package webcollector

import (
	"context"
	"log"
	"net/url"
	"regexp"
	"strings"
	"sync/atomic"
	"time"

	"spider/internal/crawler"
	"spider/internal/extractor"
	"spider/internal/plugin"
	"spider/internal/search"
)

// Collector implements plugin.Collector for web-based merchant collection.
// Combines search (Google via Serper) + page crawling + contact extraction.
// NO AI — pure regex and rule-based filtering.
type Collector struct {
	serper       *search.SerperClient
	static       *crawler.StaticCrawler
	dynamic      *crawler.DynamicCrawler
	tmeValidator *crawler.TMeValidator
	stopped      atomic.Bool
}

// New creates a new web collector.
func New(serper *search.SerperClient) *Collector {
	return &Collector{
		serper:       serper,
		static:       crawler.NewStaticCrawler(),
		dynamic:      crawler.NewDynamicCrawler(),
		tmeValidator: crawler.NewTMeValidator(),
	}
}

func (c *Collector) Name() string { return "web_collector" }

func (c *Collector) Stop() error {
	c.stopped.Store(true)
	return nil
}

// Run executes the web collection pipeline:
// 1. For each keyword, search via Serper API
// 2. Classify results: t.me links -> direct extract, web pages -> crawl
// 3. Crawl pages, extract TG usernames and contact info
// 4. Call callback for each merchant found
//
// cfg keys: (none required — keywords come from DB via the task manager)
// The cfg map can contain:
//   - "keywords": []string — override keywords (optional)
func (c *Collector) Run(ctx context.Context, cfg map[string]any, callback func(plugin.MerchantData)) error {
	c.stopped.Store(false)

	if c.serper == nil {
		log.Println("[web_collector] no serper client configured, skipping")
		return nil
	}

	keywords, _ := cfg["keywords"].([]string)
	if len(keywords) == 0 {
		log.Println("[web_collector] no keywords provided")
		return nil
	}

	for _, kw := range keywords {
		if c.stopped.Load() || ctx.Err() != nil {
			break
		}

		log.Printf("[web_collector] searching: %s", kw)

		results, err := c.serper.Search(ctx, kw)
		if err != nil {
			log.Printf("[web_collector] search error for %q: %v", kw, err)
			continue
		}

		for _, r := range results {
			if c.stopped.Load() || ctx.Err() != nil {
				break
			}

			classification := search.ClassifyURL(r.URL)

			switch classification {
			case "tg_channel":
				// Direct t.me link — extract username immediately
				username := extractTGUsername(r.URL)
				if username == "" {
					continue
				}
				callback(plugin.MerchantData{
					TgUsername: username,
					TgLink:     "https://t.me/" + username,
					SourceType: "web",
					SourceName: r.Title,
					SourceURL:  r.URL,
				})

			case "nav_site":
				// Crawl the page for TG links and contacts
				c.crawlPage(ctx, r.URL, r.Title, callback)

			default:
				// "discard" or unknown — also try rule filter for non-blacklisted
				if crawler.RuleFilter(r.URL) != crawler.FilterDiscard {
					c.crawlPage(ctx, r.URL, r.Title, callback)
				}
			}
		}

		// Delay between keywords
		select {
		case <-ctx.Done():
			return nil
		case <-time.After(2 * time.Second):
		}
	}

	log.Println("[web_collector] done")
	return nil
}

// crawlPage fetches a page and extracts merchants from it.
func (c *Collector) crawlPage(ctx context.Context, pageURL, title string, callback func(plugin.MerchantData)) {
	// Rule-based filter (no LLM)
	filterResult := crawler.RuleFilter(pageURL)
	if filterResult == crawler.FilterDiscard {
		return
	}
	// FilterUncertain: per requirements, discard without AI
	// FilterValid: proceed

	// Try static first, fallback to dynamic
	result := c.static.Crawl(ctx, pageURL)
	if result.Error != nil || result.HTML == "" {
		result = c.dynamic.Crawl(ctx, pageURL)
	}
	if result.Error != nil || result.HTML == "" {
		return
	}

	// Chinese content filter
	snippet := result.HTML
	if len(snippet) > 5000 {
		snippet = snippet[:5000]
	}
	if !extractor.ContainsChinese(snippet, 0) {
		return
	}

	// Process t.me links found on the page
	for _, tgLink := range result.TgLinks {
		username := crawler.ExtractTGUsername(tgLink)
		if username == "" {
			continue
		}
		// t.me dead check (free, unlimited)
		if !c.tmeValidator.IsAlive(ctx, username) {
			continue
		}
		callback(plugin.MerchantData{
			TgUsername: username,
			TgLink:     "https://t.me/" + username,
			SourceType: "web",
			SourceName: title,
			SourceURL:  pageURL,
		})
	}

	// Process other links — crawl merchant sub-pages for contact info
	for _, link := range result.Links {
		if c.stopped.Load() || ctx.Err() != nil {
			break
		}
		// Skip TG links (already processed) and blacklisted
		if strings.Contains(link, "t.me") || strings.Contains(link, "telegram.me") {
			continue
		}
		if crawler.RuleFilter(link) == crawler.FilterDiscard {
			continue
		}
		c.crawlMerchantSite(ctx, link, pageURL, callback)
	}
}

// crawlMerchantSite crawls a merchant's website for contact info.
func (c *Collector) crawlMerchantSite(ctx context.Context, siteURL, sourceURL string, callback func(plugin.MerchantData)) {
	subPages := []string{siteURL, siteURL + "/contact", siteURL + "/about"}

	for _, page := range subPages {
		if ctx.Err() != nil {
			break
		}
		result := c.static.Crawl(ctx, page)
		if result.Error != nil || result.HTML == "" {
			continue
		}

		info := extractor.Extract(result.HTML)
		if !info.HasContact {
			continue
		}
		if info.TgUsername == "" {
			continue // per requirements: no tg_username = don't insert
		}

		callback(plugin.MerchantData{
			TgUsername:   info.TgUsername,
			TgLink:       "https://t.me/" + info.TgUsername,
			Website:      siteURL,
			Email:        info.Email,
			Phone:        info.Phone,
			SourceType:   "web",
			SourceName:   extractDomain(siteURL),
			SourceURL:    sourceURL,
			OriginalText: "",
		})
		break // found contact info, stop
	}
}

var reTGUsername = regexp.MustCompile(`(?:t(?:elegram)?\.me)/([a-zA-Z][a-zA-Z0-9_]{4,31})`)

func extractTGUsername(rawURL string) string {
	m := reTGUsername.FindStringSubmatch(rawURL)
	if len(m) > 1 {
		return m[1]
	}
	return ""
}

func extractDomain(rawURL string) string {
	u, err := url.Parse(rawURL)
	if err != nil {
		return ""
	}
	return u.Hostname()
}