# -*- coding: UTF-8 -*
# pylint: disable=invalid-name

import base64
import datetime
import json
import os
import socket
import sys
import time
import traceback

import logging
from logging.handlers import SMTPHandler, WatchedFileHandler
from threading import Thread
import warnings

from flask import current_app, g, request
from flask import Flask
from flask import abort, flash, has_request_context
from flask import render_template
from flask.logging import default_handler
from flask_caching import Cache
from flask_json import FlaskJSON, json_response
from flask_login import LoginManager, current_user
from flask_mail import Mail
from flask_migrate import Migrate
from flask_sqlalchemy import SQLAlchemy

from jinja2 import select_autoescape
import sqlalchemy as sa
import werkzeug.debug
from wtforms.fields import HiddenField

from flask_cas import CAS

from app.scodoc.sco_exceptions import (
    AccessDenied,
    ScoBugCatcher,
    ScoException,
    ScoGenError,
    ScoInvalidCSRF,
    ScoPDFFormatError,
    ScoValueError,
    APIInvalidParams,
)
from app.scodoc.sco_vdi import ApoEtapeVDI

from config import DevConfig
import sco_version

db = SQLAlchemy()
migrate = Migrate(compare_type=True)
login = LoginManager()
login.login_view = "auth.login"
login.login_message = "Identifiez-vous pour accéder à cette page."

mail = Mail()

CACHE_TYPE = os.environ.get("CACHE_TYPE")
cache = Cache(
    config={
        # see https://flask-caching.readthedocs.io/en/latest/index.html#configuring-flask-caching
        "CACHE_TYPE": CACHE_TYPE or "RedisCache",
        # by default, never expire:
        "CACHE_DEFAULT_TIMEOUT": os.environ.get("CACHE_DEFAULT_TIMEOUT") or 0,
    }
)


def handle_sco_value_error(exc):
    "page d'erreur avec message"
    return render_template("sco_value_error.j2", exc=exc), 404


def handle_access_denied(exc):
    return render_template("error_access_denied.j2", exc=exc), 403


def handle_invalid_csrf(exc):
    """Form submit with invalid CSRF token"""
    # logout user and go back to login page with an error message
    from app import auth

    auth.logic.logout()
    return render_template("error_csrf.j2", exc=exc), 404


# def handle_pdf_format_error(exc):
#    return "ay ay ay"
handle_pdf_format_error = handle_sco_value_error


def internal_server_error(exc):
    """Bugs scodoc, erreurs 500"""
    # note that we set the 500 status explicitly
    from app.scodoc import sco_utils as scu

    # Invalide tous les caches
    log("internal_server_error: clearing caches")
    clear_scodoc_cache()

    return (
        render_template(
            "error_500.j2",
            SCOVERSION=sco_version.SCOVERSION,
            date=datetime.datetime.now().isoformat(),
            exc=exc,
            traceback_str_base64=base64.urlsafe_b64encode(
                traceback.format_exc().encode(scu.SCO_ENCODING)
            ).decode(scu.SCO_ENCODING),
            request_url=request.url,
            scu=scu,
        ),
        500,
    )


def handle_sco_bug(exc):
    """Un bug, en général rare, sur lequel les dev cherchent des
    informations pour le corriger.
    """
    if current_app.config["TESTING"] or current_app.config["DEBUG"]:
        raise ScoException  # for development servers only
    else:
        Thread(
            target=_async_dump, args=(current_app._get_current_object(), request.url)
        ).start()

    return internal_server_error(exc)


def _async_dump(app, request_url: str):
    from app.scodoc.sco_dump_db import sco_dump_and_send_db

    with app.app_context():
        ndb.open_db_connection()
        try:
            sco_dump_and_send_db("ScoBugCatcher", request_url=request_url)
        except ScoValueError:
            pass


def handle_invalid_usage(error):
    response = json_response(data_=error.to_dict())
    response.status_code = error.status_code
    return response


# JSON ENCODING
# used by some internal finctions
# the API is now using flask_json, NOT THIS ENCODER
class ScoDocJSONEncoder(json.JSONEncoder):
    def default(self, o):  # pylint: disable=E0202
        if isinstance(o, (datetime.date, datetime.datetime)):
            return o.isoformat()
        elif isinstance(o, ApoEtapeVDI):
            return str(o)
        else:
            return json.JSONEncoder.default(self, o)


def render_raw_html(template_filename: str, **args) -> str:
    """Load and render an HTML file _without_ using Flask
    Necessary for 503 error message, when DB is down and Flask may be broken.
    """
    template_path = os.path.join(
        current_app.config["SCODOC_DIR"],
        "app",
        current_app.template_folder,
        template_filename,
    )
    with open(template_path) as f:
        txt = f.read().format(**args)
    return txt


def postgresql_server_error(e):
    """Erreur de connection au serveur postgresql (voir notesdb.open_db_connection)"""
    return render_raw_html("error_503.j2", SCOVERSION=sco_version.SCOVERSION), 503


class LogRequestFormatter(logging.Formatter):
    """Ajoute URL et remote_addr for logging"""

    def format(self, record):
        if has_request_context():
            record.url = request.url
            record.remote_addr = request.remote_addr
        else:
            record.url = None
            record.remote_addr = None
        record.sco_user = current_user
        if has_request_context():
            record.sco_admin_mail = current_app.config["SCODOC_ADMIN_MAIL"]
        else:
            record.sco_admin_mail = "(pas de requête)"

        return super().format(record)


class LogExceptionFormatter(logging.Formatter):
    """Formatteur pour les exceptions: ajoute détails"""

    def format(self, record):
        if has_request_context():
            record.url = request.url
            record.remote_addr = request.environ.get(
                "HTTP_X_FORWARDED_FOR", request.remote_addr
            )
            record.http_referrer = request.referrer
            record.http_method = request.method
            if request.method == "GET":
                record.http_params = str(request.args)
            else:
                # rep = reprlib.Repr()  # abbrège
                record.http_params = str(request.form)[:2048]
        else:
            record.url = None
            record.remote_addr = None
            record.http_referrer = None
            record.http_method = None
            record.http_params = None
        record.sco_user = current_user

        if has_request_context():
            record.sco_admin_mail = current_app.config["SCODOC_ADMIN_MAIL"]
        else:
            record.sco_admin_mail = "(pas de requête)"
        return super().format(record)


class ScoSMTPHandler(SMTPHandler):
    def getSubject(self, record: logging.LogRecord) -> str:
        stack_summary = traceback.extract_tb(record.exc_info[2])
        frame_summary = stack_summary[-1]
        subject = f"ScoExc({sco_version.SCOVERSION}): {record.exc_info[0].__name__} in {frame_summary.name} {frame_summary.filename}"

        return subject


class ReverseProxied(object):
    """Adaptateur wsgi qui nous permet d'avoir toutes les URL calculées en https
    sauf quand on est en dev.
    La variable HTTP_X_FORWARDED_PROTO est positionnée par notre config nginx"""

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

    def __call__(self, environ, start_response):
        scheme = environ.get("HTTP_X_FORWARDED_PROTO")
        if scheme:
            environ["wsgi.url_scheme"] = scheme  # ou forcer à https ici ?
        return self.app(environ, start_response)


def create_app(config_class=DevConfig):
    app = Flask(__name__, static_url_path="/ScoDoc/static", static_folder="static")
    app.config.from_object(config_class)
    from app.auth import cas

    CAS(app, url_prefix="/cas", configuration_function=cas.set_cas_configuration)
    app.wsgi_app = ReverseProxied(app.wsgi_app)
    app_json = FlaskJSON(app)

    @app_json.encoder
    def scodoc_json_encoder(o):
        "Overide default date encoding (RFC 822) and use ISO"
        if isinstance(o, (datetime.date, datetime.datetime)):
            return o.isoformat()

    # Pour conserver l'ordre des objets dans les JSON:
    # e.g. l'ordre des UE dans les bulletins
    app.json.sort_keys = False

    # Evite de logguer toutes les requetes dans notre log
    logging.getLogger("werkzeug").disabled = True
    app.logger.setLevel(app.config["LOG_LEVEL"])
    if app.config["TESTING"] or app.config["DEBUG"]:
        # S'arrête sur tous les warnings, sauf
        #  flask_sqlalchemy/query (pb deprecation du model.get())
        warnings.filterwarnings("error", module="flask_sqlalchemy/query")
    # warnings.filterwarnings("ignore", module="json/provider.py") xxx sans effet en test
    if app.config["DEBUG"]:
        # comme on a désactivé ci-dessus les logs de werkzeug,
        # on affiche nous même le PIN en mode debug:
        print(
            f""" * Debugger is active!
 * Debugger PIN: {werkzeug.debug.get_pin_and_cookie_name(app)[0]}
        """
        )
    # Vérifie/crée lien sym pour les URL statiques
    link_filename = f"{app.root_path}/static/links/{sco_version.SCOVERSION}"
    if not os.path.exists(link_filename):
        app.logger.info(f"creating symlink {link_filename}")
        os.symlink("..", link_filename)

    db.init_app(app)
    migrate.init_app(app, db)
    login.init_app(app)
    mail.init_app(app)
    app.extensions["mail"].debug = 0  # disable copy of mails to stderr
    cache.init_app(app)
    sco_cache.CACHE = cache
    if CACHE_TYPE:  # non default
        app.logger.info(f"CACHE_TYPE={CACHE_TYPE}")

    app.register_error_handler(ScoGenError, handle_sco_value_error)
    app.register_error_handler(ScoValueError, handle_sco_value_error)
    app.register_error_handler(ScoBugCatcher, handle_sco_bug)
    app.register_error_handler(ScoInvalidCSRF, handle_invalid_csrf)
    app.register_error_handler(ScoPDFFormatError, handle_pdf_format_error)
    app.register_error_handler(AccessDenied, handle_access_denied)
    app.register_error_handler(500, internal_server_error)
    app.register_error_handler(503, postgresql_server_error)
    app.register_error_handler(APIInvalidParams, handle_invalid_usage)

    from app.auth import bp as auth_bp

    app.register_blueprint(auth_bp, url_prefix="/auth")

    from app.entreprises import bp as entreprises_bp

    app.register_blueprint(entreprises_bp, url_prefix="/ScoDoc/entreprises")

    from app.views import scodoc_bp
    from app.views import scolar_bp
    from app.views import notes_bp
    from app.views import users_bp
    from app.views import absences_bp
    from app.views import assiduites_bp
    from app.api import api_bp
    from app.api import api_web_bp

    # Jinja2 configuration
    # Enable autoescaping of all templates, including .j2
    app.jinja_env.autoescape = select_autoescape(default_for_string=True, default=True)
    app.jinja_env.trim_blocks = True
    app.jinja_env.lstrip_blocks = True
    # previously in Flask-Bootstrap:
    app.jinja_env.globals["bootstrap_is_hidden_field"] = lambda field: isinstance(
        field, HiddenField
    )

    # https://scodoc.fr/ScoDoc
    app.register_blueprint(scodoc_bp)
    # https://scodoc.fr/ScoDoc/RT/Scolarite/...
    app.register_blueprint(scolar_bp, url_prefix="/ScoDoc/<scodoc_dept>/Scolarite")
    # https://scodoc.fr/ScoDoc/RT/Scolarite/Notes/...
    app.register_blueprint(notes_bp, url_prefix="/ScoDoc/<scodoc_dept>/Scolarite/Notes")
    # https://scodoc.fr/ScoDoc/RT/Scolarite/Users/...
    app.register_blueprint(users_bp, url_prefix="/ScoDoc/<scodoc_dept>/Scolarite/Users")
    # https://scodoc.fr/ScoDoc/RT/Scolarite/Absences/...
    app.register_blueprint(
        absences_bp, url_prefix="/ScoDoc/<scodoc_dept>/Scolarite/Absences"
    )
    app.register_blueprint(
        assiduites_bp, url_prefix="/ScoDoc/<scodoc_dept>/Scolarite/Assiduites"
    )
    app.register_blueprint(api_bp, url_prefix="/ScoDoc/api")
    app.register_blueprint(api_web_bp, url_prefix="/ScoDoc/<scodoc_dept>/api")

    scodoc_log_formatter = LogRequestFormatter(
        "[%(asctime)s] %(sco_user)s@%(remote_addr)s requested %(url)s\n"
        "%(levelname)s: %(message)s"
    )
    # les champs additionnels sont définis dans LogRequestFormatter
    scodoc_exc_formatter = LogExceptionFormatter(
        "[%(asctime)s] %(sco_user)s@%(remote_addr)s requested %(url)s\n"
        "%(levelname)s: %(message)s\n"
        "Referrer: %(http_referrer)s\n"
        "Method: %(http_method)s\n"
        "Params: %(http_params)s\n"
        "Admin mail: %(sco_admin_mail)s\n"
    )
    if not app.testing:
        if not app.debug:
            # --- Config logs pour PRODUCTION
            # On supprime le logguer par défaut qui va vers stderr et pollue les logs systemes
            app.logger.removeHandler(default_handler)
            # --- Mail des messages ERROR et CRITICAL
            if app.config["MAIL_SERVER"]:
                auth = None
                if app.config["MAIL_USERNAME"] or app.config["MAIL_PASSWORD"]:
                    auth = (app.config["MAIL_USERNAME"], app.config["MAIL_PASSWORD"])
                secure = None
                if app.config["MAIL_USE_TLS"]:
                    secure = ()
                host_name = socket.gethostname()
                mail_handler = ScoSMTPHandler(
                    mailhost=(app.config["MAIL_SERVER"], app.config["MAIL_PORT"]),
                    fromaddr=app.config["SCODOC_MAIL_FROM"],
                    toaddrs=["exception@scodoc.org"],
                    subject="ScoDoc Exception",  # unused see ScoSMTPHandler
                    credentials=auth,
                    secure=secure,
                )
                mail_handler.setFormatter(scodoc_exc_formatter)
                mail_handler.setLevel(logging.ERROR)
                app.logger.addHandler(mail_handler)
        else:
            # Pour logs en DEV uniquement:
            default_handler.setFormatter(scodoc_log_formatter)

        # Config logs pour DEV et PRODUCTION
        # Configuration des logs (actifs aussi en mode development)
        # usually /opt/scodoc-data/log/scodoc.log:
        # rotated by logrotate
        file_handler = WatchedFileHandler(
            app.config["SCODOC_LOG_FILE"], encoding="utf-8"
        )
        file_handler.setFormatter(scodoc_log_formatter)
        file_handler.setLevel(logging.INFO)
        app.logger.addHandler(file_handler)
        # Log pour les erreurs (exceptions) uniquement:
        # usually /opt/scodoc-data/log/scodoc_exc.log
        file_handler = WatchedFileHandler(
            app.config["SCODOC_ERR_FILE"], encoding="utf-8"
        )
        file_handler.setFormatter(scodoc_exc_formatter)
        file_handler.setLevel(logging.ERROR)
        app.logger.addHandler(file_handler)

        # app.logger.setLevel(logging.INFO)
        app.logger.info(f"{sco_version.SCONAME} {sco_version.SCOVERSION} startup")
        app.logger.info(
            f"create_app({config_class.__name__}, {config_class.SQLALCHEMY_DATABASE_URI})"
        )
    # ---- INITIALISATION SPECIFIQUES A SCODOC
    from app.scodoc import sco_bulletins_generator

    from app.scodoc.sco_bulletins_legacy import BulletinGeneratorLegacy
    from app.scodoc.sco_bulletins_standard import BulletinGeneratorStandard
    from app.but.bulletin_but_pdf import BulletinGeneratorStandardBUT
    from app.scodoc.sco_bulletins_ucac import BulletinGeneratorUCAC

    # l'ordre est important, le premier sera le "défaut" pour les nouveaux départements.
    sco_bulletins_generator.register_bulletin_class(BulletinGeneratorStandard)
    sco_bulletins_generator.register_bulletin_class(BulletinGeneratorStandardBUT)
    sco_bulletins_generator.register_bulletin_class(BulletinGeneratorLegacy)
    sco_bulletins_generator.register_bulletin_class(BulletinGeneratorUCAC)
    if app.testing or app.debug:
        from app.scodoc.sco_bulletins_example import BulletinGeneratorExample

        sco_bulletins_generator.register_bulletin_class(BulletinGeneratorExample)

    from app.auth.cas import set_cas_configuration

    with app.app_context():
        try:
            set_cas_configuration(app)
        except sa.exc.ProgrammingError:
            # Si la base n'a pas été upgradée (arrive durrant l'install)
            # il se peut que la table scodoc_site_config n'existe pas encore.
            pass
    return app


def set_sco_dept(scodoc_dept: str, open_cnx=True):
    """Set global g object to given dept and open db connection if needed"""
    # Check that dept exists
    try:
        dept = Departement.query.filter_by(acronym=scodoc_dept).first()
    except sa.exc.OperationalError:
        abort(503)
    if not dept:
        raise ScoValueError(f"Invalid dept: {scodoc_dept}")
    g.scodoc_dept = scodoc_dept  # l'acronyme
    g.scodoc_dept_id = dept.id  # l'id
    if open_cnx and not hasattr(g, "db_conn"):
        ndb.open_db_connection()
    if not hasattr(g, "stored_get_formsemestre"):
        g.stored_get_formsemestre = {}


def user_db_init():
    """Initialize the users database.
    Check that basic roles and admin user exist.
    """
    from app.auth.models import User, Role

    current_app.logger.info("Init User's db")
    # Create roles:
    Role.reset_standard_roles_permissions()
    current_app.logger.info("created initial roles")
    # Ensure that admin exists
    admin_mail = current_app.config.get("SCODOC_ADMIN_MAIL")
    if admin_mail:
        admin_user_name = current_app.config["SCODOC_ADMIN_LOGIN"]
        user = User.query.filter_by(user_name=admin_user_name).first()
        if not user:
            user = User(user_name=admin_user_name, email=admin_mail)
            try:
                db.session.add(user)
                db.session.commit()
            except:
                db.session.rollback()
                raise
            current_app.logger.info(
                "created initial admin user, login: {u.user_name}, email: {u.email}".format(
                    u=user
                )
            )


def sco_db_insert_constants():
    """Initialize Sco database: insert some constants (modalités, ...)."""
    from app import models

    current_app.logger.info("Init Sco db")
    # Modalités:
    models.FormationModalite.insert_modalites()


def initialize_scodoc_database(erase=False, create_all=False):
    """Initialize the database for unit tests
    Starts from an existing database and create all necessary
    SQL tables and functions.
    If erase is True, _erase_ all database content.
    """
    # - ERASE (the truncation sql function has been defined above)
    if erase:
        truncate_database()
    # - Create all tables
    if create_all:
        # managed by migrations, except for TESTS
        db.create_all()
    # - Insert initial roles and create super-admin user
    user_db_init()
    # - Insert some constant values (modalites, ...)
    sco_db_insert_constants()
    # - Flush cache
    clear_scodoc_cache()


def truncate_database():
    """Erase content of all tables (including users !) from
    the current database.
    """
    # use a stored SQL function, see createtables.sql
    try:
        db.session.execute(sa.text("SELECT truncate_tables('scodoc');"))
        db.session.commit()
    except:
        db.session.rollback()
        raise
    # Remet les compteurs (séquences sql) à zéro
    db.session.execute(
        sa.text(
            """
    CREATE OR REPLACE FUNCTION reset_sequences(username IN VARCHAR) RETURNS void AS $$
    DECLARE
        statements CURSOR FOR
            SELECT sequence_name
            FROM information_schema.sequences
            ORDER BY sequence_name ;
    BEGIN
        FOR stmt IN statements LOOP
            EXECUTE 'ALTER SEQUENCE ' || quote_ident(stmt.sequence_name) || ' RESTART;';
        END LOOP;
    END;
    $$ LANGUAGE plpgsql;

    SELECT  reset_sequences('scodoc');
    """
        )
    )
    db.session.commit()


def clear_scodoc_cache():
    """Clear ScoDoc cache
    This cache (currently Redis) is persistent between invocation
    and it may be necessary to clear it during developement or tests.
    """
    # attaque directement redis, court-circuite ScoDoc:
    import redis

    r = redis.Redis(host=(os.environ.get("CACHE_REDIS_HOST") or "localhost"))
    r.flushall()
    # Also clear local caches:
    sco_preferences.clear_base_preferences()


# --------- Logging
def log(msg: str):
    """log a message.
    If Flask app, use configured logger, else stderr.
    """
    try:
        dept = getattr(g, "scodoc_dept", "")
        msg = f" ({dept}) {msg}"
    except RuntimeError:
        # Flask Working outside of application context.
        pass

    if current_app and not current_app.config["DEBUG"]:
        current_app.logger.info(msg)
    else:
        sys.stdout.flush()
        sys.stderr.write(
            f"""[{time.strftime("%a %b %d %H:%M:%S %Y")}] scodoc: {msg}\n"""
        )
        sys.stderr.flush()


# Debug: log call stack
def log_call_stack():
    log("Call stack:\n" + "\n".join(x.strip() for x in traceback.format_stack()[:-1]))


# Alarms by email:
def send_scodoc_alarm(subject, txt):
    from app import email

    sender = email.get_from_addr()
    email.send_email(subject, sender, ["exception@scodoc.org"], txt)


from app.models import Departement
from app.scodoc import notesdb as ndb, sco_preferences
from app.scodoc import sco_cache


def scodoc_flash_status_messages():
    """Should be called on each page: flash messages indicating specific ScoDoc status"""
    email_test_mode_address = sco_preferences.get_preference("email_test_mode_address")
    if email_test_mode_address:
        flash(
            f"Mode test: mails redirigés vers {email_test_mode_address}",
            category="warning",
        )


def critical_error(msg):
    """Handle a critical error: flush all caches, display message to the user"""
    import app.scodoc.sco_utils as scu

    log(f"\n*** CRITICAL ERROR: {msg}")
    subject = f"CRITICAL ERROR: {msg}".strip()[:68]
    send_scodoc_alarm(subject, msg)
    clear_scodoc_cache()
    raise ScoValueError(
        f"""
    Une erreur est survenue, veuillez ré-essayer.

    {msg}
    """
    )