Refactor some utils.go; add another tool 'tiledump'

cmd/tiledump/main.go

@@ -0,0 +1,62 @@
+// Command tiledump reads a CT log tile file and dumps all entries.
+// (C) Copyright 2026 Pim van Pelt <pim@ipng.ch>
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"ctfetch/internal/utils"
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Fprintf(os.Stderr, "Usage: %s <tile-file-or-url>\n", os.Args[0])
+		fmt.Fprintf(os.Stderr, "Examples:\n")
+		fmt.Fprintf(os.Stderr, "  %s tile.data\n", os.Args[0])
+		fmt.Fprintf(os.Stderr, "  %s https://halloumi2026h1.mon.ct.ipng.ch/tile/data/x002/x460/135\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	arg := os.Args[1]
+
+	var tileData []byte
+	var err error
+
+	// Check if argument is a URL
+	if strings.HasPrefix(arg, "http://") || strings.HasPrefix(arg, "https://") {
+		// Fetch from URL
+		fmt.Fprintf(os.Stderr, "Fetching: %s\n", arg)
+		tileData, err = utils.FetchURL(arg)
+		if err != nil {
+			fatal("failed to fetch URL: %v", err)
+		}
+		fmt.Fprintf(os.Stderr, "Fetched %d bytes\n", len(tileData))
+	} else {
+		// Read from file
+		tileData, err = os.ReadFile(arg)
+		if err != nil {
+			fatal("failed to read file: %v", err)
+		}
+		fmt.Fprintf(os.Stderr, "Read %d bytes from %s\n", len(tileData), arg)
+	}
+
+	// Decompress if needed
+	tileData, err = utils.Decompress(tileData)
+	if err != nil {
+		fatal("failed to decompress tile: %v", err)
+	}
+
+	fmt.Fprintf(os.Stderr, "Tile size: %d bytes\n\n", len(tileData))
+
+	// Dump all entries
+	if err := utils.DumpAllEntries(tileData); err != nil {
+		fatal("%v", err)
+	}
+}
+
+func fatal(format string, args ...any) {
+	fmt.Fprintf(os.Stderr, "Error: "+format+"\n", args...)
+	os.Exit(1)
+}