#!/usr/bin/env bash
# larry-rollback.sh — restore files modified by Larry-Anywhere from journal backups.
#
# Usage:
#   larry-rollback.sh --list                      # show every journal entry, newest first
#   larry-rollback.sh --list --session SESSION    # show entries for one session
#   larry-rollback.sh --session SESSION           # roll back ALL entries in a session (newest first)
#   larry-rollback.sh --last N                    # roll back the N most recent entries
#   larry-rollback.sh --entry ENTRY_ID            # roll back one specific entry (e.g. 2026-05-26-.../004)
#   larry-rollback.sh --target /path/to/file      # roll back all entries that touched this file (newest first)
#   larry-rollback.sh --dry-run                   # show what would be rolled back without doing it
#
# Y/N confirm on every restoration unless --yes is passed.
set -u
set -o pipefail

LARRY_HOME="${LARRY_HOME:-$HOME/.larry}"
JOURNAL_ROOT="$LARRY_HOME/journal"
JOURNAL_INDEX="$JOURNAL_ROOT/index.tsv"

DRY=0
YES=0
MODE=""
SESSION=""
N=""
ENTRY_ID=""
TARGET=""

while [ $# -gt 0 ]; do
  case "$1" in
    --list)      MODE="list" ;;
    --session)   shift; SESSION="$1"; [ -z "$MODE" ] && MODE="session" ;;
    --last)      shift; N="$1"; MODE="last" ;;
    --entry)     shift; ENTRY_ID="$1"; MODE="entry" ;;
    --target)    shift; TARGET="$1"; MODE="target" ;;
    --dry-run)   DRY=1 ;;
    --yes|-y)    YES=1 ;;
    -h|--help)   sed -n '2,16p' "$0"; exit 0 ;;
    *)           echo "unknown arg: $1" >&2; exit 2 ;;
  esac
  shift
done

[ -f "$JOURNAL_INDEX" ] || { echo "no journal (no writes have been made yet)" >&2; exit 1; }

C_BOLD=$'\033[1m'; C_DIM=$'\033[2m'; C_RESET=$'\033[0m'
C_RED=$'\033[31m'; C_GREEN=$'\033[32m'

_list_filter() {
  local ses="$1"
  awk -F'\t' -v s="$ses" '
    NR==1 { next }
    s=="" || $2==s { print }
  ' "$JOURNAL_INDEX" | tail -r 2>/dev/null || awk -F'\t' -v s="$ses" '
    NR==1 { next }
    s=="" || $2==s { print }
  ' "$JOURNAL_INDEX" | awk '{a[NR]=$0} END{for(i=NR;i>=1;i--) print a[i]}'
}

if [ "$MODE" = "list" ]; then
  printf '%stimestamp                  session-id                   seq  target%s\n' "$C_BOLD" "$C_RESET"
  _list_filter "$SESSION" | awk -F'\t' '{printf "  %-26s %-28s %-4s %s\n", $1, $2, $3, $4}'
  exit 0
fi

build_targets() {
  case "$MODE" in
    session)
      [ -n "$SESSION" ] || { echo "--session needs a value" >&2; exit 2; }
      _list_filter "$SESSION"
      ;;
    last)
      [ -n "$N" ] || { echo "--last needs N" >&2; exit 2; }
      _list_filter "" | head -n "$N"
      ;;
    entry)
      local ses seq
      ses="${ENTRY_ID%/*}"; seq="${ENTRY_ID##*/}"; seq="${seq%%_*}"
      awk -F'\t' -v s="$ses" -v sq="$seq" '$2==s && $3==sq' "$JOURNAL_INDEX"
      ;;
    target)
      awk -F'\t' -v t="$TARGET" '$4==t' "$JOURNAL_INDEX" | awk '{a[NR]=$0} END{for(i=NR;i>=1;i--) print a[i]}'
      ;;
    *)
      echo "specify --list, --session, --last N, --entry ID, or --target PATH" >&2
      exit 2
      ;;
  esac
}

ENTRIES=$(build_targets)
[ -n "$ENTRIES" ] || { echo "(no matching journal entries)"; exit 0; }

printf '%sWill roll back %s entr(y/ies):%s\n' "$C_BOLD" "$(printf '%s\n' "$ENTRIES" | wc -l | tr -d ' ')" "$C_RESET"
printf '%s' "$ENTRIES" | awk -F'\t' '{printf "  %s  %-26s %s\n", $3, $1, $4}'
echo ""

if [ "$DRY" = "1" ]; then
  echo "(dry-run; no changes)"
  exit 0
fi

if [ "$YES" != "1" ]; then
  printf '%sProceed?%s [y/N]: ' "$C_BOLD" "$C_RESET"
  read -r ans </dev/tty || ans=""
  [[ "$ans" =~ ^[Yy]$ ]] || { echo "aborted"; exit 1; }
fi

printf '%s\n' "$ENTRIES" | while IFS=$'\t' read -r ts ses seq target action orig_sha new_sha backup diffp; do
  [ -z "$target" ] && continue
  if [ "$action" = "create" ]; then
    if [ -e "$target" ]; then
      cp -p "$target" "$target.larry-prerollback.$(date +%s)"
      rm -f "$target" && printf '  %s✓ deleted%s %s (was newly created)\n' "$C_GREEN" "$C_RESET" "$target"
    else
      printf '  %s○ already absent%s %s\n' "$C_DIM" "$C_RESET" "$target"
    fi
  else
    if [ -f "$backup" ]; then
      cp -p "$target" "$target.larry-prerollback.$(date +%s)" 2>/dev/null || true
      cp -p "$backup" "$target" && printf '  %s✓ restored%s %s ← %s\n' "$C_GREEN" "$C_RESET" "$target" "$backup"
    else
      printf '  %s✗ backup missing for%s %s (looked at %s)\n' "$C_RED" "$C_RESET" "$target" "$backup"
    fi
  fi
done

echo ""
echo "Pre-rollback copies left at <target>.larry-prerollback.<ts> in case you want to redo. Clean up at your leisure."