<?php

declare(strict_types=1);

namespace App\Services\VirtualMachine;

use App\Models\ModuleDatacenter;
use App\Models\ModuleDatastore;
use App\Models\ModuleHost;
use App\Models\ModuleNetwork;
use App\Models\vCenter;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Facades\DB;
use RuntimeException;

/**
 * Single source of truth for the "active" provisioning chain:
 *
 *   vCenter (status=1, global)
 *     └── ModuleDatacenter (status=1 per vCenter)
 *           └── ModuleHost (status=1 per datacenter)
 *                 ├── ModuleDatastore (status=1 per host)
 *                 └── ModuleNetwork  (status=1 per host)
 *
 * Rules enforced here:
 *   - At most ONE row per parent scope may have status=1.
 *   - Setting status=1 on row X auto-deactivates all siblings in same parent.
 *   - Setting status=0 on row X cascade-deactivates ALL descendants below it.
 *   - resolveChain() returns the full active chain or throws if any layer is missing.
 *
 * Settings provider mirroring:
 *   - activate('vcenter', $id) also writes provider.active_vcenter_id into the
 *     setting table so the Settings → Provider page reflects the same value
 *     without owning the truth.
 */
class VmActiveProviderService
{
    public const TYPE_VCENTER    = 'vcenter';
    public const TYPE_DATACENTER = 'datacenter';
    public const TYPE_HOST       = 'host';
    public const TYPE_DATASTORE  = 'datastore';
    public const TYPE_NETWORK    = 'network';

    /** type → [modelClass, parentColumn|null (null = global), childTypes[]] */
    private const MAP = [
        self::TYPE_VCENTER    => [vCenter::class,         null,                   [self::TYPE_DATACENTER]],
        self::TYPE_DATACENTER => [ModuleDatacenter::class, 'vcenter_id',           [self::TYPE_HOST]],
        self::TYPE_HOST       => [ModuleHost::class,       'module_datacenter_id', [self::TYPE_DATASTORE, self::TYPE_NETWORK]],
        self::TYPE_DATASTORE  => [ModuleDatastore::class,  'module_host_id',       []],
        self::TYPE_NETWORK    => [ModuleNetwork::class,    'module_host_id',       []],
    ];

    public function __construct(private readonly VmProviderSettingsService $providerSettings)
    {
    }

    // ─────────────────────────────────────────────────────────────────────────
    // Resolve helpers
    // ─────────────────────────────────────────────────────────────────────────

    public function activeVcenter(): ?vCenter
    {
        return vCenter::where('status', 1)->first();
    }

    public function activeDatacenter(int $vcenterId): ?ModuleDatacenter
    {
        return ModuleDatacenter::where('vcenter_id', $vcenterId)
            ->where('status', 1)
            ->first();
    }

    public function activeHost(int $datacenterId): ?ModuleHost
    {
        return ModuleHost::where('module_datacenter_id', $datacenterId)
            ->where('status', 1)
            ->first();
    }

    public function activeDatastore(int $hostId): ?ModuleDatastore
    {
        return ModuleDatastore::where('module_host_id', $hostId)
            ->where('status', 1)
            ->first();
    }

    public function activeNetwork(int $hostId): ?ModuleNetwork
    {
        return ModuleNetwork::where('module_host_id', $hostId)
            ->where('status', 1)
            ->first();
    }

    /**
     * Return the full active chain. Throws if any layer has no active row.
     *
     * @return array{vcenter:vCenter,datacenter:ModuleDatacenter,host:ModuleHost,datastore:ModuleDatastore,network:ModuleNetwork}
     */
    public function resolveChain(): array
    {
        $vcenter = $this->activeVcenter();
        if (!$vcenter) {
            throw new RuntimeException('Không có vCenter nào đang active. Vui lòng kích hoạt 1 vCenter trong admin.');
        }

        $datacenter = $this->activeDatacenter($vcenter->id);
        if (!$datacenter) {
            throw new RuntimeException("vCenter active id={$vcenter->id} chưa có Datacenter nào active.");
        }

        $host = $this->activeHost($datacenter->id);
        if (!$host) {
            throw new RuntimeException("Datacenter active id={$datacenter->id} chưa có Host nào active.");
        }

        $datastore = $this->activeDatastore($host->id);
        if (!$datastore) {
            throw new RuntimeException("Host active id={$host->id} chưa có Datastore nào active.");
        }

        $network = $this->activeNetwork($host->id);
        if (!$network) {
            throw new RuntimeException("Host active id={$host->id} chưa có Network nào active.");
        }

        return compact('vcenter', 'datacenter', 'host', 'datastore', 'network');
    }

    // ─────────────────────────────────────────────────────────────────────────
    // Mutators
    // ─────────────────────────────────────────────────────────────────────────

    /**
     * Set this row active, deactivating all siblings in the same parent scope.
     */
    public function activate(string $type, int $id): Model
    {
        [$modelClass, $parentColumn] = $this->mapOrFail($type);

        return DB::transaction(function () use ($modelClass, $parentColumn, $type, $id) {
            /** @var Model $row */
            $row = $modelClass::query()->lockForUpdate()->findOrFail($id);

            // Deactivate siblings under same parent (or all rows if global scope)
            $siblings = $modelClass::query()->where('id', '!=', $row->getKey());
            if ($parentColumn) {
                $siblings->where($parentColumn, $row->{$parentColumn});
            }
            $siblings->update(['status' => 0]);

            $row->status = 1;
            $row->save();

            if ($type === self::TYPE_VCENTER) {
                $this->providerSettings->setActiveVcenterId((int) $row->getKey());
            }

            return $row->refresh();
        });
    }

    /**
     * Set this row inactive AND cascade-deactivate every descendant beneath it.
     */
    public function deactivate(string $type, int $id): Model
    {
        [$modelClass] = $this->mapOrFail($type);

        return DB::transaction(function () use ($modelClass, $type, $id) {
            /** @var Model $row */
            $row = $modelClass::query()->lockForUpdate()->findOrFail($id);

            $row->status = 0;
            $row->save();

            $this->cascadeDeactivate($type, (int) $row->getKey());

            if ($type === self::TYPE_VCENTER) {
                $this->providerSettings->setActiveVcenterId(null);
            }

            return $row->refresh();
        });
    }

    /**
     * Recursively set status=0 on every descendant of $parentId under $type.
     */
    private function cascadeDeactivate(string $type, int $parentId): void
    {
        $childTypes = self::MAP[$type][2] ?? [];

        foreach ($childTypes as $childType) {
            [$childModel, $childParentColumn] = $this->mapOrFail($childType);
            if (!$childParentColumn) {
                continue;
            }

            $childIds = $childModel::query()
                ->where($childParentColumn, $parentId)
                ->pluck('id')
                ->all();

            if (!$childIds) {
                continue;
            }

            $childModel::query()->whereIn('id', $childIds)->update(['status' => 0]);

            foreach ($childIds as $childId) {
                $this->cascadeDeactivate($childType, (int) $childId);
            }
        }
    }

    /**
     * @return array{0:class-string<Model>,1:?string,2:string[]}
     */
    private function mapOrFail(string $type): array
    {
        if (!isset(self::MAP[$type])) {
            throw new RuntimeException("Unknown infra type: {$type}");
        }
        return self::MAP[$type];
    }
}