module AnimationEditor::ParticleDataHelper
  module_function

  def get_duration(particles)
    ret = 0
    particles.each do |p|
      p.each_pair do |cmd, val|
        next if !val.is_a?(Array) || val.length == 0
        max = val.last[0] + val.last[1]
        ret = max if ret < max
      end
    end
    return ret
  end

  def get_keyframe_particle_value(particle, frame, property)
    if !GameData::Animation::PARTICLE_KEYFRAME_DEFAULT_VALUES.include?(property)
      raise _INTL("Couldn't get default value for property {1} for particle {2}.",
                  property, particle[:name])
    end
    ret = [GameData::Animation::PARTICLE_KEYFRAME_DEFAULT_VALUES[property], false]
    if particle[property]
      # NOTE: The commands are already in keyframe order, so we can just run
      #       through them in order, applying their changes until we reach
      #       frame.
      particle[property].each do |cmd|
        break if cmd[0] > frame   # Command is in the future; no more is needed
        break if cmd[0] == frame && cmd[1] > 0   # Start of a "MoveXYZ" command; won't have changed yet
        if cmd[0] + cmd[1] <= frame   # Command has finished; use its end value
          ret[0] = cmd[2]
          next
        end
        # In a "MoveXYZ" command; need to interpolate
        ret[0] = lerp(ret[0], cmd[2], cmd[1], cmd[0], frame).to_i
        ret[1] = true   # Interpolating
        break
      end
    end
    # NOTE: Particles are assumed to be not visible at the start of the
    #       animation, and automatically become visible when the particle has
    #       its first command. This does not apply to the "User" and "Target"
    #       particles, which start the animation visible.
    if property == :visible
      first_cmd = (["User", "Target"].include?(particle[:name])) ? 0 : -1
      first_visible_cmd = -1
      particle.each_pair do |prop, value|
        next if !value.is_a?(Array) || value.length == 0
        first_cmd = value[0][0] if first_cmd < 0 || first_cmd > value[0][0]
        first_visible_cmd = value[0][0] if prop == :visible && (first_visible_cmd < 0 || first_visible_cmd > value[0][0])
      end
      ret[0] = true if first_cmd >= 0 && first_cmd <= frame &&
                       (first_visible_cmd < 0 || frame < first_visible_cmd)
    end
    echoln "here 2: #{ret}"
    return ret
  end

  def get_all_keyframe_particle_values(particle, frame)
    ret = {}
    GameData::Animation::PARTICLE_KEYFRAME_DEFAULT_VALUES.each_pair do |prop, default|
      ret[prop] = get_keyframe_particle_value(particle, frame, prop)
    end
    return ret
  end

  # TODO: Generalise this to any property?
  # NOTE: Particles are assumed to be not visible at the start of the
  #       animation, and automatically become visible when the particle has
  #       its first command. This does not apply to the "User" and "Target"
  #       particles, which start the animation visible. They do NOT become
  #       invisible automatically after their last command.
  def get_timeline_particle_visibilities(particle, duration)
    if !GameData::Animation::PARTICLE_KEYFRAME_DEFAULT_VALUES.include?(:visible)
      raise _INTL("Couldn't get default value for property {1} for particle {2}.",
                  property, particle[:name])
    end
    value = GameData::Animation::PARTICLE_KEYFRAME_DEFAULT_VALUES[:visible]
    value = true if ["User", "Target"].include?(particle[:name])
    ret = []
    if particle[:visible]
      particle[:visible].each { |cmd| ret[cmd[0]] = cmd[2] }
    end
    duration.times do |i|
      value = ret[i] if !ret[i].nil?
      ret[i] = value
    end
    return ret
  end

  #-----------------------------------------------------------------------------

  # Returns an array indicating where command diamonds and duration lines should
  # be drawn in the AnimationParticleList.
  def get_particle_commands_timeline(particle)
    ret = []
    durations = []
    particle.each_pair do |prop, val|
      next if !val.is_a?(Array)
      val.each do |cmd|
        ret[cmd[0]] = true
        if cmd[1] > 0
          ret[cmd[0] + cmd[1]] = true
          durations.push([cmd[0], cmd[1]])
        end
      end
    end
    return ret, durations
  end

  # Returns an array, whose indexes are keyframes, where the values in the array
  # are commands. A keyframe's value can be one of these:
  #   0   - SetXYZ
  #   [+/- duration, interpolation type] --- MoveXYZ (duration's sign is whether
  #                                          it makes the value higher or lower)
  def get_particle_property_commands_timeline(commands, property)
    return nil if !commands || commands.length == 0
    if !GameData::Animation::PARTICLE_KEYFRAME_DEFAULT_VALUES.include?(property)
      raise _INTL("No default value for property {1} in PARTICLE_KEYFRAME_DEFAULT_VALUES.", property)
    end
    ret = []
    val = GameData::Animation::PARTICLE_KEYFRAME_DEFAULT_VALUES[property]
    commands.each do |cmd|
      if cmd[1] > 0   # MoveXYZ
        dur = cmd[1]
        dur *= -1 if cmd[2] < val
        # TODO: Support multiple interpolation types here (will be cmd[3]).
        ret[cmd[0]] = [dur, cmd[3] || :linear]
        ret[cmd[0] + cmd[1]] = 0
      else   # SetXYZ
        ret[cmd[0]] = 0
      end
      val = cmd[2]   # New actual value
    end
    return ret
  end

end