package main

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

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

var (
	serverName = flag.String("server", "", "Server name (required)")
	rootPath   = flag.String("path", ".", "Path to scan")
	chHost     = flag.String("ch", "192.168.1.253:9000", "ClickHouse host:port")
	source     = flag.String("source", "local", "Source type: local, gdrive, onedrive, proton")
	dryRun     = flag.Bool("dry-run", false, "Print files without inserting to DB")
	verbose    = flag.Bool("v", false, "Verbose output")
)

// Platform-specific directories to exclude (conservative - only true junk)
var excludeDirs = map[string]bool{
	// Windows system
	"$RECYCLE.BIN":              true,
	"System Volume Information": true,
	"Windows":                   true,
	// macOS system
	".Spotlight-V100": true,
	".fseventsd":      true,
	// Linux system
	"proc":       true,
	"sys":        true,
	"dev":        true,
	"run":        true,
	"lost+found": true,
	// Dev artifacts (large, reproducible)
	"node_modules": true,
	".git":         true,
	"__pycache__":  true,
}

// Additional root-level excludes per OS
func shouldExcludeRoot(path string) bool {
	switch runtime.GOOS {
	case "darwin":
		excludeRoots := []string{"/System", "/Library", "/private/var", "/Volumes/.timemachine"}
		for _, ex := range excludeRoots {
			if strings.HasPrefix(path, ex) {
				return true
			}
		}
	case "linux":
		excludeRoots := []string{"/proc", "/sys", "/dev", "/run", "/snap", "/boot"}
		for _, ex := range excludeRoots {
			if strings.HasPrefix(path, ex) {
				return true
			}
		}
	}
	return false
}

type FileEntry struct {
	Server   string
	Source   string
	Folder   string
	Filename string
	Ext      string
	Size     int64
	Created  time.Time
	Modified time.Time
	Hash     string
}

var currentFolder string

func truncatePath(path string, maxLen int) string {
	if len(path) <= maxLen {
		return path
	}
	// Show beginning and end
	half := (maxLen - 3) / 2
	return path[:half] + "..." + path[len(path)-half:]
}

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)

	// First 64KB
	n, err := f.Read(buf)
	if err != nil && err != io.EOF {
		return "", err
	}
	h.Write(buf[:n])

	// Last 64KB (if file > 128KB)
	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 getFileTimes(info os.FileInfo, path string) (created, modified time.Time) {
	modified = info.ModTime()
	created = modified // fallback - platform-specific code can override
	// Note: Getting birth time is OS-specific and complex
	// For MVP, we use modified time for both
	return
}

func scanFiles(root string, entries chan<- FileEntry) error {
	return filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			if *verbose {
				fmt.Fprintf(os.Stderr, "Error accessing %s: %v\n", path, err)
			}
			return nil // continue scanning
		}

		// Skip excluded directories
		if info.IsDir() {
			name := info.Name()
			if excludeDirs[name] {
				currentFolder = "[skip] " + path
				return filepath.SkipDir
			}
			if shouldExcludeRoot(path) {
				currentFolder = "[skip] " + path
				return filepath.SkipDir
			}
			if strings.Contains(strings.ToLower(path), "cache") {
				currentFolder = "[skip] " + path
				return filepath.SkipDir
			}
			currentFolder = path
			return nil
		}

		// Skip symlinks
		if info.Mode()&os.ModeSymlink != 0 {
			return nil
		}

		// Skip empty files
		if info.Size() == 0 {
			return nil
		}

		created, modified := getFileTimes(info, path)
		ext := strings.ToLower(filepath.Ext(info.Name()))
		if ext != "" {
			ext = ext[1:] // remove leading dot
		}

		entry := FileEntry{
			Server:   *serverName,
			Source:   *source,
			Folder:   filepath.Dir(path),
			Filename: info.Name(),
			Ext:      ext,
			Size:     info.Size(),
			Created:  created,
			Modified: modified,
		}

		entries <- entry
		return nil
	})
}

func initDB(host string) (*sql.DB, error) {
	dsn := fmt.Sprintf("clickhouse://%s/files", host)
	db, err := sql.Open("clickhouse", dsn)
	if err != nil {
		return nil, err
	}

	// Create database and table
	_, err = db.Exec(`CREATE DATABASE IF NOT EXISTS files`)
	if err != nil {
		return nil, fmt.Errorf("create database: %w", err)
	}

	_, err = db.Exec(`
		CREATE TABLE IF NOT EXISTS files.inventory (
			scan_id    String,
			scan_time  DateTime64(3),
			server     LowCardinality(String),
			source     LowCardinality(String),
			folder     String,
			filename   String,
			ext        LowCardinality(String),
			size       UInt64,
			created    DateTime64(3),
			modified   DateTime64(3),
			hash       String DEFAULT ''
		) ENGINE = MergeTree
		ORDER BY (server, folder, filename)
	`)
	if err != nil {
		return nil, fmt.Errorf("create table: %w", err)
	}

	return db, nil
}

func insertBatch(db *sql.DB, scanID string, scanTime time.Time, entries []FileEntry) error {
	if len(entries) == 0 {
		return nil
	}

	tx, err := db.Begin()
	if err != nil {
		return err
	}

	stmt, err := tx.Prepare(`
		INSERT INTO files.inventory 
		(scan_id, scan_time, server, source, folder, filename, ext, size, created, modified)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
	`)
	if err != nil {
		tx.Rollback()
		return err
	}
	defer stmt.Close()

	for _, e := range entries {
		_, err = stmt.Exec(scanID, scanTime, e.Server, e.Source, e.Folder, e.Filename, e.Ext, e.Size, e.Created, e.Modified)
		if err != nil {
			tx.Rollback()
			return err
		}
	}

	return tx.Commit()
}

func main() {
	flag.Parse()

	if *serverName == "" {
		hostname, _ := os.Hostname()
		*serverName = hostname
	}

	absPath, err := filepath.Abs(*rootPath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Invalid path: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Scanning: %s on server %s\n", absPath, *serverName)

	var db *sql.DB
	if !*dryRun {
		db, err = initDB(*chHost)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Database error: %v\n", err)
			os.Exit(1)
		}
		defer db.Close()
	}

	scanID := fmt.Sprintf("%s-%d", *serverName, time.Now().Unix())
	scanTime := time.Now()

	entries := make(chan FileEntry, 1000)
	done := make(chan error)

	// Scanner goroutine
	go func() {
		err := scanFiles(absPath, entries)
		close(entries)
		done <- err
	}()

	// Collector
	var batch []FileEntry
	var totalFiles int64
	var totalSize int64
	batchSize := 1000

	for entry := range entries {
		totalFiles++
		totalSize += entry.Size

		if *dryRun {
			fmt.Printf("%s/%s (%d bytes)\n", entry.Folder, entry.Filename, entry.Size)
		} else {
			batch = append(batch, entry)
			if len(batch) >= batchSize {
				if err := insertBatch(db, scanID, scanTime, batch); err != nil {
					fmt.Fprintf(os.Stderr, "Insert error: %v\n", err)
				}
				batch = batch[:0]
			}
			if totalFiles%100 == 0 {
				folder := truncatePath(currentFolder, 90)
				fmt.Printf("\r%-120s", fmt.Sprintf("%d files (%.2f GB) %s", totalFiles, float64(totalSize)/(1024*1024*1024), folder))
			}
		}
	}

	// Insert remaining
	if !*dryRun && len(batch) > 0 {
		if err := insertBatch(db, scanID, scanTime, batch); err != nil {
			fmt.Fprintf(os.Stderr, "Insert error: %v\n", err)
		}
	}

	// Wait for scanner
	if err := <-done; err != nil {
		fmt.Fprintf(os.Stderr, "Scan error: %v\n", err)
	}

	fmt.Printf("\r%-120s\r", "") // clear progress line
	fmt.Printf("Scan complete: %d files, %.2f GB\n", totalFiles, float64(totalSize)/(1024*1024*1024))
	fmt.Printf("Scan ID: %s\n", scanID)
}