import csv
from datetime import date

from django.contrib.auth.decorators import login_required
from django.http import HttpResponse
from django.shortcuts import render, get_object_or_404

from .models import Entreprise
from . import services

MOIS = services.MOIS_FR


def _entreprise(request):
    """Entreprise courante, restreinte à celles accessibles par l'utilisateur."""
    accessibles = Entreprise.accessibles(request.user)
    eid = request.GET.get("entreprise")
    if eid:
        return get_object_or_404(accessibles, pk=eid)
    return accessibles.first()


def _annee(request):
    return int(request.GET.get("annee", date.today().year))


TRIMESTRES = [(1, "T1 (janv.–mars)", [1, 2, 3]), (2, "T2 (avr.–juin)", [4, 5, 6]),
              (3, "T3 (juil.–sept.)", [7, 8, 9]), (4, "T4 (oct.–déc.)", [10, 11, 12])]


def _periode(request, entreprise, champ):
    """Retourne (mois_filtre, periode_sel, label, options, type) selon la
    périodicité (mensuelle/trimestrielle) configurée sur l'entreprise."""
    if getattr(entreprise, champ, "mensuelle") == "trimestrielle":
        defaut = (date.today().month - 1) // 3 + 1
        sel = min(max(int(request.GET.get("periode", defaut)), 1), 4)
        _, label, mois = TRIMESTRES[sel - 1]
        return mois, sel, label, [(i, lab) for i, lab, _ in TRIMESTRES], "trimestre"
    defaut = date.today().month
    sel = min(max(int(request.GET.get("periode", request.GET.get("mois", defaut))), 1), 12)
    return sel, sel, MOIS[sel - 1], [(i, MOIS[i - 1]) for i in range(1, 13)], "mois"


def _base_ctx(request, entreprise, annee, vue):
    return {
        "entreprise": entreprise,
        "entreprises": Entreprise.accessibles(request.user),
        "annee": annee,
        "annees": services.annees_disponibles(entreprise) or [annee],
        "vue": vue,
        "mois_liste": list(enumerate(MOIS, start=1)),
    }


@login_required
def dashboard(request):
    entreprise = _entreprise(request)
    if entreprise is None:
        return render(request, "compta/dashboard.html", {"entreprise": None})
    annee = _annee(request)
    ctx = services.synthese(entreprise, annee)
    ctx.update(_base_ctx(request, entreprise, annee, "global"))
    ctx.update({
        "mois_labels": ["Jan", "Fév", "Mar", "Avr", "Mai", "Juin",
                        "Juil", "Août", "Sep", "Oct", "Nov", "Déc"],
        "ca_mensuel_json": [float(v) for v in ctx["ca_mensuel"]],
    })
    return render(request, "compta/dashboard.html", ctx)


@login_required
def vue_mensuelle(request):
    entreprise = _entreprise(request)
    if entreprise is None:
        return render(request, "compta/mensuel.html", {"entreprise": None})
    annee = _annee(request)
    ctx = _base_ctx(request, entreprise, annee, "mensuel")
    ctx["rows"] = services.tableau_mensuel(entreprise, annee)
    return render(request, "compta/mensuel.html", ctx)


@login_required
def declaration_urssaf(request):
    entreprise = _entreprise(request)
    if entreprise is None:
        return render(request, "compta/decl_urssaf.html", {"entreprise": None})
    annee = _annee(request)
    mois, periode_sel, label, options, ptype = _periode(request, entreprise, "periodicite_urssaf")
    ctx = _base_ctx(request, entreprise, annee, "urssaf")
    ctx.update({"periode_sel": periode_sel, "periode_options": options, "periode_type": ptype})
    ctx["decl"] = services.declaration_urssaf(entreprise, annee, mois, label)
    return render(request, "compta/decl_urssaf.html", ctx)


@login_required
def declaration_tva(request):
    entreprise = _entreprise(request)
    if entreprise is None:
        return render(request, "compta/decl_tva.html", {"entreprise": None})
    annee = _annee(request)
    mois, periode_sel, label, options, ptype = _periode(request, entreprise, "periodicite_tva")
    mode = request.GET.get("mode") or entreprise.vue_tva
    ctx = _base_ctx(request, entreprise, annee, "tva")
    ctx.update({"periode_sel": periode_sel, "periode_options": options,
                "periode_type": ptype, "mode": mode})
    ctx["decl"] = services.declaration_tva(entreprise, annee, mois, label)
    return render(request, "compta/decl_tva.html", ctx)


# ---- Exports CSV --------------------------------------------------------

def _csv(filename):
    resp = HttpResponse(content_type="text/csv; charset=utf-8")
    resp["Content-Disposition"] = f'attachment; filename="{filename}"'
    resp.write("")
    return resp


@login_required
def export_ventes(request):
    entreprise = _entreprise(request)
    annee = _annee(request)
    resp = _csv(f"ventes_{annee}.csv")
    w = csv.writer(resp, delimiter=";")
    w.writerow(["Numero", "Client", "Activite", "Date emission",
                "Date encaissement", "Statut", "HT", "TVA", "TTC"])
    for f in services.factures_encaissees(entreprise, annee).select_related("client"):
        w.writerow([f.numero, f.client.nom, f.get_activite_display(),
                    f.date_emission, f.date_encaissement, f.get_statut_display(),
                    f.montant_ht, f.montant_tva, f.montant_ttc])
    return resp


@login_required
def export_tva(request):
    entreprise = _entreprise(request)
    annee = _annee(request)
    s = services.synthese(entreprise, annee)
    resp = _csv(f"tva_{annee}.csv")
    w = csv.writer(resp, delimiter=";")
    w.writerow(["Annee", "TVA sur ventes", "TVA autoliquidee", "TVA collectee",
                "TVA deductible", "TVA a reverser"])
    w.writerow([annee, s["tva_sur_ventes"], s["tva_autoliquidee"],
                s["tva_collectee"], s["tva_deductible"], s["tva_a_reverser"]])
    return resp


@login_required
def export_urssaf(request):
    entreprise = _entreprise(request)
    annee = _annee(request)
    s = services.synthese(entreprise, annee)
    resp = _csv(f"urssaf_{annee}.csv")
    w = csv.writer(resp, delimiter=";")
    w.writerow(["Annee", "Activite", "CA HT", "Taux URSSAF", "Cotisations",
                "Taux VL", "Versement liberatoire", "Abattement", "Revenu imposable"])
    for l in s["lignes_activite"]:
        w.writerow([annee, l["label"], l["ca_ht"], l["taux_urssaf"], l["cotisations"],
                    l["taux_vl"], l["versement_liberatoire"], l["abattement_fiscal"],
                    l["revenu_imposable"]])
    w.writerow([annee, "TOTAL", s["ca_ht"], "", s["cotisations_urssaf"], "",
                s["versement_liberatoire"], "", s["revenu_imposable"]])
    return resp