<?php

namespace App\Http\Controllers\Admin;

use App\Http\Controllers\Controller;
use App\Models\ChatConversation;
use App\Models\ChatMessage;
use Illuminate\Http\JsonResponse;
use Illuminate\Http\RedirectResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Str;
use Illuminate\Validation\Rule;
use Illuminate\Validation\ValidationException;
use Illuminate\View\View;

class ChatController extends Controller
{
    public function index(Request $request): View
    {
        $conversations = ChatConversation::query()
            ->with('user', 'latestMessage')
            ->withCount([
                'messages as unread_count' => fn ($query) => $query
                    ->where('sender', 'customer')
                    ->where('is_read', false),
            ])
            ->orderByDesc('last_message_at')
            ->orderByDesc('id')
            ->paginate(30);

        $selectedConversation = $this->resolveSelectedConversation($request, $conversations);
        $initialMessages = collect();

        if ($selectedConversation) {
            $this->markCustomerMessagesAsRead($selectedConversation);
            $initialMessages = $this->conversationMessages($selectedConversation);
        }

        return view('admin.chats.index', [
            'conversations' => $conversations,
            'selectedConversation' => $selectedConversation,
            'initialMessages' => $initialMessages->map(fn (ChatMessage $message) => $this->messagePayload($message))->values(),
        ]);
    }

    public function messages(ChatConversation $conversation): JsonResponse
    {
        $this->markCustomerMessagesAsRead($conversation);

        return response()->json([
            'conversation' => $this->conversationPayload($conversation->loadMissing('user')),
            'messages' => $this->conversationMessages($conversation)
                ->map(fn (ChatMessage $message) => $this->messagePayload($message))
                ->values(),
        ]);
    }

    public function storeMessage(Request $request, ChatConversation $conversation): JsonResponse
    {
        $validated = $request->validate([
            'message' => ['required', 'string', 'max:2000'],
        ]);

        $messageText = $this->sanitizeMessage((string) $validated['message']);
        if ($messageText === '') {
            throw ValidationException::withMessages([
                'message' => 'Сообщение содержит недопустимые символы.',
            ]);
        }

        $message = $conversation->messages()->create([
            'sender' => 'admin',
            'body' => $messageText,
            'is_read' => false,
        ]);

        $conversation->update([
            'status' => 'open',
            'last_message_at' => now(),
        ]);

        return response()->json([
            'message' => $this->messagePayload($message),
        ]);
    }

    public function updateStatus(Request $request, ChatConversation $conversation): RedirectResponse
    {
        $validated = $request->validate([
            'status' => ['required', 'string', Rule::in([
                ChatConversation::STATUS_OPEN,
                ChatConversation::STATUS_CLOSED,
            ])],
        ]);

        $conversation->update([
            'status' => $validated['status'],
        ]);

        return redirect()
            ->route('admin.chats.index', ['conversation' => $conversation->id])
            ->with('status', $conversation->isClosed() ? 'Чат закрыт.' : 'Чат открыт.');
    }

    public function destroy(ChatConversation $conversation): RedirectResponse
    {
        $conversation->delete();

        return redirect()
            ->route('admin.chats.index')
            ->with('status', 'Чат удален.');
    }

    private function resolveSelectedConversation(Request $request, $conversations): ?ChatConversation
    {
        $selectedId = $request->integer('conversation');
        if ($selectedId > 0) {
            return ChatConversation::query()->with('user')->find($selectedId);
        }

        $firstConversation = $conversations->first();
        if (!$firstConversation) {
            return null;
        }

        return ChatConversation::query()->with('user')->find($firstConversation->id);
    }

    private function markCustomerMessagesAsRead(ChatConversation $conversation): void
    {
        $conversation->messages()
            ->where('sender', 'customer')
            ->where('is_read', false)
            ->update(['is_read' => true]);
    }

    private function conversationMessages(ChatConversation $conversation)
    {
        return $conversation->messages()
            ->orderBy('id')
            ->limit(200)
            ->get();
    }

    private function messagePayload(ChatMessage $message): array
    {
        return [
            'id' => $message->id,
            'sender' => $message->sender,
            'body' => $message->body,
            'created_at' => $message->created_at?->toIso8601String(),
            'time' => $message->created_at?->format('H:i'),
        ];
    }

    private function conversationPayload(ChatConversation $conversation): array
    {
        $preview = $conversation->latestMessage?->body;

        return [
            'id' => $conversation->id,
            'title' => $conversation->display_name,
            'subtitle' => $conversation->user?->email ?: ('Токен: ' . Str::limit($conversation->visitor_token, 14, '...')),
            'preview' => $preview ? Str::limit($preview, 80) : 'Нет сообщений',
            'status' => $conversation->status,
            'is_closed' => $conversation->isClosed(),
        ];
    }

    private function sanitizeMessage(string $value): string
    {
        $text = strip_tags($value);
        $text = str_replace(["\r\n", "\r"], "\n", $text);
        $text = preg_replace('/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/u', '', $text) ?? $text;

        return trim(Str::limit($text, 2000, ''));
    }
}