#!/usr/bin/python

# Run a simple addition program on the WDR paper computer
# and output steps as PNGs

# Create GIF animation with ImageMagick:
# convert -delay 150 wdr_step*.png -loop 0 wdr.gif

from PIL import Image, ImageDraw, ImageFont

w, h = 800, 800
fnt = ImageFont.truetype('Courier Prime.ttf', 40)

# the paper computer program to run
prog = """# Add register 2 to register 1
1 jmp 4
2 inc 1
3 dec 2
4 isz 2
5 jmp 2
6 stp"""

# set up registers
reg = 10 * [0]
reg[1] = 5
reg[2] = 4

# set up program counter
pc = 1

pp = prog.splitlines()
step = 0

while True:
    ins = pp[pc].split()
    step += 1
    print(pp[pc])
    print(step, reg)

    # create output image for current step
    im = Image.new('RGBA', (w, h), (0,0,0))
    d = ImageDraw.Draw(im)
    for n, x in enumerate(pp):
        if pc == n:
            col = (255, 255, 255)
            s = "> "
        else:
            col = (0, 255, 0)
            s = "  "
        d.text((0, 50 * n), s + pp[n], font = fnt, fill = col, align = "left")
    for n in range(1, 3):
        d.text((0, 50 * (n + len(pp) + 2)), "REGISTER %u: %u" % (n, reg[n]), font = fnt, fill = (255, 255, 0), align = "left")
    d.text((0, 50 * (n + len(pp) + 4)), "PROGRAM STEP: %u" % step, font = fnt, fill = (255, 0, 0), align = "left")
    im.save("wdr_step%04u.png" % step)

    # carry out the current instruction
    if ins[1] == "stp":
        break
    if ins[1] == "isz":
        if reg[int(ins[2])] == 0:
            pc += 2
        else:
            pc += 1
        continue
    if ins[1] == "jmp":
        pc = int(ins[2])
        continue
    if ins[1] == "inc":
        reg[int(ins[2])] += 1
    if ins[1] == "dec":
        reg[int(ins[2])] -= 1

    pc += 1