#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""
    Copyright © 2020 Mia Herkt
    Licensed under the EUPL, Version 1.2 or - as soon as approved
    by the European Commission - subsequent versions of the EUPL
    (the "License");
    You may not use this work except in compliance with the License.
    You may obtain a copy of the license at:

        https://joinup.ec.europa.eu/software/page/eupl

    Unless required by applicable law or agreed to in writing,
    software distributed under the License is distributed on an
    "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
    either express or implied.
    See the License for the specific language governing permissions
    and limitations under the License.
"""

from flask import Flask, abort, escape, make_response, redirect, request, send_from_directory, url_for, Response
from flask_sqlalchemy import SQLAlchemy
from flask_script import Manager
from flask_migrate import Migrate, MigrateCommand
from hashlib import sha256
from humanize import naturalsize
from magic import Magic
from mimetypes import guess_extension
import os, sys
import requests
from short_url import UrlEncoder
from validators import url as url_valid

app = Flask(__name__)
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False

app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///db.sqlite" # "postgresql://0x0@/0x0"
app.config["PREFERRED_URL_SCHEME"] = "https" # nginx users: make sure to have 'uwsgi_param UWSGI_SCHEME $scheme;' in your config
app.config["MAX_CONTENT_LENGTH"] = 256 * 1024 * 1024
app.config["MAX_URL_LENGTH"] = 4096
app.config["FHOST_STORAGE_PATH"] = "up"
app.config["FHOST_USE_X_ACCEL_REDIRECT"] = True # expect nginx by default
app.config["USE_X_SENDFILE"] = False
app.config["FHOST_EXT_OVERRIDE"] = {
    "audio/flac" : ".flac",
    "image/gif" : ".gif",
    "image/jpeg" : ".jpg",
    "image/png" : ".png",
    "image/svg+xml" : ".svg",
    "video/webm" : ".webm",
    "video/x-matroska" : ".mkv",
    "application/octet-stream" : ".bin",
    "text/plain" : ".txt",
    "text/x-diff" : ".diff",
}

# default blacklist to avoid AV mafia extortion
app.config["FHOST_MIME_BLACKLIST"] = [
    "application/x-dosexec",
    "application/java-archive",
    "application/java-vm"
]

app.config["FHOST_UPLOAD_BLACKLIST"] = "tornodes.txt"

app.config["NSFW_DETECT"] = False
app.config["NSFW_THRESHOLD"] = 0.608

if app.config["NSFW_DETECT"]:
    from nsfw_detect import NSFWDetector
    nsfw = NSFWDetector()

try:
    mimedetect = Magic(mime=True, mime_encoding=False)
except:
    print("""Error: You have installed the wrong version of the 'magic' module.
Please install python-magic.""")
    sys.exit(1)

if not os.path.exists(app.config["FHOST_STORAGE_PATH"]):
    os.mkdir(app.config["FHOST_STORAGE_PATH"])

db = SQLAlchemy(app)
migrate = Migrate(app, db)

manager = Manager(app)
manager.add_command("db", MigrateCommand)

su = UrlEncoder(alphabet='DEQhd2uFteibPwq0SWBInTpA_jcZL5GKz3YCR14Ulk87Jors9vNHgfaOmMXy6Vx-', block_size=16)

class URL(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    url = db.Column(db.UnicodeText, unique = True)

    def __init__(self, url):
        self.url = url

    def getname(self):
        return su.enbase(self.id, 1)

    def geturl(self):
        return url_for("get", path=self.getname(), _external=True) + "\n"

class File(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    sha256 = db.Column(db.String, unique = True)
    ext = db.Column(db.UnicodeText)
    mime = db.Column(db.UnicodeText)
    addr = db.Column(db.UnicodeText)
    removed = db.Column(db.Boolean, default=False)
    nsfw_score = db.Column(db.Float)

    def __init__(self, sha256, ext, mime, addr, nsfw_score):
        self.sha256 = sha256
        self.ext = ext
        self.mime = mime
        self.addr = addr
        self.nsfw_score = nsfw_score

    def getname(self):
        return u"{0}{1}".format(su.enbase(self.id, 1), self.ext)

    def geturl(self):
        n = self.getname()

        if self.nsfw_score and self.nsfw_score > app.config["NSFW_THRESHOLD"]:
            return url_for("get", path=n, _external=True, _anchor="nsfw") + "\n"
        else:
            return url_for("get", path=n, _external=True) + "\n"

    def pprint(self):
        print("url: {}".format(self.getname()))
        vals = vars(self)

        for v in vals:
            if not v.startswith("_sa"):
                print("{}: {}".format(v, vals[v]))

def getpath(fn):
    return os.path.join(app.config["FHOST_STORAGE_PATH"], fn)

def fhost_url(scheme=None):
    if not scheme:
        return url_for(".fhost", _external=True).rstrip("/")
    else:
        return url_for(".fhost", _external=True, _scheme=scheme).rstrip("/")

def is_fhost_url(url):
    return url.startswith(fhost_url()) or url.startswith(fhost_url("https"))

def shorten(url):
    if len(url) > app.config["MAX_URL_LENGTH"]:
        abort(414)

    if not url_valid(url) or is_fhost_url(url) or "\n" in url:
        abort(400)

    existing = URL.query.filter_by(url=url).first()

    if existing:
        return existing.geturl()
    else:
        u = URL(url)
        db.session.add(u)
        db.session.commit()

        return u.geturl()

def in_upload_bl(addr):
    if os.path.isfile(app.config["FHOST_UPLOAD_BLACKLIST"]):
        with open(app.config["FHOST_UPLOAD_BLACKLIST"], "r") as bl:
            check = addr.lstrip("::ffff:")
            for l in bl.readlines():
                if not l.startswith("#"):
                    if check == l.rstrip():
                        return True

    return False

def store_file(f, addr):
    if in_upload_bl(addr):
        return "Your host is blocked from uploading files.\n", 451

    data = f.stream.read()
    digest = sha256(data).hexdigest()
    existing = File.query.filter_by(sha256=digest).first()

    if existing:
        if existing.removed:
            return legal()

        epath = getpath(existing.sha256)

        if not os.path.exists(epath):
            with open(epath, "wb") as of:
                of.write(data)

        if existing.nsfw_score == None:
            if app.config["NSFW_DETECT"]:
                existing.nsfw_score = nsfw.detect(epath)

        os.utime(epath, None)
        existing.addr = addr
        db.session.commit()

        return existing.geturl()
    else:
        guessmime = mimedetect.from_buffer(data)

        if not f.content_type or not "/" in f.content_type or f.content_type == "application/octet-stream":
            mime = guessmime
        else:
            mime = f.content_type

        if mime in app.config["FHOST_MIME_BLACKLIST"] or guessmime in app.config["FHOST_MIME_BLACKLIST"]:
            abort(415)

        if mime.startswith("text/") and not "charset" in mime:
            mime += "; charset=utf-8"

        ext = os.path.splitext(f.filename)[1]

        if not ext:
            gmime = mime.split(";")[0]

            if not gmime in app.config["FHOST_EXT_OVERRIDE"]:
                ext = guess_extension(gmime)
            else:
                ext = app.config["FHOST_EXT_OVERRIDE"][gmime]
        else:
            ext = ext[:8]

        if not ext:
            ext = ".bin"

        spath = getpath(digest)

        with open(spath, "wb") as of:
            of.write(data)

        if app.config["NSFW_DETECT"]:
            nsfw_score = nsfw.detect(spath)
        else:
            nsfw_score = None

        sf = File(digest, ext, mime, addr, nsfw_score)
        db.session.add(sf)
        db.session.commit()

        return sf.geturl()

def store_url(url, addr):
    if is_fhost_url(url):
        return segfault(508)

    h = { "Accept-Encoding" : "identity" }
    r = requests.get(url, stream=True, verify=False, headers=h)

    try:
        r.raise_for_status()
    except requests.exceptions.HTTPError as e:
        return str(e) + "\n"

    if "content-length" in r.headers:
        l = int(r.headers["content-length"])

        if l < app.config["MAX_CONTENT_LENGTH"]:
            def urlfile(**kwargs):
                return type('',(),kwargs)()

            f = urlfile(stream=r.raw, content_type=r.headers["content-type"], filename="")

            return store_file(f, addr)
        else:
            hl = naturalsize(l, binary = True)
            hml = naturalsize(app.config["MAX_CONTENT_LENGTH"], binary=True)

            return "Remote file too large ({0} > {1}).\n".format(hl, hml), 413
    else:
        return "Could not determine remote file size (no Content-Length in response header; shoot admin).\n", 411

@app.route("/<path:path>")
def get(path):
    p = os.path.splitext(path)
    id = su.debase(p[0])

    if p[1]:
        f = File.query.get(id)

        if f and f.ext == p[1]:
            if f.removed:
                return legal()

            fpath = getpath(f.sha256)

            if not os.path.exists(fpath):
                abort(404)

            fsize = os.path.getsize(fpath)

            if app.config["FHOST_USE_X_ACCEL_REDIRECT"]:
                response = make_response()
                response.headers["Content-Type"] = f.mime
                response.headers["Content-Length"] = fsize
                response.headers["X-Accel-Redirect"] = "/" + fpath
                return response
            else:
                return send_from_directory(app.config["FHOST_STORAGE_PATH"], f.sha256, mimetype = f.mime)
    else:
        u = URL.query.get(id)

        if u:
            return redirect(u.url)

    abort(404)

@app.route("/dump_urls/")
@app.route("/dump_urls/<int:start>")
def dump_urls(start=0):
    meta = "#FORMAT: BEACON\n#PREFIX: {}/\n\n".format(fhost_url("https"))

    def gen():
        yield meta

        for url in URL.query.order_by(URL.id.asc()).offset(start):
            if url.url.startswith("http") or url.url.startswith("https"):
                bar = "|"
            else:
                bar = "||"

            yield url.getname() + bar + url.url + "\n"

    return Response(gen(), mimetype="text/plain")

@app.route("/", methods=["GET", "POST"])
def fhost():
    if request.method == "POST":
        sf = None

        if "file" in request.files:
            return store_file(request.files["file"], request.remote_addr)
        elif "url" in request.form:
            return store_url(request.form["url"], request.remote_addr)
        elif "shorten" in request.form:
            return shorten(request.form["shorten"])

        abort(400)
    else:
        fmts = list(app.config["FHOST_EXT_OVERRIDE"])
        fmts.sort()
        maxsize = naturalsize(app.config["MAX_CONTENT_LENGTH"], binary=True)
        maxsizenum, maxsizeunit = maxsize.split(" ")
        maxsizenum = float(maxsizenum)
        maxsizehalf = maxsizenum / 2

        if maxsizenum.is_integer():
            maxsizenum = int(maxsizenum)
        if maxsizehalf.is_integer():
            maxsizehalf = int(maxsizehalf)

        return """<pre>
THE NULL POINTER
================

HTTP POST files here:
    curl -F'file=@yourfile.png' {0}
You can also POST remote URLs:
    curl -F'url=http://example.com/image.jpg' {0}
Or you can shorten URLs:
    curl -F'shorten=http://example.com/some/long/url' {0}

File URLs are valid for at least 30 days and up to a year (see below).
Shortened URLs do not expire.

Maximum file size: {1}
Not allowed: {5}


FILE RETENTION PERIOD
---------------------

retention = min_age + (-max_age + min_age) * pow((file_size / max_size - 1), 3)

   days
    365 |  \\
        |   \\
        |    \\
        |     \\
        |      \\
        |       \\
        |        ..
        |          \\
  197.5 | ----------..-------------------------------------------
        |             ..
        |               \\
        |                ..
        |                  ...
        |                     ..
        |                       ...
        |                          ....
        |                              ......
     30 |                                    ....................
          0{2}{3}
           {4}


ABUSE
-----

If you would like to request permanent deletion, please contact lachs0r via
IRC on Freenode, or send an email to lachs0r@(this domain).

Please allow up to 24 hours for a response.
</pre>
""".format(fhost_url(),
           maxsize, str(maxsizehalf).rjust(27), str(maxsizenum).rjust(27),
           maxsizeunit.rjust(54),
           ", ".join(app.config["FHOST_MIME_BLACKLIST"]))

@app.route("/robots.txt")
def robots():
    return """User-agent: *
Disallow: /
"""

def legal():
    return "451 Unavailable For Legal Reasons\n", 451

@app.errorhandler(400)
@app.errorhandler(404)
@app.errorhandler(414)
@app.errorhandler(415)
def segfault(e):
    return "Segmentation fault\n", e.code

@app.errorhandler(404)
def notfound(e):
    return u"""<pre>Process {0} stopped
* thread #1: tid = {0}, {1:#018x}, name = '{2}'
    frame #0:
Process {0} stopped
* thread #8: tid = {0}, {3:#018x} fhost`get(path='{4}') + 27 at fhost.c:139, name = 'fhost/responder', stop reason = invalid address (fault address: 0x30)
    frame #0: {3:#018x} fhost`get(path='{4}') + 27 at fhost.c:139
   136   get(SrvContext *ctx, const char *path)
   137   {{
   138       StoredObj *obj = ctx->store->query(shurl_debase(path));
-> 139       switch (obj->type) {{
   140           case ObjTypeFile:
   141               ctx->serve_file_id(obj->id);
   142               break;
(lldb) q</pre>
""".format(os.getpid(), id(app), "fhost", id(get), escape(request.path)), e.code

@manager.command
def debug():
    app.config["FHOST_USE_X_ACCEL_REDIRECT"] = False
    app.run(debug=True, port=4562,host="0.0.0.0")

@manager.command
def permadelete(name):
    id = su.debase(name)
    f = File.query.get(id)

    if f:
        if os.path.exists(getpath(f.sha256)):
            os.remove(getpath(f.sha256))
        f.removed = True
        db.session.commit()

@manager.command
def query(name):
    id = su.debase(name)
    f = File.query.get(id)

    if f:
        f.pprint()

@manager.command
def queryhash(h):
    f = File.query.filter_by(sha256=h).first()

    if f:
        f.pprint()

@manager.command
def queryaddr(a, nsfw=False, removed=False):
    res = File.query.filter_by(addr=a)

    if not removed:
        res = res.filter(File.removed != True)

    if nsfw:
        res = res.filter(File.nsfw_score > app.config["NSFW_THRESHOLD"])

    for f in res:
        f.pprint()

@manager.command
def deladdr(a):
    res = File.query.filter_by(addr=a).filter(File.removed != True)

    for f in res:
        if os.path.exists(getpath(f.sha256)):
            os.remove(getpath(f.sha256))
        f.removed = True

    db.session.commit()

def nsfw_detect(f):
    try:
        open(f["path"], 'r').close()
        f["nsfw_score"] = nsfw.detect(f["path"])
        return f
    except:
        return None

@manager.command
def update_nsfw():
    if not app.config["NSFW_DETECT"]:
        print("NSFW detection is disabled in app config")
        return 1

    from multiprocessing import Pool
    import tqdm

    res = File.query.filter_by(nsfw_score=None, removed=False)

    with Pool() as p:
        results = []
        work = [{ "path" : getpath(f.sha256), "id" : f.id} for f in res]

        for r in tqdm.tqdm(p.imap_unordered(nsfw_detect, work), total=len(work)):
            if r:
                results.append({"id": r["id"], "nsfw_score" : r["nsfw_score"]})

        db.session.bulk_update_mappings(File, results)
        db.session.commit()


@manager.command
def querybl(nsfw=False, removed=False):
    blist = []
    if os.path.isfile(app.config["FHOST_UPLOAD_BLACKLIST"]):
        with open(app.config["FHOST_UPLOAD_BLACKLIST"], "r") as bl:
            for l in bl.readlines():
                if not l.startswith("#"):
                    if not ":" in l:
                        blist.append("::ffff:" + l.rstrip())
                    else:
                        blist.append(l.strip())

    res = File.query.filter(File.addr.in_(blist))

    if not removed:
        res = res.filter(File.removed != True)

    if nsfw:
        res = res.filter(File.nsfw_score > app.config["NSFW_THRESHOLD"])

    for f in res:
        f.pprint()

if __name__ == "__main__":
    manager.run()