#!/usr/bin/env python3
"""Generate independent PDFium/Poppler comparison evidence.
Requires the built pdf-worker-evidence target, Pillow and Poppler utils.
The result is comparison evidence; it is not a human-approved golden image.
"""
import argparse
import hashlib
import json
import os
from pathlib import Path
import shutil
import subprocess
from PIL import Image, ImageChops, ImageDraw

root = Path(__file__).resolve().parent.parent
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument('--build-dir', type=Path, default=root / os.environ.get('DOCVIEW_BUILD_DIR', 'build'))
parser.add_argument('--output', type=Path, default=root / 'tests/results/pdf')
args = parser.parse_args()
build = args.build_dir.resolve()
out = args.output.resolve()
out.mkdir(parents=True, exist_ok=True)
helper = build / 'pdf-worker-evidence'
if not helper.is_file(): raise SystemExit('Build the pdf-worker-evidence target before comparison.')
fixture = root / 'tests/fixtures/pdf/navigation.pdf'
subprocess.run([str(helper), str(fixture), str(out / 'worker')], check=True)
shutil.copyfile(out / 'worker/page-1.png', out / 'pdfium.png')
poppler = '/usr/bin/pdftoppm' if Path('/usr/bin/pdftoppm').exists() else shutil.which('pdftoppm')
if not poppler: raise SystemExit('Poppler pdftoppm is required for the independent comparison.')
subprocess.run([poppler, '-cropbox', '-f', '1', '-singlefile', '-r', '144', '-png', str(fixture), str(out / 'poppler')], check=True)
a = Image.open(out / 'pdfium.png').convert('RGB')
b = Image.open(out / 'poppler.png').convert('RGB')
if a.size != b.size: raise SystemExit('Renderer dimensions disagree.')
diff = ImageChops.difference(a, b)
diff.save(out / 'difference.png')
pixels = list(diff.getdata()); count = len(pixels)
metrics = {'transport': 'production sandboxed PDF worker and FontBroker', 'worker_sha256': hashlib.sha256((build / 'docview-pdf-worker').read_bytes()).hexdigest(), 'broker_sha256': hashlib.sha256((build / 'libdocview_font_broker.a').read_bytes()).hexdigest(), 'fixture_sha256': hashlib.sha256(fixture.read_bytes()).hexdigest(), 'size': list(a.size), 'pixels': count,
    'equal_pixels': sum(max(p) == 0 for p in pixels), 'pixels_max_delta_gt_16': sum(max(p) > 16 for p in pixels),
    'mean_absolute_channel_error': sum(sum(p) for p in pixels) / (count * 3),
    'reference_status': 'independent Poppler comparison, not human-approved golden image'}
(out / 'comparison.json').write_text(json.dumps(metrics, indent=2) + '\n')
canvas = Image.new('RGB', (1200, 430), '#eeeeee'); draw = ImageDraw.Draw(canvas)
for x, label, image in [(0, 'PDFium 155.0.8057.0', a), (400, 'Poppler independent renderer', b), (800, 'Absolute RGB difference', diff)]:
    draw.text((x + 10, 9), label, fill='black'); canvas.paste(image, (x, 30))
canvas.save(out / 'comparison.png')
print(json.dumps(metrics, indent=2))