package main

import (
	"crypto/md5"
	"database/sql"
	"flag"
	"fmt"
	"io"
	"os"
	"path/filepath"

	_ "github.com/ClickHouse/clickhouse-go/v2"
)

var (
	serverName = flag.String("server", "", "Server name to process")
	chHost     = flag.String("ch", "192.168.1.253:9000", "ClickHouse host:port")
	verbose    = flag.Bool("v", false, "Verbose output")
)

func quickHash(path string) (string, error) {
	f, err := os.Open(path)
	if err != nil {
		return "", err
	}
	defer f.Close()

	stat, err := f.Stat()
	if err != nil {
		return "", err
	}
	size := stat.Size()

	h := md5.New()
	buf := make([]byte, 65536)

	n, err := f.Read(buf)
	if err != nil && err != io.EOF {
		return "", err
	}
	h.Write(buf[:n])

	if size > 131072 {
		_, err = f.Seek(-65536, io.SeekEnd)
		if err != nil {
			return "", err
		}
		n, err = f.Read(buf)
		if err != nil && err != io.EOF {
			return "", err
		}
		h.Write(buf[:n])
	}

	return fmt.Sprintf("%x", h.Sum(nil)), nil
}

func main() {
	flag.Parse()

	if *serverName == "" {
		fmt.Fprintln(os.Stderr, "Server name required: -server <n>")
		os.Exit(1)
	}

	dsn := fmt.Sprintf("clickhouse://%s/files", *chHost)
	db, err := sql.Open("clickhouse", dsn)
	if err != nil {
		fmt.Fprintf(os.Stderr, "DB error: %v\n", err)
		os.Exit(1)
	}
	defer db.Close()

	// Find sizes that appear more than once (potential dupes)
	rows, err := db.Query(`
		SELECT DISTINCT size 
		FROM files.inventory 
		WHERE server = ? AND hash = '' AND size > 0
		GROUP BY size 
		HAVING count(*) > 1
		ORDER BY size DESC
	`, *serverName)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Query error: %v\n", err)
		os.Exit(1)
	}

	var sizes []int64
	for rows.Next() {
		var size int64
		rows.Scan(&size)
		sizes = append(sizes, size)
	}
	rows.Close()

	fmt.Printf("Found %d file sizes with potential duplicates\n", len(sizes))

	// Get files to hash
	var totalHashed int64
	for _, size := range sizes {
		fileRows, err := db.Query(`
			SELECT folder, filename 
			FROM files.inventory 
			WHERE server = ? AND size = ? AND hash = ''
		`, *serverName, size)
		if err != nil {
			continue
		}

		for fileRows.Next() {
			var folder, filename string
			fileRows.Scan(&folder, &filename)

			fullPath := filepath.Join(folder, filename)
			hash, err := quickHash(fullPath)
			if err != nil {
				if *verbose {
					fmt.Fprintf(os.Stderr, "Hash error %s: %v\n", fullPath, err)
				}
				continue
			}

			_, err = db.Exec(`
				ALTER TABLE files.inventory 
				UPDATE hash = ? 
				WHERE server = ? AND folder = ? AND filename = ?
			`, hash, *serverName, folder, filename)

			if err != nil {
				if *verbose {
					fmt.Fprintf(os.Stderr, "Update error: %v\n", err)
				}
				continue
			}

			totalHashed++
			if *verbose {
				fmt.Printf("Hashed: %s -> %s\n", fullPath, hash)
			}
		}
		fileRows.Close()
	}

	fmt.Printf("Hashed %d files\n", totalHashed)
}