#!/usr/bin/env bash
# svn_git_sync — sync current SVN working copy into a Git mirror
# Usage:
#   svn_git_sync init [mirror_name]

set -euo pipefail

show_usage() {
  echo "Usage: $0 init [mirror_name]" >&2
  exit 1
}

subcommand="${1:-}"
[[ -n "$subcommand" ]] || show_usage
shift

case "$subcommand" in
  init)
    ;;
  -h|--help|help)
    show_usage
    ;;
  *)
    echo "Unknown command: $subcommand" >&2
    show_usage
    ;;
esac

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=""
if total=$(svn list -R . 2>/dev/null | wc -l || true); then
  total_items="$total"
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 . "$DEST" &
export_pid=$!

last_reported=-1
while kill -0 "$export_pid" 2>/dev/null; do
  if [[ -d "$DEST" ]]; then
    current=$(find "$DEST" -mindepth 1 -print | wc -l)
  else
    current=0
  fi

  if [[ "$current" -ne "$last_reported" ]]; then
    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" "$elapsed_val" "$current" "$pct"
    last_reported="$current"
  fi

  sleep 1
done

wait "$export_pid"

final_count=$(find "$DEST" -mindepth 1 -print | wc -l 2>/dev/null || echo 0)
printf "[%ss] Exported %d items (done)\n" "$(elapsed)" "$final_count"

cd "$DEST"

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

# Seed ignores for common noise (pyc/cache)
if [[ ! -e .gitignore ]]; then
  echo "[$(elapsed) s] Adding default ignores (.pyc/__pycache__)..."
  printf "*.pyc\n__pycache__/\n" > .gitignore
fi

echo "[$(elapsed) s] Staging files..."
git add -A

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 -- .