import hashlib
import time
import ssl
import traceback
import re
import logging
from pathlib import Path
from datetime import datetime

import imaplib
from smtplib import SMTP_SSL

import email
from email import encoders
from email.mime.base import MIMEBase
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.mime.application import MIMEApplication

import pdfkit
from jinja2 import Environment, FileSystemLoader

from werkzeug.security import generate_password_hash

from . model import db, UploadRegular, UploadSolar, RegisteredUser, UserInstitutionMapping, Institution, InstitutionContract, CorpusAccess


#REGEX_EMAIL = re.compile('^[a-z0-9]+[\._]?[a-z0-9]+[@]\w+[.]\w{2,3}$')
REGEX_EMAIL = re.compile('^(?:[a-z0-9!#$%&\'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&\'*+/=?^_`{|}~-]+)*|\"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*\")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9]))\.){3}(?:(2(5[0-5]|[0-4][0-9])|1[0-9][0-9]|[1-9]?[0-9])|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])$')

MAX_FNAME_LEN = 100


class ContractCreator:

    def __init__(self, base_path, template_path):
        self.base = base_path
        template_loader = FileSystemLoader(searchpath="./")
        template_env = Environment(loader=template_loader)
        self.template = template_env.get_template(template_path)

        self.pdfkit_options = {
            'page-size': 'A4',
            'margin-top': '0.75in',
            'margin-right': '0.75in',
            'margin-bottom': '0.75in',
            'margin-left': '0.75in',
            'encoding': "UTF-8",
            'custom-header' : [
                ('Accept-Encoding', 'gzip')
            ]
        }

    def fill_template(self, **kwargs):
        return self.template.render(**kwargs)

    def create_pdf(self, f_name, fields_dict):
        sub_dir = self.base / Path(f_name[:2])
        if not sub_dir.exists():
            sub_dir.mkdir()
        out_f = sub_dir / Path(f_name[2:])
        html_str = self.fill_template(**fields_dict)
        pdfkit.from_string(html_str, out_f, options=self.pdfkit_options)


class UploadHandler:

    ENABLED_FILETYPES = ['txt', 'csv', 'pdf', 'doc', 'docx', 'xls', 'xlsx', 'ppt', 'pptx', 'xml', 'mxliff', 'tmx']

    def __init__(self, **kwargs):
        self.config = kwargs
    
    def set_contract_creator(self, contract_creator):
        assert isinstance(contract_creator, ContractCreator)
        self._contract_creator = contract_creator

    def get_uploads_subdir(self, dir_name):
        subdir = Path(self.config['UPLOADS_DIR']) / dir_name
        if not subdir.exists():
            subdir.mkdir(parents=True)
        return subdir

    @staticmethod
    def extract_upload_metadata(corpus_name, request):
        upload_metadata = dict()

        file_hashes = UploadHandler.create_file_hashes(request.files)
        file_names = file_hashes.keys()
        form_data = request.form.copy()
        upload_timestamp = int(time.time())
        upload_id = UploadHandler.create_upload_id(corpus_name, form_data, upload_timestamp, file_hashes)

        # Strip form fieds.
        for key, val in form_data.items():
            form_data[key] = val.strip()

        upload_metadata['corpus_name'] = corpus_name
        upload_metadata['form_data'] = form_data
        upload_metadata['upload_id'] = upload_id
        upload_metadata['timestamp'] = upload_timestamp
        upload_metadata['file_hashes_dict'] = file_hashes
        upload_metadata['file_names'] = file_names
        upload_metadata['contract_file'] = upload_id + '.pdf'

        return upload_metadata

    @staticmethod
    def create_upload_id(corpus_name, form_data, upload_timestamp, file_hashes):
        # Order is important while hashing, hence the sorting.
        val_buff = [str(upload_timestamp)]
        for key in sorted(form_data):
            val_buff.append(form_data[key])

        # This hash serves as an unique identifier for the whole upload.
        metahash = hashlib.md5((''.join(val_buff)).encode())
        # Include file hashes to avoid metafile name collisions if they have the same form values,
        # but different data files. Sort hashes first so upload order doesn't matter.
        sorted_f_hashes = list(file_hashes.values())
        sorted_f_hashes.sort()
        metahash.update(''.join(sorted_f_hashes).encode())
        metahash = metahash.hexdigest()

        return metahash

    @staticmethod
    def create_file_hashes(files):
        res = dict()
        for key, f in files.items():
            if key.startswith('file'):
                h = hashlib.md5(f.filename.encode())
                h.update(f.stream.read())
                res[f.filename] = h.hexdigest()
                f.seek(0)
        return res

    @staticmethod
    def store_model(model_obj):
        try:
            db.session.add(model_obj)
            db.session.commit()
        except Exception:
            traceback.print_exc()
    

    def store_datafiles(self, files, upload_metadata):
        base = self.get_uploads_subdir('files')
        file_hashes = upload_metadata['file_hashes_dict']

        for key, f in files.items():
            if key.startswith('file'):
                f_hash = file_hashes[f.filename]
                
                # First byte used for indexing, similarly like git does for example.
                sub_dir = base / f_hash[:2]
                if not sub_dir.exists():
                    sub_dir.mkdir()

                path = sub_dir / f_hash[2:]
                if not path.exists():
                    path.mkdir()
                    f.save(path / f.filename)


    def send_confirm_mail(self, upload_metadata, attach_contract_file=False):
        upload_id = upload_metadata['upload_id']

        message = MIMEMultipart()
        message['From'] = self.config['MAIL_LOGIN']
        message['To'] = upload_metadata['form_data']['email']
        message['Subject'] = self.config['MAIL_SUBJECT'].format(upload_id=upload_id)
        body = self.config['MAIL_BODY'].format(upload_id=upload_id)
        message.attach(MIMEText(body, "plain"))

        if attach_contract_file:
            contracts_dir = self.contract_creator.base
            f_name = upload_metadata['contract_file']
            sub_dir = contracts_dir / Path(f_name[:2])
            contract_file = sub_dir / Path(f_name[2:])
            with open(contract_file, "rb") as f:
                part = MIMEApplication(
                        f.read(),
                        Name = f_name
                    )
            part['Content-Disposition'] = 'attachment; filename="%s"' % f_name
            message.attach(part)

        text = message.as_string()

        # Create a secure SSL context
        context = ssl.create_default_context()

        # TODO: Implement timeout.
        try:
            with SMTP_SSL(self.config['MAIL_HOST'], self.config['SMTP_PORT'], context=context) as server:
                server.login(self.config['MAIL_LOGIN'], self.config['MAIL_PASS'])
                server.sendmail(message['From'], message['To'], text)

            # Save copy of sent mail in Sent mailbox
            #imap = imaplib.IMAP4_SSL(self.config['MAIL_HOST'], self.config['IMAP_PORT'])
            #imap.login(self.config['MAIL_LOGIN'], self.config['MAIL_PASS'])
            #imap.append('Sent', '\\Seen', imaplib.Time2Internaldate(time.time()), text.encode('utf8'))
            #imap.logout()
        except Exception:
            traceback.print_exc()

    def check_suffixes(self, files):
        for key, f in files.items():
            if key.startswith('file'):
                suffix = f.filename.split('.')[-1]
                if self.ENABLED_FILETYPES and suffix not in self.ENABLED_FILETYPES:
                    return 'Datoteka "{}" ni pravilnega formata.'.format(f.filename)
        return None

    @staticmethod
    def check_fname_lengths(files):
        for key, f in files.items():
            if key.startswith('file'):
                if len(f.filename) > MAX_FNAME_LEN:
                    return 'Ime datoteke presega dolžino {} znakov.'.format(MAX_FNAME_LEN)
        return None

    def check_upload_request(self, request):
        files = request.files
        max_files = self.config['MAX_FILES_PER_UPLOAD']
        if len(files) > max_files:
            return 'Naložite lahko do {} datotek hkrati.'.format(max_files), 400
        elif len(files) < 1:
            return 'Priložena ni bila nobena datoteka.', 400

        err = self.check_suffixes(files)
        if err:
            return err, 400

        err = UploadHandler.check_fname_lengths(files)
        if err:
            return err, 400

        return None


def get_user_institutions(user_id):
    return UserInstitutionMapping.query.filter_by(user=user_id).all()


def has_user_corpus_access(user_id, corpus_name):
    user = RegisteredUser.query.filter_by(id=user_id).first()

    # TODO: check if user even is active?

    # Admins always have access to everything.
    if user.role == 'admin':
        return True

    # Check if user belongs to an institution, that has access to this corpus.
    institutions = get_user_institutions(user_id)
    has_access = False
    for institution in institutions:
        row = CorpusAccess.query.filter_by(institution=institution.id, corpus=corpus_name).first()
        if row:
            has_access = True
            break
    return has_access


def is_admin(user_id):
    user = RegisteredUser.query.filter_by(id=user_id).first()
    if user.role == 'admin':
        return True
    return False


def get_user_obj(user_id):
    return RegisteredUser.query.filter_by(id=user_id).first()


def get_institution_obj(institution_id):
    return Institution.query.filter_by(id=institution_id).first()


def register_new_user(name, email, password, active=True, admin=False):
    model_obj = RegisteredUser(
                name=name,
                email=email,
                role='admin' if admin else 'user',
                pass_hash=generate_password_hash(password),
                active=active,
                registered=datetime.now()
           )
    db.session.add(model_obj)
    db.session.commit()
    return model_obj.id


def add_institution(name, region):
    model_obj = Institution(
                name=name,
                region=region
           )
    db.session.add(model_obj)
    db.session.commit()
    return model_obj.id


def grant_institution_corpus_access(institution_id, corpus_name):
    model_obj = CorpusAccess(
                institution=institution_id,
                corpus=corpus_name
           )
    db.session.add(model_obj)
    db.session.commit()
    return model_obj.id


def add_user_to_institution(user_id, institution_id, role):
    model_obj = UserInstitutionMapping(
                user=user_id,
                institution=institution_id,
                role=role
           )
    db.session.add(model_obj)
    db.session.commit()
    return model_obj.id


def get_all_active_users():
    return RegisteredUser.query.filter_by(active=True).all()


def is_institution_moderator(user_id, institution_id):
    user_inst_mapping = UserInstitutionMapping.query.filter_by(user=user_id).first()
    if not user_inst_mapping:
        return False
    if user_inst_mapping.role != 'moderator':
        return False
    return True