package processor

import (
	"context"
	"log"
	"spider/internal/crawler"
	"spider/internal/model"
	"sync"
)

// TMeChecker filters dead TG accounts via HTTP t.me page scraping.
// Uses a concurrent worker pool for performance.
type TMeChecker struct {
	validator   *crawler.TMeValidator
	concurrency int
}

// NewTMeChecker creates a new TMeChecker with default concurrency.
func NewTMeChecker() *TMeChecker {
	return &TMeChecker{
		validator:   crawler.NewTMeValidator(),
		concurrency: 10,
	}
}

// checkedMerchant pairs a raw merchant with its alive status.
type checkedMerchant struct {
	raw   model.MerchantRaw
	alive bool
}

// Filter checks each raw merchant's tg_username against t.me concurrently.
// Returns alive merchants; dead ones are returned separately.
func (c *TMeChecker) Filter(ctx context.Context, raws []model.MerchantRaw) (alive []model.MerchantRaw, dead []model.MerchantRaw) {
	if len(raws) == 0 {
		return nil, nil
	}

	// For small batches, run sequentially
	if len(raws) <= 3 {
		return c.filterSequential(ctx, raws)
	}

	workers := c.concurrency
	if workers > len(raws) {
		workers = len(raws)
	}

	jobs := make(chan model.MerchantRaw, len(raws))
	results := make(chan checkedMerchant, len(raws))

	// Start workers
	var wg sync.WaitGroup
	for i := 0; i < workers; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for raw := range jobs {
				if ctx.Err() != nil {
					results <- checkedMerchant{raw: raw, alive: true} // assume alive on cancel
					continue
				}
				if raw.TgUsername == "" {
					results <- checkedMerchant{raw: raw, alive: true}
					continue
				}
				isAlive := c.validator.IsAlive(ctx, raw.TgUsername)
				if !isAlive {
					log.Printf("[tmechecker] dead: @%s", raw.TgUsername)
				}
				results <- checkedMerchant{raw: raw, alive: isAlive}
			}
		}()
	}

	// Send jobs
	for _, raw := range raws {
		jobs <- raw
	}
	close(jobs)

	// Collect results in background
	go func() {
		wg.Wait()
		close(results)
	}()

	for r := range results {
		if r.alive {
			alive = append(alive, r.raw)
		} else {
			dead = append(dead, r.raw)
		}
	}

	return
}

// filterSequential is the simple path for small batches.
func (c *TMeChecker) filterSequential(ctx context.Context, raws []model.MerchantRaw) (alive []model.MerchantRaw, dead []model.MerchantRaw) {
	for _, raw := range raws {
		if ctx.Err() != nil {
			break
		}
		if raw.TgUsername == "" {
			alive = append(alive, raw)
			continue
		}
		if c.validator.IsAlive(ctx, raw.TgUsername) {
			alive = append(alive, raw)
		} else {
			log.Printf("[tmechecker] dead: @%s", raw.TgUsername)
			dead = append(dead, raw)
		}
	}
	return
}