from __future__ import annotations

from django.contrib import admin
from django.db.models import Count
from django.urls import reverse
from django.utils.html import format_html
from django.utils.http import urlencode

from .models import BackupRun, GlobalConfig, HostConfig, ScheduleConfig, SnapshotRecord


@admin.register(GlobalConfig)
class GlobalConfigAdmin(admin.ModelAdmin):
    list_display = ("name", "backup_root", "ssh_user", "ssh_port", "updated_at")
    readonly_fields = ("created_at", "updated_at")
    fieldsets = (
        (None, {"fields": ("name", "backup_root", "pobsync_home")}),
        ("SSH", {"fields": ("ssh_user", "ssh_port", "ssh_options")}),
        (
            "Rsync",
            {
                "fields": (
                    "rsync_binary",
                    "rsync_args",
                    "rsync_extra_args",
                    "rsync_timeout_seconds",
                    "rsync_bwlimit_kbps",
                )
            },
        ),
        ("Defaults", {"fields": ("default_source_root", "default_destination_subdir", "excludes_default")}),
        ("Retention defaults", {"fields": ("retention_daily", "retention_weekly", "retention_monthly", "retention_yearly")}),
        ("Legacy JSON", {"fields": ("data",), "classes": ("collapse",)}),
        ("Timestamps", {"fields": ("created_at", "updated_at"), "classes": ("collapse",)}),
    )


@admin.register(HostConfig)
class HostConfigAdmin(admin.ModelAdmin):
    list_display = (
        "host",
        "address",
        "enabled",
        "schedule_state",
        "snapshot_count_link",
        "backup_run_count_link",
        "latest_run_state",
        "updated_at",
    )
    list_filter = ("enabled",)
    search_fields = ("host", "address")
    readonly_fields = ("created_at", "updated_at")
    fieldsets = (
        (None, {"fields": ("host", "address", "enabled")}),
        ("SSH override", {"fields": ("ssh_user", "ssh_port")}),
        ("Source", {"fields": ("source_root", "includes", "excludes_add", "excludes_replace")}),
        ("Rsync override", {"fields": ("rsync_extra_args",)}),
        ("Retention", {"fields": ("retention_daily", "retention_weekly", "retention_monthly", "retention_yearly")}),
        ("Legacy JSON", {"fields": ("config",), "classes": ("collapse",)}),
        ("Timestamps", {"fields": ("created_at", "updated_at"), "classes": ("collapse",)}),
    )

    def get_queryset(self, request):
        return super().get_queryset(request).annotate(
            snapshot_count=Count("snapshots", distinct=True),
            backup_run_count=Count("runs", distinct=True),
        )

    @admin.display(description="Schedule")
    def schedule_state(self, obj: HostConfig) -> str:
        try:
            schedule = obj.schedule
        except ScheduleConfig.DoesNotExist:
            return "none"
        if not schedule.enabled:
            return "disabled"
        return schedule.cron_expr

    @admin.display(description="Snapshots", ordering="snapshot_count")
    def snapshot_count_link(self, obj: HostConfig) -> str:
        count = getattr(obj, "snapshot_count", None)
        if count is None:
            count = obj.snapshots.count()
        url = _admin_changelist_url("pobsync_backend", "snapshotrecord", {"host__id__exact": obj.pk})
        return format_html('<a href="{}">{}</a>', url, count)

    @admin.display(description="Runs", ordering="backup_run_count")
    def backup_run_count_link(self, obj: HostConfig) -> str:
        count = getattr(obj, "backup_run_count", None)
        if count is None:
            count = obj.runs.count()
        url = _admin_changelist_url("pobsync_backend", "backuprun", {"host__id__exact": obj.pk})
        return format_html('<a href="{}">{}</a>', url, count)

    @admin.display(description="Latest run")
    def latest_run_state(self, obj: HostConfig) -> str:
        latest = obj.runs.order_by("-created_at").first()
        if latest is None:
            return "none"
        return f"{latest.status} {latest.started_at:%Y-%m-%d %H:%M}" if latest.started_at else latest.status


@admin.register(BackupRun)
class BackupRunAdmin(admin.ModelAdmin):
    list_display = ("host", "run_type", "status", "started_at", "ended_at", "snapshot_link")
    list_filter = ("run_type", "status", "started_at")
    search_fields = ("host__host", "snapshot_path", "snapshot__dirname", "snapshot__path")
    autocomplete_fields = ("snapshot",)
    list_select_related = ("host", "snapshot")
    date_hierarchy = "started_at"

    @admin.display(description="Snapshot", ordering="snapshot__dirname")
    def snapshot_link(self, obj: BackupRun) -> str:
        if obj.snapshot is None:
            return ""
        url = reverse("admin:pobsync_backend_snapshotrecord_change", args=[obj.snapshot.pk])
        return format_html('<a href="{}">{}</a>', url, obj.snapshot.dirname)


@admin.register(SnapshotRecord)
class SnapshotRecordAdmin(admin.ModelAdmin):
    list_display = ("host", "kind", "dirname", "status", "base_link", "backup_run_count_link", "started_at", "discovered_at")
    list_filter = ("kind", "status", "base_kind", "started_at", "discovered_at")
    search_fields = (
        "host__host",
        "dirname",
        "path",
        "base__dirname",
        "base_path",
        "base_snapshot_id",
    )
    autocomplete_fields = ("base",)
    list_select_related = ("host", "base")
    readonly_fields = ("discovered_at",)

    def get_queryset(self, request):
        return super().get_queryset(request).annotate(backup_run_count=Count("backup_runs"))

    @admin.display(description="Base", ordering="base__dirname")
    def base_link(self, obj: SnapshotRecord) -> str:
        if obj.base is not None:
            url = reverse("admin:pobsync_backend_snapshotrecord_change", args=[obj.base.pk])
            return format_html('<a href="{}">{}</a>', url, obj.base.dirname)
        if obj.base_dirname:
            return obj.base_dirname
        return ""

    @admin.display(description="Runs", ordering="backup_run_count")
    def backup_run_count_link(self, obj: SnapshotRecord) -> str:
        count = getattr(obj, "backup_run_count", None)
        if count is None:
            count = obj.backup_runs.count()
        url = _admin_changelist_url("pobsync_backend", "backuprun", {"snapshot__id__exact": obj.pk})
        return format_html('<a href="{}">{}</a>', url, count)


@admin.register(ScheduleConfig)
class ScheduleConfigAdmin(admin.ModelAdmin):
    list_display = ("host", "cron_expr", "enabled", "prune", "last_status", "last_started_at", "updated_at")
    list_filter = ("enabled", "prune", "last_status")
    search_fields = ("host__host", "cron_expr")
    list_select_related = ("host",)


def _admin_changelist_url(app_label: str, model_name: str, params: dict[str, object]) -> str:
    base_url = reverse(f"admin:{app_label}_{model_name}_changelist")
    return f"{base_url}?{urlencode(params)}"