import os
import subprocess
import sys

DELIMITER = " "
HOME = os.environ[list(filter(lambda k: k.lower() == "userprofile", os.environ.keys()))[0]]
os.environ["HOME"] = HOME

os.chdir(HOME)


class State:
    running = True


def cwd_name():
    cwd = os.getcwd()
    if cwd == os.environ["HOME"]:
        return "~"

    return os.path.basename(cwd)


def cmd_exit():
    State.running = False
    print("Goodbye")


def cmd_pwd():
    print(os.path.abspath(os.getcwd()))


def cmd_ls():
    cwd = os.path.abspath(os.getcwd())
    print(f"Listing the contents of {cwd}\n")

    listing = os.listdir(cwd)

    if len(listing) > 0:
        for file in listing:
            path = os.path.join(cwd, file)
            stat = os.stat(path)

            type_str = "?"
            if os.path.isfile(path):
                type_str = "f"

            elif os.path.isdir(path):
                type_str = "d"

            print(f"{type_str} {file if len(file) < 60 else file[:57] + '...'} ({stat.st_size / 1024 / 1024} MiB)")

    else:
        print("Directory is empty!", file=sys.stderr)


def cmd_cd(target):
    cwd = os.path.abspath(os.getcwd())
    target_path = os.path.join(cwd, target)
    target_path = os.path.abspath(target_path)

    if os.path.exists(target_path):
        os.chdir(target_path)
        return

    possible_targets = list(filter(lambda path: path.startswith(target), os.listdir(cwd)))

    if len(possible_targets) > 1:
        print(f"Multiple possible targets to cd into:{str(possible_targets)}", file=sys.stderr)
        return

    if len(possible_targets) == 1:
        cmd_cd(possible_targets[0])
        return

    print(f"Could not cd to {target}, it does not exist!", file=sys.stderr)


def cmd_cat(*files):
    output = []
    for file in files:
        path = os.path.join(os.path.abspath(os.getcwd()), file)

        with open(path, "rb") as fp:
            output.append(fp.read().decode("UTF-8"))

    print("".join(output))


BUILTIN_COMMANDS = {
    "exit": cmd_exit,
    "pwd": cmd_pwd,
    "ls": cmd_ls,
    "dir": cmd_ls,
    "cd": cmd_cd,
    "cat": cmd_cat
}

while State.running:
    prompt = f"{cwd_name()} -> "
    command = input(prompt).split(DELIMITER)
    command, arguments = command[0], command[1:]

    if not command:
        continue

    else:
        try:
            if command in BUILTIN_COMMANDS:
                BUILTIN_COMMANDS[command](*arguments)

            else:
                subprocess.check_call([command, *arguments])

        except Exception as e:
            print(e, file=sys.stderr)