#!/usr/bin/env cabal
{- cabal:
build-depends: base
            , reanimate
            , reanimate-svg
            , JuicyPixels
-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecursiveDo       #-}
module Main (main) where

import           Codec.Picture
import           Control.Lens
import           Control.Monad    (forM_)
import           Graphics.SvgTree (Tree)
import           Reanimate

main :: IO ()
main = reanimate $ bg `parA` mainScene
  where
    bg = animate $ const $ mkBackgroundPixel (PixelRGBA8 252 252 252 0xFF)

mainScene :: Animation
mainScene = scene $ mdo
    play $ drawCircle
      & setDuration drawCircleT
      & applyE (constE flipXAxis)
      & signalA (curveS 2)
    fork $ play $ drawCircle
      & freezeAtPercentage 1
      & setDuration rotDur
    rotDur <- withSceneDuration $ waitOn $
      forM_ svgs $ \svg -> do
        fork $ play $ drawTick
          & setDuration rotateT
          & repeatA rotateN
          & applyE (overBeginning 0.5 drawInE)
          & applyE (overEnding 0.5 drawOutE)
        fork $ play $ drawSVG svg
          & setDuration rotateT
          & repeatA rotateN
          & applyE (overBeginning rotateT drawInE)
          & applyE (delayE rotateT $ overBeginning 1 fillInE)
          & applyE (overEnding 0.5 fadeOutE)
        wait (rotateT / fromIntegral (1+length svgs))
    play $ drawCircle
      & setDuration drawCircleT
      & reverseA
      & signalA (curveS 2)
    return ()
  where
    drawCircleT = 2.5
    rotateT     = 5
    rotateN     = 3

    svgCAF = center $ latex "\\LaTeX"
    getNth n = snd (splitGlyphs [n] svgCAF)
    svgs = [
        withStrokeWidth defaultStrokeWidth $
        scale 2 $
        translate 0 (tickLength*2) $
        withStrokeColor "black" $
        withFillColor "black" $
        center $ getNth n
      | n <- [0..4]]

radius, tickLength :: Double
radius = 1.25
tickLength = 0.25

drawCircle :: Animation
drawCircle = animate $ \t ->
    withFillOpacity 0 $
    withStrokeColor "black" $
    rotate (-90) $
    partialSvg t circPath
  where
    circPath = pathify $ mkCircle radius

drawTick :: Animation
drawTick = drawSVG $ mkLine (0, 0) (0, tickLength)

drawSVG :: Tree -> Animation
drawSVG svg = animate $ \t ->
    withStrokeColor "black" $
    rotate (t*360) $
    translate 0 radius $
    svg