#!/usr/bin/env python3

from flask import Flask, request, abort, make_response, \
                  render_template, redirect, url_for, \
                  json, jsonify, session, flash
from collections import namedtuple
from subprocess import check_call, call
from fcntl import flock, LOCK_EX, LOCK_SH, LOCK_UN

import hashlib
import random
import shutil
import time
import sys
import re
import os


#app = Flask("ISABEL-2 Verifier") # That app name breaks Ubuntu 14.04 :-o
app = Flask("main")
app.secret_key = "6ab77f3c45447429c2ae163c260a626029519a66450e474c"

users_file = "/etc/freeradius/users.dpto2"
dhcp_hosts_file = "/etc/dnsmasq.d/dpto2/dhcp-hosts"
dhcp_opts_file = "/etc/dnsmasq.d/dpto2/dhcp-opts"

class Lock:
    def __init__(self, lockfile):
        self.lockfile = lockfile

    def __enter__(self):
        flock(self.lockfile, LOCK_EX)

    def __exit__(self, exc_type, exc_val, exc_tb):
        flock(self.lockfile, LOCK_UN)

class SharedLock(Lock):
    def __init__(self, lockfile):
        super().__init__(lockfile)

    def __enter__(self, exc_type, exc_val, exc_tb):
        flock(self.lockfile, LOCK_SH)

lock_file = open("/run/lock/dpto2.lock","w")
exclusive_lock = Lock(lock_file)
shared_lock = SharedLock(lock_file)

def reload_freeradius():
    call("./reload_freeradius")

def delete_user(deluser):
    f = open(users_file)
    lines = f.readlines()
    f.close()
    timestamp = time.time()
    tempfile = "{}.{}".format(users_file, timestamp)
    f = open(tempfile,"w")
    for line in lines:
        if line.startswith(deluser):
            continue
        f.write(line)
    f.close()
    shutil.move(tempfile, users_file)
    reload_freeradius()

def nthash(password):
    return hashlib.new('md4',password.encode('utf-16le')).hexdigest().upper()

def create_user(username, password, creator):
    with exclusive_lock:
        f = open(users_file,"a")
        f.write('{} NT-Password := "{}" # created by {} \n'.format(username, nthash(password), creator))
        f.close()
    reload_freeradius()

@app.route("/")
def index():
    f = open(users_file)
    guestpass = "?"
    for line in f:
        if line.startswith("guest"):
            m = re.search(':=\s+"(.+?)"\s*$',line)
            if m:
                guestpass = m.group(1)
                break

    return render_template("index.html", guestpass=guestpass)

def load_users():
    users = []
    with open(users_file) as f:
        for l in f:
            if l.strip().startswith("#"):
                continue
            m = re.match("(^\S+).*-Password\s+:=\s+\"(\S+)\"(?:\s+#.*created.by\s+(\S+))?", l)
            if m:
                users.append(m.groups())
    return users

def check_login(username, password):
    for u,p,c in load_users():
        if u == username and p == nthash(password):
            return True
    raise ValueError("Invalid username or password")

@app.route("/login",methods=['GET','POST'])
def login():
    if session.get('logged_in',False):
        return redirect(url_for('admin'))
    if request.method == 'GET':
        return render_template("login.html")
    if request.method == 'POST':
        username = request.form.get("username",None)
        password = request.form.get("password",None)

        if username is None or password is None:
            return render_template("login.html",error=True,errormsg="invalid username or password")

        if username == 'guest':
            return render_template("login.html",error=True,errormsg="guest user has no admin privileges")

        try:
            check_login(username, password)
        except Exception as e:
            return render_template("login.html",error=True,errormsg=str(e))

        session['logged_in'] = True
        session['username'] = username
        return redirect(url_for('admin'))

@app.route("/admin",methods=['GET','POST'])
def admin():
    if not session.get('logged_in', False):
        return redirect(url_for('login'))
    if request.method == 'POST':
        deluser = request.form.get('deluser',None)
        if deluser is not None:
            if deluser == 'guest':
                return render_template("admin.html", delete_error=True, errormsg="Cannot delete guest user")
            delete_user(deluser)
            flash("User deleted succesfully")

        username = request.form.get('username',None)
        pass1 = request.form.get('password1',None)
        pass2 = request.form.get('password2',None)
        creator = session['username']
        if username is not None:
            if username == 'guest':
                return render_template("admin.html", create_error=True, errormsg="Cannot create guest user")
            if pass1 is None or \
               pass2 is None or \
               pass1 != pass2:
                return render_template("admin.html", create_error=True, errormsg="Password do not match")
            create_user(username,pass1,creator)
            flash("User created successfully")

    return render_template("admin.html")

def render_users_tree(tree):
    lines = []
    def _render(user, edges, is_last):
        lines.append((edges + (" └─" if is_last else " ├─"), user))
        n = len(tree[user])
        for i,u in enumerate(tree[user]):
            _render(u, edges + ("   " if is_last else " │ "), i == n - 1)
        return lines
    # root = tree(""); n = len(root)
    # for i,u in enumerate(root):
    _render("", "", True)
    return lines

@app.route("/users")
def list_users():
    if not session.get('logged_in', False):
        return redirect(url_for('login'))
    users = load_users()
    users_set = set(x[0] for x in users)
    tree = { "": [] }
    for user,passwd,creator in users:
        if user == "guest":
            continue
        tree[user] = []
        if creator is None:
            tree[""].append(user)
        else:
            if creator not in users_set:
                creator += " (invalid username)"
                tree[""].append(creator)
            tree[creator] = tree.get(creator,[]) + [user]
    lines = render_users_tree(tree)
    return render_template("users.html", users=lines)

mac_re = re.compile("(?:[0-9a-fA-F]{2}:){5}[0-9a-fA-F]{2}")
ip_re = re.compile("\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}")
DhcpHostLine = namedtuple("DhcpHostLine","macs ip tag")

def parse_dchp_host(line):
    macs = []
    ip = ""
    tag = ""
    parts = line.split(",")
    for p in parts:
        p = p.strip()
        m = mac_re.match(p)
        if m:
            macs.append(m.group(0))
            continue
        m = ip_re.match(p)
        if m:
            ip = m.group(0)
            continue
        if p.startswith("set:"):
            tag = p[4:]
    return DhcpHostLine(macs, ip, tag)

Ip = namedtuple("Ip","reserved_by dhcp locked")

def load_ips():
    ipmap = {}
    for i in range(1,255):
        ipmap[i] = Ip("",True,False)
    ipmap[0] = ipmap[255] = Ip("", False, False)
    prefix = None
    with open(dhcp_hosts_file) as f:
        meta = {}
        for line in f:
            line = line.strip()
            if line.startswith("#"):
                try:
                    meta = json.loads(line[1:])
                except:
                    meta = {}
                    continue
                if not isinstance(meta,dict):
                    meta = {}
                    continue
            if re.match("^[0-9a-fA-F]{2}:",line):
                r = parse_dchp_host(line)
                ip = int(r.ip.split(".")[-1])
                if prefix is None:
                    prefix = ".".join(r.ip.split(".")[:-1])
                ipmap[ip] = Ip(
                    reserved_by=meta.get("reserved-by",""),
                    dhcp=False,
                    locked=meta.get("locked",False)
                )
                meta = {}
    ipmap["prefix"] = prefix
    return ipmap

@app.route("/ips")
def ips():
    ipmap = load_ips()
    return render_template("ips.html", ipmap=ipmap)

@app.route("/ip/<int:last_byte>")
def ip(last_byte):
    ipmap = load_ips()
    addr = "{}.{}".format(ipmap["prefix"], last_byte)
    return render_template(
            "ip.html",
            addr=addr,
            meta=ipmap[last_byte],
    )

@app.route("/logout")
def logout():
    session.pop("logged_in",None)
    return redirect(url_for("index"))

if __name__ == '__main__':
    if "debug" in sys.argv:
        users_file = "users.dpto2"
        dhcp_hosts_file = "dhcp-hosts.dpto2"
        dhcp_opts_file = "dhcp-opts.dpto2"
    app.debug = True
    app.run(host="0.0.0.0")