diff --git a/src/change_commit_date.sh b/src/change_commit_date.sh
index fcb1468..2f574d6 100755
--- a/src/change_commit_date.sh
+++ b/src/change_commit_date.sh
@@ -1,84 +1,317 @@
 #!/usr/bin/env bash
+set -euo pipefail
 
-# Script Name: commit_date_modifier.sh
-# Description: Modifies the date of the latest Git commit to a user-provided date
-# Usage: commit_date_modifier.sh DD-MM-YYYY
-#        The date is in the format day-month-year
-# Example: commit_date_modifier.sh 25-12-2022
+# -----------------------------------------------------------------------------
+# commit_date_tools.sh
+#
+# Powerful Git commit-date tools:
+#   1) amend-latest: set latest commit to a specific date/time
+#   2) shift: shift ALL commits by hours/days
+#   3) move: move ALL commits into day or night hours (randomized within window)
+#
+# Defaults:
+#   - Timezone offset: +0200 (UTC+2)
+#   - Day window:      09-18  (9am..6pm)
+#   - Night window:    20-23,00-05  (8pm..11pm and midnight..5am)
+#
+# Requirements: git, GNU date (Linux 'date' or macOS 'gdate' from coreutils)
+#
+# Examples:
+#   # 1) Set latest commit to specific day (random time) in UTC+2
+#   ./commit_date_tools.sh amend-latest --date 25-12-2022
+#
+#   # 1b) Set latest commit to specific day & time with custom tz
+#   ./commit_date_tools.sh amend-latest --date 25-12-2022 --time 14:30 --tz +0530
+#
+#   # 2) Shift entire history forward 7 hours
+#   ./commit_date_tools.sh shift --hours 7
+#
+#   # 2b) Shift entire history back 2 days and 3 hours, timezone +0200
+#   ./commit_date_tools.sh shift --days -2 --hours -3 --tz +0200
+#
+#   # 3) Move all commits into daytime (random hour in window)
+#   ./commit_date_tools.sh move --to day
+#
+#   # 3b) Move to night hours with custom windows and timezone
+#   ./commit_date_tools.sh move --to night --night-window 21-23,00-04 --tz -0500
+#
+# After rewriting history:
+#   git push --force-with-lease
+# -----------------------------------------------------------------------------
 
-# Function: Returns absolute value of a number
-abs() {
-    echo "${1#-}"
+# ---------- Utilities ----------
+
+# Pick GNU date (Linux: date, macOS: gdate)
+DATE_BIN="$(command -v gdate || command -v date)"
+if ! "$DATE_BIN" -d "@0" +%s >/dev/null 2>&1; then
+  echo "Error: GNU 'date' required. On macOS: brew install coreutils (use gdate)." >&2
+  exit 1
+fi
+
+require_git_repo() {
+  git rev-parse --git-dir >/dev/null 2>&1 || { echo "Not a git repo."; exit 1; }
 }
 
-# Function: Convert the input date into a weekday string
-day_string_converter() {
-    local day=$1
-    local month=$2
-    local year=$3
+# Parse "+HHMM" or "-HHMM" into seconds (supports half-hours like +0530)
+tz_to_seconds() {
+  local tz="$1" sign hh mm secs
+  [[ "$tz" =~ ^[+-][0-9]{4}$ ]] || { echo "Invalid tz offset '$tz' (use +HHMM/-HHMM)"; exit 1; }
+  sign="${tz:0:1}"
+  hh=$((10#${tz:1:2}))
+  mm=$((10#${tz:3:2}))
+  secs=$((hh*3600 + mm*60))
+  if [[ "$sign" == "-" ]]; then secs=$((-secs)); fi
+  echo "$secs"
+}
 
-    # Zeller's Congruence algorithm for calculating the day of the week
-    local a=$(( (14 - month) / 12 ))
-    local y=$(( year - a ))
-    local m=$(( month + (12 * a) - 2 ))
-    local d=$(( (day + y + (y / 4) - (y / 100) + (y / 400) + ((31 * m) / 12)) % 7 ))
+# Random int in [min,max] inclusive
+rand_int() {
+  local min=$1 max=$2
+  echo $(( min + RANDOM % (max - min + 1) ))
+}
 
-    local days=("Sun" "Mon" "Tue" "Wed" "Thu" "Fri" "Sat")
+# Build a space-separated list of allowed hours from a window spec like "09-18" or "20-23,00-05"
+expand_windows_to_hours() {
+  local spec="$1" part start end h hours=()
+  IFS=',' read -ra PARTS <<< "$spec"
+  for part in "${PARTS[@]}"; do
+    [[ "$part" =~ ^([0-1][0-9]|2[0-3])\-([0-1][0-9]|2[0-3])$ ]] \
+      || { echo "Invalid window '$part' (use HH-HH,HH-HH)"; exit 1; }
+    start="${part%-*}"; end="${part#*-}"
+    start=$((10#$start)); end=$((10#$end))
+    if (( start <= end )); then
+      for ((h=start; h<=end; h++)); do hours+=("$h"); done
+    else
+      # Wrap around midnight (e.g., 20-05)
+      for ((h=start; h<=23; h++)); do hours+=("$h"); done
+      for ((h=0; h<=end; h++));   do hours+=("$h"); done
+    fi
+  done
+  echo "${hours[*]}"
+}
 
-    echo "${days[d]}"
+# Turn Y-m-d H:M:S in the *local tz* into epoch seconds:
+ymd_hms_to_epoch_in_tz() {
+  local y="$1" m="$2" d="$3" H="$4" M="$5" S="$6" tz="$7"
+  "$DATE_BIN" -d "${y}-${m}-${d} ${H}:${M}:${S} ${tz}" +%s
 }
 
-# Function: Convert numeric month into a month string
-month_string_converter() {
-    local month_strs=("Jan" "Feb" "Mar" "Apr" "May" "Jun" "Jul" "Aug" "Sep" "Oct" "Nov" "Dec")
+# ---------- Modes ----------
+
+print_help() {
+cat <<'EOF'
+Usage:
+  commit_date_tools.sh <mode> [options]
+
+Modes:
+  amend-latest      Set the latest commit to a specific date/time.
+  shift             Shift ALL commits by hours/days.
+  move              Move ALL commits into day or night hours (randomized).
+
+Common options:
+  --tz <+HHMM|-HHMM>   Timezone offset to use when writing dates (default +0200).
+
+amend-latest options:
+  --date DD-MM-YYYY    Required (e.g., 25-12-2024)
+  --time HH:MM         Optional (random if omitted)
 
-    echo "${month_strs[$1-1]}"
+shift options:
+  --hours N            Integer hours to shift (can be negative)
+  --days N             Integer days to shift   (can be negative)
+
+move options:
+  --to day|night       Required
+  --day-window  HH-HH          Default 09-18
+  --night-window HH-HH,HH-HH   Default 20-23,00-05
+
+Notes:
+  • This rewrites history (all branches & tags). Backup first.
+  • After running: git push --force-with-lease
+EOF
 }
 
-# Function: Generate a random time string in the format HH:MM
-random_time() {
-    printf -v time "%02d:%02d" $((RANDOM % 24)) $((RANDOM % 60))
-    echo "$time"
+# ---------- Argument parsing ----------
+
+MODE="${1:-}"
+[[ -z "${MODE}" ]] && { print_help; exit 1; }
+shift || true
+
+TZ_OFFSET="+0200"
+DATE_DDMMYYYY=""
+TIME_HHMM=""
+SHIFT_HOURS="0"
+SHIFT_DAYS="0"
+MOVE_TO=""
+DAY_WINDOW="09-18"
+NIGHT_WINDOW="20-23,00-05"
+
+while (( "$#" )); do
+  case "$1" in
+    --tz)            TZ_OFFSET="${2:?}"; shift 2;;
+    --date)          DATE_DDMMYYYY="${2:?}"; shift 2;;
+    --time)          TIME_HHMM="${2:?}"; shift 2;;
+    --hours)         SHIFT_HOURS="${2:?}"; shift 2;;
+    --days)          SHIFT_DAYS="${2:?}"; shift 2;;
+    --to)            MOVE_TO="${2:?}"; shift 2;;
+    --day-window)    DAY_WINDOW="${2:?}"; shift 2;;
+    --night-window)  NIGHT_WINDOW="${2:?}"; shift 2;;
+    -h|--help)       print_help; exit 0;;
+    *) echo "Unknown option: $1"; echo; print_help; exit 1;;
+  esac
+done
+
+# ---------- Validations ----------
+
+require_git_repo
+TZ_SECS="$(tz_to_seconds "$TZ_OFFSET")"
+
+# ---------- Implementations ----------
+
+amend_latest() {
+  [[ "$DATE_DDMMYYYY" =~ ^([0-2][0-9]|3[0-1])-([0][1-9]|1[0-2])-[0-9]{4}$ ]] \
+    || { echo "Invalid --date. Use DD-MM-YYYY"; exit 1; }
+  IFS='-' read -r DD MM YYYY <<< "$DATE_DDMMYYYY"
+
+  if [[ -z "$TIME_HHMM" ]]; then
+    HH=$(rand_int 0 23)
+    MMm=$(rand_int 0 59)
+    printf -v TIME_HHMM "%02d:%02d" "$HH" "$MMm"
+  else
+    [[ "$TIME_HHMM" =~ ^([0-1][0-9]|2[0-3]):([0-5][0-9])$ ]] \
+      || { echo "Invalid --time. Use HH:MM"; exit 1; }
+  fi
+
+  HH="${TIME_HHMM%:*}"
+  MI="${TIME_HHMM#*:}"
+  SS="00"
+
+  EPOCH="$("$DATE_BIN" -d "${YYYY}-${MM}-${DD} ${HH}:${MI}:${SS} ${TZ_OFFSET}" +%s)"
+
+  GIT_AUTHOR_DATE="${EPOCH} ${TZ_OFFSET}" \
+  GIT_COMMITTER_DATE="${EPOCH} ${TZ_OFFSET}" \
+    git commit --amend --no-edit
+
+  echo "✓ Amended latest commit date to ${YYYY}-${MM}-${DD} ${HH}:${MI}:${SS} ${TZ_OFFSET}"
 }
 
-# Function: Validate the input date format
-validate_date() {
-    if [[ $1 =~ ^([1-9]|0[1-9]|[12][0-9]|3[01])-(0[1-9]|1[0-2])-([0-9]{4})$ ]]; then
-        IFS='-' read -r day month year <<< "$1"
-        # Check the date validity
-        if ! date -d"$month/$day/$year" >/dev/null 2>&1; then
-            echo "Invalid date: $1"
-            exit 1
-        fi
-    else
-        echo "Incorrect date format: $1. Expected format: DD-MM-YYYY"
-        exit 1
-    fi
+shift_history() {
+  local shift_secs=$(( SHIFT_DAYS*86400 + SHIFT_HOURS*3600 ))
+  echo "Shifting ALL commits by ${SHIFT_DAYS} day(s) and ${SHIFT_HOURS} hour(s) [${shift_secs}s]; tz=${TZ_OFFSET}"
+  if [[ "$shift_secs" -eq 0 ]]; then
+    echo "Nothing to do (shift is zero)."; exit 0
+  fi
+
+  git filter-branch -f --tag-name-filter cat --env-filter "
+    shift_secs=${shift_secs}
+    tz='${TZ_OFFSET}'
+    to_epoch() { $DATE_BIN -d \"\$1\" +%s; }
+
+    a_ep=\$(to_epoch \"\$GIT_AUTHOR_DATE\");     c_ep=\$(to_epoch \"\$GIT_COMMITTER_DATE\")
+    a_new=\$((a_ep + shift_secs));               c_new=\$((c_ep + shift_secs))
+    export GIT_AUTHOR_DATE=\"\$a_new \$tz\"
+    export GIT_COMMITTER_DATE=\"\$c_new \$tz\"
+  " -- --branches --tags >/dev/null
+  echo "✓ Done. Remember to: git push --force-with-lease"
 }
 
-# Function: Main function to control the script flow
-main() {
-    if [ $# -ne 1 ]; then
-        echo "Error: No arguments provided."
-        echo "Usage: commit_date_modifier.sh DD-MM-YYYY"
-        echo "       The date is in the format day-month-year."
-        echo "Example: commit_date_modifier.sh 25-12-2022"
-        exit 1
-    fi
+move_history() {
+  local target="$1"
+
+  local hours_list=""
+  if [[ "$target" == "day" ]]; then
+    hours_list="$(expand_windows_to_hours "$DAY_WINDOW")"
+    echo "Moving ALL commits into DAY hours [${DAY_WINDOW}] in tz=${TZ_OFFSET}"
+  else
+    hours_list="$(expand_windows_to_hours "$NIGHT_WINDOW")"
+    echo "Moving ALL commits into NIGHT hours [${NIGHT_WINDOW}] in tz=${TZ_OFFSET}"
+  fi
+
+  # Pack the hours list into a bash array initializer string
+  local hours_csv="${hours_list// /,}"
+
+  git filter-branch -f --tag-name-filter cat --env-filter "
+    tz='${TZ_OFFSET}'
+    tz_secs=$(tz_to_seconds "${TZ_OFFSET}")
+  " -- --branches --tags >/dev/null 2>&1 && true
+
+  # We need the tz_to_seconds helper inside the filter; inject it plus logic:
+  git filter-branch -f --tag-name-filter cat --env-filter "
+    tz='${TZ_OFFSET}'
+    tz_to_seconds() {
+      local tz=\"\$1\" sign hh mm secs
+      [[ \"\$tz\" =~ ^[+-][0-9]{4}\$ ]] || { echo 'bad tz' >&2; exit 1; }
+      sign=\"\${tz:0:1}\"; hh=\$((10#\${tz:1:2})); mm=\$((10#\${tz:3:2}))
+      secs=\$((hh*3600 + mm*60)); [[ \"\$sign\" == '-' ]] && secs=\$((-secs))
+      echo \"\$secs\"
+    }
+
+    tz_secs=\$(tz_to_seconds \"\$tz\")
+    to_epoch() { $DATE_BIN -d \"\$1\" +%s; }
+    from_local_YmdHMS_to_epoch() { # args: Y M D H M S, interpret as LOCAL (tz offset), return UTC epoch
+      local Y=\"\$1\" Mo=\"\$2\" D=\"\$3\" H=\"\$4\" Mi=\"\$5\" S=\"\$6\"
+      $DATE_BIN -d \"\${Y}-\${Mo}-\${D} \${H}:\${Mi}:\${S} UTC\" +%s
+    }
+
+    # Pick a random allowed hour (uniform)
+    pick_hour() {
+      local IFS=','; local raw='${hours_csv}'
+      read -ra H <<< \"\$raw\"
+      local count=\${#H[@]}
+      local idx=\$((RANDOM % count))
+      echo \${H[\$idx]}
+    }
+
+    # For each commit:
+    a_ep=\$(to_epoch \"\$GIT_AUTHOR_DATE\")
+    c_ep=\$(to_epoch \"\$GIT_COMMITTER_DATE\")
+
+    # Convert to 'local' by applying tz offset (so windows are in given tz)
+    a_local=\$((a_ep + tz_secs))
+    c_local=\$((c_ep + tz_secs))
+
+    # Extract local Y-m-d; choose random HH:MM:SS in allowed window
+    Y=\$($DATE_BIN -u -d @\$a_local +%Y)
+    Mo=\$($DATE_BIN -u -d @\$a_local +%m)
+    D=\$($DATE_BIN -u -d @\$a_local +%d)
+
+    H=\$(pick_hour)
+    Mi=\$((RANDOM % 60))
+    S=\$((RANDOM % 60))
+
+    new_local_epoch=\$($DATE_BIN -u -d \"\${Y}-\${Mo}-\${D} \${H}:\${Mi}:\${S}\" +%s)
+    a_new=\$((new_local_epoch - tz_secs))
+
+    # Mirror author -> committer with same new time on that commit's day
+    Yc=\$($DATE_BIN -u -d @\$c_local +%Y)
+    Moc=\$($DATE_BIN -u -d @\$c_local +%m)
+    Dc=\$($DATE_BIN -u -d @\$c_local +%d)
+    new_local_epoch_c=\$($DATE_BIN -u -d \"\${Yc}-\${Moc}-\${Dc} \${H}:\${Mi}:\${S}\" +%s)
+    c_new=\$((new_local_epoch_c - tz_secs))
+
+    export GIT_AUTHOR_DATE=\"\$a_new \$tz\"
+    export GIT_COMMITTER_DATE=\"\$c_new \$tz\"
+  " -- --branches --tags >/dev/null
 
-    local date="$1"
-    validate_date "$date"
-    IFS='-' read -r day month year <<< "$date"
-    local day_string
-    local month_string
-    local time_string
-    day_string=$(day_string_converter "$day" "$month" "$year")
-    month_string=$(month_string_converter "$month")
-    time_string=$(random_time)
-
-    GIT_COMMITTER_DATE="$day_string $month_string $day $time_string $year +0100" git commit --amend --no-edit --date "$day_string $month_string $day $time_string $year +0100"
-    echo "Commit date modified to $day_string $month_string $day $time_string $year"
+  echo "✓ Done. Remember to: git push --force-with-lease"
 }
 
-main "$@"
+# ---------- Dispatch ----------
 
+case "$MODE" in
+  amend-latest)
+    [[ -n "$DATE_DDMMYYYY" ]] || { echo "amend-latest requires --date DD-MM-YYYY"; exit 1; }
+    amend_latest
+    ;;
+  shift)
+    shift_history
+    ;;
+  move)
+    [[ "$MOVE_TO" =~ ^(day|night)$ ]] || { echo "move requires --to day|night"; exit 1; }
+    move_history "$MOVE_TO"
+    ;;
+  *)
+    echo "Unknown mode: $MODE"
+    print_help
+    exit 1
+    ;;
+esac