Improve svn_git_init progress and mirror setup

svn_interact/svn_git_init

@@ -1,10 +1,17 @@
 # From inside the SVN subdir you want to extract:
 set -euo pipefail
 
-DEST="${1:-trunk-git}"
+SRC_DIR="$(pwd)"
+MIRROR_ROOT="${GIT_SVN_MIRROR_ROOT:-$HOME/git_svn_mirror}"
+
+# Derive a collision-resistant mirror name from the full path (unless overridden).
+raw_name="${1:-$(pwd -P)}"
+BASE_NAME="$(printf "%s" "$raw_name" | sed 's#^[\\/]*##; s#[\\/]#_#g')"
+DEST="${MIRROR_ROOT}/${BASE_NAME}"
 
 echo "Exporting SVN working copy to $DEST (versioned files only)..."
 rm -rf -- "$DEST"
+mkdir -p "$MIRROR_ROOT"
 
 # Optionally compute total items upfront for a rough percentage
 total_items=""
@@ -13,6 +20,11 @@ if total=$(svn list -R . 2>/dev/null | wc -l || true); then
 fi
 
 start_ts="$(date +%s.%N)"
+elapsed() {
+  local now
+  now="${1:-$(date +%s.%N)}"
+  awk -v s="$start_ts" -v n="$now" 'BEGIN{split(s,sa,".");split(n,na,".");printf "%.1f", (na[1]-sa[1]) + (na[2]-sa[2])/1e9}'
+}
 
 # Run export in background so we can emit our own progress based on files created.
 svn export --quiet . "$DEST" &
@@ -28,13 +40,12 @@ while kill -0 "$export_pid" 2>/dev/null; do
 
   # Only log when count changes to reduce noise.
   if [[ "$current" -ne "$last_reported" ]]; then
-    now="$(date +%s.%N)"
-    elapsed=$(awk -v s="$start_ts" -v n="$now" 'BEGIN{split(s,sa,".");split(n,na,".");printf "%.1f", (na[1]-sa[1]) + (na[2]-sa[2])/1e9}')
+    elapsed_val="$(elapsed)"
     pct=""
     if [[ -n "$total_items" && "$total_items" -gt 0 ]]; then
       pct=$(awk -v c="$current" -v t="$total_items" 'BEGIN{printf(" (%.1f%%)", (c*100)/t)}')
     fi
-    printf "[%ss] Exported %d items%s\n" "$elapsed" "$current" "$pct"
+    printf "[%ss] Exported %d items%s\n" "$elapsed_val" "$current" "$pct"
     last_reported="$current"
   fi
 
@@ -44,12 +55,34 @@ done
 wait "$export_pid"
 
 final_count=$(find "$DEST" -mindepth 1 -print | wc -l 2>/dev/null || echo 0)
-end_now="$(date +%s.%N)"
-end_elapsed=$(awk -v s="$start_ts" -v n="$end_now" 'BEGIN{split(s,sa,".");split(n,na,".");printf "%.1f", (na[1]-sa[1]) + (na[2]-sa[2])/1e9}')
-printf "[%ss] Exported %d items (done)\n" "$end_elapsed" "$final_count"
+printf "[%ss] Exported %d items (done)\n" "$(elapsed)" "$final_count"
 
 cd "$DEST"
-git init
+
+echo "[$(elapsed) s] Initializing git repository..."
+GIT_QUIET=1 git init >/dev/null
 git config init.defaultBranch trunk || true
+git config core.fileMode false || true
+git config core.autocrlf true || true
+git config core.safecrlf false || true
+
+echo "[$(elapsed) s] Staging files..."
 git add -A
-git commit -m "Import SVN snapshot" || true
+
+echo "[$(elapsed) s] Creating initial commit..."
+GIT_QUIET=1 git commit -q -m "Import SVN snapshot" || true
+
+# Reuse the repo for the source working tree by linking .git back to the new repo.
+echo "[$(elapsed) s] Linking git metadata to source working tree..."
+DEST_ABS="$(pwd -P)"
+cd "$SRC_DIR"
+if [[ -e .git || -L .git ]]; then
+  echo "[$(elapsed)s] Replacing existing .git in $SRC_DIR..."
+  rm -rf -- .git
+fi
+printf "gitdir: %s/.git\n" "$DEST_ABS" > .git
+echo "[$(elapsed)s] Linked .git to $DEST_ABS/.git"
+
+# Normalize working tree to match repo filters (e.g., CRLF handling).
+echo "[$(elapsed) s] Syncing working tree to repo content..."
+GIT_QUIET=1 git checkout -q -- .