#!/usr/bin/python3

# author: Ole Schuett

import ast
import argparse
import json
from time import time, sleep
import re
import os
import sys
import concurrent.futures
from subprocess import PIPE, STDOUT
import subprocess
import traceback
from urllib.request import urlopen, Request
from urllib.error import HTTPError
import uuid
from difflib import unified_diff
from pathlib import Path
import shutil

SCRATCH_DIR = Path("./obj/precommit")
CACHE_FILE = SCRATCH_DIR / "cache.json"
SERVER = os.environ.get("CP2K_PRECOMMIT_SERVER", "https://precommit.cp2k.org")


# ======================================================================================
def main():
    # Parse command line arguments.
    parser = argparse.ArgumentParser(
        description="Check source code for formatting and linter problems."
    )
    parser.add_argument(
        "-a",
        "--no-cache",
        action="store_true",
        help="ignore the cache and check all files",
    )
    parser.add_argument(
        "-m",
        "--allow-modifications",
        action="store_true",
        help="allow the tools to modify files",
    )
    parser.add_argument(
        "-j",
        "--num_workers",
        type=int,
        default=min(16, os.cpu_count() + 2),
        help="number of parallel workers",
    )
    parser.add_argument(
        "--progressbar-wait",
        metavar="SECONDS",
        type=int,
        default=1,
        help="number seconds in between progressbar updates",
    )
    parser.add_argument("files", metavar="FILE", nargs="*", help="files to process")
    args = parser.parse_args()

    # Say hello to the server.
    print(
        f"Running precommit checks using {args.num_workers} workers and server: {SERVER}"
    )
    server_hello = urlopen(Request(SERVER + "/"), timeout=10).read().decode("utf8")
    assert server_hello.startswith("cp2k precommit server")

    # Store candidate before changing base directory and creating scratch dir.
    candidate_file_list = [os.path.abspath(fn) for fn in args.files]
    base_dir = Path(__file__).parent.parent.parent.resolve()
    os.chdir(base_dir)
    SCRATCH_DIR.mkdir(parents=True, exist_ok=True)

    # Collect candidate files.
    if not candidate_file_list:
        sys.stdout.write("Searching for files...\r")
        sys.stdout.flush()
        for root, dirs, files in os.walk("."):
            if root.startswith("./tools/toolchain/build"):
                continue
            if root.startswith("./tools/toolchain/install"):
                continue
            if root.startswith("./tools/prettify/fprettify"):
                continue
            if root.startswith("./tools/build_utils/fypp"):
                continue
            if root.startswith("./tools/autotune_grid"):
                continue
            if root.startswith("./exts"):
                continue
            if root.startswith("./obj"):
                continue
            if root.startswith("./lib"):
                continue
            if root.startswith("./exe"):
                continue
            if root.startswith("./regtesting"):
                continue
            if root.startswith("./.git"):
                continue
            candidate_file_list += [os.path.join(root, fn) for fn in files]

    # Find eligible files and sort by size as larger ones will take longer to process.
    eligible_file_pattern = re.compile(r".*(_POTENTIALS|(\.(F|fypp|c|cu|h|py|md)))$")
    file_list = [fn for fn in candidate_file_list if eligible_file_pattern.match(fn)]
    file_list.sort(reverse=True, key=lambda fn: os.path.getsize(fn))

    # Load cache.
    should_load_cache = CACHE_FILE.exists() and not args.no_cache
    cache = json.loads(CACHE_FILE.read_text()) if should_load_cache else {}

    # Launch async processing of files.
    futures = {}
    executor = concurrent.futures.ThreadPoolExecutor(max_workers=args.num_workers)
    for fn in file_list:
        if os.path.getmtime(fn) != cache.get(fn, -1):
            futures[fn] = executor.submit(process_file, fn, args.allow_modifications)
    num_skipped = len(file_list) - len(futures)

    # Continuously update progressbar, save cache file, and print errors.
    failed_files = set()
    while True:
        num_done = num_skipped
        for fn, f in futures.items():
            if f.done():
                num_done += 1
                if not f.exception():
                    cache[fn] = os.path.getmtime(fn)
                elif fn not in failed_files:
                    failed_files.add(fn)
                    print_box(fn, str(f.exception()))
        CACHE_FILE.write_text(json.dumps(cache))
        progressbar = "=" * int(60 * num_done / len(file_list))
        sys.stdout.write(
            f"[{progressbar:60s}] {num_done} / {len(file_list)} files processed\r"
        )
        sys.stdout.flush()
        if num_done == len(file_list) or len(failed_files) >= 10:
            executor.shutdown(wait=False)
            break
        sleep(args.progressbar_wait)

    # Print final message.
    print(
        f"Summary: Found {len(file_list)}, "
        f"skipped {num_skipped}, "
        f"checked {num_done - num_skipped}, "
        f"and failed {len(failed_files)} files." + (" " * 50)
    )
    print("Status: " + ("FAILED" if failed_files else "OK"))
    sys.exit(len(failed_files))


# ======================================================================================
def print_box(fn, message):
    print("+" + "-" * 160 + "+")
    print(f"| {fn:^158s} |")
    print("+" + "-" * 160 + "+")
    for line in message.strip().split("\n"):
        print(f"| {line:<158s} |")
    print("+" + "-" * 160 + "+\n\n")


# ======================================================================================
def process_file(fn, allow_modifications):
    # Make a backup copy.
    orig_content = Path(fn).read_bytes()
    bak_fn = SCRATCH_DIR / f"{Path(fn).name}_{time()}.bak"
    shutil.copy2(fn, bak_fn)

    if re.match(r".*\.(F|fypp)$", fn):
        run_local_tool("./tools/doxify/doxify.sh", fn)
        run_prettify(fn)
        run_analyze_src(fn)

    elif re.match(r".*\.(c|cu|cpp|h|hpp)$", fn):
        run_remote_tool("clangformat", fn)
        run_analyze_src(fn)

    elif re.match(r".*\.py$", fn):
        ast.parse(orig_content, filename=fn)
        run_remote_tool("black", fn)
        run_analyze_src(fn)

    elif re.match(r".*\.sh$", fn):
        run_remote_tool("shellcheck", fn)

    elif re.match(r".*\.md$", fn):
        run_remote_tool("markdownlint", fn)

    elif re.match(r".*_POTENTIALS$", fn):
        run_local_tool("make", "data/POTENTIAL")

    else:
        raise Exception("Unknown file extension: " + fn)

    new_content = Path(fn).read_bytes()
    if new_content == orig_content:
        bak_fn.unlink()  # remove backup

    elif not allow_modifications:
        bak_fn.replace(fn)  # restore origin content
        try:
            orig_lines = orig_content.decode("utf8").split("\n")
            new_lines = new_content.decode("utf8").split("\n")
            diff = unified_diff(orig_lines, new_lines, "before", "after", lineterm="")
        except:
            diff = []  #
        raise Exception(f"File modified:\n" + "\n".join(diff))


# ======================================================================================
def run_prettify(fn):
    if fn in ("./src/base/base_uses.f90", "./src/common/util.F"):
        return  # Skipping because of prettify bugs.

    # The prettify tool processes only about 1k lines of code per second.
    # Hence, setting a generous timeout as our largest file has 100k lines.
    run_local_tool(
        "./tools/prettify/prettify.py", "--no-report-errors", fn, timeout=300
    )


# ======================================================================================
def run_analyze_src(fn):
    run_local_tool(
        "./tools/conventions/analyze_src.py",
        "--fail",
        "--suppressions",
        "./tools/conventions/conventions.supp",
        fn,
    )


# ======================================================================================
def run_local_tool(*cmd, timeout=20):
    p = subprocess.run(cmd, timeout=timeout, stdout=PIPE, stderr=STDOUT)
    if p.returncode != 0:
        raise Exception(p.stdout.decode("utf8"))


# ======================================================================================
def run_remote_tool(tool, fn):
    url = f"{SERVER}/{tool}"
    r = http_post(url, fn)
    if r.status == 304:
        pass  # file not modified
    elif r.status == 200:
        Path(fn).write_bytes(r.read())
    else:
        raise Exception(r.read().decode("utf8"))  # something went wrong


# ======================================================================================
def http_post(url, fn):
    # This would be so much easier with the Requests library where it'd be a one-liner:
    #    return requests.post(url, files={Path(fn).name: Path(fn).read_bytes()})

    boundary = uuid.uuid1().hex
    name = Path(fn).name
    data = b"".join(
        [
            f"--{boundary}\r\nContent-Disposition: ".encode("utf8"),
            f'form-data; name="{name}"; filename="{name}"\r\n\r\n'.encode("utf8"),
            Path(fn).read_bytes(),
            f"\r\n--{boundary}--\r\n".encode("utf8"),
        ]
    )
    headers = {
        "Content-Length": len(data),
        "Content-Type": f"multipart/form-data; boundary={boundary}",
    }
    try:
        return urlopen(Request(url, data=data, headers=headers), timeout=60)
    except HTTPError as err:
        return err  # HTTPError has .status and .read() just like a normal HTTPResponse.


# ======================================================================================
if __name__ == "__main__":
    main()

# EOF