import re

from django.db.models import Q
from django.shortcuts import render
from django.views.generic.list import ListView

import troggle.settings as settings
from troggle.core.models.logbooks import LogbookEntry, PersonLogEntry, QM
from troggle.core.models.survex import SurvexBlock, SurvexFile
from troggle.core.models.troggle import Expedition, Person
from troggle.core.models.wallets import Wallet
from troggle.core.utils import TROG, current_expo
from troggle.parsers.imports import import_logbook


"""These views are for logbook items when they appear in an 'expedition' page
and for persons: their individual pages and their perseonexpedition pages.

It uses the global object TROG to hold some cached pages.
"""

todo = """- Fix the get_person_chronology() display bug.

- Fix id= value preservation on editing
"""


def notablepersons(request):
    def notabilitykey(person):
        return person.notability()

    persons = Person.objects.all()
    # From what I can tell, "persons" seems to be the table rows, while "pcols" is the table columns. - AC 16 Feb 09
    pcols = []
    ncols = 4
    nc = int((len(persons) + ncols - 1) / ncols)
    for i in range(ncols):
        pcols.append(persons[i * nc : (i + 1) * nc])

    notablepersons = []
    #   Needed recoding because of Django CVE-2021-45116
    for person in persons:
        if person.bisnotable():
            notablepersons.append(person)
    notablepersons.sort(key=notabilitykey, reverse=True)

    return render(
        request, "notablepersons.html", {"persons": persons, "pcols": pcols, "notablepersons": notablepersons}
    )


def expedition(request, expeditionname):
    """Returns a rendered page for one expedition, specified by the year e.g. '2019'.
    If page caching is enabled, it caches the dictionaries used to render the template page.

    This is not as difficult to understand as it looks. 
    Yes there are many levels of indirection, with multiple trees being traversed at the same time. 
    And the Django special syntax makes this hard for normal Python programmers.

    Remember that 'personexpedition__expedition' is interpreted by Django to mean the
    'expedition' object which is connected by a foreign key to the 'personexpedition'
    object, which is a field of the PersonLogEntry object:
    PersonLogEntry.objects.filter(personexpedition__expedition=expo)

    Queries are not evaluated to hit the database until a result is actually used. Django
    does lazy evaluation.

    """
    current = current_expo() # creates new expo after 31st Dec.
    try:
        expo = Expedition.objects.get(year=int(expeditionname))
    except:
        message = (
            "Expedition not found - database apparently empty, you probably need to do a full re-import of all data."
        )
        return render(request, "errors/generic.html", {"message": message})

    ts = TROG["pagecache"]["expedition"]  # not much use unless single user!
    if request.user.is_authenticated:
        logged_in = True
        if "reload" in request.GET:
            if expeditionname in ts:
                del ts[expeditionname] # clean out cache for page
            expo.logbookentry_set.all().delete()
            import_logbook(year=expo.year)
    else:
        logged_in = False

    if settings.CACHEDPAGES:
        if expeditionname in ts:
            # print('! - expo {expeditionanme} using cached page')
            return render(request, "expedition.html", {**ts[expeditionname], "logged_in": logged_in})

    expeditions = Expedition.objects.all()  # top menu only, evaluated only when template renders

    entries = expo.logbookentry_set.all()
    blocks = expo.survexblock_set.all()
    dateditems = list(entries) + list(blocks)  # evaluates the Django query and hits db
    dates = sorted(set([item.date for item in dateditems]))

    allpersonlogentries = PersonLogEntry.objects.filter(personexpedition__expedition=expo)

    personexpodays = []
    for personexpedition in expo.personexpedition_set.all():
        expotrips = allpersonlogentries.filter(personexpedition=personexpedition)  # lazy
        expoblocks = blocks.filter(survexpersonrole__personexpedition=personexpedition)

        prow = []

        for date in dates:
            personentries = expotrips.filter(logbook_entry__date=date)  # lazy
            personblocks = set(expoblocks.filter(date=date))  # not lazy
            pcell = {}
            pcell["personentries"] = personentries
            pcell["survexblocks"] = personblocks
            if issunday := (date.weekday() == 6):  # WALRUS
                pcell["sunday"] = issunday
            prow.append(pcell)
        personexpodays.append({"personexpedition": personexpedition, "personrow": prow})

    ts[expeditionname] = {
        "year": int(expeditionname),
        "expedition": expo,
        "expeditions": expeditions,
        "personexpodays": personexpodays,
        "settings": settings,
        "dateditems": dateditems,
        "dates": dates,
    }
    TROG["pagecache"]["expedition"][expeditionname] = ts[expeditionname]

    return render(request, "expedition.html", {**ts[expeditionname], "logged_in": logged_in})


class Expeditions_tsvListView(ListView):
    """This uses the Django built-in shortcut mechanism
    It defaults to use a template with name <app-label>/<model-name>_list.html.
    https://www.agiliq.com/blog/2017/12/when-and-how-use-django-listview/
    https://developer.mozilla.org/en-US/docs/Learn/Server-side/Django/Generic_views
    Either a queryset variable  or set_queryset() function is used, but not needed
    if you want all the obejcts of a particaulr type in which case just set model = <object>
    """

    template_name = "core/expeditions_tsv_list.html"  # if not present then uses core/expedition_list.html
    # queryset = Expedition.objects.all()
    # context_object_name = 'expedition'
    model = Expedition  # equivalent to .objects.all() for a queryset


class Expeditions_jsonListView(ListView):
    template_name = "core/expeditions_json_list.html"
    model = Expedition

class QMs_jsonListView(ListView):
    template_name = "core/QMs_json_list.html"
    model = QM
    
def person(request, slug=""):
    """Now very much simpler with an unambiguous slug
    """
    this_person = Person.objects.get(slug=slug)
    return render(request, "person.html", {"person": this_person})

def get_person_chronology(personexpedition):
    """
    This is just a nasty convoluted way of trying the make the template do more work than it is sensible to ask it to do.
    Rewrite more simply with the login in the python, not in Django template language (you bastard Curtis).
    """
    res = {}
    for personlogentry in personexpedition.personlogentry_set.all():
        a = res.setdefault(personlogentry.logbook_entry.date, {})
        a.setdefault("personlogentries", []).append(personlogentry)

    for personrole in personexpedition.survexpersonrole_set.all():
        if personrole.survexblock.date:  # avoid bad data from another bug
            a = res.setdefault(personrole.survexblock.date, {})
            a.setdefault("personroles", []).append(personrole.survexblock)

    # build up the tables
    rdates = sorted(list(res.keys()))

    res2 = []
    for rdate in rdates:
        personlogentries = res[rdate].get("personlogentries", [])
        personroles = res[rdate].get("personroles", [])
        for n in range(max(len(personlogentries), len(personroles))):
            res2.append(
                (
                    (n == 0 and rdate or "--"),
                    (n < len(personlogentries) and personlogentries[n]),
                    (n < len(personroles) and personroles[n]),
                )
            )

    return res2


def personexpedition(request, slug="", year=""):
    try:
        person = Person.objects.get(slug=slug)
        this_expedition = Expedition.objects.get(year=year)
        personexpedition = person.personexpedition_set.get(expedition=this_expedition)
        personchronology = get_person_chronology(personexpedition)

        return render(
            request, "personexpedition.html", {"personexpedition": personexpedition, "personchronology": personchronology}
        )
    except:
        msg = f" Person '{slug=}' or year '{year=}' not found in database. Please report this to a nerd." 
        print(msg)
        return render(request, "errors/generic.html", {"message": msg})


def logbookentry(request, date, slug):
    # start = time.time()
    trips = LogbookEntry.objects.filter(date=date)  # all the trips not just this one
    this_logbookentry = trips.filter(date=date, slug=slug)

    if this_logbookentry:
        if len(this_logbookentry) > 1:
            # BUG
            return render(request, "object_list.html", {"object_list": this_logbookentry})
        else:
            # https://stackoverflow.com/questions/739776/how-do-i-do-an-or-filter-in-a-django-query
            wallets = Wallet.objects.filter(Q(survexblock__date=date) | Q(walletdate=date)).distinct()
            svxothers = SurvexFile.objects.filter(survexblock__date=date).distinct()
            
            this_logbookentry = this_logbookentry[0]
            # This is the only page that uses next_.. and prev_..
            # and it is calculated on the fly in the model
            return render(
                request,
                "logbookentry.html",
                {"logbookentry": this_logbookentry,"trips": trips, "svxothers": svxothers, "wallets": wallets},
            )
    else:
        msg = f' Logbook entry slug:"{slug}" not found in database on date:"{date}" '
        print(msg)
        return render(request, "errors/generic.html", {"message": msg})


def get_people(request, expeditionslug):
    exp = Expedition.objects.get(year=expeditionslug)
    return render(request, "options.html", {"items": [(pe.slug, pe.name) for pe in exp.personexpedition_set.all()]})


def get_logbook_entries(request, expeditionslug):
    exp = Expedition.objects.get(year=expeditionslug)
    return render(
        request, "options.html", {"items": [(le.slug, f"{le.date} - {le.title}") for le in exp.logbookentry_set.all()]}
    )