<?php

namespace Modules\Communication\Services;

use App\User;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;
use Modules\Communication\Entities\ChatRoom;

class ChatRoomService
{
    public function findOrCreateDirectRoom(int $businessId, User $user, int $otherUserId): ChatRoom
    {
        $this->assertColleague($businessId, $otherUserId);

        $existing = ChatRoom::where('business_id', $businessId)
            ->where('type', 'direct')
            ->whereHas('members', fn ($q) => $q->where('users.id', $user->id))
            ->whereHas('members', fn ($q) => $q->where('users.id', $otherUserId))
            ->first();

        if ($existing) {
            return $existing->load(['members', 'latestMessage.user']);
        }

        return DB::transaction(function () use ($businessId, $user, $otherUserId) {
            $room = ChatRoom::create([
                'business_id' => $businessId,
                'type' => 'direct',
                'created_by' => $user->id,
            ]);
            $room->members()->attach([$user->id, $otherUserId]);

            return $room->load(['members', 'latestMessage.user']);
        });
    }

    public function createGroupRoom(int $businessId, User $user, string $name, array $memberIds): ChatRoom
    {
        $memberIds = array_values(array_unique(array_map('intval', array_merge($memberIds, [$user->id]))));
        foreach ($memberIds as $memberId) {
            $this->assertColleague($businessId, $memberId);
        }

        return DB::transaction(function () use ($businessId, $user, $name, $memberIds) {
            $room = ChatRoom::create([
                'business_id' => $businessId,
                'type' => 'group',
                'name' => $name,
                'created_by' => $user->id,
            ]);
            $room->members()->attach($memberIds);

            return $room->load(['members', 'latestMessage.user']);
        });
    }

    public function assertRoomMember(ChatRoom $room, User $user): void
    {
        if (! $room->members()->where('users.id', $user->id)->exists()) {
            throw ValidationException::withMessages(['room' => __('communication::lang.not_room_member')]);
        }
    }

    public function assertColleague(int $businessId, int $userId): void
    {
        $exists = User::where('business_id', $businessId)->where('id', $userId)->exists();
        if (! $exists) {
            throw ValidationException::withMessages(['user_id' => __('communication::lang.user_not_in_business')]);
        }
    }

    public function addMember(ChatRoom $room, int $businessId, User $actor, int $memberId): ChatRoom
    {
        $this->assertRoomMember($room, $actor);
        if ($room->type !== 'group') {
            throw ValidationException::withMessages(['room' => __('communication::lang.group_only')]);
        }
        $this->assertColleague($businessId, $memberId);
        if (! $room->members()->where('users.id', $memberId)->exists()) {
            $room->members()->attach($memberId);
        }

        return $room->load(['members', 'latestMessage.user']);
    }

    public function removeMember(ChatRoom $room, User $actor, int $memberId): ChatRoom
    {
        $this->assertRoomMember($room, $actor);
        if ($room->type !== 'group') {
            throw ValidationException::withMessages(['room' => __('communication::lang.group_only')]);
        }
        if ($memberId !== $actor->id && (int) $room->created_by !== (int) $actor->id) {
            abort(403, 'Unauthorized action.');
        }
        $room->members()->detach($memberId);

        return $room->load(['members', 'latestMessage.user']);
    }
}