import logging
from pathlib import Path

from django.contrib import messages
from django.contrib.auth.decorators import login_required
from django.http import FileResponse, Http404, HttpResponse
from django.shortcuts import get_object_or_404, redirect, render
from django.urls import reverse
from django.views.decorators.http import require_http_methods, require_POST

from .forms import LetterTemplateForm, MailMergeJobForm
from .models import LetterTemplate, MailMergeJob
from .services.docx_renderer import extract_placeholders
from .services.preview import PreviewError, build_preview
from .tasks import run_mailmerge

logger = logging.getLogger(__name__)


@login_required
def dashboard(request):
    templates = LetterTemplate.objects.all()[:20]
    jobs = MailMergeJob.objects.select_related("template")[:20]
    return render(request, "mailmerge/dashboard.html",
                  {"templates": templates, "jobs": jobs})


@login_required
@require_http_methods(["GET", "POST"])
def template_upload(request):
    form = LetterTemplateForm(request.POST or None, request.FILES or None)
    if request.method == "POST" and form.is_valid():
        tpl = form.save(commit=False)
        tpl.created_by = request.user
        tpl.save()
        # Platzhalter extrahieren – Datei liegt jetzt auf Disk
        tpl.placeholders = extract_placeholders(Path(tpl.file.path))
        tpl.save(update_fields=["placeholders"])
        return redirect(reverse("template-detail", args=[tpl.id]))
    return render(request, "mailmerge/template_form.html", {"form": form})


@login_required
def template_detail(request, pk):
    tpl = get_object_or_404(LetterTemplate, pk=pk)
    return render(request, "mailmerge/template_detail.html", {"template": tpl})


@login_required
@require_http_methods(["GET", "POST"])
def job_create(request):
    form = MailMergeJobForm(request.POST or None, request.FILES or None)
    if request.method == "POST" and form.is_valid():
        job = form.save(commit=False)
        job.created_by = request.user
        job.save()
        run_mailmerge.delay(str(job.id))
        return redirect(reverse("job-detail", args=[job.id]))
    return render(request, "mailmerge/job_form.html", {"form": form})


@login_required
@require_POST
def job_preview(request):
    """Rendert nur die erste CSV-Zeile gegen das gewählte Template und
    liefert das PDF inline aus. Persistiert nichts."""
    form = MailMergeJobForm(request.POST, request.FILES)
    if not form.is_valid():
        # Form-Errors zurück ins Hauptformular leiten
        return render(request, "mailmerge/job_form.html",
                      {"form": form, "preview_error": None})

    template = form.cleaned_data["template"]
    csv_upload = form.cleaned_data["recipients_csv"]

    try:
        result = build_preview(
            template_path=Path(template.file.path),
            csv_file=csv_upload,
        )
    except PreviewError as exc:
        messages.error(request, str(exc))
        return render(request, "mailmerge/job_form.html",
                      {"form": form, "preview_error": str(exc)})
    except Exception as exc:  # noqa: BLE001 – defensiv, breite Fehlerklasse von LibreOffice
        logger.exception("Preview-Render fehlgeschlagen")
        messages.error(
            request,
            "Vorschau konnte nicht erstellt werden: " + str(exc),
        )
        return render(request, "mailmerge/job_form.html",
                      {"form": form, "preview_error": str(exc)})

    response = HttpResponse(result.pdf_bytes, content_type="application/pdf")
    response["Content-Disposition"] = 'inline; filename="vorschau.pdf"'
    response["X-Preview-Placeholders"] = ",".join(result.placeholders)
    response["X-Preview-Extra-Columns"] = ",".join(result.extra_columns)
    return response


@login_required
def job_detail(request, pk):
    job = get_object_or_404(
        MailMergeJob.objects.select_related("template"), pk=pk
    )
    logs = job.logs.all()
    # HTMX partials: nur das Status-Fragment ausliefern
    if request.headers.get("HX-Request"):
        return render(request, "mailmerge/_job_status.html",
                      {"job": job, "logs": logs})
    return render(request, "mailmerge/job_detail.html",
                  {"job": job, "logs": logs})


@login_required
def job_download(request, pk):
    """PDF-Download – via X-Accel-Redirect in Production, direkter Stream im Dev."""
    job = get_object_or_404(MailMergeJob, pk=pk)
    if not job.result_pdf:
        raise Http404("Kein Ergebnis-PDF vorhanden.")

    # In Dev (settings.DEBUG) direkt streamen
    from django.conf import settings
    if settings.DEBUG:
        return FileResponse(job.result_pdf.open("rb"),
                            as_attachment=True,
                            filename=Path(job.result_pdf.name).name)

    # In Production: Nginx serviert die Datei via internem Mount.
    response = HttpResponse()
    response["Content-Type"] = "application/pdf"
    response["Content-Disposition"] = (
        f'attachment; filename="{Path(job.result_pdf.name).name}"'
    )
    # Pfad relativ zu MEDIA_ROOT, gemappt auf /protected-media/
    relative = job.result_pdf.name
    response["X-Accel-Redirect"] = f"/protected-media/{relative}"
    return response