# -*- mode: python -*-
# -*- coding: utf-8 -*-

##############################################################################
#
# Gestion scolarite IUT
#
# Copyright (c) 1999 - 2023 Emmanuel Viennet.  All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
#   Emmanuel Viennet      emmanuel.viennet@viennet.net
#
##############################################################################

"""Accès aux emplois du temps

XXX usage uniquement experimental pour tests implémentations

"""
from datetime import timezone
import re
import icalendar

from flask import flash, g, url_for
from app import log
from app.models import FormSemestre, GroupDescr, ModuleImpl, ScoDocSiteConfig
from app.scodoc.sco_exceptions import ScoValueError
import app.scodoc.sco_utils as scu


def get_ics_filename(edt_id: str) -> str:
    "Le chemin vers l'ics de cet edt_id"
    edt_ics_path = ScoDocSiteConfig.get("edt_ics_path")
    if not edt_ics_path.strip():
        return None
    return edt_ics_path.format(edt_id=edt_id)


def formsemestre_load_calendar(
    formsemestre: FormSemestre = None, edt_id: str = None
) -> tuple[bytes, icalendar.cal.Calendar]:
    """Load ics data, return raw ics and decoded calendar.
    Raises ScoValueError if not configured or not available or invalid format.
    """
    if edt_id is None and formsemestre:
        edt_id = formsemestre.get_edt_id()
    if not edt_id:
        raise ScoValueError(
            "accès aux emplois du temps non configuré pour ce semestre (pas d'edt_id)"
        )
    ics_filename = get_ics_filename(edt_id)
    try:
        with open(ics_filename, "rb") as file:
            log(f"Loading edt from {ics_filename}")
            data = file.read()
            try:
                calendar = icalendar.Calendar.from_ical(data)
            except ValueError as exc:
                log(
                    f"""formsemestre_load_calendar: error importing ics for {
                        formsemestre or ''}\npath='{ics_filename}'"""
                )
                raise ScoValueError(
                    f"calendrier ics illisible (edt_id={edt_id})"
                ) from exc
    except FileNotFoundError as exc:
        log(
            f"formsemestre_load_calendar: ics not found for {formsemestre or ''}\npath='{ics_filename}'"
        )
        raise ScoValueError(
            f"Fichier ics introuvable (filename={ics_filename})"
        ) from exc
    except PermissionError as exc:
        log(
            f"""formsemestre_load_calendar: permission denied for {formsemestre or ''
                                                                 }\npath='{ics_filename}'"""
        )
        raise ScoValueError(
            f"Fichier ics inaccessible: vérifier permissions (filename={ics_filename})"
        ) from exc

    return data, calendar


# --- Couleurs des évènements emploi du temps
_COLOR_PALETTE = [
    "#ff6961",
    "#ffb480",
    "#f8f38d",
    "#42d6a4",
    "#08cad1",
    "#59adf6",
    "#9d94ff",
    "#c780e8",
]
_EVENT_DEFAULT_COLOR = "rgb(214, 233, 248)"


def formsemestre_edt_dict(formsemestre: FormSemestre) -> list[dict]:
    """EDT complet du semestre, comme une liste de dict serialisable en json.
    Fonction appellée par l'API /formsemestre/<int:formsemestre_id>/edt
    TODO: spécifier intervalle de dates start et end
    """
    try:
        events_scodoc = _load_and_convert_ics(formsemestre)
    except ScoValueError as exc:
        return exc.args[0]
    # Génération des événements pour le calendrier html
    events_cal = []
    for event in events_scodoc:
        group: GroupDescr | bool = event["group"]
        if group is False:
            group_disp = f"""<div class="group-edt">
                <span title="extraction emploi du temps non configurée">
                {scu.EMO_WARNING} non configuré</span>
                </div>"""
        else:
            group_disp = (
                f"""<div class="group-name">{group.get_nom_with_part(default="promo")}</div>"""
                if group
                else f"""<div class="group-edt">{event['edt_group']}
                    <span title="vérifier noms de groupe ou configuration extraction edt">
                    {scu.EMO_WARNING} non reconnu</span>
                    </div>"""
            )
        modimpl: ModuleImpl | bool = event["modimpl"]
        if modimpl is False:
            mod_disp = f"""<div class="module-edt" title="extraction emploi du temps non configurée">
                {scu.EMO_WARNING} non configuré
                </div>"""
        else:
            mod_disp = (
                f"""<div class="module-edt mod-name" title="{modimpl.module.abbrev or ""}">{
                        modimpl.module.code}</div>"""
                if modimpl
                else f"""<div class="module-edt mod-etd" title="code module non trouvé dans ScoDoc.
                Vérifier configuration.">{
                        scu.EMO_WARNING} {event['edt_module']}</div>"""
            )
        # --- Lien saisie abs
        link_abs = (
            f"""<div class="module-edt link-abs"><a class="stdlink" href="{
                        url_for("assiduites.signal_assiduites_group",
                                scodoc_dept=g.scodoc_dept,
                                formsemestre_id=formsemestre.id,
                                group_ids=group.id,
                                heure_deb=event["heure_deb"],
                                heure_fin=event["heure_fin"],
                                moduleimpl_id=modimpl.id,
                                jour = event["jour"],
                        )}">absences</a>
            </div>"""
            if modimpl and group
            else ""
        )
        d = {
            # Champs utilisés par tui.calendar
            "calendarId": "cal1",
            "title": event["title"] + group_disp + mod_disp + link_abs,
            "start": event["start"],
            "end": event["end"],
            "backgroundColor": event["group_bg_color"],
            # Infos brutes pour usage API éventuel
            "group_id": group.id if group else None,
            "group_edt_id": event["edt_group"],
            "moduleimpl_id": modimpl.id if modimpl else None,
        }
        events_cal.append(d)

    return events_cal


def _load_and_convert_ics(formsemestre: FormSemestre) -> list[dict]:
    "chargement fichier, filtrage et extraction des identifiants."
    # Chargement du calendier ics
    _, calendar = formsemestre_load_calendar(formsemestre)
    if not calendar:
        return []
    # --- Paramètres d'extraction
    edt_ics_title_field = ScoDocSiteConfig.get("edt_ics_title_field")
    edt_ics_title_regexp = ScoDocSiteConfig.get("edt_ics_title_regexp")
    try:
        edt_ics_title_pattern = (
            re.compile(edt_ics_title_regexp) if edt_ics_title_regexp else None
        )
    except re.error as exc:
        raise ScoValueError(
            "expression d'extraction du titre depuis l'emploi du temps invalide"
        ) from exc
    edt_ics_group_field = ScoDocSiteConfig.get("edt_ics_group_field")
    edt_ics_group_regexp = ScoDocSiteConfig.get("edt_ics_group_regexp")
    try:
        edt_ics_group_pattern = (
            re.compile(edt_ics_group_regexp) if edt_ics_group_regexp else None
        )
    except re.error as exc:
        raise ScoValueError(
            "expression d'extraction du groupe depuis l'emploi du temps invalide"
        ) from exc
    edt_ics_mod_field = ScoDocSiteConfig.get("edt_ics_mod_field")
    edt_ics_mod_regexp = ScoDocSiteConfig.get("edt_ics_mod_regexp")
    try:
        edt_ics_mod_pattern = (
            re.compile(edt_ics_mod_regexp) if edt_ics_mod_regexp else None
        )
    except re.error as exc:
        raise ScoValueError(
            "expression d'extraction du module depuis l'emploi du temps invalide"
        ) from exc
    # --- Correspondances id edt -> id scodoc pour groupes, modules et enseignants
    edt2group = formsemestre_retreive_groups_from_edt_id(formsemestre)
    group_colors = {
        group_name: _COLOR_PALETTE[i % (len(_COLOR_PALETTE) - 1) + 1]
        for i, group_name in enumerate(edt2group)
    }
    default_group = formsemestre.get_default_group()
    edt2modimpl = formsemestre_retreive_modimpls_from_edt_id(formsemestre)
    # ---
    events = [e for e in calendar.walk() if e.name == "VEVENT"]
    events_sco = []
    for event in events:
        if "DESCRIPTION" in event:
            # --- Titre de l'évènement
            title = (
                extract_event_data(event, edt_ics_title_field, edt_ics_title_pattern)
                if edt_ics_title_pattern
                else "non configuré"
            )
            # --- Group
            if edt_ics_group_pattern:
                edt_group = extract_event_data(
                    event, edt_ics_group_field, edt_ics_group_pattern
                )
                # si pas de groupe dans l'event, ou si groupe non reconnu,
                # prend toute la promo ("tous")
                group: GroupDescr = (
                    edt2group.get(edt_group, default_group)
                    if edt_group
                    else default_group
                )
                group_bg_color = (
                    group_colors.get(edt_group, _EVENT_DEFAULT_COLOR)
                    if group
                    else "lightgrey"
                )
            else:
                edt_group = ""
                group = False
                group_bg_color = _EVENT_DEFAULT_COLOR

            # --- ModuleImpl
            if edt_ics_mod_pattern:
                edt_module = extract_event_data(
                    event, edt_ics_mod_field, edt_ics_mod_pattern
                )
                modimpl: ModuleImpl = edt2modimpl.get(edt_module, None)
            else:
                modimpl = False
                edt_module = ""
            # --- TODO: enseignant
            #
            events_sco.append(
                {
                    "title": title,
                    "edt_group": edt_group,  # id group edt non traduit
                    "group": group,  # False si extracteur non configuré
                    "group_bg_color": group_bg_color,  # associée au groupe
                    "modimpl": modimpl,  # False si extracteur non configuré
                    "edt_module": edt_module,  # id module edt non traduit
                    # heures pour saisie abs: en heure LOCALE DU SERVEUR
                    "heure_deb": event.decoded("dtstart")
                    .replace(tzinfo=timezone.utc)
                    .astimezone(tz=None)
                    .strftime("%H:%M"),
                    "heure_fin": event.decoded("dtend")
                    .replace(tzinfo=timezone.utc)
                    .astimezone(tz=None)
                    .strftime("%H:%M"),
                    "jour": event.decoded("dtstart").isoformat(),
                    "start": event.decoded("dtstart").isoformat(),
                    "end": event.decoded("dtend").isoformat(),
                }
            )
    return events_sco


def extract_event_data(
    event: icalendar.cal.Event, ics_field: str, pattern: re.Pattern
) -> str:
    """Extrait la chaine (id) de l'évènement."""
    if not event.has_key(ics_field):
        return "-"
    data = event.decoded(ics_field).decode("utf-8")  # assume ics in utf8
    m = pattern.search(data)
    if m and len(m.groups()) > 0:
        return m.group(1)
    # fallback: ics field, complete
    return data


# def extract_event_title(event: icalendar.cal.Event) -> str:
#     """Extrait le titre à afficher dans nos calendriers.
#     En effet, le titre présent dans l'ics emploi du temps est souvent complexe et peu parlant.
#     Par exemple, à l'USPN, Hyperplanning nous donne:
#     'Matière : VRETR113 - Mathematiques du sig (VRETR113\nEnseignant : 1234 - M. DUPONT PIERRE\nTD : TDB\nSalle : L112 (IUTV) - L112\n'
#     """
#     # TODO: fonction ajustée à l'USPN, devra être paramétrable d'une façon ou d'une autre: regexp ?
#     if not event.has_key("DESCRIPTION"):
#         return "-"
#     description = event.decoded("DESCRIPTION").decode("utf-8")  # assume ics in utf8
#     # ici on prend le nom du module
#     m = re.search(r"Matière : \w+ - ([\w\.\s']+)", description)
#     if m and len(m.groups()) > 0:
#         return m.group(1)
#     # fallback: full description
#     return description


# def extract_event_module(event: icalendar.cal.Event) -> str:
#     """Extrait le code module de l'emplois du temps.
#     Chaine vide si ne le trouve pas.
#     Par exemple, à l'USPN, Hyperplanning nous donne le code 'VRETR113' dans DESCRIPTION
#     'Matière : VRETR113 - Mathematiques du sig (VRETR113\nEnseignant : 1234 - M. DUPONT PIERRE\nTD : TDB\nSalle : L112 (IUTV) - L112\n'
#     """
#     # TODO: fonction ajustée à l'USPN, devra être paramétrable d'une façon ou d'une autre: regexp ?
#     if not event.has_key("DESCRIPTION"):
#         return "-"
#     description = event.decoded("DESCRIPTION").decode("utf-8")  # assume ics in utf8
#     # extraction du code:
#     m = re.search(r"Matière : ([A-Z][A-Z0-9]+)", description)
#     if m and len(m.groups()) > 0:
#         return m.group(1)
#     return ""


# def extract_event_group(event: icalendar.cal.Event) -> str:
#     """Extrait le nom du groupe (TD, ...). "" si pas de match."""
#     # Utilise ici le SUMMARY
#     # qui est de la forme
#     # SUMMARY;LANGUAGE=fr:TP2 GPR1 - VCYR303 - Services reseaux ava (VCYR303) - 1234 - M. VIENNET EMMANUEL - V2ROM - BUT2 RT pa. ROM - Groupe 1
#     if not event.has_key("SUMMARY"):
#         return "-"
#     summary = event.decoded("SUMMARY").decode("utf-8")  # assume ics in utf8
#     # extraction du code:
#     m = re.search(r".*- ([\w\s]+)$", summary)
#     if m and len(m.groups()) > 0:
#         return m.group(1).strip()
#     return ""


def formsemestre_retreive_modimpls_from_edt_id(
    formsemestre: FormSemestre,
) -> dict[str, ModuleImpl]:
    """Construit un dict donnant le moduleimpl de chaque edt_id"""
    edt2modimpl = {modimpl.get_edt_id(): modimpl for modimpl in formsemestre.modimpls}
    edt2modimpl.pop("", None)
    return edt2modimpl


def formsemestre_retreive_groups_from_edt_id(
    formsemestre: FormSemestre,
) -> dict[str, GroupDescr]:
    """Construit un dict donnant le groupe de chaque edt_id"""
    edt2group = {}
    for partition in formsemestre.partitions:
        edt2group.update({g.get_edt_id(): g for g in partition.groups})
    edt2group.pop("", None)
    return edt2group