaiting respawn keeps its
		// slot; everything else with no quantity is gone for good.
		kept := entries[:0]
		for _, e := range entries {
			if e.quantity <= 0 && e.respawnTimer <= 0 {
				continue
			}
			kept = append(kept, e)
		}
		if len(kept) == 0 {
			delete(w.groundItems, roomID)
		} else {
			w.groundItems[roomID] = kept
		}
	}
}

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.quality == target.quality && other.maxQuality == target.maxQuality &&
			(other.reserveTimer <= 0 || other.reservedFor == "") &&
			other.despawnTimer <= 0 {
			target.quantity += other.quantity
			other.quantity = 0
		}
	}
}