# prices.ludic - what a thing costs and what it fetches. One standing moves both, toward each
# other and never past: a newcomer pays a little over and sells a little under.
function shop_rep01() -> float { return Math.clamp(float(ShopWorld.rep()), 0.0, 100.0) / 100.0 }

# the fraction of base a buyer pays, and a seller is paid before the item's own fraction
export function shop_buy_factor(shop_st: ShopState) -> float { return shop_st.shop_buy_new + (shop_st.shop_buy_best - shop_st.shop_buy_new) * shop_rep01() }
export function shop_sell_factor(shop_st: ShopState) -> float { return shop_st.shop_sell_new + (shop_st.shop_sell_best - shop_st.shop_sell_new) * shop_rep01() }

export function shop_price_buy(shop_st: ShopState, it: int) -> int {
  if not shop_item_ok(shop_st, it) { return 0 }
  let p = int(float(shop_st.shop_base[it]) * shop_buy_factor(shop_st) * ShopWorld.buy_mult() + 0.5)
  return Math.max(p, 1)
}

# what vendor `v` pays (-1: no vendor, no demand). ROUNDED, so cheap raw material keeps its
# order; and a vendor that stocks the thing never pays what it charges, not even a floor of $1
export function shop_price_sell_at(shop_st: ShopState, v: int, it: int) -> int {
  if not shop_item_ok(shop_st, it) { return 0 }
  let f = shop_sell_factor(shop_st) * shop_st.shop_sell_frac[it] * shop_demand_mult(shop_st, v, it)
  var p = Math.max(int(float(shop_st.shop_base[it]) * f + 0.5), 1)
  if shop_stocks(shop_st, v, it) { p = Math.max(Math.min(p, shop_price_buy(shop_st, it) - 1), 0) }
  return p
}

# what the vendor at the counter pays
export function shop_price_sell(shop_st: ShopState, it: int) -> int { return shop_price_sell_at(shop_st, shop_st.shop_at, it) }

export function shop_stocks(shop_st: ShopState, v: int, it: int) -> bool {
  if not shop_vendor_ok(shop_st, v) or shop_st.shop_vendor_list[v].stock == null { return false }
  let st = shop_st.shop_vendor_list[v].stock
  for k in 0 .. len(st) { if st[k] == it { return true } }
  return false
}

# what `v` takes: its list and whatever the world says, and never the one thing it refuses
export function shop_buys(shop_st: ShopState, v: int, it: int) -> bool {
  if not shop_vendor_ok(shop_st, v) or it == shop_st.shop_vendor_list[v].refuses { return false }
  if ShopWorld.also_buys(v, it) { return true }
  let b = shop_st.shop_vendor_list[v].buys
  if b == null { return false }
  for k in 0 .. len(b) { if b[k] == it { return true } }
  return false
}