import argparse
import datetime
import difflib
import subprocess
import sys
import tempfile
from pathlib import Path

parser = argparse.ArgumentParser(description="Process some integers.")
parser.add_argument("src", default="src", type=Path, help="src directory", nargs="?")
parser.add_argument(
    "tests", default="tests", type=Path, help="tests directory", nargs="?"
)
args = parser.parse_args()


def make_log_file():
    time = datetime.datetime.now().strftime("%Y-%m-%d_%H-%M-%S")
    return (args.tests / time).with_suffix(".log")


def log_new_test(in_path):
    global LOG_FILE
    with open(LOG_FILE, "a") as f:
        f.write("# ======================================\n")
        f.write(f"# Test: {in_path}\n")
        f.write("# ======================================\n")


def log_message(message):
    global LOG_FILE
    with open(LOG_FILE, "a") as f:
        f.write(message)
        f.write("\n")


def log_return(ret):
    if ret[0]:
        log_message("Passed")
    else:
        log_message(f"Error: {ret[1]}")

    log_message("# ======================================\n")
    return ret


def attempt_decode(out):
    try:
        return out.decode("utf-8")
    except UnicodeDecodeError:
        return "Invalid utf-8 in output"


def diff_files(file1, file2):
    with open(file1, "r") as f1, open(file2, "r") as f2:
        diff = difflib.unified_diff(
            f1.readlines(),
            f2.readlines(),
            fromfile=str(file1),
            tofile=str(file2),
        )
        return "".join(diff)


def run_test(exe_path, in_path):
    expected_file = in_path.with_suffix(".out")
    log_new_test(in_path)

    with tempfile.TemporaryDirectory() as tmp:
        temp = Path(tmp)
        out_path = temp / "output"

        test = subprocess.Popen(
            [sys.executable, str(exe_path), str(in_path), "--out", str(out_path)],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.PIPE,
        )

        try:
            _, stderr = test.communicate(1)
        except subprocess.TimeoutExpired:
            return [False, "Timed out"]

        if test.returncode != 0:
            log_message(attempt_decode(stderr))
            return log_return(
                [
                    False,
                    f"Expected returncode 0 got: {test.returncode}",
                ]
            )

        diff = diff_files(expected_file, out_path)

        if diff != "":
            log_message(diff)
            return log_return([False, "Output did not match"])

    return log_return([True])


if __name__ == "__main__":
    LOG_FILE = make_log_file()
    PASS_MESSAGE = "✅ Passed"
    ERROR_MESSAGE = "❌ Error:"

    tests = list(Path(args.tests).glob("**/*.in"))
    max_len = max(len(str(t)) for t in tests)

    for test in tests:
        print(f"{test}...", end="")
        res = run_test(args.src / "main.py", test)

        if res[0]:
            dots = 80 - len(str(test)) - 3 - len(PASS_MESSAGE)

            if dots > 0:
                print("." * dots, end="")
            print(PASS_MESSAGE)
        else:
            dots = 80 - len(str(test)) - 3 - len(ERROR_MESSAGE) - len(res[1])

            if dots > 0:
                print("." * dots, end="")
            print(f"{ERROR_MESSAGE} {res[1]}")

    print(f"Log file at: {LOG_FILE}")