assets builder tools (#39)

Reviewed-on: #39
Reviewed-by: xtul <mpiasecki720@protonmail.com>

internal/assets/dupes.go

@@ -0,0 +1,151 @@
+package assets
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+)
+
+// allFiles returns every regular file under root (recursive).
+func allFiles(root string) ([]string, error) {
+	var out []string
+	err := filepath.WalkDir(root, func(p string, d os.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if !d.IsDir() {
+			out = append(out, p)
+		}
+		return nil
+	})
+	sort.Strings(out)
+	return out, err
+}
+
+// runCheckDupes reports files whose lower-cased basename collides across the
+// given dirs. Read-only. Exit exitFail if any collision is found.
+func runCheckDupes(args []string, stdout, stderr io.Writer) int {
+	fs := flag.NewFlagSet("check-dupes", flag.ContinueOnError)
+	fs.SetOutput(stderr)
+	if err := fs.Parse(args); err != nil {
+		return exitUsage
+	}
+	dirs := fs.Args()
+	if len(dirs) == 0 {
+		fmt.Fprintln(stderr, "assets check-dupes: usage: check-dupes <dir>...")
+		return exitUsage
+	}
+
+	first := map[string]string{}
+	fail := false
+	for _, dir := range dirs {
+		if fi, err := os.Stat(dir); err != nil || !fi.IsDir() {
+			fmt.Fprintf(stderr, "assets check-dupes: no such dir: %s\n", dir)
+			return exitUsage
+		}
+		files, err := allFiles(dir)
+		if err != nil {
+			fmt.Fprintln(stderr, "assets check-dupes:", err)
+			return exitTool
+		}
+		for _, f := range files {
+			key := strings.ToLower(filepath.Base(f))
+			if prev, ok := first[key]; ok {
+				fmt.Fprintf(stderr, "runtime-name collision: %s collides with %s\n", f, prev)
+				fail = true
+			} else {
+				first[key] = f
+			}
+		}
+	}
+	if fail {
+		fmt.Fprintln(stderr, "check-dupes: found runtime-name collision(s)")
+		return exitFail
+	}
+	fmt.Fprintln(stdout, "check-dupes: OK")
+	return exitOK
+}
+
+// runCleanDupes deletes files from <clean> whose lower-cased basename collides
+// with any file in <primary>. Mutates only <clean>. Refuses to run if the two
+// trees overlap.
+func runCleanDupes(args []string, stdout, stderr io.Writer) int {
+	fs := flag.NewFlagSet("clean-dupes", flag.ContinueOnError)
+	fs.SetOutput(stderr)
+	dryRun := fs.Bool("dry-run", false, "report deletions without removing")
+	if err := fs.Parse(args); err != nil {
+		return exitUsage
+	}
+	pos := fs.Args()
+	if len(pos) != 2 {
+		fmt.Fprintln(stderr, "assets clean-dupes: usage: clean-dupes [--dry-run] <primary> <clean>")
+		return exitUsage
+	}
+	primary, clean := pos[0], pos[1]
+	for _, d := range []string{primary, clean} {
+		if fi, err := os.Stat(d); err != nil || !fi.IsDir() {
+			fmt.Fprintf(stderr, "assets clean-dupes: no such dir: %s\n", d)
+			return exitUsage
+		}
+	}
+	primaryReal, err1 := filepath.EvalSymlinks(primary)
+	cleanReal, err2 := filepath.EvalSymlinks(clean)
+	if err1 != nil || err2 != nil {
+		fmt.Fprintln(stderr, "assets clean-dupes: cannot resolve dirs")
+		return exitTool
+	}
+	if overlaps(primaryReal, cleanReal) {
+		fmt.Fprintln(stderr, "assets clean-dupes: primary and clean dirs must not overlap")
+		return exitUsage
+	}
+
+	primaryFiles, err := allFiles(primary)
+	if err != nil {
+		fmt.Fprintln(stderr, "assets clean-dupes:", err)
+		return exitTool
+	}
+	names := map[string]bool{}
+	for _, f := range primaryFiles {
+		names[strings.ToLower(filepath.Base(f))] = true
+	}
+
+	cleanFiles, err := allFiles(clean)
+	if err != nil {
+		fmt.Fprintln(stderr, "assets clean-dupes:", err)
+		return exitTool
+	}
+	removed := 0
+	for _, f := range cleanFiles {
+		if !names[strings.ToLower(filepath.Base(f))] {
+			continue
+		}
+		if *dryRun {
+			fmt.Fprintf(stderr, "would delete clean-tree collision: %s\n", f)
+		} else {
+			if err := os.Remove(f); err != nil {
+				fmt.Fprintln(stderr, "assets clean-dupes:", err)
+				return exitTool
+			}
+			fmt.Fprintf(stderr, "deleted clean-tree collision: %s\n", f)
+		}
+		removed++
+	}
+	verb := "removed"
+	if *dryRun {
+		verb = "would remove"
+	}
+	fmt.Fprintf(stdout, "clean-dupes: %s %d file(s)\n", verb, removed)
+	return exitOK
+}
+
+// overlaps reports whether either directory contains the other (or they are
+// equal), using cleaned absolute-ish paths with a trailing separator.
+func overlaps(a, b string) bool {
+	as := a + string(filepath.Separator)
+	bs := b + string(filepath.Separator)
+	return strings.HasPrefix(as, bs) || strings.HasPrefix(bs, as)
+}