from __future__ import annotations

from typing import Any

from django.contrib.admin.views.decorators import staff_member_required
from django.db.models import Count
from django.http import JsonResponse

from .models import BackupRun, HostConfig, ScheduleConfig, SnapshotRecord


@staff_member_required
def api_index(request) -> JsonResponse:
    return JsonResponse(
        {
            "ok": True,
            "endpoints": {
                "hosts": request.build_absolute_uri("/api/hosts/"),
                "snapshots": request.build_absolute_uri("/api/snapshots/"),
                "runs": request.build_absolute_uri("/api/runs/"),
            },
        }
    )


@staff_member_required
def hosts(request) -> JsonResponse:
    host_qs = (
        HostConfig.objects.annotate(snapshot_count=Count("snapshots", distinct=True), run_count=Count("runs", distinct=True))
        .select_related("schedule")
        .order_by("host")
    )
    return JsonResponse({"ok": True, "hosts": [_host_payload(host) for host in host_qs]})


@staff_member_required
def snapshots(request) -> JsonResponse:
    snapshot_qs = SnapshotRecord.objects.select_related("host", "base").order_by("host__host", "-started_at", "dirname")
    host_filter = request.GET.get("host")
    kind_filter = request.GET.get("kind")
    if host_filter:
        snapshot_qs = snapshot_qs.filter(host__host=host_filter)
    if kind_filter:
        snapshot_qs = snapshot_qs.filter(kind=kind_filter)
    limit = _limit_from_request(request)
    return JsonResponse({"ok": True, "snapshots": [_snapshot_payload(snapshot) for snapshot in snapshot_qs[:limit]]})


@staff_member_required
def runs(request) -> JsonResponse:
    run_qs = BackupRun.objects.select_related("host", "snapshot").order_by("-created_at")
    host_filter = request.GET.get("host")
    status_filter = request.GET.get("status")
    if host_filter:
        run_qs = run_qs.filter(host__host=host_filter)
    if status_filter:
        run_qs = run_qs.filter(status=status_filter)
    limit = _limit_from_request(request)
    return JsonResponse({"ok": True, "runs": [_run_payload(run) for run in run_qs[:limit]]})


def _host_payload(host: HostConfig) -> dict[str, Any]:
    try:
        schedule = host.schedule
    except ScheduleConfig.DoesNotExist:
        schedule = None
    return {
        "host": host.host,
        "address": host.address,
        "enabled": host.enabled,
        "snapshot_count": host.snapshot_count,
        "run_count": host.run_count,
        "retention": {
            "daily": host.retention_daily,
            "weekly": host.retention_weekly,
            "monthly": host.retention_monthly,
            "yearly": host.retention_yearly,
        },
        "schedule": None
        if schedule is None
        else {
            "cron_expr": schedule.cron_expr,
            "enabled": schedule.enabled,
            "prune": schedule.prune,
            "last_status": schedule.last_status,
            "last_started_at": _iso(schedule.last_started_at),
            "last_finished_at": _iso(schedule.last_finished_at),
        },
    }


def _snapshot_payload(snapshot: SnapshotRecord) -> dict[str, Any]:
    return {
        "host": snapshot.host.host,
        "kind": snapshot.kind,
        "dirname": snapshot.dirname,
        "path": snapshot.path,
        "status": snapshot.status,
        "started_at": _iso(snapshot.started_at),
        "ended_at": _iso(snapshot.ended_at),
        "discovered_at": _iso(snapshot.discovered_at),
        "base": _base_payload(snapshot),
    }


def _base_payload(snapshot: SnapshotRecord) -> dict[str, Any] | None:
    if snapshot.base is not None:
        return {
            "kind": snapshot.base.kind,
            "dirname": snapshot.base.dirname,
            "path": snapshot.base.path,
            "resolved": True,
        }
    if snapshot.base_kind and snapshot.base_dirname:
        return {
            "kind": snapshot.base_kind,
            "dirname": snapshot.base_dirname,
            "path": snapshot.base_path,
            "snapshot_id": snapshot.base_snapshot_id,
            "resolved": False,
        }
    return None


def _run_payload(run: BackupRun) -> dict[str, Any]:
    return {
        "id": run.pk,
        "host": run.host.host,
        "run_type": run.run_type,
        "status": run.status,
        "started_at": _iso(run.started_at),
        "ended_at": _iso(run.ended_at),
        "snapshot": None
        if run.snapshot is None
        else {
            "kind": run.snapshot.kind,
            "dirname": run.snapshot.dirname,
            "path": run.snapshot.path,
        },
        "snapshot_path": run.snapshot_path,
        "base_path": run.base_path,
        "rsync_exit_code": run.rsync_exit_code,
    }


def _limit_from_request(request, *, default: int = 100, maximum: int = 500) -> int:
    value = request.GET.get("limit", str(default))
    try:
        limit = int(value)
    except ValueError:
        return default
    return max(1, min(limit, maximum))


def _iso(value) -> str | None:
    return value.isoformat() if value is not None else None