package tgcollector

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

	"spider/internal/extractor"
	"spider/internal/llm"
	"spider/internal/model"
	"spider/internal/plugin"
	"spider/internal/store"
	"spider/internal/telegram"
)

// Collector implements plugin.Collector for TG channel collection.
// Combines BFS channel discovery (from seeds) + message scraping.
// AI: regex first, LLM fallback only for non-standard contact formats.
type Collector struct {
	tgManager *telegram.AccountManager
	llmClient *llm.Client // can be nil
	store     *store.Store
	stopped   atomic.Bool
}

// New creates a new TG collector.
func New(tgManager *telegram.AccountManager, llmClient *llm.Client, s *store.Store) *Collector {
	return &Collector{
		tgManager: tgManager,
		llmClient: llmClient,
		store:     s,
	}
}

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

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

// Run executes the TG collection pipeline:
// 1. BFS discover channels from seeds
// 2. Scrape messages from discovered channels
// 3. Extract merchants via regex (+ LLM fallback)
//
// cfg keys:
//   - "seeds": []string — seed channel names
//   - "max_depth": int — BFS max depth (default 3)
//   - "max_channels": int — max channels to discover (default 500)
//   - "message_limit": int — messages per channel (default 500)
func (c *Collector) Run(ctx context.Context, cfg map[string]any, callback func(plugin.MerchantData)) error {
	c.stopped.Store(false)

	if c.tgManager == nil {
		log.Println("[tg_collector] no TG account manager, skipping")
		return nil
	}

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

	maxDepth := getIntCfg(cfg, "max_depth", 3)
	maxChannels := getIntCfg(cfg, "max_channels", 500)
	msgLimit := getIntCfg(cfg, "message_limit", 500)

	// Phase 1: BFS channel discovery
	channels := c.discover(ctx, seeds, maxDepth, maxChannels)
	log.Printf("[tg_collector] discovered %d channels", len(channels))

	// Phase 2: Scrape each channel
	for i, ch := range channels {
		if c.stopped.Load() || ctx.Err() != nil {
			break
		}

		log.Printf("[tg_collector] scraping %d/%d: @%s", i+1, len(channels), ch)
		c.scrapeChannel(ctx, ch, msgLimit, callback)

		// Delay between channels
		select {
		case <-ctx.Done():
			return nil
		case <-time.After(5 * time.Second):
		}
	}

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

type queueItem struct {
	Username string
	Depth    int
	Source   string
}

func (c *Collector) discover(ctx context.Context, seeds []string, maxDepth, maxTotal int) []string {
	queue := make([]queueItem, 0, len(seeds))
	for _, s := range seeds {
		queue = append(queue, queueItem{Username: cleanUsername(s), Depth: 0, Source: "seed"})
	}

	visited := map[string]bool{}
	var result []string

	for len(queue) > 0 && len(result) < maxTotal {
		if c.stopped.Load() || ctx.Err() != nil {
			break
		}

		item := queue[0]
		queue = queue[1:]

		username := cleanUsername(item.Username)
		if username == "" || visited[username] {
			continue
		}
		visited[username] = true

		acc, err := c.tgManager.Acquire(ctx)
		if err != nil {
			log.Printf("[tg_collector] no available TG account: %v", err)
			break
		}

		if err := acc.Client.Connect(ctx); err != nil {
			log.Printf("[tg_collector] connect failed: %v", err)
			c.tgManager.Release(acc, 0)
			continue
		}

		_, err = acc.Client.GetChannelInfo(ctx, username)
		if err != nil {
			if fw, ok := err.(*telegram.FloodWaitError); ok {
				c.tgManager.HandleFloodWait(acc, fw.Seconds)
			} else {
				c.tgManager.Release(acc, 0)
			}
			continue
		}

		// Save channel to DB
		c.store.UpsertChannel(&model.Channel{
			Username: username,
			Source:   item.Source,
			Status:   "pending",
		})
		result = append(result, username)

		// BFS: read messages to find more channels
		if item.Depth < maxDepth {
			msgs, err := acc.Client.GetMessages(ctx, username, 0, 100)
			if err == nil {
				for _, msg := range msgs {
					if msg.ForwardFromChannel != "" {
						fwd := cleanUsername(msg.ForwardFromChannel)
						if fwd != "" && !visited[fwd] {
							queue = append(queue, queueItem{fwd, item.Depth + 1, "snowball"})
						}
					}
					for _, link := range msg.Links {
						name := extractUsernameFromLink(link)
						if name != "" && !visited[name] {
							queue = append(queue, queueItem{name, item.Depth + 1, "snowball"})
						}
					}
				}
			}
		}

		c.tgManager.Release(acc, 0)

		select {
		case <-ctx.Done():
			return result
		case <-time.After(5 * time.Second):
		}
	}

	return result
}

func (c *Collector) scrapeChannel(ctx context.Context, username string, msgLimit int, callback func(plugin.MerchantData)) {
	acc, err := c.tgManager.Acquire(ctx)
	if err != nil {
		return
	}

	if err := acc.Client.Connect(ctx); err != nil {
		c.tgManager.Release(acc, 0)
		return
	}

	// Read pinned messages
	pinnedMsgs, _ := acc.Client.GetPinnedMessages(ctx, username)
	c.processMessages(ctx, pinnedMsgs, username, callback)

	// Read historical messages
	offsetID := 0
	fetched := 0
	for fetched < msgLimit {
		if c.stopped.Load() || ctx.Err() != nil {
			break
		}

		batchSize := 100
		if msgLimit-fetched < batchSize {
			batchSize = msgLimit - fetched
		}

		msgs, err := acc.Client.GetMessages(ctx, username, offsetID, batchSize)
		if err != nil {
			if fw, ok := err.(*telegram.FloodWaitError); ok {
				c.tgManager.HandleFloodWait(acc, fw.Seconds)
				acc = nil
			}
			break
		}
		if len(msgs) == 0 {
			break
		}

		c.processMessages(ctx, msgs, username, callback)

		offsetID = msgs[len(msgs)-1].ID
		fetched += len(msgs)
	}

	if acc != nil {
		c.tgManager.Release(acc, 0)
	}

	// Update channel status
	c.store.DB.Model(&model.Channel{}).Where("username = ?", username).
		Update("status", "scraped")
}

func (c *Collector) processMessages(ctx context.Context, msgs []telegram.Message, channelUsername string, callback func(plugin.MerchantData)) {
	for _, msg := range msgs {
		if msg.IsService || msg.Text == "" {
			continue
		}
		if !extractor.ContainsChinese(msg.Text, 0) {
			continue
		}
		if !extractor.HasContact(msg.Text) {
			continue
		}

		// Regex first
		info := extractor.Extract(msg.Text)
		merchantName := ""
		industry := ""

		// LLM fallback only when regex found no TG username
		if info.TgUsername == "" && c.llmClient != nil {
			merchantInfo, err := c.llmClient.ParseMerchant(ctx, msg.Text)
			if err == nil && merchantInfo != nil && merchantInfo.TgUsername != "" {
				info.TgUsername = strings.TrimPrefix(merchantInfo.TgUsername, "@")
				if merchantInfo.Website != "" && info.Website == "" {
					info.Website = merchantInfo.Website
				}
				if merchantInfo.Email != "" && info.Email == "" {
					info.Email = merchantInfo.Email
				}
				if merchantInfo.Phone != "" && info.Phone == "" {
					info.Phone = merchantInfo.Phone
				}
				merchantName = extractor.CleanMerchantName(merchantInfo.MerchantName)
				industry = merchantInfo.Industry
			}
		}

		if info.TgUsername == "" {
			continue
		}

		callback(plugin.MerchantData{
			TgUsername:   info.TgUsername,
			TgLink:       "https://t.me/" + info.TgUsername,
			MerchantName: merchantName,
			Website:      info.Website,
			Email:        info.Email,
			Phone:        info.Phone,
			SourceType:   "tg_channel",
			SourceName:   channelUsername,
			SourceURL:    "https://t.me/" + channelUsername,
			OriginalText: msg.Text,
			IndustryTag:  industry,
		})
	}
}

func cleanUsername(s string) string {
	return strings.TrimPrefix(strings.TrimSpace(s), "@")
}

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

func extractUsernameFromLink(link string) string {
	m := reUsernameFromLink.FindStringSubmatch(link)
	if len(m) > 1 {
		return m[1]
	}
	return ""
}

func getIntCfg(cfg map[string]any, key string, def int) int {
	if v, ok := cfg[key].(int); ok {
		return v
	}
	if v, ok := cfg[key].(float64); ok {
		return int(v)
	}
	return def
}