package main

import (
	"bufio"
	"fmt"
	"net/http"
	"strings"
	"time"
)

const (
	IANATLDListURL = "https://data.iana.org/TLD/tlds-alpha-by-domain.txt"
)

// fetchOfficialTLDs retrieves the current TLD list from IANA
func fetchOfficialTLDs() (map[string]bool, error) {
	resp, err := http.Get(IANATLDListURL)
	if err != nil {
		return nil, fmt.Errorf("failed to fetch TLD list: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
	}

	tlds := make(map[string]bool)
	scanner := bufio.NewScanner(resp.Body)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		// Skip comments and empty lines
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		// IANA list is uppercase, convert to lowercase
		tlds[strings.ToLower(line)] = true
	}

	if err := scanner.Err(); err != nil {
		return nil, fmt.Errorf("error reading TLD list: %w", err)
	}

	return tlds, nil
}

// getEnumTLDs retrieves all TLDs currently in the tld_enum type
func (c *Crawler) getEnumTLDs() (map[string]bool, error) {
	rows, err := c.db.Query(`
		SELECT enumlabel FROM pg_enum
		WHERE enumtypid = 'tld_enum'::regtype
	`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	tlds := make(map[string]bool)
	for rows.Next() {
		var tld string
		if err := rows.Scan(&tld); err != nil {
			continue
		}
		tlds[tld] = true
	}
	return tlds, rows.Err()
}

// syncTLDs fetches the official IANA TLD list and:
// 1. Marks domains/feeds with unofficial TLDs as 'dead'
// 2. Adds any new official TLDs to the enum
func (c *Crawler) syncTLDs() error {
	fmt.Println("TLD sync: fetching official TLD list from IANA...")

	officialTLDs, err := fetchOfficialTLDs()
	if err != nil {
		return fmt.Errorf("TLD sync failed: %w", err)
	}
	fmt.Printf("TLD sync: %d official TLDs from IANA\n", len(officialTLDs))

	enumTLDs, err := c.getEnumTLDs()
	if err != nil {
		return fmt.Errorf("TLD sync: failed to get enum TLDs: %w", err)
	}
	fmt.Printf("TLD sync: %d TLDs in enum\n", len(enumTLDs))

	// Find unofficial TLDs (in enum but not in IANA)
	var unofficialTLDs []string
	for tld := range enumTLDs {
		if !officialTLDs[tld] {
			unofficialTLDs = append(unofficialTLDs, tld)
		}
	}

	if len(unofficialTLDs) > 0 {
		fmt.Printf("TLD sync: %d unofficial TLDs found\n", len(unofficialTLDs))

		// Mark feeds with unofficial TLDs as dead
		for _, tld := range unofficialTLDs {
			result, err := c.db.Exec(`
				UPDATE feeds SET status = 'dead'
				WHERE domain_tld = $1::tld_enum AND status != 'dead'
			`, tld)
			if err != nil {
				fmt.Printf("TLD sync: error marking feeds for TLD %s: %v\n", tld, err)
			} else if result > 0 {
				fmt.Printf("TLD sync: marked %d feeds as dead for TLD .%s\n", result, tld)
			}
		}

		// Mark domains with unofficial TLDs as dead
		for _, tld := range unofficialTLDs {
			result, err := c.db.Exec(`
				UPDATE domains SET status = 'dead'
				WHERE tld = $1::tld_enum AND status != 'dead'
			`, tld)
			if err != nil {
				fmt.Printf("TLD sync: error marking domains for TLD %s: %v\n", tld, err)
			} else if result > 0 {
				fmt.Printf("TLD sync: marked %d domains as dead for TLD .%s\n", result, tld)
			}
		}
	}

	// Find new TLDs (in IANA but not in enum)
	var newTLDs []string
	for tld := range officialTLDs {
		if !enumTLDs[tld] {
			newTLDs = append(newTLDs, tld)
		}
	}

	if len(newTLDs) > 0 {
		fmt.Printf("TLD sync: %d new TLDs to add\n", len(newTLDs))

		// Add new TLDs to enum
		for _, tld := range newTLDs {
			_, err := c.db.Exec(fmt.Sprintf(`ALTER TYPE tld_enum ADD VALUE IF NOT EXISTS '%s'`, tld))
			if err != nil {
				fmt.Printf("TLD sync: error adding TLD %s: %v\n", tld, err)
			} else {
				fmt.Printf("TLD sync: added TLD .%s to enum\n", tld)
			}
		}
	}

	fmt.Println("TLD sync: complete")
	return nil
}

// startTLDSyncLoop runs TLD sync on startup and daily at noon GMT
func (c *Crawler) startTLDSyncLoop() {
	// Run immediately on startup
	if err := c.syncTLDs(); err != nil {
		fmt.Printf("TLD sync error: %v\n", err)
	}

	go func() {
		for {
			// Calculate time until next noon GMT
			now := time.Now().UTC()
			nextNoon := time.Date(now.Year(), now.Month(), now.Day(), 12, 0, 0, 0, time.UTC)
			if now.After(nextNoon) {
				// Already past noon today, schedule for tomorrow
				nextNoon = nextNoon.Add(24 * time.Hour)
			}
			sleepDuration := nextNoon.Sub(now)

			fmt.Printf("TLD sync: next sync at %s (in %s)\n", nextNoon.Format(time.RFC3339), sleepDuration.Round(time.Minute))
			time.Sleep(sleepDuration)

			if err := c.syncTLDs(); err != nil {
				fmt.Printf("TLD sync error: %v\n", err)
			}
		}
	}()
}