# migrate.ludic - each morning the ranges slide toward where the season wants them, and the animals
# that live in them are dragged along rather than teleported; an animal keeps inside its own
export function wildlife_ranges_migrate(wildlife_st: WildlifeState) -> void {
  let rs = wildlife_ranges(wildlife_st)
  let w = WildlifeWorld.winterness()
  for i in 0 .. len(rs) {
    rs[i].x = Math.lerp(rs[i].sx, rs[i].wx, w)
    rs[i].z = Math.lerp(rs[i].sz, rs[i].wz, w)
  }
  let all = wildlife_all(wildlife_st)
  for i in 0 .. len(all) {
    let a = all[i]
    let r = wildlife_range(wildlife_st, a.rg)
    if r == null { continue }
    wl_clamp(wildlife_st, a)
    if wildlife_range_dist(r, a.home_x, a.home_z) > r.r * 1.2 {
      a.home_x = r.x
      a.home_z = r.z
      a.x = r.x
      a.z = r.z
      a.y = WildlifeWorld.ground(a.x, a.z)
    }
  }
}

# its home kept inside its range
function wl_clamp(wildlife_st: WildlifeState, a: WildAnimal) -> void {
  let r = wildlife_range(wildlife_st, a.rg)
  if r == null { return }
  let d = wildlife_range_dist(r, a.home_x, a.home_z)
  if d < r.r { return }
  a.home_x = r.x + (a.home_x - r.x) / d * (r.r * 0.9)
  a.home_z = r.z + (a.home_z - r.z) / d * (r.r * 0.9)
}

# how many live in range `i`, legends apart
export function wildlife_range_alive(wildlife_st: WildlifeState, i: int) -> int {
  var n = 0
  let all = wildlife_all(wildlife_st)
  for k in 0 .. len(all) { if all[k].alive and not all[k].legend and all[k].rg == i { n += 1 } }
  return n
}

# how many are alive in the whole valley, legends apart
export function wildlife_total(wildlife_st: WildlifeState) -> int {
  var n = 0
  let all = wildlife_all(wildlife_st)
  for k in 0 .. len(all) { if all[k].alive and not all[k].legend { n += 1 } }
  return n
}

# the nearest range of `sp` a player has found, to (x, z), or -1
export function wildlife_range_found_near(wildlife_st: WildlifeState, sp: int, x: float, z: float) -> int {
  var best = -1
  var bd = 99999.0
  let rs = wildlife_ranges(wildlife_st)
  for i in 0 .. len(rs) {
    if rs[i].sp != sp or not rs[i].found { continue }
    let d = wildlife_range_dist(rs[i], x, z)
    if d < bd {
      bd = d
      best = i
    }
  }
  return best
}