SpeakerType = {
  NONE = 0,
  MAN = 1,
  WOMAN = 2,
  BOY = 3,
  GIRL = 4,
  NONHUMAN = 5
}

Direction = {
  UP = 0,
  UP_RIGHT = 1,
  RIGHT = 2,
  DOWN_RIGHT = 3,
  DOWN = 4,
  DOWN_LEFT = 5,
  LEFT = 6,
  UP_LEFT = 7
}

CharacterState = {
  STILL = 0,
  WALKING = 1,
  CROUCHING = 2,
  RUNNING = 3
}

SpriteLayer = {
  MASK = 0,
  NORMAL = 1,
  ABOVE = 2
}

BehaviourType = {
  NONE = 0,
  WANDER = 1,
  PATH = 2,
  FOLLOW = 3
}

CutsceneOptions = {
  DO_NOT_CHANGE_ANIMATION = 1 -- Prevents player party animation being set to "frozen" at the start of a cutscene or "still" at the end
}

ChangeMapOptions = {
  DO_NOT_FADE         = 1, -- Prevents fading to and from black
  DO_NOT_CHANGE_MUSIC = 2  -- Prevents stopping or starting music as part of the map change
}

PathfindingOptions = {
  CARDINAL_DIRECTIONS_ONLY = 1
}

gamestate = {}

--- Yields until the specified amount of time has passed.
-- @param time in milliseconds
function Delay(time)
  while time > 0 do
    time = time - coroutine.yield()
  end
end

--- Starts a cutscene.
-- This takes care of showing the cutscene bars, as well as halting character
-- movement. It does not block. See CutsceneOptions for modifiers.
function StartCutscene(options)
  options = options or 0

  local playerId = getPlayerSprite()
  local playerSprite = getSprite(playerId)
  playerSprite.controllable = false
  character():halt(playerId)

  if (options & CutsceneOptions.DO_NOT_CHANGE_ANIMATION == 0) then
    SetPartyAnimation(playerId, "frozen")
  end

  message():displayCutsceneBars()

  local allSprites = getAllSprites()
  for k,v in pairs(allSprites) do
    getSprite(v).paused = true
  end
end

--- Queues a message for display.
-- Non-blocking! If you want to block until the message has been fully
-- revealed, use WaitForEndOfMessage().
-- @param msg the text of the message
-- @param name the name of the character speaking (leave blank to not show a character name)
-- @param type the SpeakerType for the character, which determines which beep sound is played, if any
function DisplayMessage(msg, name, type)
  message():displayMessage(msg, name, type)
end

--- Queues a choice prompt for the player.
-- This should be called after DisplayMessage(), as it is not valid for a choice
-- prompt to be the first line of the text box. This also does not block. You
-- should use WaitForEndOfMessage() after this.
-- @param one the text of the first option
-- @param two the text of the second option
function ShowChoice(one, two)
  message():showChoice(one, two)
end

--- Gets the result of the last choice prompt.
-- @return 0 for the left choice, 1 for the right choice
function GetChoiceSelection()
  return message():getChoiceSelection()
end

--- Yields until all queued messages / choice prompts have been dismissed.
-- This does not hide the cutscene bars, nor does it wait for them to hide.
function WaitForEndOfMessage()
  while (message().isMessageActive) do
    coroutine.yield()
  end
end

--- Hides the cutscene bars.
-- This also re-enables player movement. See CutsceneOptions for modifiers.
function HideCutsceneBars(options)
  options = options or 0

  WaitForEndOfMessage()
  message():hideCutsceneBars()

  local playerId = getPlayerSprite()
  local playerSprite = getSprite(playerId)
  playerSprite.controllable = true

  if (options & CutsceneOptions.DO_NOT_CHANGE_ANIMATION == 0) then
    SetPartyAnimation(playerId, "still")
  end

  local allSprites = getAllSprites()
  for k,v in pairs(allSprites) do
    getSprite(v).paused = false
  end
end

--- Unpauses a sprite's movement.
-- Use this during cutscenes to allow the sprite's movement to be controlled
-- either by the InputSystem or the BehaviourSystem.
function UnpauseSprite(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.paused = false
end

--- Re-pauses a sprite's movement.
-- Use this after UnpauseSprite() when you are done moving the sprite.
function PauseSprite(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.paused = true
end

function GetPosition(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  return sprite.loc
end

function SetPosition(spriteName, x, y)
  local spriteId = getSpriteByAlias(spriteName)
  transform():moveSprite(spriteId, vec2i.new(x, y))
end

--- Moves a sprite to the specified warp point.
function MoveSpriteToWarp(spriteName, warp)
  local spriteId = getSpriteByAlias(spriteName)
  local warpPos = getMap():getWarpPoint(warp)
  transform():moveSprite(spriteId, warpPos)
end

function SetDirection(spriteName, dir)
  local spriteId = getSpriteByAlias(spriteName)
  animation():setSpriteDirection(spriteId, dir)
end

function SetAnimation(spriteName, animName)
  local spriteId = getSpriteByAlias(spriteName)
  animation():setSpriteAnimation(spriteId, animName)
end

function WaitForAnimation(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  repeat
    coroutine.yield()
  until sprite.animFinished
end

function Halt(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  character():halt(spriteId)
end

function PlaySound(filename)
  mixer():playSound("../res/sfx/" .. filename)
end

function LoopSound(filename)
  return mixer():loopSound("../res/sfx/" .. filename)
end

function StopSound(soundId)
  mixer():stopChannel(soundId)
end

function FadeToBlack(length)
  effect():fadeScreen(length, 1.0)
  repeat
    coroutine.yield()
  until effect():isScreenFadeComplete()
end

function RemoveFadeout(length)
  effect():fadeScreen(length, 0.0)
  repeat
    coroutine.yield()
  until effect():isScreenFadeComplete()
end

function FadeMap(length, amount)
  effect():fadeMap(length, amount)
end

function WaitForMapFade()
  while not effect():isMapFadeComplete() do
    coroutine.yield()
  end
end

function ShakeCamera(period)
  effect():shakeCamera(period)
end

function StopShakingCamera()
  effect():stopShakingCamera()
end

function PanToSprite(spriteName, length)
  local spriteId = getSpriteByAlias(spriteName)
  camera():panToSprite(spriteId, length)
end

function WaitForPan()
  while camera():isPanning() do
    coroutine.yield()
  end
end

function CameraFollowSprite(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  camera():setFollowingSprite(spriteId)
  camera():unlockCamera()
end

function ReturnCamera(length)
  local playerId = getPlayerSprite()
  camera():panToSprite(playerId, length)

  while camera():isPanning() do
    coroutine.yield()
  end

  camera():setFollowingSprite(playerId)
  camera():unlockCamera()
end

function SetPartyDirection(spriteId, direction)
  animation():setSpriteDirection(spriteId, direction)

  local sprite = getSprite(spriteId)

  for i=1,#sprite.followers do
    animation():setSpriteDirection(sprite.followers[i], direction)
  end
end

function SetPartyAnimation(spriteId, animName)
  animation():setSpriteAnimation(spriteId, animName)

  local sprite = getSprite(spriteId)

  for i=1,#sprite.followers do
    animation():setSpriteAnimation(sprite.followers[i], animName)
  end
end

function ChangeMap(map, warp, options)
  options = options or 0

  local playerId = getPlayerSprite()
  local playerSprite = getSprite(playerId)
  local direction = playerSprite.dir

  DisablePlayerControl()
  if (options & ChangeMapOptions.DO_NOT_FADE == 0) then
    FadeToBlack(150)
  end
  loadMap(map)
  character():transplantParty(playerId, getMap():getWarpPoint(warp), direction)

  if (options & ChangeMapOptions.DO_NOT_CHANGE_MUSIC == 0) then
    if (mixer():isPlayingMusic() and not getMap():hasMusic()) then
      mixer():fadeoutMusic(150)
    elseif (getMap():hasMusic() and (not mixer():isPlayingMusic() or not (mixer():getPlayingTrack() == getMap():getMusic()))) then
      mixer():playMusic(getMap():getMusic(), 150)
    end
  end

  coroutine.yield()
  if (options & ChangeMapOptions.DO_NOT_FADE == 0) then
    RemoveFadeout(150)
  end
  EnablePlayerControl()
end

function CreateAnimatedSpriteAtPosition(alias, character, x, y, animName, direction, layer)
  local spriteId = emplaceSprite(alias)
  transform():initSprite(spriteId, x, y, layer)
  animation():initSprite(spriteId, "../res/sprites/" .. character .. "_anim.txt")
  animation():setSpriteDirection(spriteId, direction)
  animation():setSpriteAnimation(spriteId, animName)
end

function CreateAnimatedSpriteAtWarpPoint(alias, character, warp, animName, direction, layer)
  local spriteId = emplaceSprite(alias)
  local loc = getMap():getWarpPoint(warp)
  transform():initSprite(spriteId, loc:x(), loc:y(), layer)
  animation():initSprite(spriteId, "../res/sprites/" .. character .. "_anim.txt")
  animation():setSpriteDirection(spriteId, direction)
  animation():setSpriteAnimation(spriteId, animName)
end

function DestroyNamedSprite(alias)
  local spriteId = getSpriteByAlias(alias)
  destroySprite(spriteId)
end

function AliasForSpriteExpression(spriteName)
  return "expression (" .. spriteName .. ")"
end

function ShowExpression(spriteName, expression)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  local animFrame = sprite:getCurrentFrame()
  local x = sprite.loc:x()
  local y = sprite.loc:y() - animFrame.center:y()

  CreateAnimatedSpriteAtPosition(AliasForSpriteExpression(spriteName), "expression", x, y, expression, Direction.DOWN, SpriteLayer.ABOVE)
end

function RemoveExpression(spriteName)
  DestroyNamedSprite(AliasForSpriteExpression(spriteName))
end

--- Turns on clipping for the player.
-- This allows walking through solid objects. For debug only!
function StartClipping()
  local playerId = getPlayerSprite()
  local playerSprite = getSprite(playerId)
  playerSprite.clipping = true
end

--- Turns off clipping for the player.
-- For debug only!
function StopClipping()
  local playerId = getPlayerSprite()
  local playerSprite = getSprite(playerId)
  playerSprite.clipping = false
end

--- Turns off crouching (and thus running) for the player.
function PreventCrouching()
  local playerId = getPlayerSprite()
  local playerSprite = getSprite(playerId)
  playerSprite.cantCrouch = true
end

--- Undoes the effect of PreventCrouching().
function AllowCrouching()
  local playerId = getPlayerSprite()
  local playerSprite = getSprite(playerId)
  playerSprite.cantCrouch = false
end

--- Makes a sprite start bobbing up and down (for underwater).
-- This only applies when the sprite is on a normal medium (so, not on ladders).
function StartBobbing(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.bobsWhenNormal = true
end

--- Makes a sprite stop bobbing up and down.
function StopBobbing(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.bobsWhenNormal = false
end

--- Sets the animation slowdown for a sprite.
-- @param spriteName the alias of the sprite to modify
-- @param amount the number of animation frames needed to advance the sprite's animation (1 means the effect is disabled)
function SetAnimationSlowdown(spriteName, amount)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.animSlowdown = amount
end

--- Sets the opacity of the sprite when it is rendered.
-- @param spriteName the alias of the sprite to modify
-- @param amount a value from 0.0 to 1.0
function SetOpacity(spriteName, amount)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.opacity = amount
end

--- Fades out the given sprite.
function FadeOutSprite(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.shouldBeFadedIn = false
end

--- Fades out the given sprite.
function FadeInSprite(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.shouldBeFadedIn = true
end

--- Sets the enclosure zone for a sprite.
-- The sprite will be prevented from exiting the area defined by that zone.
function AddEnclosureZone(spriteName, zone)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.enclosureZone = zone
end

--- Removes the enclosure zone for the specified sprite.
-- This allows the sprite to move outside of the confines of the zone.
function RemoveEnclosureZone(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.enclosureZone = ""
end

--- Set a sprite on a path to the specified location.
function DirectSpriteToLocation(spriteName, warpPoint, options)
  options = options or 0

  local spriteId = getSpriteByAlias(spriteName)
  local dest = getMap():getWarpPoint(warpPoint)

  behaviour():directSpriteToLocation(spriteId, dest, options)
end

--- Blocks until the specified sprite has completed their path.
function WaitForSpritePath(spriteName)
  local spriteId = getSpriteByAlias(spriteName)

  while (behaviour():isFollowingPath(spriteId)) do
    coroutine.yield()
  end
end

--- Sets a sprite to wander.
function StartWandering(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.behaviourType = BehaviourType.WANDER
end

--- Turns off the sprite's behaviour.
function DisableBehaviour(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.behaviourType = BehaviourType.NONE
end

--- Directs a sprite to start following a target sprite.
function FollowSprite(spriteName, targetName)
  local spriteId = getSpriteByAlias(spriteName)
  local targetId = getSpriteByAlias(targetName)
  local sprite = getSprite(spriteId)
  sprite.followSpriteId = targetId
  sprite.behaviourType = BehaviourType.FOLLOW
end

--- Makes a sprite stop following whatever sprite it was following.
function StopFollowingSprite(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.followSpriteId = -1
  sprite.behaviourType = BehaviourType.NONE
end

--- Fades out the currently playing music.
-- This does not block. If you want it to block, call Delay for the same amount
-- of time.
-- @param length the fadeout time in milliseconds
function FadeoutMusic(length)
  mixer():fadeoutMusic(length)
end

--- Plays the specified track.
-- @param song the name of the song to play
-- @param length the time in milliseconds to fade in. if left blank, the track starts immediately
function PlayMusic(song, length)
  length = length or 0

  mixer():playMusic(song, length)
end

--- Makes the player sprite non-controllable.
function DisablePlayerControl()
  local playerId = getPlayerSprite()
  local playerSprite = getSprite(playerId)
  playerSprite.controllable = false
end

--- Makes the player sprite controllable again.
function EnablePlayerControl()
  local playerId = getPlayerSprite()
  local playerSprite = getSprite(playerId)
  playerSprite.controllable = true
end

--- Makes the specified sprite face toward the †arget sprite.
-- This version of the function uses any of the eight directions.
-- @param spriteName the name of the sprite to change the direction of
-- @param targetName the name of the sprite to face toward
function FaceTowardSprite(spriteName, targetName)
  local spriteId = getSpriteByAlias(spriteName)
  local targetId = getSpriteByAlias(targetName)
  local sprite = getSprite(spriteId)
  local target = getSprite(targetId)
  local diff = vec2i.new(target.loc:x() - sprite.loc:x(), target.loc:y() - sprite.loc:y())
  local dir = directionFacingPoint(diff)

  SetDirection(spriteName, dir)
end

--- Makes the specified sprite's entire party face toward the †arget sprite.
-- This version of the function uses any of the eight directions.
-- @param spriteName the name of the sprite to change the direction of
-- @param targetName the name of the sprite to face toward
function FacePartyTowardSprite(spriteName, targetName)
  FaceTowardSprite(spriteName, targetName)

  local sprite = getSprite(getSpriteByAlias(spriteName))

  for i=1,#sprite.followers do
    local follower = getSprite(sprite.followers[i])
    FaceTowardSprite(follower.alias, targetName)
  end
end

--- Makes the specified sprite face toward the †arget sprite.
-- This version of the function uses the closest cardinal direction.
-- @param spriteName the name of the sprite to change the direction of
-- @param targetName the name of the sprite to face toward
function FaceTowardSpriteCardinally(spriteName, targetName)
  local spriteId = getSpriteByAlias(spriteName)
  local targetId = getSpriteByAlias(targetName)
  local sprite = getSprite(spriteId)
  local target = getSprite(targetId)
  local diff = vec2i.new(target.loc:x() - sprite.loc:x(), target.loc:y() - sprite.loc:y())
  local dir = cardinalDirectionFacingPoint(diff)

  SetDirection(spriteName, dir)
end

--- Detaches the sprite's followers and erases their following trails.
function BreakUpParty(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  character():breakUpParty(spriteId)
end

--- Makes the specified sprite solid.
-- This means that other sprites will be blocked if they collide with this one.
function MakeSpriteSolid(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.solid = true
end

--- Makes the specified sprite not solid.
-- This means that other sprites will not be blocked if they collide with this
-- one.
function MakeSpriteNotSolid(spriteName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.solid = false
end

--- Sets the sprite's movement speed.
-- As a reference: 1 is slow (good for NPCs), 2 is Lucas's default walking speed
function SetMovementSpeed(spriteName, speed)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.movementSpeed = speed
end

--- Performs the beginning of the exit area transition.
-- This does the circle effect and plays the sound effect. The circle effect
-- then gets removed and replaced with a screen fade.
function ExitAreaTransition()
  DisablePlayerControl()
  --character():halt(getPlayerSprite())
  coroutine.yield()
  PlaySound("exit_area.wav")
  FadeoutMusic(679)
  effect():circleTransition(679, 1.0)
  while not effect():isCircleTransitionComplete() do
    coroutine.yield()
  end
  character():halt(getPlayerSprite())
  FadeToBlack(1)
  effect():circleTransition(1, 0.0)
  Delay(1000)
end

--- Checks whether a sprite is in a zone.
-- @param spriteName the name of the sprite to locate
-- @param zoneName the name of the zone on the current map to use as a boundary
function IsSpriteInZone(spriteName, zoneName)
  local pos = GetPosition(spriteName)
  local zone = getMap():getZone(zoneName)

  return (pos:x() >= zone.ul:x()) and (pos:x() <= zone.dr:x()) and (pos:y() >= zone.ul:y()) and (pos:y() <= zone.dr:y())
end

--- Sets the name of the script on the current map that will be executed when the player interacts with this sprite.
function SetInteractionScript(spriteName, scriptName)
  local spriteId = getSpriteByAlias(spriteName)
  local sprite = getSprite(spriteId)
  sprite.interactionScript = scriptName
end