import os
import secrets
from flask import Flask, abort, request, Response, url_for
from pygments.formatters.html import HtmlFormatter
from pygments import highlight
import pygments.lexers as lexers
import base64
import magic
import mimetypes

magic = magic.Magic(mime=True)

mit_license = """
Copyright (c) 2022 Immae

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""

config = {
        "directory": os.environ["PASTE_DIRECTORY"],
        "self_paste_id": "abcd123",
        "license_paste_id": "license",
        "max_content_length": 16 * 1000 * 1000
        }

app = Flask(__name__)
app.config['MAX_CONTENT_LENGTH'] = config["max_content_length"]

def file_location(paste_id):
    if paste_id == config["self_paste_id"]:
        return os.path.realpath(__file__)
    else:
        return os.path.join(config['directory'], paste_id + ".dat")

def read_paste(paste_id):
    file = file_location(paste_id)
    if os.path.isfile(file):
        content = open(file, "rb").read()
        mime = magic.from_buffer(content)
        if mime.startswith("text/x-script."):
            mime="text/plain"
        return (content, mime)
    elif paste_id == config["license_paste_id"]:
        return (mit_license, "text/plain")
    else:
        abort(404)

def generate_paste_id(n=3, attempts=0):
    path = secrets.token_hex(n)[:n]
    file = file_location(path)
    if os.path.isfile(file):
        attempts = attempts + 1
        if attempts > 5:
            n = n + 1
        return generate_paste_id(n, attempts)
    return path

@app.route('/', methods=["GET"])
def index():
    return Response('''<pre>
$ curl -X POST --data-binary @{self} {host}
{paste}

-> GET {paste}
   guesses mimetype
-> GET {paste}/raw
   text/plain
-> GET {paste}/bin
   application/octet-stream
-> GET {paste}/b64
   base64 encoded
-> GET {paste}/ub64
   tries to decode base64
-> GET {paste}/python
   pretty-print python (replace with anything known by pygments)
-> GET {paste}/guess
   pretty-print (language guessed by pygments)
-> GET {paste}/download
   force download of file
</pre>
<a href="{paste}/py">Get the source</a><br />
Software licensed under the terms of the <a href="{host}/license">MIT license</a>
'''.format(host=url_for('post_paste', _external=True, _scheme="https"),
                 paste=url_for('get_paste', _external=True, _scheme="https", paste_id=config["self_paste_id"]),
                 license=url_for('get_paste', _external=True, _scheme="https", paste_id=config["license_paste_id"]),
                 self=os.path.basename(__file__)
                 ), mimetype="text/html")

@app.route('/', methods=["POST"])
def post_paste():
    content = request.get_data()
    paste_id = generate_paste_id()
    with open(file_location(paste_id), "wb") as f:
        f.write(content)
    return url_for('get_paste', _external=True, _scheme="https", paste_id=paste_id) + "\n"


@app.route('/<paste_id>', methods=["GET"])
def get_paste(paste_id):
    content, mime = read_paste(paste_id)
    return Response(content, mimetype=mime)

@app.route('/<paste_id>/<lang>', methods=["GET"])
def get_paste_with(paste_id, lang):
    content, mime = read_paste(paste_id)
    if lang == "raw":
        return Response(content, mimetype="text/plain")
    elif lang == "bin":
        return Response(content, mimetype="application/octet-stream")
    elif lang == "b64":
        return Response(base64.encodebytes(content), mimetype="text/plain")
    elif lang == "download":
        extension = mimetypes.guess_extension(mime, strict=False)
        if extension is None:
            cd = "attachment"
        else:
            cd = 'attachment; filename="{}{}"'.format(paste_id, extension)
        return Response(content, mimetype=mime,
                headers={"Content-Disposition": cd})
    elif lang == "ub64":
        try:
            return base64.b64decode(content)
        except:
            abort(400)
    try:
        if lang == "guess":
            lexer = lexers.guess_lexer(content)
        else:
            lexer = lexers.find_lexer_class_by_name(lang)()
    except:
        abort(400)
    fmter = HtmlFormatter(
        noclasses=True, full=True, style="colorful", linenos="table")

    return Response(highlight(content, lexer, fmter), mimetype="text/html")