from __future__ import annotations

from django.contrib import messages
from django.contrib.admin.views.decorators import staff_member_required
from django.db.models import Count
from django.shortcuts import get_object_or_404, redirect, render
from django.views.decorators.http import require_POST

from pobsync.errors import ConfigError

from .forms import ScheduleConfigForm
from .models import BackupRun, HostConfig, ScheduleConfig, SnapshotRecord
from .retention import run_sql_retention_plan
from .snapshot_discovery import discover_snapshots


@staff_member_required
def dashboard(request):
    host_qs = (
        HostConfig.objects.annotate(snapshot_count=Count("snapshots", distinct=True), run_count=Count("runs", distinct=True))
        .order_by("host")
    )
    context = {
        "hosts": host_qs,
        "latest_runs": BackupRun.objects.select_related("host", "snapshot").order_by("-created_at")[:10],
        "counts": {
            "hosts": HostConfig.objects.count(),
            "enabled_hosts": HostConfig.objects.filter(enabled=True).count(),
            "schedules": ScheduleConfig.objects.count(),
            "enabled_schedules": ScheduleConfig.objects.filter(enabled=True).count(),
            "snapshots": SnapshotRecord.objects.count(),
            "runs": BackupRun.objects.count(),
            "running_runs": BackupRun.objects.filter(status=BackupRun.Status.RUNNING).count(),
            "failed_runs": BackupRun.objects.filter(status=BackupRun.Status.FAILED).count(),
        },
    }
    return render(request, "pobsync_backend/dashboard.html", context)


@staff_member_required
def host_detail(request, host: str):
    host_config = get_object_or_404(HostConfig, host=host)
    context = {
        "host": host_config,
        "schedule": _schedule_for_host(host_config),
        "latest_runs": host_config.runs.select_related("snapshot").order_by("-created_at")[:10],
        "snapshots": host_config.snapshots.select_related("base").order_by("-started_at", "dirname")[:20],
        "counts": {
            "snapshots": host_config.snapshots.count(),
            "runs": host_config.runs.count(),
            "failed_runs": host_config.runs.filter(status=BackupRun.Status.FAILED).count(),
            "incomplete_snapshots": host_config.snapshots.filter(kind=SnapshotRecord.Kind.INCOMPLETE).count(),
        },
    }
    return render(request, "pobsync_backend/host_detail.html", context)


@staff_member_required
@require_POST
def discover_host_snapshots(request, host: str):
    host_config = get_object_or_404(HostConfig, host=host)
    try:
        result = discover_snapshots(host=host_config)
    except Exception as exc:
        messages.error(request, f"Snapshot discovery failed for {host_config.host}: {exc}")
    else:
        messages.success(
            request,
            (
                f"Snapshot discovery scanned {result['scanned']} items for {host_config.host}: "
                f"{result['created']} created, {result['updated']} updated."
            ),
        )
    return redirect("host_detail", host=host_config.host)


@staff_member_required
def host_retention_plan(request, host: str):
    host_config = get_object_or_404(HostConfig, host=host)
    kind = request.GET.get("kind", "scheduled")
    if kind not in {"scheduled", "manual", "all"}:
        messages.error(request, "Retention kind must be scheduled, manual, or all.")
        return redirect("host_detail", host=host_config.host)
    protect_bases = request.GET.get("protect_bases") in {"1", "true", "on", "yes"}
    try:
        plan = run_sql_retention_plan(host=host_config.host, kind=kind, protect_bases=protect_bases)
    except ConfigError as exc:
        messages.error(request, str(exc))
        return redirect("host_detail", host=host_config.host)
    context = {
        "host": host_config,
        "kind": kind,
        "protect_bases": protect_bases,
        "plan": plan,
    }
    return render(request, "pobsync_backend/retention_plan.html", context)


@staff_member_required
def edit_host_schedule(request, host: str):
    host_config = get_object_or_404(HostConfig, host=host)
    schedule = _schedule_for_host(host_config)
    if request.method == "POST":
        form = ScheduleConfigForm(request.POST, instance=schedule)
        if form.is_valid():
            saved_schedule = form.save(commit=False)
            saved_schedule.host = host_config
            saved_schedule.save()
            messages.success(request, f"Schedule saved for {host_config.host}.")
            return redirect("host_detail", host=host_config.host)
    else:
        form = ScheduleConfigForm(instance=schedule, initial=_default_schedule_initial())

    return render(
        request,
        "pobsync_backend/schedule_form.html",
        {
            "host": host_config,
            "schedule": schedule,
            "form": form,
        },
    )


def _schedule_for_host(host_config: HostConfig) -> ScheduleConfig | None:
    try:
        return host_config.schedule
    except ScheduleConfig.DoesNotExist:
        return None


def _default_schedule_initial() -> dict[str, object]:
    return {
        "cron_expr": "15 2 * * *",
        "user": "root",
        "enabled": True,
        "prune_max_delete": 10,
    }