<?php

namespace App\Services;

use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;

class ZaloBotService
{
    protected LinkConverterService $linkConverterService;
    protected SettingService $settingService;

    public function __construct(
        LinkConverterService $linkConverterService,
        SettingService $settingService
    ) {
        $this->linkConverterService = $linkConverterService;
        $this->settingService = $settingService;
    }

    /**
     * Handle incoming Zalo Bot webhook request.
     */
    public function handleWebhook(array $payload): void
    {
        Log::info('Zalo Webhook payload received', $payload);

        // Check if message structure exists (mimics Telegram format)
        $message = $payload['message'] ?? null;
        if (!$message) {
            return;
        }

        $chatId = $message['chat']['id'] ?? null;
        $text = $message['text'] ?? '';
        
        if (!$chatId || empty($text)) {
            return;
        }

        // Get sender name (fallback to "Bạn")
        $fromName = trim(
            ($message['from']['first_name'] ?? '') . ' ' . ($message['from']['last_name'] ?? '')
        );
        if (empty($fromName)) {
            $fromName = $message['from']['username'] ?? 'Bạn';
        }

        // Find Shopee links
        $urls = $this->extractShopeeUrls($text);
        if (empty($urls)) {
            return;
        }

        foreach ($urls as $url) {
            $this->processAndReplyLink($chatId, $fromName, $url);
        }
    }

    /**
     * Process a single Shopee link and reply to the chat.
     */
    protected function processAndReplyLink(string $chatId, string $fromName, string $url): void
    {
        try {
            // 1. Resolve redirects if it's a short URL (e.g. s.shopee.vn or shp.ee)
            $resolvedUrl = $this->resolveShortUrl($url);

            // 2. Extract product name from resolved URL
            $productName = $this->extractProductName($resolvedUrl) ?? 'Sản phẩm Shopee';

            // 3. Estimate commission
            $commission = $this->estimateCommission($resolvedUrl);

            // 4. Convert link to our local affiliate short link
            $convertResult = $this->linkConverterService->process($resolvedUrl);

            if ($convertResult && $convertResult->isSuccess) {
                $shortLink = $convertResult->affiliateUrl;

                // 5. Construct the message template matching competitor's chatbot
                $replyText = "Hi @{$fromName}, Link của bạn đây ạ:\n\n" .
                             "📦 {$productName}\n" .
                             "🔗 Link: {$shortLink}\n" .
                             "💵 Hoa hồng ước tính: {$commission}\n\n" .
                             "⚠️ Lưu ý: Để hoa hồng hợp lệ, KHÔNG mua qua Livestream, KHÔNG xem video/live bất kỳ sau khi click & XÓA sản phẩm ra khỏi giỏ hàng TRƯỚC KHI bấm link!";

                // 6. Send reply message
                $this->sendMessage($chatId, $replyText);
            } else {
                Log::error("Failed to convert Shopee URL via Zalo: " . ($convertResult->errorMessage ?? 'Unknown error'));
            }
        } catch (\Exception $e) {
            Log::error("Error processing link in ZaloBotService: " . $e->getMessage());
        }
    }

    /**
     * Extract all Shopee URLs from text.
     */
    public function extractShopeeUrls(string $text): array
    {
        $pattern = '/(?:https?:\/\/)?(?:[a-zA-Z0-9-]+\.)?shopee\.vn\/[^\s]+|(?:https?:\/\/)?shp\.ee\/[^\s]+/i';
        if (preg_match_all($pattern, $text, $matches)) {
            $urls = [];
            foreach ($matches[0] as $url) {
                if (!str_starts_with(strtolower($url), 'http://') && !str_starts_with(strtolower($url), 'https://')) {
                    $url = 'https://' . $url;
                }
                $urls[] = $url;
            }
            return $urls;
        }
        return [];
    }

    /**
     * Resolve short URLs (s.shopee.vn or shp.ee) to get the final redirected URL.
     */
    public function resolveShortUrl(string $url): string
    {
        if (str_contains($url, '/an_redir') || (!str_contains($url, 's.shopee.vn') && !str_contains($url, 'shp.ee'))) {
            return $url;
        }

        try {
            $ch = curl_init($url);
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
            curl_setopt($ch, CURLOPT_HEADER, true);
            curl_setopt($ch, CURLOPT_NOBODY, true); // Get headers only
            curl_setopt($ch, CURLOPT_FOLLOWLOCATION, false); // Check redirect location manually
            curl_setopt($ch, CURLOPT_TIMEOUT, 5);
            curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36');
            
            $response = curl_exec($ch);
            $info = curl_getinfo($ch);
            curl_close($ch);

            if ($info['http_code'] >= 300 && $info['http_code'] < 400) {
                if (preg_match('/[Ll]ocation:\s*(.+)/', $response, $matches)) {
                    $resolvedUrl = trim($matches[1]);
                    // Recursively resolve redirect if it's still a redirect link
                    return $this->resolveShortUrl($resolvedUrl);
                }
            }
        } catch (\Exception $e) {
            Log::warning("Could not resolve short URL redirect: " . $e->getMessage());
        }

        return $url;
    }

    /**
     * Extract product/shop name from Shopee URL.
     */
    public function extractProductName(string $url): ?string
    {
        $parsedUrl = parse_url($url);
        if (!isset($parsedUrl['path'])) {
            return null;
        }

        $path = urldecode($parsedUrl['path']);
        $path = trim($path, '/');

        // Match typical Shopee product paths ending with -i.SHOP_ID.ITEM_ID
        if (preg_match('/^(.*?)-i\.\d+\.\d+$/', $path, $matches)) {
            $slug = $matches[1];
            $name = str_replace(['-', '_'], ' ', $slug);
            return trim($name);
        }

        // Shop pages / Usernames
        if (!str_contains($path, '/')) {
            $name = str_replace(['-', '_'], ' ', $path);
            return trim($name);
        }

        return null;
    }

    /**
     * Predictable estimate of product commission based on the item ID.
     */
    public function estimateCommission(string $url): string
    {
        $itemId = 0;
        if (preg_match('/-i\.\d+\.(\d+)$/', $url, $matches)) {
            $itemId = (int)$matches[1];
        }
        
        if ($itemId === 0) {
            $itemId = crc32($url);
        }
        
        // Predictable single estimate between 4.0% and 7.5% based on itemId or crc32
        $rate = 4.0 + (abs($itemId) % 36) / 10.0;
        return number_format($rate, 1) . '%';
    }

    /**
     * Send message using Zalo Bot Creator HTTP API.
     */
    public function sendMessage(string $chatId, string $text): bool
    {
        $token = $this->settingService->get('zalo_bot_token') ?? env('ZALO_BOT_TOKEN');

        if (!$token) {
            Log::error('Zalo Bot Token is not configured. Cannot send message.');
            return false;
        }

        $apiUrl = "https://bot-api.zaloplatforms.com/bot{$token}/sendMessage";

        Log::info('Sending message to Zalo Bot', [
            'chat_id' => $chatId,
            'url' => "https://bot-api.zaloplatforms.com/bot[HIDDEN]/sendMessage"
        ]);

        $response = Http::timeout(10)->post($apiUrl, [
            'chat_id' => $chatId,
            'text' => $text,
        ]);

        if ($response->successful()) {
            Log::info('Message sent successfully to Zalo Bot');
            return true;
        }

        Log::error('Failed to send message to Zalo Bot', [
            'status' => $response->status(),
            'body' => $response->body()
        ]);

        return false;
    }
}