package game

import (
	"fmt"
	"strconv"
	"strings"

	"thehouseoficarus/internal/behavior"
	"thehouseoficarus/internal/item"
	"thehouseoficarus/internal/net"
	"thehouseoficarus/internal/player"
	"thehouseoficarus/internal/ui"
	"thehouseoficarus/internal/world"
)

// ---- Command entry points ----

func (g *Game) executeShopList(sess *net.Session, args []string, rawInput string) {
	p := sess.Player
	if p == nil {
		return
	}
	mob := g.resolveShopMob(sess, p, strings.Join(args, " "))
	if mob == nil {
		return
	}
	g.showShopInventory(sess, mob)
}

func (g *Game) executeShopBuy(sess *net.Session, args []string, rawInput string) {
	p := sess.Player
	if p == nil {
		return
	}
	itemArgs, mobName := splitOnKeyword(args, "from")
	qty, itemName, all := parseShopQty(itemArgs)
	if itemName == "" {
		sess.WriteLine("Buy what? Use 'list' to see what's for sale.")
		return
	}
	mob := g.resolveShopMob(sess, p, mobName)
	if mob == nil {
		return
	}
	g.doShopBuy(sess, mob, itemName, qty, all)
}

func (g *Game) executeShopSell(sess *net.Session, args []string, rawInput string) {
	p := sess.Player
	if p == nil {
		return
	}
	itemArgs, mobName := splitOnKeyword(args, "to")
	qty, itemName, all := parseShopQty(itemArgs)
	if itemName == "" {
		sess.WriteLine("Sell what?")
		return
	}
	mob := g.resolveShopMob(sess, p, mobName)
	if mob == nil {
		return
	}
	g.doShopSell(sess, mob, itemName, qty, all)
}

// ---- Helpers ----

// splitOnKeyword splits args around the first standalone keyword (e.g. "from",
// "to"), returning the words before it and the joined words after it.
func splitOnKeyword(args []string, kw string) (before []string, after string) {
	for i, a := range args {
		if strings.EqualFold(a, kw) {
			return args[:i], strings.Join(args[i+1:], " ")
		}
	}
	return args, ""
}

func parseShopQty(args []string) (int, string, bool) {
	if len(args) == 0 {
		return 1, "", false
	}
	if strings.EqualFold(args[0], "all") {
		return 0, strings.Join(args[1:], " "), true
	}
	if n, err := strconv.Atoi(args[0]); err == nil && n > 0 {
		return n, strings.Join(args[1:], " "), false
	}
	return 1, strings.Join(args, " "), false
}

// resolveShopMob finds the shop-owning mob in the player's room. If name is
// empty and exactly one shop exists it is returned; multiple shops prompt
// "Which shop?". A non-empty name matches a specific mob. Errors are written to
// the session and nil is returned when resolution fails.
func (g *Game) resolveShopMob(sess *net.Session, p *player.Player, name string) *world.MobInstance {
	var shops []*world.MobInstance
	for _, m := range g.MobStore.MobsInRoom(p.RoomID) {
		if m.HasShop() {
			shops = append(shops, m)
		}
	}
	if len(shops) == 0 {
		sess.WriteLine("There is no shop here.")
		return nil
	}

	name = strings.TrimSpace(name)
	if name != "" {
		var matched []*world.MobInstance
		for _, m := range shops {
			if m.MatchQuality(name) > world.MatchNone {
				matched = append(matched, m)
			}
		}
		if len(matched) == 0 {
			sess.WriteLine(fmt.Sprintf("There is no shop here run by \"%s\".", name))
			return nil
		}
		if len(matched) > 1 {
			g.promptWhichShop(sess, matched)
			return nil
		}
		return matched[0]
	}

	if len(shops) == 1 {
		return shops[0]
	}
	g.promptWhichShop(sess, shops)
	return nil
}

func (g *Game) promptWhichShop(sess *net.Session, shops []*world.MobInstance) {
	sess.WriteLine("Which shop? Try again naming one of:")
	for _, m := range shops {
		sess.WriteLine("  - " + m.Name)
	}
}

type shopCandidate struct {
	itemID string
	def    *item.ItemDef
	name   string
	stock  int
}

// shopCandidates lists everything the shop currently offers for sale: its
// configured items (even when out of stock) plus any dynamically-held items
// with stock remaining.
func (g *Game) shopCandidates(mob *world.MobInstance) []shopCandidate {
	stock := g.MobStore.ShopStockSnapshot(mob.InstanceID)
	seen := map[string]bool{}
	var out []shopCandidate
	add := func(id string) {
		if id == "" || seen[id] {
			return
		}
		seen[id] = true
		def, _ := g.ItemStore.Load(id)
		name := id
		if def != nil {
			name = def.Name
		}
		out = append(out, shopCandidate{itemID: id, def: def, name: name, stock: stock[id]})
	}
	for i := range mob.Shop.Items {
		add(mob.Shop.Items[i].ItemID)
	}
	for id, n := range stock {
		if n > 0 {
			add(id)
		}
	}
	return out
}

func (g *Game) showShopInventory(sess *net.Session, mob *world.MobInstance) {
	if mob.Shop.Message != "" {
		sess.WriteLine(g.colorize(sess, "dialog", mob.Shop.Message))
	}

	candidates := g.shopCandidates(mob)
	if len(candidates) == 0 {
		sess.WriteLine(fmt.Sprintf("%s has nothing for sale.", mob.Name))
		return
	}

	unicode := true
	wrapWidth := 0
	if p := sess.Player; p != nil {
		unicode = p.OptionBool("unicode")
		wrapWidth = p.OptionInt("wrap_width")
	}

	t := ui.Table{
		Title:   mob.Name,
		Columns: []string{"Item", "Stock", "Buy", "Sell"},
	}
	for _, c := range candidates {
		value := 0
		if c.def != nil {
			value = c.def.Value
		}
		sellStr := "\u2014"
		if mob.Shop.FindItem(c.itemID) != nil || mob.Shop.Buys() {
			sellStr = fmt.Sprintf("%d cr", mob.Shop.SellPrice(value, c.stock))
		}
		t.Rows = append(t.Rows, []string{
			g.itemColorize(sess, c.def, c.name),
			fmt.Sprintf("%d", c.stock),
			g.colorize(sess, "currency_pickup", fmt.Sprintf("%d cr", value)),
			g.colorize(sess, "currency_pickup", sellStr),
		})
	}
	for _, line := range t.Render(unicode, wrapWidth) {
		sess.WriteLine(line)
	}
}

func (g *Game) doShopBuy(sess *net.Session, mob *world.MobInstance, input string, qty int, all bool) {
	var matches []shopCandidate
	for _, c := range g.shopCandidates(mob) {
		if behavior.WordPrefixMatch(input, c.name) {
			matches = append(matches, c)
		}
	}
	if len(matches) == 0 {
		sess.WriteLine("That item isn't for sale here. Use 'list' to see the inventory.")
		return
	}
	if len(matches) > 1 {
		sess.WriteLine("That's ambiguous, which one?")
		for _, m := range matches {
			sess.WriteLine("  - " + g.itemColorize(sess, m.def, m.name))
		}
		return
	}

	c := matches[0]
	p := sess.Player
	price := 0
	if c.def != nil {
		price = c.def.Value
	}

	stock := g.MobStore.ShopStockOf(mob.InstanceID, c.itemID)
	if stock <= 0 {
		sess.WriteLine(fmt.Sprintf("%s is out of stock.", g.itemColorize(sess, c.def, c.name)))
		return
	}

	const unlimited = 1 << 30
	want := qty
	if all || qty == 0 {
		want = unlimited
	}
	if want > stock {
		want = stock
	}
	capacity := g.shopInvCapacity(p, c.itemID, c.def)
	if want > capacity {
		want = capacity
	}
	if price > 0 {
		if afford := p.Credits / price; want > afford {
			want = afford
		}
	}

	if want <= 0 {
		switch {
		case capacity <= 0:
			sess.WriteLine("Your inventory is full.")
		case price > 0 && p.Credits < price:
			sess.WriteLine(fmt.Sprintf("You need %d credits to buy that (you have %d).", price, p.Credits))
		default:
			sess.WriteLine("You can't buy that right now.")
		}
		return
	}

	taken := g.MobStore.ShopTake(mob.InstanceID, c.itemID, want)
	if taken <= 0 {
		sess.WriteLine(fmt.Sprintf("%s is out of stock.", g.itemColorize(sess, c.def, c.name)))
		return
	}

	total := price * taken
	p.Credits -= total
	g.giveShopItems(p, c.itemID, taken, c.def)
	g.AccountStore.SaveCharacter(p)

	itemColor := g.itemColorize(sess, c.def, c.name)
	credits := g.colorize(sess, "currency_pickup", fmt.Sprintf("%d", total))
	if taken == 1 {
		sess.WriteLine(fmt.Sprintf("You buy a %s for %s credits.", itemColor, credits))
	} else {
		sess.WriteLine(fmt.Sprintf("You buy %d %s for %s credits.", taken, itemColor, credits))
	}
}

func (g *Game) doShopSell(sess *net.Session, mob *world.MobInstance, input string, qty int, all bool) {
	p := sess.Player

	matches := g.findInventoryMatches(input, p)
	if len(matches) == 0 {
		sess.WriteLine("You don't have that item.")
		return
	}
	if len(matches) > 1 {
		sess.WriteLine("That's ambiguous, which one?")
		for _, m := range matches {
			def, _ := g.ItemStore.Load(m.ID)
			sess.WriteLine("  - " + g.itemColorize(sess, def, m.Name))
		}
		return
	}

	match := matches[0]
	def, _ := g.ItemStore.Load(match.ID)
	displayName := match.Name
	itemColor := g.itemColorize(sess, def, displayName)

	if mob.Shop.FindItem(match.ID) == nil && !mob.Shop.Buys() {
		sess.WriteLine(fmt.Sprintf("%s doesn't want to buy %s.", mob.Name, itemColor))
		return
	}

	value := 0
	if def != nil {
		value = def.Value
	}

	totalInInv := p.CountItem(match.ID)
	actualQty := qty
	if all || qty == 0 {
		actualQty = totalInInv
	} else if actualQty > totalInInv {
		actualQty = totalInInv
	}
	if actualQty <= 0 {
		sess.WriteLine("You don't have that item.")
		return
	}

	stock := g.MobStore.ShopStockOf(mob.InstanceID, match.ID)
	total := 0
	for k := 0; k < actualQty; k++ {
		total += mob.Shop.SellPrice(value, stock+k)
	}

	p.RemoveItem(match.ID, actualQty)
	p.Credits += total
	g.MobStore.ShopAdd(mob.InstanceID, match.ID, actualQty)
	g.AccountStore.SaveCharacter(p)

	credits := g.colorize(sess, "currency_pickup", fmt.Sprintf("%d", total))
	if actualQty == 1 {
		sess.WriteLine(fmt.Sprintf("You sell a %s for %s credits.", itemColor, credits))
	} else {
		sess.WriteLine(fmt.Sprintf("You sell %d %s for %s credits.", actualQty, itemColor, credits))
	}
}

// shopInvCapacity reports how many of an item the player can still carry.
func (g *Game) shopInvCapacity(p *player.Player, itemID string, def *item.ItemDef) int {
	if def != nil && def.Stackable {
		for i := 0; i < 28; i++ {
			if slot := p.InvSlot(i); slot != nil && slot.ItemID == itemID {
				return 1 << 30
			}
		}
		if p.FirstFreeSlot() != -1 {
			return 1 << 30
		}
		return 0
	}
	return p.FreeSlots()
}

// giveShopItems places qty of an item into the player's inventory, stacking when
// possible. Callers must ensure capacity via shopInvCapacity first.
func (g *Game) giveShopItems(p *player.Player, itemID string, qty int, def *item.ItemDef) {
	if def != nil && def.Stackable {
		for i := 0; i < 28; i++ {
			if slot := p.InvSlot(i); slot != nil && slot.ItemID == itemID {
				slot.Quantity += qty
				return
			}
		}
		if slot := p.FirstFreeSlot(); slot != -1 {
			p.SetInvSlot(slot, g.newInventorySlot(itemID, qty))
		}
		return
	}
	for j := 0; j < qty; j++ {
		slot := p.FirstFreeSlot()
		if slot == -1 {
			return
		}
		p.SetInvSlot(slot, g.newInventorySlot(itemID, 1))
	}
}