from django.shortcuts import render, redirect, get_object_or_404
from django.contrib.auth import authenticate, login
from django.contrib.auth.decorators import login_required, user_passes_test
from django.http import HttpResponse, HttpResponseForbidden
from django.contrib import messages
from django.db.models import Q
import csv
from django.utils.timezone import now
from .forms import ImportForm
from .models import Entry
from .utils import import_csv, SEARCHABLE_FIELDS, build_query

def is_admin(user):
    return user.is_superuser or user.is_staff

def login_view(request):
    if request.user.is_authenticated:
        return redirect("search")
    ctx = {}
    if request.method == "POST":
        username = request.POST.get("username")
        password = request.POST.get("password")
        user = authenticate(request, username=username, password=password)
        if user:
            login(request, user)
            return redirect("search")
        ctx["error"] = "Invalid credentials"
    return render(request, "login.html", ctx)

@login_required
def redirect_to_search(request):
    return redirect("search")

@login_required
def search_view(request):
    total = Entry.objects.count()
    query = request.GET.get("q", "").strip()
    selected = request.GET.getlist("fields") or list(SEARCHABLE_FIELDS.keys())
    entries = []
    results_count = 0
    current_id = None

    if query:
        q = build_query(selected, query)
        entries = list(Entry.objects.filter(q).order_by("-date_added","-id").values_list("id", flat=True))
        results_count = len(entries)
        request.session["search_ids"] = entries
        request.session["search_index"] = 0
        if entries:
            current_id = entries[0]
            return redirect("record_view", entry_id=current_id)

    return render(request, "search.html", {
        "total": total,
        "q": query,
        "selected": selected,
        "fields": list(SEARCHABLE_FIELDS.keys()),
        "results_count": results_count,
    })

@login_required
def record_view(request, entry_id):
    ids = request.session.get("search_ids", [])
    if entry_id in ids:
        request.session["search_index"] = ids.index(entry_id)
    idx = request.session.get("search_index", 0)
    total = Entry.objects.count()
    results_count = len(ids)
    pos = (idx+1) if ids else 1
    entry = get_object_or_404(Entry, id=entry_id)
    return render(request, "record.html", {
        "entry": entry,
        "locked": True,
        "total": total,
        "results_count": results_count,
        "position": pos,
    })

@login_required
def nav_prev(request):
    ids = request.session.get("search_ids", [])
    idx = request.session.get("search_index", 0)
    if ids:
        idx = max(0, idx-1)
        request.session["search_index"] = idx
        return redirect("record_view", entry_id=ids[idx])
    messages.info(request, "No search results loaded.")
    return redirect("search")

@login_required
def nav_next(request):
    ids = request.session.get("search_ids", [])
    idx = request.session.get("search_index", 0)
    if ids:
        idx = min(len(ids)-1, idx+1)
        request.session["search_index"] = idx
        return redirect("record_view", entry_id=ids[idx])
    messages.info(request, "No search results loaded.")
    return redirect("search")

@login_required
def record_save(request, entry_id):
    if request.method != "POST":
        return redirect("record_view", entry_id=entry_id)
    e = get_object_or_404(Entry, id=entry_id)
    # Save edited fields
    e.subject = request.POST.get("subject","")
    e.illustration = request.POST.get("illustration","")
    e.application = request.POST.get("application","")
    e.scripture_raw = request.POST.get("scripture_raw","")
    e.source = request.POST.get("source","")
    e.talk_title = request.POST.get("talk_title","")
    tn = request.POST.get("talk_number","").strip()
    e.talk_number = int(tn) if tn.isdigit() else None
    e.entry_code = request.POST.get("entry_code","")
    e.date_added = request.POST.get("date_added") or None
    e.date_edited = request.POST.get("date_edited") or None
    e.save()
    messages.success(request, "Saved changes.")
    return redirect("record_view", entry_id=entry_id)

@login_required
def record_delete(request, entry_id):
    if request.method == "POST":
        e = get_object_or_404(Entry, id=entry_id)
        e.delete()
        messages.success(request, "Entry deleted.")
        # After delete, move to previous or search page
        ids = request.session.get("search_ids", [])
        idx = request.session.get("search_index", 0)
        if ids:
            ids = [i for i in ids if i != entry_id]
            request.session["search_ids"] = ids
            if not ids:
                return redirect("search")
            idx = max(0, min(idx, len(ids)-1))
            request.session["search_index"] = idx
            return redirect("record_view", entry_id=ids[idx])
        return redirect("search")
    return HttpResponseForbidden("Use POST to delete.")

@login_required
@user_passes_test(is_admin)
def import_wizard(request):
    from .forms import ImportForm
    if request.method == "POST":
        form = ImportForm(request.POST, request.FILES)
        if form.is_valid():
            fbytes = form.cleaned_data["file"].read()
            dry = form.cleaned_data["dry_run"]
            try:
                report = import_csv(fbytes, dry_run=dry)
                return render(request, "import_result.html", {"report": report, "dry_run": dry})
            except Exception as e:
                messages.error(request, f"Import failed: {e}")
    else:
        form = ImportForm()
    return render(request, "import_wizard.html", {"form": form})

@login_required
@user_passes_test(is_admin)
def export_csv(request):
    response = HttpResponse(content_type='text/csv')
    ts = now().strftime("%Y-%m-%d_%H-%M-%S")
    response['Content-Disposition'] = f'attachment; filename="illustrations_backup_{ts}.csv"'
    writer = csv.writer(response)
    writer.writerow(["Subject","Illustration","Application","Scripture","Source","Talk Title","Talk Number","Code","Date","Date Edited"])    
    for e in Entry.objects.all().order_by("id"):
        writer.writerow([
            e.subject, e.illustration, e.application, e.scripture_raw, e.source,
            e.talk_title, e.talk_number if e.talk_number is not None else "", e.entry_code,
            e.date_added.isoformat() if e.date_added else "",
            e.date_edited.isoformat() if e.date_edited else "",
        ])
    return response