"""Minimalistic EXIF Editor.

Commands overview:
    ls, get, set, del       operate with EXIF tags.
    cget, cset, cdel        operate with JSON in UserComment EXIF tag.

Usage:
    mee ls <file>
    mee get [-k <key>] <file>
    mee set -k <key> -v <value> <file> [-o <file>]
    mee del -k <key> <file> [-o <file>]
    mee cget [-k <key>] <file>
    mee cset -k <key> -v <value> <file> [-o <file>]
    mee cdel -k <key> <file> [-o <file>]
    mee (--help | --version)

Options:
    -o, --output <file>     output file. Same as input file by default.
    -k, --key <key>         set EXIF/JSON key.
    -v, --value <value>     EXIF/JSON key value.
    --help                  print this message and exit.
    --version               print version and exit.
"""

__version__ = "0.1.0"

import re
import sys
import json
from tempfile import NamedTemporaryFile
from typing import Optional
from pathlib import Path

from docopt import docopt
from exif import Image


def open_image(infile: Path) -> Image:
    with open(infile, "rb") as in_img:
        return Image(in_img)


def commit_image(img: Image, infile: Path = None, outfile: Path = None) -> None:
    if not outfile:
        with NamedTemporaryFile(suffix="~") as out_tmp, open(infile, "wb") as out_img:
            out_tmp.write(img.get_file())
            out_tmp.seek(0)
            out_img.write(out_tmp.read())
    else:
        with open(outfile, "wb") as out_img:
            out_img.write(img.get_file())


def get_exif(key: str, infile: Path, echo: bool = True) -> None:
    image = open_image(infile)
    value = image.get(key, "n/a")
    if echo:
        print(f"{key}: {value}")
    else:
        return value


def ls_exif(infile: Path) -> None:
    image = open_image(infile)
    tags = image.list_all()
    print(tags)


def set_exif(key: str, value: str, infile: Path, outfile: Path = None) -> None:
    image = open_image(infile)
    image.set(key, value)
    commit_image(image, infile, outfile)


def del_exif(key: str, infile: Path, outfile: Path = None) -> None:
    image = open_image(infile)
    image.delete(key)
    commit_image(image, infile, outfile)


def get_user_comment(infile: Path) -> dict:
    user_comment = get_exif("user_comment", infile, echo=False)
    try:
        return json.loads(user_comment)
    except (TypeError, json.JSONDecodeError):
        return {}


def get_json(infile: Path, key: str = None) -> None:
    user_comment = get_user_comment(infile)
    if key:
        try:
            print(user_comment[key])
        except KeyError as e:
            sys.exit(f"No key: {e}")
    else:
        print(json.dumps(user_comment, indent=4, sort_keys=True))


def mod_json(key: str, value: str, infile: Path, outfile: Path = None, delete: bool = False) -> None:
    user_comment = get_user_comment(infile)
    if delete:
        del user_comment[key]
    else:
        user_comment[key] = value
    try:
        del_exif("user_comment", infile, outfile)
    except AttributeError:
        pass
    set_exif("user_comment", json.dumps(user_comment), infile, outfile)


def cli() -> None:
    args = docopt(__doc__, version=__version__)
    key = args["--key"]
    value = args["--value"]
    infile = args['<file>']
    outfile = args['--output']

    if args['ls']:
        ls_exif(infile)

    if args['get']:
        if not key:
            ls_exif(infile)
        else:
            get_exif(key, infile)

    if args["set"]:
        set_exif(key, value, infile, outfile)

    if args['del']:
        del_exif(key, infile, outfile)

    if args['cget']:
        get_json(infile, key)

    if args["cset"]:
        mod_json(key, value, infile, outfile)

    if args['cdel']:
        mod_json(key, None, infile, outfile, delete=True)


if __name__ == "__main__":
    cli()