#!/usr/bin/env python3
"""Fetch only the fixed Linux GN, Clang and sysroot inputs for the isolated build."""
from concurrent.futures import ThreadPoolExecutor
import hashlib
import json
from pathlib import Path
import time
import urllib.request

ROOT=Path(__file__).resolve().parents[2]


def sha(path):
    with path.open('rb') as stream: return hashlib.file_digest(stream,'sha256').hexdigest()


def main():
    pins=json.loads((ROOT/'tests/results/source-correspondence/pdfium/dependency-pins.json').read_text())
    source=ROOT/'build-pdfium-intent/source'
    clang=next(row for row in pins['root']['deps']['third_party/llvm-build/Release+Asserts']['objects']
               if row['object_name'].startswith('Linux_x64/clang-llvmorg-'))
    sysroot=json.loads((source/'build/linux/sysroot_scripts/sysroots.json').read_text())['bullseye_amd64']
    gn_version=pins['root']['vars']['gn_version']
    inputs=[{'name':'clang.tar.xz','url':'https://commondatastorage.googleapis.com/chromium-browser-clang/'+clang['object_name']+'?generation='+str(clang['generation']),
             'expectedSha256':clang['sha256sum'],'expectedBytes':clang['size_bytes']},
            {'name':'sysroot.tar.xz','url':sysroot['URL']+'/'+sysroot['Sha256Sum'],'expectedSha256':sysroot['Sha256Sum']},
            {'name':'gn.zip','url':'https://chrome-infra-packages.appspot.com/dl/gn/gn/linux-amd64/+/'+gn_version,
             'cipdPackage':'gn/gn/linux-amd64','cipdVersion':gn_version}]
    cache=ROOT/'build-pdfium-intent/downloads'; cache.mkdir(parents=True,exist_ok=False)
    def fetch(row):
        path=cache/row['name']; total=0; started=time.monotonic()
        with urllib.request.urlopen(row['url'],timeout=60) as response, path.open('xb') as stream:
            content_length=response.headers.get('Content-Length')
            if content_length: assert int(content_length)<=512*1024**2
            for chunk in iter(lambda:response.read(1024*1024),b''):
                total+=len(chunk)
                assert total<=512*1024**2 and time.monotonic()-started<=600
                stream.write(chunk)
        digest=sha(path)
        if 'expectedSha256' in row: assert row['expectedSha256']==digest
        if 'expectedBytes' in row: assert row['expectedBytes']==total
        print(row['name']+' '+str(total)+' bytes; SHA-256 '+digest,flush=True)
        return {**row,'path':str(path.relative_to(ROOT)),'bytes':total,'sha256':digest}
    with ThreadPoolExecutor(max_workers=3) as pool: rows=list(pool.map(fetch,inputs))
    record={'success':True,'fetcherSha256':sha(Path(__file__)),'inputs':rows,
            'scope':'Clang and sysroot checked against source-pinned SHA-256. GN fetched from the official CIPD fixed Git-revision selector; archive SHA-256 recorded. No downloaded executable or installer has been run.'}
    (ROOT/'tests/results/pdfium-intent-build/tool-downloads.json').write_text(json.dumps(record,indent=2)+'\n')


if __name__=='__main__':main()