#!/usr/bin/env python3

import tempfile
import os
import sys


def main():
    try:
        from posix_parity import mergerfs_mount
        with mergerfs_mount() as (mount, _):
            (fd, filepath) = tempfile.mkstemp(dir=mount)

            try:
                test_data = b"passthrough io test data for create\n" * 100

                bytes_written = os.write(fd, test_data)
                if bytes_written != len(test_data):
                    print("create write failed: expected {} bytes, wrote {}".format(len(test_data), bytes_written))
                    return 1

                os.lseek(fd, 0, os.SEEK_SET)
                read_data = os.read(fd, len(test_data))
                if read_data != test_data:
                    print("create read failed: data mismatch")
                    return 1

                os.close(fd)
                fd = -1

                fd = os.open(filepath, os.O_RDWR)

                os.lseek(fd, 0, os.SEEK_SET)
                read_data = os.read(fd, len(test_data))
                if read_data != test_data:
                    print("open read failed: data mismatch")
                    return 1

                os.lseek(fd, 0, os.SEEK_END)
                more_data = b"additional passthrough data for open\n" * 50
                bytes_written = os.write(fd, more_data)
                if bytes_written != len(more_data):
                    print("open write failed: expected {} bytes, wrote {}".format(len(more_data), bytes_written))
                    return 1

                os.lseek(fd, 0, os.SEEK_SET)
                all_data = os.read(fd, len(test_data) + len(more_data))
                if all_data != test_data + more_data:
                    print("open final read failed: data mismatch")
                    return 1

                fd2 = os.open(filepath, os.O_RDWR)

                try:
                    os.lseek(fd2, 0, os.SEEK_SET)
                    read_data2 = os.read(fd2, len(test_data) + len(more_data))
                    if read_data2 != test_data + more_data:
                        print("second open read failed: data mismatch")
                        return 1

                    os.lseek(fd2, 0, os.SEEK_END)
                    extra_data = b"data from second file descriptor\n" * 25
                    bytes_written = os.write(fd2, extra_data)
                    if bytes_written != len(extra_data):
                        print("second open write failed: expected {} bytes, wrote {}".format(len(extra_data), bytes_written))
                        return 1

                    os.lseek(fd, 0, os.SEEK_SET)
                    combined_data = os.read(fd, len(test_data) + len(more_data) + len(extra_data))
                    expected_data = test_data + more_data + extra_data
                    if combined_data != expected_data:
                        print("cross-fd read failed: data mismatch (writes from fd2 not visible on fd)")
                        return 1
                finally:
                    os.close(fd2)

                fd3 = os.open(filepath, os.O_RDONLY)
                try:
                    os.lseek(fd3, 0, os.SEEK_SET)
                    read_data3 = os.read(fd3, len(expected_data))
                    if read_data3 != expected_data:
                        print("third open read failed: data mismatch")
                        return 1
                finally:
                    os.close(fd3)

                os.close(fd)
                fd = -1

                return 0
            finally:
                if fd >= 0:
                    os.close(fd)
                try:
                    os.unlink(filepath)
                except FileNotFoundError:
                    pass
    except RuntimeError as exc:
        print(str(exc), end="")
        return 77


if __name__ == "__main__":
    raise SystemExit(main())