#===============================================================================
#
#===============================================================================
module MultipleForms
  @@formSpecies = SpeciesHandlerHash.new

  def self.copy(sym, *syms)
    @@formSpecies.copy(sym, *syms)
  end

  def self.register(sym, hash)
    @@formSpecies.add(sym, hash)
  end

  def self.registerIf(sym, cond, hash)
    @@formSpecies.addIf(sym, cond, hash)
  end

  def self.hasFunction?(pkmn, func)
    spec = (pkmn.is_a?(Pokemon)) ? pkmn.species : pkmn
    sp = @@formSpecies[spec]
    return sp && sp[func]
  end

  def self.getFunction(pkmn, func)
    spec = (pkmn.is_a?(Pokemon)) ? pkmn.species : pkmn
    sp = @@formSpecies[spec]
    return (sp && sp[func]) ? sp[func] : nil
  end

  def self.call(func, pkmn, *args)
    sp = @@formSpecies[pkmn.species]
    return nil if !sp || !sp[func]
    return sp[func].call(pkmn, *args)
  end
end

#===============================================================================
#
#===============================================================================
def drawSpot(bitmap, spotpattern, x, y, red, green, blue)
  height = spotpattern.length
  width  = spotpattern[0].length
  height.times do |yy|
    spot = spotpattern[yy]
    width.times do |xx|
      next if spot[xx] != 1
      xOrg = (x + xx) * 2
      yOrg = (y + yy) * 2
      color = bitmap.get_pixel(xOrg, yOrg)
      r = color.red + red
      g = color.green + green
      b = color.blue + blue
      color.red   = [[r, 0].max, 255].min
      color.green = [[g, 0].max, 255].min
      color.blue  = [[b, 0].max, 255].min
      bitmap.set_pixel(xOrg, yOrg, color)
      bitmap.set_pixel(xOrg + 1, yOrg, color)
      bitmap.set_pixel(xOrg, yOrg + 1, color)
      bitmap.set_pixel(xOrg + 1, yOrg + 1, color)
    end
  end
end

def pbSpindaSpots(pkmn, bitmap)
  # NOTE: These spots are doubled in size when drawing them.
  spot1 = [
    [0, 0, 1, 1, 1, 1, 0, 0],
    [0, 1, 1, 1, 1, 1, 1, 0],
    [1, 1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1, 1],
    [0, 1, 1, 1, 1, 1, 1, 0],
    [0, 0, 1, 1, 1, 1, 0, 0]
  ]
  spot2 = [
    [0, 0, 1, 1, 1, 0, 0],
    [0, 1, 1, 1, 1, 1, 0],
    [1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1],
    [0, 1, 1, 1, 1, 1, 0],
    [0, 0, 1, 1, 1, 0, 0]
  ]
  spot3 = [
    [0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
    [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
    [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
    [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
    [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
    [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
    [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
    [0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
    [0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0]
  ]
  spot4 = [
    [0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0],
    [0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
    [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
    [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
    [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
    [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
    [0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0]
  ]
  id = pkmn.personalID
  h = (id >> 28) & 15
  g = (id >> 24) & 15
  f = (id >> 20) & 15
  e = (id >> 16) & 15
  d = (id >> 12) & 15
  c = (id >> 8) & 15
  b = (id >> 4) & 15
  a = (id) & 15
  # NOTE: The coordinates below (b + 33, a + 25 and so on) are doubled when
  #       drawing the spot.
  if pkmn.shiny?
    drawSpot(bitmap, spot1, b + 33, a + 25, -75, -10, -150)
    drawSpot(bitmap, spot2, d + 21, c + 24, -75, -10, -150)
    drawSpot(bitmap, spot3, f + 39, e + 7, -75, -10, -150)
    drawSpot(bitmap, spot4, h + 15, g + 6, -75, -10, -150)
  else
    drawSpot(bitmap, spot1, b + 33, a + 25, 0, -115, -75)
    drawSpot(bitmap, spot2, d + 21, c + 24, 0, -115, -75)
    drawSpot(bitmap, spot3, f + 39, e + 7, 0, -115, -75)
    drawSpot(bitmap, spot4, h + 15, g + 6, 0, -115, -75)
  end
end

#===============================================================================
# Regular form differences
#===============================================================================

MultipleForms.register(:UNOWN, {
  "getFormOnCreation" => proc { |pkmn|
    next rand(28)
  }
})

MultipleForms.register(:DUNSPARCE, {
  "getFormOnCreation" => proc { |pkmn|
    next (rand(100) == 0) ? 1 : 0   # 99% form 0, 1% form 1
  }
})

MultipleForms.register(:SPINDA, {
  "alterBitmap" => proc { |pkmn, bitmap|
    pbSpindaSpots(pkmn, bitmap)
  }
})

MultipleForms.register(:CASTFORM, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0
  }
})

MultipleForms.register(:GROUDON, {
  "getPrimalForm" => proc { |pkmn|
    next 1 if pkmn.hasItem?(:REDORB)
    next
  }
})

MultipleForms.register(:KYOGRE, {
  "getPrimalForm" => proc { |pkmn|
    next 1 if pkmn.hasItem?(:BLUEORB)
    next
  }
})

MultipleForms.register(:BURMY, {
  "getFormOnCreation" => proc { |pkmn|
    case pbGetEnvironment
    when :Rock, :Sand, :Cave
      next 1   # Sandy Cloak
    when :None
      next 2   # Trash Cloak
    else
      next 0   # Plant Cloak
    end
  },
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next if !endBattle || !usedInBattle
    case battle.environment
    when :Rock, :Sand, :Cave
      next 1   # Sandy Cloak
    when :None
      next 2   # Trash Cloak
    else
      next 0   # Plant Cloak
    end
  }
})

MultipleForms.register(:WORMADAM, {
  "getFormOnCreation" => proc { |pkmn|
    case pbGetEnvironment
    when :Rock, :Sand, :Cave
      next 1   # Sandy Cloak
    when :None
      next 2   # Trash Cloak
    else
      next 0   # Plant Cloak
    end
  }
})

MultipleForms.register(:CHERRIM, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0
  }
})

MultipleForms.register(:ROTOM, {
  "onSetForm" => proc { |pkmn, form, oldForm|
    form_moves = [
      :OVERHEAT,    # Heat (microwave oven)
      :HYDROPUMP,   # Wash (washing machine)
      :BLIZZARD,    # Frost (refrigerator)
      :AIRSLASH,    # Fan (electric fan)
      :LEAFSTORM    # Mow (lawn mower)
    ]
    # Find a known move that should be forgotten
    old_move_index = -1
    pkmn.moves.each_with_index do |move, i|
      next if !form_moves.include?(move.id)
      old_move_index = i
      break
    end
    # Determine which new move to learn (if any)
    new_move_id = (form > 0) ? form_moves[form - 1] : nil
    new_move_id = nil if !GameData::Move.exists?(new_move_id)
    if new_move_id.nil? && old_move_index >= 0 && pkmn.numMoves == 1
      new_move_id = :THUNDERSHOCK
      new_move_id = nil if !GameData::Move.exists?(new_move_id)
      raise _INTL("Rotom is trying to forget its last move, but there isn't another move to replace it with.") if new_move_id.nil?
    end
    new_move_id = nil if pkmn.hasMove?(new_move_id)
    # Forget a known move (if relevant) and learn a new move (if relevant)
    if old_move_index >= 0
      old_move_name = pkmn.moves[old_move_index].name
      if new_move_id.nil?
        # Just forget the old move
        pkmn.forget_move_at_index(old_move_index)
        pbMessage(_INTL("{1} forgot {2}...", pkmn.name, old_move_name))
      else
        # Replace the old move with the new move (keeps the same index)
        pkmn.moves[old_move_index].id = new_move_id
        new_move_name = pkmn.moves[old_move_index].name
        pbMessage(_INTL("{1} forgot {2}...", pkmn.name, old_move_name) + "\1")
        pbMessage("\\se[]" + _INTL("{1} learned {2}!", pkmn.name, new_move_name) + "\\se[Pkmn move learnt]")
      end
    elsif !new_move_id.nil?
      # Just learn the new move
      pbLearnMove(pkmn, new_move_id, true)
    end
  }
})

MultipleForms.register(:GIRATINA, {
  "getForm" => proc { |pkmn|
    next 1 if pkmn.hasItem?(:GRISEOUSORB) && Settings::MECHANICS_GENERATION <= 8
    next 1 if $game_map&.metadata&.has_flag?("DistortionWorld")
    next 0
  }
})

MultipleForms.register(:SHAYMIN, {
  "getForm" => proc { |pkmn|
    next 0 if pkmn.fainted? || pkmn.status == :FROZEN || PBDayNight.isNight?
  }
})

MultipleForms.register(:ARCEUS, {
  "getForm" => proc { |pkmn|
    next nil if !pkmn.hasAbility?(:MULTITYPE)
    typeArray = {
      1  => [:FISTPLATE,   :FIGHTINIUMZ],
      2  => [:SKYPLATE,    :FLYINIUMZ],
      3  => [:TOXICPLATE,  :POISONIUMZ],
      4  => [:EARTHPLATE,  :GROUNDIUMZ],
      5  => [:STONEPLATE,  :ROCKIUMZ],
      6  => [:INSECTPLATE, :BUGINIUMZ],
      7  => [:SPOOKYPLATE, :GHOSTIUMZ],
      8  => [:IRONPLATE,   :STEELIUMZ],
      10 => [:FLAMEPLATE,  :FIRIUMZ],
      11 => [:SPLASHPLATE, :WATERIUMZ],
      12 => [:MEADOWPLATE, :GRASSIUMZ],
      13 => [:ZAPPLATE,    :ELECTRIUMZ],
      14 => [:MINDPLATE,   :PSYCHIUMZ],
      15 => [:ICICLEPLATE, :ICIUMZ],
      16 => [:DRACOPLATE,  :DRAGONIUMZ],
      17 => [:DREADPLATE,  :DARKINIUMZ],
      18 => [:PIXIEPLATE,  :FAIRIUMZ]
    }
    ret = 0
    typeArray.each do |f, items|
      items.each do |item|
        next if !pkmn.hasItem?(item)
        ret = f
        break
      end
      break if ret > 0
    end
    next ret
  }
})

MultipleForms.register(:DARMANITAN, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 2 * (pkmn.form / 2)
  }
})

MultipleForms.register(:DEERLING, {
  "getForm" => proc { |pkmn|
    next pbGetSeason
  }
})

MultipleForms.copy(:DEERLING, :SAWSBUCK)

MultipleForms.register(:KYUREM, {
  "getFormOnEnteringBattle" => proc { |pkmn, wild|
    next pkmn.form + 2 if pkmn.form == 1 || pkmn.form == 2
  },
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next pkmn.form - 2 if pkmn.form >= 3   # Fused forms stop glowing
  },
  "onSetForm" => proc { |pkmn, form, oldForm|
    case form
    when 0   # Normal
      pkmn.moves.each_with_index do |move, i|
        case move.id
        when :ICEBURN, :FREEZESHOCK
          next if !GameData::Move.exists?(:GLACIATE)
          if pkmn.hasMove?(:GLACIATE)
            pkmn.moves[i] = nil
          else
            move.id = :GLACIATE
          end
        when :FUSIONFLARE, :FUSIONBOLT
          next if !GameData::Move.exists?(:SCARYFACE)
          if pkmn.hasMove?(:SCARYFACE)
            pkmn.moves[i] = nil
          else
            move.id = :SCARYFACE
          end
        end
        pkmn.moves.compact!
      end
    when 1   # White
      pkmn.moves.each do |move|
        case move.id
        when :GLACIATE
          next if !GameData::Move.exists?(:ICEBURN) || pkmn.hasMove?(:ICEBURN)
          move.id = :ICEBURN
        when :SCARYFACE
          next if !GameData::Move.exists?(:FUSIONFLARE) || pkmn.hasMove?(:FUSIONFLARE)
          move.id = :FUSIONFLARE
        end
      end
    when 2   # Black
      pkmn.moves.each do |move|
        case move.id
        when :GLACIATE
          next if !GameData::Move.exists?(:FREEZESHOCK) || pkmn.hasMove?(:FREEZESHOCK)
          move.id = :FREEZESHOCK
        when :SCARYFACE
          next if !GameData::Move.exists?(:FUSIONBOLT) || pkmn.hasMove?(:FUSIONBOLT)
          move.id = :FUSIONBOLT
        end
      end
    end
  }
})

MultipleForms.register(:KELDEO, {
  "getForm" => proc { |pkmn|
    next 1 if pkmn.hasMove?(:SECRETSWORD) # Resolute Form
    next 0                                # Ordinary Form
  }
})

MultipleForms.register(:MELOETTA, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0
  }
})

MultipleForms.register(:GENESECT, {
  "getForm" => proc { |pkmn|
    next 1 if pkmn.hasItem?(:SHOCKDRIVE)
    next 2 if pkmn.hasItem?(:BURNDRIVE)
    next 3 if pkmn.hasItem?(:CHILLDRIVE)
    next 4 if pkmn.hasItem?(:DOUSEDRIVE)
    next 0
  }
})

MultipleForms.register(:GRENINJA, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 1 if pkmn.form == 2 && (pkmn.fainted? || endBattle)
  }
})

MultipleForms.register(:SCATTERBUG, {
  "getFormOnCreation" => proc { |pkmn|
    next $player.secret_ID % 18
  }
})

MultipleForms.copy(:SCATTERBUG, :SPEWPA, :VIVILLON)

MultipleForms.register(:FURFROU, {
  "getForm" => proc { |pkmn|
    if !pkmn.time_form_set ||
       pbGetTimeNow.to_i > pkmn.time_form_set.to_i + (60 * 60 * 24 * 5)   # 5 days
      next 0
    end
  },
  "onSetForm" => proc { |pkmn, form, oldForm|
    pkmn.time_form_set = (form > 0) ? pbGetTimeNow.to_i : nil
  }
})

MultipleForms.register(:ESPURR, {
  "getForm" => proc { |pkmn|
    next pkmn.gender
  }
})

MultipleForms.copy(:ESPURR, :MEOWSTIC)

MultipleForms.register(:AEGISLASH, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0
  }
})

MultipleForms.register(:PUMPKABOO, {
  "getFormOnCreation" => proc { |pkmn|
    r = rand(100)
    next 3 if r < 5    # Super Size (5%)
    next 2 if r < 20   # Large (15%)
    next 1 if r < 65   # Average (45%)
    next 0             # Small (35%)
  }
})

MultipleForms.copy(:PUMPKABOO, :GOURGEIST)

MultipleForms.register(:XERNEAS, {
  "getFormOnStartingBattle" => proc { |pkmn, wild|
    next 1
  },
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0 if endBattle
  }
})

MultipleForms.register(:ZYGARDE, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next pkmn.form - 2 if pkmn.form >= 2 && (pkmn.fainted? || endBattle)
  }
})

MultipleForms.register(:HOOPA, {
  "getForm" => proc { |pkmn|
    if !pkmn.time_form_set ||
       pbGetTimeNow.to_i > pkmn.time_form_set.to_i + (60 * 60 * 24 * 3)   # 3 days
      next 0
    end
  },
  "onSetForm" => proc { |pkmn, form, oldForm|
    pkmn.time_form_set = (form > 0) ? pbGetTimeNow.to_i : nil
  }
})

MultipleForms.register(:ROCKRUFF, {
  "getForm" => proc { |pkmn|
    next if pkmn.form_simple >= 2   # Own Tempo Rockruff cannot become another form
    next 1 if PBDayNight.isNight?
    next 0
  }
})

MultipleForms.register(:LYCANROC, {
  "getFormOnCreation" => proc { |pkmn|
    next 2 if PBDayNight.isEvening?   # Dusk
    next 1 if PBDayNight.isNight?     # Midnight
    next 0                            # Midday
  }
})

MultipleForms.register(:WISHIWASHI, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0
  }
})

MultipleForms.register(:SILVALLY, {
  "getForm" => proc { |pkmn|
    next nil if !pkmn.hasAbility?(:RKSSYSTEM)
    typeArray = {
      1  => [:FIGHTINGMEMORY],
      2  => [:FLYINGMEMORY],
      3  => [:POISONMEMORY],
      4  => [:GROUNDMEMORY],
      5  => [:ROCKMEMORY],
      6  => [:BUGMEMORY],
      7  => [:GHOSTMEMORY],
      8  => [:STEELMEMORY],
      10 => [:FIREMEMORY],
      11 => [:WATERMEMORY],
      12 => [:GRASSMEMORY],
      13 => [:ELECTRICMEMORY],
      14 => [:PSYCHICMEMORY],
      15 => [:ICEMEMORY],
      16 => [:DRAGONMEMORY],
      17 => [:DARKMEMORY],
      18 => [:FAIRYMEMORY]
    }
    ret = 0
    typeArray.each do |f, items|
      items.each do |item|
        next if !pkmn.hasItem?(item)
        ret = f
        break
      end
      break if ret > 0
    end
    next ret
  }
})

MultipleForms.register(:MINIOR, {
  "getFormOnCreation" => proc { |pkmn|
    next rand(7..13)   # Meteor forms are 0-6, Core forms are 7-13
  },
  "getFormOnEnteringBattle" => proc { |pkmn, wild|
    next pkmn.form - 7 if pkmn.form >= 7 && wild   # Wild Minior always appear in Meteor form
  },
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next pkmn.form + 7 if pkmn.form < 7
  }
})

MultipleForms.register(:MIMIKYU, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0 if pkmn.fainted? || endBattle
  }
})

MultipleForms.register(:NECROZMA, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    # Fused forms are 1 and 2, Ultra form is 3 or 4 depending on which fusion
    next pkmn.form - 2 if pkmn.form >= 3 && (pkmn.fainted? || endBattle)
  },
  "onSetForm" => proc { |pkmn, form, oldForm|
    next if form > 2 || oldForm > 2   # Ultra form changes don't affect moveset
    form_moves = [
      :SUNSTEELSTRIKE,   # Dusk Mane (with Solgaleo) (form 1)
      :MOONGEISTBEAM     # Dawn Wings (with Lunala) (form 2)
    ]
    if form == 0   # Normal
      # Turned back into the base form; forget form-specific moves
      form_moves.each do |move|
        next if !pkmn.hasMove?(move)
        pkmn.forget_move(move)
        pbMessage(_INTL("{1} forgot {2}...", pkmn.name, GameData::Move.get(move).name))
      end
      pbLearnMove(pkmn, :CONFUSION) if pkmn.numMoves == 0
    else   # Dusk Mane, Dawn Wings
      # Turned into an alternate form; try learning that form's unique move
      new_move_id = form_moves[form - 1]
      pbLearnMove(pkmn, new_move_id, true)
    end
  }
})

MultipleForms.register(:CRAMORANT, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0
  }
})

MultipleForms.register(:TOXEL, {
  "getFormOnCreation" => proc { |pkmn|
    next 1 if [:LONELY, :BOLD, :RELAXED, :TIMID, :SERIOUS, :MODEST, :MILD,
               :QUIET, :BASHFUL, :CALM, :GENTLE, :CAREFUL].include?(pkmn.nature_id)
    next 0
  }
})

MultipleForms.copy(:TOXEL, :TOXTRICITY)

MultipleForms.register(:POLTEAGEIST, {
  "getFormOnCreation" => proc { |pkmn|
    next 1 if rand(100) < 10   # Antique
    next 0                     # Phony
  }
})

MultipleForms.copy(:POLTEAGEIST, :SINISTEA)

# A Milcery will always have the same flavor, but it is randomly chosen.
MultipleForms.register(:MILCERY, {
  "getForm" => proc { |pkmn|
    num_flavors = 9
    sweets = [:STRAWBERRYSWEET, :BERRYSWEET, :LOVESWEET, :STARSWEET,
              :CLOVERSWEET, :FLOWERSWEET, :RIBBONSWEET]
    if sweets.include?(pkmn.item_id)
      next sweets.index(pkmn.item_id) + ((pkmn.personalID % num_flavors) * sweets.length)
    end
    next 0
  }
})

MultipleForms.register(:ALCREMIE, {
  "getFormOnCreation" => proc { |pkmn|
    num_flavors = 9
    num_sweets = 7
    next rand(num_flavors * num_sweets)
  }
})

MultipleForms.register(:EISCUE, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0 if pkmn.fainted? || endBattle
  }
})

MultipleForms.register(:INDEEDEE, {
  "getForm" => proc { |pkmn|
    next pkmn.gender
  }
})

MultipleForms.register(:MORPEKO, {
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0 if pkmn.fainted? || endBattle
  }
})

MultipleForms.register(:ZACIAN, {
  "getFormOnStartingBattle" => proc { |pkmn, wild|
    next 1 if pkmn.hasItem?(:RUSTEDSWORD)
    next 0
  },
  "changePokemonOnStartingBattle" => proc { |pkmn, battle|
    if GameData::Move.exists?(:BEHEMOTHBLADE) && pkmn.hasItem?(:RUSTEDSWORD)
      pkmn.moves.each { |move| move.id = :BEHEMOTHBLADE if move.id == :IRONHEAD }
    end
  },
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0 if endBattle
  },
  "changePokemonOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    if endBattle
      pkmn.moves.each { |move| move.id = :IRONHEAD if move.id == :BEHEMOTHBLADE }
    end
  }
})

MultipleForms.register(:ZAMAZENTA, {
  "getFormOnStartingBattle" => proc { |pkmn, wild|
    next 1 if pkmn.hasItem?(:RUSTEDSHIELD)
    next 0
  },
  "changePokemonOnStartingBattle" => proc { |pkmn, battle|
    if GameData::Move.exists?(:BEHEMOTHBASH) && pkmn.hasItem?(:RUSTEDSHIELD)
      pkmn.moves.each { |move| move.id = :BEHEMOTHBASH if move.id == :IRONHEAD }
    end
  },
  "getFormOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    next 0 if endBattle
  },
  "changePokemonOnLeavingBattle" => proc { |pkmn, battle, usedInBattle, endBattle|
    if endBattle
      pkmn.moves.each { |move| move.id = :IRONHEAD if move.id == :BEHEMOTHBASH }
    end
  }
})

MultipleForms.register(:URSHIFU, {
  "getFormOnCreation" => proc { |pkmn|
    next rand(2)
  }
})

MultipleForms.register(:CALYREX, {
  "onSetForm" => proc { |pkmn, form, oldForm|
    form_moves = [
      :GLACIALLANCE,   # Ice Rider (with Glastrier) (form 1)
      :ASTRALBARRAGE   # Shadow Rider (with Spectrier) (form 2)
    ]
    if form == 0   # Normal
      # Forget special form moves
      form_moves.each do |move|
        next if !pkmn.hasMove?(move)
        pkmn.forget_move(move)
        pbMessage(_INTL("{1} forgot {2}...", pkmn.name, GameData::Move.get(move).name))
      end
      # Forget all other moves not accessible to the base form
      sp_data = pkmn.species_data
      pkmn.moves.each_with_index do |move, i|
        next if sp_data.moves.any? { |learn_move| learn_move[1] == move.id }
        next if sp_data.tutor_moves.include?(move.id)
        next if sp_data.egg_moves.include?(move.id)
        pbMessage(_INTL("{1} forgot {2}...", pkmn.name, move.name))
        pkmn.moves[i] = nil
      end
      pkmn.moves.compact!
      # Ensure pkmn has at least one move in the end
      pbLearnMove(pkmn, :CONFUSION) if pkmn.numMoves == 0
    else   # Ice Rider, Shadow Rider
      new_move = form_moves[form - 1]
      pbLearnMove(pkmn, new_move, true)
    end
  }
})

MultipleForms.register(:LECHONK, {
  "getForm" => proc { |pkmn|
    next pkmn.gender
  }
})

MultipleForms.copy(:LECHONK, :OINKOLOGNE)

MultipleForms.register(:TANDEMAUS, {
  "getFormOnCreation" => proc { |pkmn|
    next (rand(100) == 0) ? 1 : 0   # 99% form 0, 1% form 1
  }
})

MultipleForms.copy(:TANDEMAUS, :MAUSHOLD)

MultipleForms.register(:SQUAWKABILLY, {
  "getFormOnCreation" => proc { |pkmn|
    next rand(4)
  }
})

MultipleForms.register(:TATSUGIRI, {
  "getFormOnCreation" => proc { |pkmn|
    next rand(3)
  }
})

# NOTE: Wild Dudunsparce is always form 0.
# NOTE: Wild Gimmighoul is always form 0.

MultipleForms.register(:POLTCHAGEIST, {
  "getFormOnCreation" => proc { |pkmn|
    next 1 if rand(100) < 10   # Artisan
    next 0                     # Counterfeit
  }
})

MultipleForms.copy(:POLTCHAGEIST, :SINISCHA)

MultipleForms.register(:OGERPON, {
  "getForm" => proc { |pkmn|
    next 1 if pkmn.hasItem?(:WELLSPRINGMASK)
    next 2 if pkmn.hasItem?(:HEARTHFLAMEMASK)
    next 3 if pkmn.hasItem?(:CORNERSTONEMASK)
    next 0
  }
})

#===============================================================================
# Regional forms
# This code is for determining the form of a Pokémon in an egg created at the
# Day Care, where that Pokémon's species has regional forms. The regional form
# chosen depends on the region in which the egg was produced (not where it
# hatches). The form should have a flag called "EggInRegion_2" where the number
# is the number of the region in which the egg was produced.
#===============================================================================

MultipleForms.register(:RATTATA, {
  "getFormOnEggCreation" => proc { |pkmn|
    if $game_map
      map_pos = $game_map.metadata&.town_map_position
      region_num = map_pos[0]
      found_form = -1
      GameData::Species.each_form_for_species(pkmn.species) do |sp_data|
        sp_data.flags.each do |flag|
          if flag[/^EggInRegion_(\d+)$/i] && $~[1].to_i == region_num
            found_form = sp_data.form
            break
          end
        end
        break if found_form >= 0
      end
      next found_form if found_form >= 0
    end
    next 0
  }
})

MultipleForms.copy(
  # Alolan forms
  :RATTATA, :SANDSHREW, :VULPIX, :DIGLETT, :MEOWTH, :GEODUDE, :GRIMER,
  # Galarian forms (excluding Meowth which is above)
  :PONYTA, :SLOWPOKE, :FARFETCHD, :ARTICUNO, :ZAPDOS, :MOLTRES, :CORSOLA,
  :ZIGZAGOON, :DARUMAKA, :YAMASK, :STUNFISK,
  # Hisuian forms
  :GROWLITHE, :VOLTORB, :QWILFISH, :SNEASEL, :ZORUA,
  # Paldean forms
  :TAUROS, :WOOPER
)

#===============================================================================
# Regional forms
# These species don't have visually different regional forms, but they need to
# evolve into different forms depending on the location where they evolve.
#===============================================================================

# Alolan forms
MultipleForms.register(:PIKACHU, {
  "getForm" => proc { |pkmn|
    next if pkmn.form_simple >= 2
    if $game_map
      map_pos = $game_map.metadata&.town_map_position
      next 1 if map_pos && map_pos[0] == 1   # Tiall region
    end
    next 0
  }
})

MultipleForms.copy(:PIKACHU, :EXEGGCUTE, :CUBONE)

# Galarian forms
MultipleForms.register(:KOFFING, {
  "getForm" => proc { |pkmn|
    next if pkmn.form_simple >= 2
    if $game_map
      map_pos = $game_map.metadata&.town_map_position
      next 1 if map_pos && map_pos[0] == 2   # Galar region
    end
    next 0
  }
})

MultipleForms.copy(:KOFFING, :MIMEJR)

# Hisuian forms
MultipleForms.register(:QUILAVA, {
  "getForm" => proc { |pkmn|
    next if pkmn.form_simple >= 2
    if $game_map
      map_pos = $game_map.metadata&.town_map_position
      next 1 if map_pos && map_pos[0] == 3   # Hisui region
    end
    next 0
  }
})

MultipleForms.copy(:QUILAVA,
                   :DEWOTT, :PETILILL, :RUFFLET, :GOOMY, :BERGMITE, :DARTRIX)

# Paldean forms
# None!