<?php

namespace App\Services\IpPool;

use App\Mail\IpAllocationMail;
use App\Models\Customer;
use App\Models\IpPool;
use App\Models\IpPoolLog;
use App\Models\Mail as MailLog;
use App\Models\ModuleIpAddress;
use App\Models\User;
use App\Services\Email\EmailTemplateService;
use App\Support\AutoEmailGate;
use App\Support\EmailRecipients;
use App\Support\MailAttachments;
use Illuminate\Database\Eloquent\Collection;
use Illuminate\Database\Eloquent\ModelNotFoundException;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Mail;
use Illuminate\Validation\ValidationException;

class IpAllocationService
{
    public function __construct(private readonly EmailTemplateService $templates) {}

    /**
     * @param  array<int, int>  $ids
     */
    public function previewAllocation(array $ids, Customer $customer, array $data): array
    {
        $pools = $this->allocatable($this->pools($ids));
        $pools->each(fn (IpPool $pool) => $pool->service_name = $this->serviceNameFor($pool, $data));

        return $this->preview($this->allocationMail($customer, $pools, $data));
    }

    /**
     * @param  array<int, int>  $ids
     */
    public function allocate(array $ids, Customer $customer, array $data, User $admin): int
    {
        $this->ensureMailReady(IpAllocationMail::ALLOCATED);

        $files = MailAttachments::store($data['attachments'] ?? [], "customer-emails/{$customer->id}");

        return DB::transaction(function () use ($ids, $customer, $data, $admin, $files) {
            $pools = $this->allocatable($this->pools($ids, lock: true));

            foreach ($pools as $pool) {
                $from = $pool->status;
                $pool->update([
                    'status'          => 'assigned',
                    'customer_id'     => $customer->id,
                    'customer_name'   => $customer->fullname,
                    'service_name'    => $this->serviceNameFor($pool, $data),
                    'allocated_at'    => $data['date'],
                    'revoked_at'      => null,
                    'contact_email'   => $data['to'],
                    'contact_cc'      => $data['cc'] ?? null,
                    'last_email_type' => 'ALLOCATED_SENT',
                    'last_email_at'   => now(),
                    'updated_by'      => $admin->username,
                ]);
                IpPoolLog::record($pool, IpPoolLog::ALLOCATED, $from, [
                    'effective_date' => $data['date'],
                    'customer_id'   => $customer->id,
                    'customer_name' => $customer->fullname,
                    'service_name'  => $pool->service_name,
                    'email_to'      => $data['to'],
                    'note'          => $data['note'] ?? null,
                ]);
            }

            $this->send($this->allocationMail($customer, $pools, $data, $files), $data['to'], $data['cc'] ?? null, $customer->id, $admin);

            return $pools->count();
        });
    }

    /**
     * @param  array<int, int>  $ids
     * @return array<int, array<string, mixed>>
     */
    public function previewRevocation(array $ids, array $data): array
    {
        return $this->revocationGroups($this->revocable($this->pools($ids)))
            ->map(fn (Collection $pools, string $key) => [
                'key'           => $key,
                'customer_id'   => $pools->first()->customer_id,
                'customer_name' => $pools->first()->customer_name,
                'to'            => $pools->first()->contact_email,
                'cc'            => $pools->first()->contact_cc,
                'ips'           => $pools->pluck('ip_address')->values(),
                ...$this->preview($this->revocationMail($pools, $data)),
            ])
            ->values()
            ->all();
    }

    /**
     * @param  array<int, int>  $ids
     * @param  array<string, array{to: string, cc?: string|null}>  $recipients
     */
    public function revoke(array $ids, array $data, array $recipients, User $admin): int
    {
        $this->ensureMailReady(IpAllocationMail::REVOKED);

        $groups = $this->revocationGroups($this->revocable($this->pools($ids)));
        $missing = $groups->keys()->reject(fn ($key) => filled($recipients[$key]['to'] ?? null));
        if ($missing->isNotEmpty()) {
            throw ValidationException::withMessages(['recipients' => 'Chưa nhập email người nhận cho: ' . $groups->only($missing->all())
                ->map(fn ($pools) => $pools->first()->customer_name ?: $pools->pluck('ip_address')->implode(', '))->implode('; ')]);
        }

        return DB::transaction(function () use ($ids, $data, $recipients, $admin) {
            $groups = $this->revocationGroups($this->revocable($this->pools($ids, lock: true)));

            return $groups->map(function (Collection $pools, string $key) use ($data, $recipients, $admin) {
                $mail = $this->revocationMail($pools, $data, $recipients[$key]['subject'] ?? null);
                $customerId = $pools->first()->customer_id;
                foreach ($pools as $pool) {
                    $from = $pool->status;
                    $before = $pool->only(['customer_id', 'customer_name', 'service_name']);
                    $pool->update([
                        'status'          => 'free',
                        'customer_id'     => null,
                        'customer_name'   => null,
                        'service_name'    => null,
                        'contact_email'   => null,
                        'revoked_at'      => $data['date'],
                        'last_email_type' => 'REVOKE_SENT',
                        'last_email_at'   => now(),
                        'updated_by'      => $admin->username,
                    ]);
                    IpPoolLog::record($pool, IpPoolLog::REVOKED, $from, [
                        ...$before,
                        'effective_date' => $data['date'],
                        'email_to' => $recipients[$key]['to'],
                        'note'     => $data['note'] ?? null,
                    ]);
                }

                $this->send($mail, $recipients[$key]['to'], $recipients[$key]['cc'] ?? null, $customerId, $admin);

                return $pools->count();
            })->sum();
        });
    }

    /**
     * @param  array<int, int>  $ids
     * @return Collection<int, IpPool>
     */
    private function pools(array $ids, bool $lock = false): Collection
    {
        $query = IpPool::whereIn('id', $ids)->orderBy('ip_address');

        $pools = ($lock ? $query->lockForUpdate() : $query)->get();
        if ($pools->isEmpty()) {
            throw ValidationException::withMessages(['ids' => 'Không tìm thấy IP nào.']);
        }

        return $pools;
    }

    private function allocatable(Collection $pools): Collection
    {
        $blocked = $pools->reject(fn (IpPool $pool) => $pool->status === 'free');
        if ($blocked->isNotEmpty()) {
            throw ValidationException::withMessages(['ids' => 'Chỉ cấp phát được IP đang trống. IP không hợp lệ: ' . $blocked->pluck('ip_address')->implode(', ')]);
        }

        return $pools;
    }

    private function revocable(Collection $pools): Collection
    {
        $inUse = ModuleIpAddress::where('status', 1)->whereIn('ip', $pools->pluck('ip_address'))->pluck('ip')->all();
        $blocked = $pools->filter(fn (IpPool $pool) => $pool->status !== 'assigned'
            || $pool->service_id !== null
            || in_array($pool->ip_address, $inUse, true));

        if ($blocked->isNotEmpty()) {
            throw ValidationException::withMessages(['ids' => 'Chỉ thu hồi được IP đã cấp và không gắn VM/dịch vụ (IP gắn VM thu hồi qua dịch vụ). IP không hợp lệ: ' . $blocked->pluck('ip_address')->implode(', ')]);
        }

        return $pools;
    }

    /**
     * @return \Illuminate\Support\Collection<string, Collection<int, IpPool>>
     */
    private function revocationGroups(Collection $pools): \Illuminate\Support\Collection
    {
        return $pools->groupBy(fn (IpPool $pool) => $pool->customer_id
            ? 'customer:' . $pool->customer_id
            : 'name:' . mb_strtolower(trim((string) $pool->customer_name)) . '|' . mb_strtolower(trim((string) $pool->contact_email)))
            ->toBase();
    }

    private function allocationMail(Customer $customer, Collection $pools, array $data, array $files = []): IpAllocationMail
    {
        return new IpAllocationMail(
            IpAllocationMail::ALLOCATED,
            $customer->fullname,
            IpAllocationMail::ipsFrom($pools),
            $data['date'],
            $data['note'] ?? null,
            $data['subject'] ?? null,
            $files,
        );
    }

    private function serviceNameFor(IpPool $pool, array $data): ?string
    {
        $name = trim((string) (($data['services'][$pool->id] ?? null) ?: ($data['service_name'] ?? '')));

        return $name === '' ? null : $name;
    }

    private function revocationMail(Collection $pools, array $data, ?string $subject = null): IpAllocationMail
    {
        return new IpAllocationMail(
            IpAllocationMail::REVOKED,
            $pools->first()->customer_name ?: 'Quý khách',
            IpAllocationMail::ipsFrom($pools),
            $data['date'],
            $data['note'] ?? null,
            $subject,
        );
    }

    /**
     * @return array{subject: string, html: string}
     */
    private function preview(IpAllocationMail $mail): array
    {
        try {
            return ['subject' => $mail->envelope()->subject, 'html' => $mail->render()];
        } catch (ModelNotFoundException) {
            throw ValidationException::withMessages(['template' => 'Chưa có mẫu email đang bật cho thao tác này (Mẫu email → ' . $mail->type . ').']);
        }
    }

    private function ensureMailReady(string $scenario): void
    {
        if (!AutoEmailGate::mailEnabled()) {
            throw ValidationException::withMessages(['mail' => 'Hệ thống đang tắt gửi email (Mẫu email → Cài đặt → Bật gửi email).']);
        }

        try {
            $this->templates->loadTemplate($scenario);
        } catch (ModelNotFoundException) {
            throw ValidationException::withMessages(['template' => "Chưa có mẫu email {$scenario} đang bật trong Mẫu email."]);
        }
    }

    private function send(IpAllocationMail $mail, string $to, ?string $cc, ?int $customerId, User $admin): void
    {
        AutoEmailGate::markManual();
        $template = $this->templates->loadTemplate($mail->type);
        $toList = EmailRecipients::parse($to);
        $ccList = EmailRecipients::parse($cc);

        MailLog::create([
            'template_id'  => $template->id,
            'subject'      => $mail->envelope()->subject,
            'from_address' => $template->mailConfig()['from_email'] ?? config('mail.from.address'),
            'to'           => implode(', ', $toList),
            'cc'           => $ccList ? implode(', ', $ccList) : null,
            'customer_id'  => $customerId,
            'sent_by'      => $admin->id,
            'message'      => (clone $mail)->render(),
        ]);

        Mail::to($toList)->cc($ccList)->queue($mail);
    }
}