ImgResizer/main.go26

/*
——————————————————————————————————————————————————————————————————————————
Proyecto  Imaginator

—————————————————————————————————————————————————————————————————————————

    Fichero  main.go
    Package  Imaginator
    Autor    Juan V. Navarro juanvnl@activething.com
    Creado   26/01/2026
    Mejorado 20/03/2026

—————————————————————————————————————————————————————————————————————————

    LICENSES AND TERMS OF USE
    -------------------------

    This software is licensed under the Elastic License v2.0 (the "License").
    For full terms and additional information regarding permitted and prohibited
    uses, please visit:
        https://activething.com/ATGO/licenses

    You may use, copy, modify, and redistribute this software internally within
    your organization for any purpose, including research, development, and
    testing, subject to the terms of this License.

    You may NOT, however, use, provide, distribute, or make this software
    available to any third party as part of a hosted service, SaaS offering, or
    commercial product without first obtaining a commercial license from
    Active Thing.

—————————————————————————————————————————————————————————————————————————

    Web    :   activething.com     |   activething.com/Imaginator
    git    :   g.activething.com   |   github.com/activething/Imaginator
    Correo :   dev@activething.com

—————————————————————————————————————————————————————————————————————————

    "No deseo caminar sobre el agua", dijo Siddhartha.
    Que los antiguos chamanes se contenten con tales habilidades.
    —— Hermann Hesse, Siddhartha

—————————————————————————————————————————————————————————————————————————

    Copyright (c) 2026 Active Thing

—————————————————————————————————————————————————————————————————————————
*/
package main

import (
	"bytes"
	"encoding/base64"
	"flag"
	"fmt"
	"image"
	"image/jpeg"
	"image/png"
	"log"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"sync"
	"sync/atomic"
	"time"
	"unicode"

	"github.com/disintegration/imaging"
	_ "golang.org/x/image/bmp"
	"golang.org/x/image/tiff"
	_ "golang.org/x/image/webp"
)

const version = "2.6.0"

// ─────────────────────────────────────────────────────────────────────────────
// Tipos
// ─────────────────────────────────────────────────────────────────────────────

type Config struct {
	InputDir      string
	OutputDir     string
	Width         int
	Height        int
	Quality       int
	Format        string
	Filter        string
	Workers       int
	Verbose       bool
	KeepStructure bool
	Prefix        string
	Suffix        string
	DryRun        bool
	Replace       string // pares orig/dest separados por coma, case sensitive
	ReplaceI      string // ídem, case insensitive
	ReplaceP      string // ídem, case insensitive + preserve case
	FileFilter    string // glob sobre el nombre del fichero
	Lowercase     bool   // normalize output filename to lowercase
	Uppercase     bool   // normalize output filename to uppercase
	B64Ext        string // if set, encode output as base64 with this extension ("" = disabled, "b64" = default)
	B64Enabled    bool   // true when -b64 flag was provided
	TSFile        string // if set, write a TypeScript file with all images as base64 data URIs
	NoSpaces      string // replacement char for spaces in output filename ("" = disabled, "_" = default)
	NoSpacesOn    bool   // true when -nospaces flag was provided
}

// ReplacePair representa un par de sustitución ya parseado
type ReplacePair struct {
	From string
	To   string
}

type ProcessResult struct {
	Filename   string
	OutputPath string
	Success    bool
	Error      error
	Duration   time.Duration
	InputSize  int64
	OutputSize int64
	B64Data    string // populated when B64Enabled or TSFile is set: "data:image/png;base64,..."
	ImageKey   string // stem used as key in the TS file
}

type ImageSummary struct {
	Files        []string
	ByExt        map[string]int
	ReadOnlyExts []string // read-only formats present in the batch
}

// ─────────────────────────────────────────────────────────────────────────────
// Entrada
// ─────────────────────────────────────────────────────────────────────────────

func main() {
	cfg := parseFlags()

	if err := validateConfig(cfg); err != nil {
		log.Fatal(err)
	}

	if err := os.MkdirAll(cfg.OutputDir, 0755); err != nil {
		log.Fatalf("error creating output directory: %v", err)
	}

	summary, err := collectImageFiles(cfg.InputDir, cfg.FileFilter)
	if err != nil {
		log.Fatalf("error reading source directory: %v", err)
	}

	if len(summary.Files) == 0 {
		fmt.Println("  No images found to process.")
		return
	}

	// Type breakdown
	fmt.Printf("  Found %d images:\n", len(summary.Files))
	for _, ext := range []string{".jpg", ".jpeg", ".png", ".tif", ".tiff", ".bmp", ".webp"} {
		if n := summary.ByExt[ext]; n > 0 {
			line := fmt.Sprintf("    %-8s %d", ext, n)
			if (ext == ".webp" || ext == ".bmp") && cfg.Format == "" {
				line += "   ⚠  read-only"
			}
			fmt.Println(line)
		}
	}

	if len(summary.ReadOnlyExts) > 0 && cfg.Format == "" {
		joined := strings.Join(summary.ReadOnlyExts, ", ")
		fmt.Println()
		fmt.Printf("  WARNING: batch contains read-only formats (%s).\n", joined)
		fmt.Println("           Output files in that format may be corrupted.")
		fmt.Println("           Add  -format jpg  or  -format png  to convert them.")
	}
	fmt.Println()

	if cfg.DryRun {
		fmt.Println("  [dry-run] Output paths:")
		fmt.Println()
		for _, f := range summary.Files {
			out := buildOutputPath(f, cfg)
			fmt.Printf("    %s  →  %s\n", f, out)
		}
		fmt.Println()
		return
	}

	fmt.Printf("  Processing with %d workers...\n\n", cfg.Workers)
	processImages(summary.Files, cfg)
}

// ─────────────────────────────────────────────────────────────────────────────
// Flags y validación
// ─────────────────────────────────────────────────────────────────────────────

func parseFlags() *Config {
	cfg := &Config{}

	flag.StringVar(&cfg.InputDir, "dir", "", "Source directory")
	flag.StringVar(&cfg.OutputDir, "out", "", "Output directory")
	flag.IntVar(&cfg.Width, "width", 0, "Target width")
	flag.IntVar(&cfg.Height, "height", 0, "Target height")
	flag.IntVar(&cfg.Quality, "quality", 85, "JPEG quality (1-100)")
	flag.StringVar(&cfg.Format, "format", "", "Output format: jpg, png, tif")
	flag.StringVar(&cfg.Filter, "resample", "lanczos", "Resampling filter: lanczos, cubic, linear, box")
	flag.IntVar(&cfg.Workers, "workers", 4, "Concurrent workers")
	flag.BoolVar(&cfg.Verbose, "verbose", false, "Verbose output")
	flag.BoolVar(&cfg.KeepStructure, "keepstructure", false, "Preserve subdirectory structure")
	flag.StringVar(&cfg.Prefix, "prefix", "", "Prefix for output filename")
	flag.StringVar(&cfg.Suffix, "suffix", "", "Suffix for output filename (before extension)")
	flag.BoolVar(&cfg.DryRun, "dry-run", false, "Show what would be processed without executing")
	flag.StringVar(&cfg.Replace, "replace", "", "Replace tokens in filename: orig/dest[,orig2/dest2]  (case sensitive)")
	flag.StringVar(&cfg.ReplaceI, "replacei", "", "Replace tokens in filename: orig/dest[,...]  (case insensitive)")
	flag.StringVar(&cfg.ReplaceP, "replacep", "", "Replace tokens in filename: orig/dest[,...]  (case insensitive + preserve case)")
	flag.StringVar(&cfg.FileFilter, "filter", "", "Glob pattern to filter filenames, e.g: photo_*.jpg")
	flag.BoolVar(&cfg.Lowercase, "lowercase", false, "Normalize output filename to lowercase")
	flag.BoolVar(&cfg.Uppercase, "uppercase", false, "Normalize output filename to uppercase")
	flag.StringVar(&cfg.B64Ext, "b64", "", "Encode output as base64; optional value sets the file extension (default: b64)")
	flag.StringVar(&cfg.TSFile, "ts", "", "Write a TypeScript file with all images as base64 data URIs")
	flag.StringVar(&cfg.NoSpaces, "nospaces", "", "Replace spaces in output filename; optional value sets replacement char (default: _)")

	configurarAyuda()
	flag.Parse()

	// -b64 without a value: detect if the flag was provided but left empty
	// and default the extension to "b64"
	flag.Visit(func(f *flag.Flag) {
		if f.Name == "b64" {
			cfg.B64Enabled = true
			if cfg.B64Ext == "" {
				cfg.B64Ext = "b64"
			}
		}
		if f.Name == "nospaces" {
			cfg.NoSpacesOn = true
			if cfg.NoSpaces == "" {
				cfg.NoSpaces = "_"
			}
		}
	})

	return cfg
}

func validateConfig(cfg *Config) error {
	if cfg.InputDir == "" || cfg.OutputDir == "" {
		flag.Usage()
		return fmt.Errorf("missing required flags: -dir and -out are required")
	}

	if cfg.Width == 0 && cfg.Height == 0 {
		return fmt.Errorf("at least one of -width or -height must be specified")
	}

	if cfg.Width < 0 || cfg.Height < 0 {
		return fmt.Errorf("dimensions cannot be negative")
	}

	if cfg.Quality < 1 || cfg.Quality > 100 {
		return fmt.Errorf("quality must be between 1 and 100")
	}

	if cfg.Format != "" &&
		cfg.Format != "jpg" && cfg.Format != "jpeg" &&
		cfg.Format != "png" &&
		cfg.Format != "tif" && cfg.Format != "tiff" {
		return fmt.Errorf("unsupported output format: %s (options: jpg, png, tif)", cfg.Format)
	}

	absInput, err := filepath.Abs(cfg.InputDir)
	if err != nil {
		return fmt.Errorf("error resolving source path: %v", err)
	}

	absOutput, err := filepath.Abs(cfg.OutputDir)
	if err != nil {
		return fmt.Errorf("error resolving output path: %v", err)
	}

	if absInput == absOutput && cfg.Prefix == "" && cfg.Suffix == "" && cfg.TSFile == "" && !cfg.B64Enabled {
		return fmt.Errorf(
			"input and output directories cannot be the same\n" +
				"  hint: use -prefix, -suffix, -b64 or -ts to process in place without overwriting originals")
	}

	if _, err := os.Stat(cfg.InputDir); os.IsNotExist(err) {
		return fmt.Errorf("source directory does not exist: %s", cfg.InputDir)
	}

	if cfg.Workers < 1 {
		cfg.Workers = 1
	}

	// Validate replacement pairs
	for _, raw := range []string{cfg.Replace, cfg.ReplaceI, cfg.ReplaceP} {
		if raw == "" {
			continue
		}
		for _, pair := range strings.Split(raw, ",") {
			parts := strings.SplitN(pair, "/", 2)
			if len(parts) != 2 || parts[0] == "" {
				return fmt.Errorf("invalid replacement pair %q — expected format: old/new", pair)
			}
		}
	}

	// Validate filter glob
	if cfg.FileFilter != "" {
		if _, err := filepath.Match(cfg.FileFilter, ""); err != nil {
			return fmt.Errorf("invalid -filter pattern %q: %v", cfg.FileFilter, err)
		}
	}

	if cfg.Lowercase && cfg.Uppercase {
		return fmt.Errorf("-lowercase and -uppercase are mutually exclusive")
	}

	if cfg.B64Enabled && cfg.TSFile != "" {
		return fmt.Errorf("-b64 and -ts are mutually exclusive")
	}

	return nil
}

// ─────────────────────────────────────────────────────────────────────────────
// Recolección de ficheros
// ─────────────────────────────────────────────────────────────────────────────

func collectImageFiles(root string, glob string) (*ImageSummary, error) {
	validExts := map[string]bool{
		".jpg":  true,
		".jpeg": true,
		".png":  true,
		".webp": true,
		".tif":  true,
		".tiff": true,
		".bmp":  true,
	}

	readOnlyExts := map[string]bool{
		".webp": true,
		".bmp":  true,
	}

	summary := &ImageSummary{
		ByExt: make(map[string]int),
	}

	seen := map[string]bool{}

	err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() {
			return nil
		}
		ext := strings.ToLower(filepath.Ext(path))
		if !validExts[ext] {
			return nil
		}
		// Aplicar glob sobre el nombre del fichero (sin ruta)
		if glob != "" {
			matched, merr := filepath.Match(glob, filepath.Base(path))
			if merr != nil || !matched {
				return nil
			}
		}
		summary.Files = append(summary.Files, path)
		summary.ByExt[ext]++
		if readOnlyExts[ext] && !seen[ext] {
			summary.ReadOnlyExts = append(summary.ReadOnlyExts, ext)
			seen[ext] = true
		}
		return nil
	})

	return summary, err
}

// ─────────────────────────────────────────────────────────────────────────────
// Ruta de salida
// ─────────────────────────────────────────────────────────────────────────────

func buildOutputPath(inputPath string, cfg *Config) string {
	relPath, err := filepath.Rel(cfg.InputDir, inputPath)
	if err != nil {
		relPath = filepath.Base(inputPath)
	}

	base := filepath.Base(relPath)
	dir := filepath.Dir(relPath)

	ext := filepath.Ext(base)
	stem := base[:len(base)-len(ext)]

	// Formato de salida
	outExt := ext
	if cfg.Format != "" {
		outExt = "." + cfg.Format
		switch cfg.Format {
		case "jpeg":
			outExt = ".jpg"
		case "tiff":
			outExt = ".tif"
		}
	}

	stem = applyStemReplacements(stem, cfg)

	// Replace spaces
	if cfg.NoSpacesOn {
		stem = strings.ReplaceAll(stem, " ", cfg.NoSpaces)
	}

	// Case normalisation — applied after all other stem transformations,
	// never on the extension (avoids .JPG or .TIF on case-sensitive filesystems)
	switch {
	case cfg.Lowercase:
		stem = strings.ToLower(stem)
	case cfg.Uppercase:
		stem = strings.ToUpper(stem)
	}

	// Base64 extension override — applied last, replaces the image extension
	if cfg.B64Enabled {
		outExt = "." + cfg.B64Ext
	}

	newName := cfg.Prefix + stem + cfg.Suffix + outExt

	if cfg.KeepStructure {
		return filepath.Join(cfg.OutputDir, dir, newName)
	}
	return filepath.Join(cfg.OutputDir, newName)
}

// ─────────────────────────────────────────────────────────────────────────────
// Orquestación de workers
// ─────────────────────────────────────────────────────────────────────────────

func processImages(files []string, cfg *Config) {
	var (
		wg        sync.WaitGroup
		mu        sync.Mutex
		processed atomic.Int32
		errCount  atomic.Int32
		totalIn   atomic.Int64
		totalOut  atomic.Int64
		total     = int32(len(files))
		start     = time.Now()
		tsEntries []ProcessResult // collected in order for -ts
	)

	jobs := make(chan string, len(files))
	resultsCh := make(chan ProcessResult, len(files))

	for i := 0; i < cfg.Workers; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for inputPath := range jobs {
				result := processImage(inputPath, cfg)
				resultsCh <- result
				current := processed.Add(1)

				mu.Lock()
				if result.Success {
					totalIn.Add(result.InputSize)
					totalOut.Add(result.OutputSize)
					if cfg.Verbose {
						fmt.Printf("  [%d/%d] ✓  %-40s  →  %-40s  (%s)\n",
							current, total,
							truncate(result.Filename, 40),
							truncate(filepath.Base(result.OutputPath), 40),
							result.Duration.Round(time.Millisecond))
					} else {
						fmt.Printf("  [%d/%d] ✓  %s\n", current, total, result.Filename)
					}
				} else {
					errCount.Add(1)
					fmt.Printf("  [%d/%d] ✗  %s: %v\n", current, total, result.Filename, result.Error)
				}
				mu.Unlock()
			}
		}()
	}

	for _, f := range files {
		jobs <- f
	}
	close(jobs)

	// Collect results while workers run
	go func() {
		wg.Wait()
		close(resultsCh)
	}()

	for r := range resultsCh {
		if r.Success && cfg.TSFile != "" {
			tsEntries = append(tsEntries, r)
		}
	}

	// Write TypeScript file
	if cfg.TSFile != "" && len(tsEntries) > 0 {
		if err := writeTSFile(cfg.TSFile, tsEntries); err != nil {
			fmt.Printf("\n  ✗  error writing TypeScript file: %v\n", err)
		} else {
			fmt.Printf("\n  ✓  TypeScript file written: %s  (%d images)\n", cfg.TSFile, len(tsEntries))
		}
	}

	elapsed := time.Since(start).Round(time.Millisecond)
	ok := total - errCount.Load()
	inMB := float64(totalIn.Load()) / 1024 / 1024
	outMB := float64(totalOut.Load()) / 1024 / 1024

	var saving string
	if totalIn.Load() > 0 {
		pct := 100.0 - (float64(totalOut.Load())/float64(totalIn.Load()))*100.0
		saving = fmt.Sprintf("%.1f%%", pct)
	} else {
		saving = "n/a"
	}

	fmt.Printf("\n")
	fmt.Printf("  ══════════════════════════════════════════════════════\n")
	fmt.Printf("  Done in %s\n\n", elapsed)
	fmt.Printf("  Images   %d total  /  %d ok  /  %d errors\n",
		total, ok, errCount.Load())
	fmt.Printf("  Size     %.2f MB in  →  %.2f MB out  (%s saved)\n",
		inMB, outMB, saving)
	fmt.Printf("  ══════════════════════════════════════════════════════\n\n")
}

// ─────────────────────────────────────────────────────────────────────────────
// Procesado individual
// ─────────────────────────────────────────────────────────────────────────────

func processImage(inputPath string, cfg *Config) ProcessResult {
	start := time.Now()

	result := ProcessResult{
		Filename: filepath.Base(inputPath),
	}

	if fi, err := os.Stat(inputPath); err == nil {
		result.InputSize = fi.Size()
	}

	outputPath := buildOutputPath(inputPath, cfg)
	result.OutputPath = outputPath

	// Stem for TS key (after all naming transformations, without extension)
	base := filepath.Base(outputPath)
	result.ImageKey = base[:len(base)-len(filepath.Ext(base))]

	if err := os.MkdirAll(filepath.Dir(outputPath), 0755); err != nil {
		result.Error = fmt.Errorf("error creating directory: %v", err)
		return result
	}

	f, err := os.Open(inputPath)
	if err != nil {
		result.Error = fmt.Errorf("error opening file: %v", err)
		return result
	}
	defer f.Close()

	img, srcFormat, err := image.Decode(f)
	if err != nil {
		result.Error = fmt.Errorf("error decoding image: %v", err)
		return result
	}

	if cfg.Verbose {
		bounds := img.Bounds()
		log.Printf("  %s: format=%s  size=%dx%d",
			result.Filename, srcFormat, bounds.Dx(), bounds.Dy())
	}

	resized := imaging.Resize(img, cfg.Width, cfg.Height, getResampleFilter(cfg.Filter))

	// Encode image into an in-memory buffer first
	var buf bytes.Buffer
	outputFormat := cfg.Format
	if outputFormat == "" {
		// When b64 or ts mode, we need a real image format — default to the source format
		srcExt := strings.ToLower(filepath.Ext(inputPath))
		srcMime := extToFormat(strings.TrimPrefix(srcExt, "."))
		if cfg.B64Enabled || cfg.TSFile != "" {
			outputFormat = srcMime
		} else {
			ext := strings.ToLower(filepath.Ext(outputPath))
			outputFormat = strings.TrimPrefix(ext, ".")
		}
	}

	mimeType, encErr := encodeImage(&buf, resized, outputFormat, cfg.Quality)
	if encErr != nil {
		result.Error = fmt.Errorf("error encoding image: %v", encErr)
		return result
	}

	// ── Base64 mode ──────────────────────────────────────────────────────────
	if cfg.B64Enabled || cfg.TSFile != "" {
		encoded := base64.StdEncoding.EncodeToString(buf.Bytes())
		result.B64Data = "data:" + mimeType + ";base64," + encoded
	}

	// ── Write output file ────────────────────────────────────────────────────
	if cfg.TSFile == "" {
		// Write b64 text file or normal binary image
		var writeErr error
		if cfg.B64Enabled {
			writeErr = os.WriteFile(outputPath, []byte(result.B64Data), 0644)
		} else {
			writeErr = os.WriteFile(outputPath, buf.Bytes(), 0644)
		}
		if writeErr != nil {
			result.Error = fmt.Errorf("error writing output file: %v", writeErr)
			return result
		}
	}
	// When -ts is active, writing is deferred to processImages after all goroutines finish

	if fi, err := os.Stat(outputPath); err == nil {
		result.OutputSize = fi.Size()
	}

	result.Success = true
	result.Duration = time.Since(start)
	return result
}

// ─────────────────────────────────────────────────────────────────────────────
// Utilidades
// ─────────────────────────────────────────────────────────────────────────────

func getResampleFilter(name string) imaging.ResampleFilter {
	switch strings.ToLower(name) {
	case "lanczos":
		return imaging.Lanczos
	case "cubic":
		return imaging.CatmullRom
	case "linear":
		return imaging.Linear
	case "box":
		return imaging.Box
	default:
		return imaging.Lanczos
	}
}

// encodeImage writes the image into buf using the given format and returns
// the MIME type string to use in data URIs.
func encodeImage(buf *bytes.Buffer, img image.Image, format string, quality int) (mimeType string, err error) {
	switch strings.ToLower(format) {
	case "jpg", "jpeg":
		err = jpeg.Encode(buf, img, &jpeg.Options{Quality: quality})
		mimeType = "image/jpeg"
	case "png":
		err = png.Encode(buf, img)
		mimeType = "image/png"
	case "tif", "tiff":
		err = tiff.Encode(buf, img, &tiff.Options{Compression: tiff.Deflate, Predictor: true})
		mimeType = "image/tiff"
	case "webp", "bmp":
		err = fmt.Errorf("format %s is read-only — use -format jpg, png or tif", format)
	default:
		err = fmt.Errorf("unknown output format: %s", format)
	}
	return
}

// extToFormat normalises a file extension to a canonical format name.
func extToFormat(ext string) string {
	switch ext {
	case "jpeg":
		return "jpg"
	case "tiff":
		return "tif"
	default:
		return ext
	}
}

func truncate(s string, max int) string {
	if len(s) <= max {
		return s
	}
	return "…" + s[len(s)-(max-1):]
}

// ─────────────────────────────────────────────────────────────────────────────
// TypeScript export file
// ─────────────────────────────────────────────────────────────────────────────

func writeTSFile(path string, entries []ProcessResult) error {
	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
		return err
	}

	var sb strings.Builder
	sb.WriteString("export const images: Record<string, string> = {\n")
	for _, e := range entries {
		// Sanitize key: replace any non-alphanumeric/underscore chars with _
		key := sanitizeTSKey(e.ImageKey)
		fmt.Fprintf(&sb, "  %s: %q,\n", key, e.B64Data)
	}
	sb.WriteString("}\n")

	return os.WriteFile(path, []byte(sb.String()), 0644)
}

// sanitizeTSKey ensures the key is a valid JS identifier.
// Replaces sequences of non-word characters with underscores,
// and prepends _ if the key starts with a digit.
func sanitizeTSKey(s string) string {
	re := regexp.MustCompile(`[^\w]`)
	key := re.ReplaceAllString(s, "_")
	if len(key) > 0 && key[0] >= '0' && key[0] <= '9' {
		key = "_" + key
	}
	return key
}

// applyStemReplacements aplica los tres modos de sustitución al stem del fichero.
// El orden de aplicación es: -replace → -replacei → -replacep.
func applyStemReplacements(stem string, cfg *Config) string {
	if cfg.Replace != "" {
		for _, p := range parsePairs(cfg.Replace) {
			stem = strings.ReplaceAll(stem, p.From, p.To)
		}
	}
	if cfg.ReplaceI != "" {
		for _, p := range parsePairs(cfg.ReplaceI) {
			stem = replaceInsensitive(stem, p.From, p.To, false)
		}
	}
	if cfg.ReplaceP != "" {
		for _, p := range parsePairs(cfg.ReplaceP) {
			stem = replaceInsensitive(stem, p.From, p.To, true)
		}
	}
	return stem
}

// parsePairs descompone "orig1/dest1,orig2/dest2" en una slice de ReplacePair.
func parsePairs(raw string) []ReplacePair {
	var pairs []ReplacePair
	for _, item := range strings.Split(raw, ",") {
		parts := strings.SplitN(strings.TrimSpace(item), "/", 2)
		if len(parts) == 2 && parts[0] != "" {
			pairs = append(pairs, ReplacePair{From: parts[0], To: parts[1]})
		}
	}
	return pairs
}

// replaceInsensitive sustituye todas las ocurrencias de from en s de forma
// case-insensitive. Si preserveCase es true, la sustitución adapta las
// mayúsculas del token de destino para que reflejen las del token encontrado.
func replaceInsensitive(s, from, to string, preserveCase bool) string {
	if from == "" {
		return s
	}
	re := regexp.MustCompile(`(?i)` + regexp.QuoteMeta(from))
	return re.ReplaceAllStringFunc(s, func(match string) string {
		if !preserveCase {
			return to
		}
		return matchCase(match, to)
	})
}

// matchCase aplica el patrón de mayúsculas de src a dst.
//
//	"imagen"  → "picture"   (todo minúsculas → todo minúsculas)
//	"Imagen"  → "Picture"   (primera mayúscula → primera mayúscula)
//	"IMAGEN"  → "PICTURE"   (todo mayúsculas  → todo mayúsculas)
//	"iMaGeN"  → "picture"   (mixto            → minúsculas, caso seguro)
func matchCase(src, dst string) string {
	srcRunes := []rune(src)
	dstRunes := []rune(dst)
	if len(srcRunes) == 0 || len(dstRunes) == 0 {
		return dst
	}

	allUpper := true
	allLower := true
	for _, r := range srcRunes {
		if unicode.IsLetter(r) {
			if !unicode.IsUpper(r) {
				allUpper = false
			}
			if !unicode.IsLower(r) {
				allLower = false
			}
		}
	}

	switch {
	case allUpper:
		return strings.ToUpper(dst)
	case allLower:
		return strings.ToLower(dst)
	case unicode.IsUpper(srcRunes[0]):
		// Primera letra mayúscula, resto minúsculas
		out := make([]rune, len(dstRunes))
		for i, r := range dstRunes {
			if i == 0 {
				out[i] = unicode.ToUpper(r)
			} else {
				out[i] = unicode.ToLower(r)
			}
		}
		return string(out)
	default:
		return strings.ToLower(dst)
	}
}

func configurarAyuda() {
	flag.Usage = func() {
		fmt.Print(`
██╗███╗   ███╗ █████╗  ██████╗ ██╗███╗   ██╗ █████╗ ████████╗ ██████╗ ██████╗
██║████╗ ████║██╔══██╗██╔════╝ ██║████╗  ██║██╔══██╗╚══██╔══╝██╔═══██╗██╔══██╗
██║██╔████╔██║███████║██║  ███╗██║██╔██╗ ██║███████║   ██║   ██║   ██║██████╔╝
██║██║╚██╔╝██║██╔══██║██║   ██║██║██║╚██╗██║██╔══██║   ██║   ██║   ██║██╔══██╗
██║██║ ╚═╝ ██║██║  ██║╚██████╔╝██║██║ ╚████║██║  ██║   ██║   ╚██████╔╝██║  ██║
╚═╝╚═╝     ╚═╝╚═╝  ╚═╝ ╚═════╝ ╚═╝╚═╝  ╚═══╝╚═╝  ╚═╝   ╚═╝    ╚═════╝ ╚═╝  ╚═╝

  
 IMAGINATOR VER 2.7                                           
──────────────────────────────────────────────────────────────────────────────
 activething.com/imaginator   ·   dev@activething.com   ·    ©2026 ActiveThing
──────────────────────────────────────────────────────────────────────────────

USAGE
  imaginator -dir <source> -out <dest> { -width N | -height N } [options]
 
REQUIRED
  -dir    string   Source directory
  -out    string   Output directory
 
           At least one of:
  -width  int      Target width   (keeps aspect ratio if -height is omitted)
  -height int      Target height  (keeps aspect ratio if -width is omitted)
 
SUPPORTED FORMATS
  Read     jpg · jpeg · png · tif · tiff · bmp · webp
  Write    jpg · png · tif
           (bmp and webp are read-only — use -format jpg, png or tif to convert)
 
IMAGE OPTIONS
  -quality    int     JPEG quality 1–100                              [85]
  -format     string  Output format: jpg, png, tif                    [keep original]
  -resample   string  Resampling filter: lanczos · cubic · linear · box  [lanczos]
  -b64        string  Encode output as base64; optional value = file extension  [b64]
                        -b64          → saves as nombre.b64
                        -b64 png      → saves as nombre.png (base64 content)
  -ts         string  Write a TypeScript file with all images as base64 data URIs
                        -ts assets.ts → export const images: Record<string,string> = { ... }
                        (-b64 and -ts are mutually exclusive)
 
NAMING OPTIONS
  -prefix     string  Prefix for output filename                      [""]
  -suffix     string  Suffix for output filename (before extension)   [""]
  -lowercase          Normalize output filename to lowercase          [false]
  -uppercase          Normalize output filename to uppercase          [false]
  -nospaces   string  Replace spaces in filename; optional value = replacement char  [_]
                        -nospaces       → "foto de viaje.jpg"  →  "foto_de_viaje.jpg"
                        -nospaces -     → "foto de viaje.jpg"  →  "foto-de-viaje.jpg"
                        -nospaces ""    → "foto de viaje.jpg"  →  "fotodeviaje.jpg"
  -replace    string  Replace token in filename: old/new[,old2/new2]
                        case sensitive:    photo→picture, Photo→Photo
  -replacei   string  Same as -replace but case insensitive
                        photo→picture,    Photo→picture,  PHOTO→picture
  -replacep   string  Same as -replacei but preserves capitalization
                        photo→picture,    Photo→Picture,  PHOTO→PICTURE
 
FILTER OPTIONS
  -filter     string  Glob pattern on filename to select input files  [""]
                        e.g: "photo_*.jpg"  "DSC_????.png"  "*.webp"
 
EXECUTION OPTIONS
  -workers       int  Concurrent workers                              [4]
  -keepstructure      Preserve subdirectory structure                 [false]
  -dry-run            Show what would be processed without running    [false]
  -verbose            Verbose output per image                        [false]
 
EXAMPLES
  # Resize to 800 px wide, preserve aspect ratio
  imaginator -dir ./photos -out ./thumbs -width 800
 
  # Convert everything to JPG 1920×1080 at quality 90
  imaginator -dir ./raw -out ./web -width 1920 -height 1080 -format jpg -quality 90
 
  # 8 workers, preserve folder tree, quality 85
  imaginator -dir ./raw -out ./web -width 1024 -workers 8 -keepstructure -quality 85
 
  # Process in place adding suffix "_800w"
  imaginator -dir ./photos -out ./photos -width 800 -suffix _800w
 
  # Process only files matching a glob
  imaginator -dir ./raw -out ./web -width 1920 -filter "DSC_*.jpg"
 
  # Replace tokens in output filenames (case sensitive)
  imaginator -dir ./raw -out ./web -width 800 -replace "photo/img,picture/pic"
 
  # Replace preserving capitalization
  imaginator -dir ./raw -out ./web -width 800 -replacep "photo/image"
  #   photo_001.jpg → image_001.jpg
  #   Photo_001.jpg → Image_001.jpg
  #   PHOTO_001.jpg → IMAGE_001.jpg
 
  # Encode all output images as base64 files (.b64)
  imaginator -dir ./raw -out ./web -width 800 -b64
 
  # Encode as base64 but keep .png extension
  imaginator -dir ./raw -out ./web -width 800 -format png -b64 png
 
  # Generate a TypeScript file with all images as data URIs
  imaginator -dir ./icons -out ./dist -width 64 -format png -ts src/assets/icons.ts
 
  # Replace spaces in output filenames with underscores
  imaginator -dir ./raw -out ./web -width 800 -nospaces
 
  # Replace spaces with hyphens
  imaginator -dir ./raw -out ./web -width 800 -nospaces -
 
  # Normalize all output filenames to lowercase
  imaginator -dir ./raw -out ./web -width 800 -lowercase
 
  # Normalize mixed batch (jpg+png+webp) all to jpg
  imaginator -dir ./raw -out ./web -width 1920 -format jpg
 
  ─────────────────────────────────────────────────────────────────────────────
  "I do not wish to walk on water." — Hermann Hesse, Siddhartha
  ─────────────────────────────────────────────────────────────────────────────
 
`, version)
	}
}