#!/usr/bin/env bash
set -euo pipefail

# remove_text.sh — conceal on-screen text in a rectangular area for a chosen time window.
# Requires: ffmpeg (with delogo filter)

show_help() {
  cat <<'EOF'
Usage:
  remove_text.sh -i INPUT -o OUTPUT --x X --y Y --w W --h H [--start SEC] [--end SEC] [--feather PX] [--preview] [--dry-run]

Params:
  -i, --input     Input video file
  -o, --output    Output video file
      --x         Left coordinate of the box (pixels)
      --y         Top coordinate of the box (pixels)
      --w         Box width (pixels)
      --h         Box height (pixels)
      --start     Start time in seconds (e.g. 12 or 12.5). If omitted, applies from t=0.
      --end       End time in seconds (exclusive). If omitted, applies to end of video.
      --feather   Feather thickness for delogo (default: 8). Higher = softer edge.
      --preview   Instead of removing, draw a red box to help align the area.
      --dry-run   Print the ffmpeg command but don't execute it.
  -h, --help      Show this help

Examples:
  Preview the area (draws box only):
    remove_text.sh -i in.mp4 -o preview.mp4 --x 120 --y 940 --w 680 --h 60 --start 12.5 --end 28.3 --preview

  Remove text in that area/time range:
    remove_text.sh -i in.mp4 -o out.mp4    --x 120 --y 940 --w 680 --h 60 --start 12.5 --end 28.3
EOF
}

# ---- defaults ----
INPUT=""
OUTPUT=""
X=""
Y=""
W=""
H=""
START=""
END=""
FEATHER="8"
PREVIEW="0"
DRYRUN="0"

# ---- parse args ----
if [[ $# -eq 0 ]]; then show_help; exit 1; fi

while [[ $# -gt 0 ]]; do
  case "$1" in
    -i|--input)   INPUT="${2:-}"; shift 2;;
    -o|--output)  OUTPUT="${2:-}"; shift 2;;
    --x)          X="${2:-}"; shift 2;;
    --y)          Y="${2:-}"; shift 2;;
    --w)          W="${2:-}"; shift 2;;
    --h)          H="${2:-}"; shift 2;;
    --start)      START="${2:-}"; shift 2;;
    --end)        END="${2:-}"; shift 2;;
    --feather)    FEATHER="${2:-}"; shift 2;;
    --preview)    PREVIEW="1"; shift;;
    --dry-run)    DRYRUN="1"; shift;;
    -h|--help)    show_help; exit 0;;
    *) echo "Unknown argument: $1"; echo; show_help; exit 1;;
  esac
done

# ---- validation ----
if [[ -z "$INPUT" || -z "$OUTPUT" || -z "$X" || -z "$Y" || -z "$W" || -z "$H" ]]; then
  echo "Error: Missing required arguments."; echo
  show_help; exit 1
fi

if ! command -v ffmpeg >/dev/null 2>&1; then
  echo "Error: ffmpeg not found in PATH."; exit 1
fi

# Build enable expression based on start/end
ENABLE_EXPR=""
if [[ -n "$START" && -n "$END" ]]; then
  ENABLE_EXPR="between(t\,${START}\,${END})"
elif [[ -n "$START" ]]; then
  ENABLE_EXPR="gte(t\,${START})"
elif [[ -n "$END" ]]; then
  ENABLE_EXPR="lte(t\,${END})"
else
  ENABLE_EXPR=""  # apply for whole video
fi

# Build filter chain
if [[ "$PREVIEW" == "1" ]]; then
  if [[ -n "$ENABLE_EXPR" ]]; then
    VFILTER="drawbox=x=${X}:y=${Y}:w=${W}:h=${H}:color=red@0.5:thickness=2:enable='${ENABLE_EXPR}'"
  else
    VFILTER="drawbox=x=${X}:y=${Y}:w=${W}:h=${H}:color=red@0.5:thickness=2"
  fi
else
  # delogo: x, y, w, h, t = feather thickness; show=0 (no outline)
  # delogo: x, y, w, h, band = feather thickness; show=0 (no outline)
  if [[ -n "$ENABLE_EXPR" ]]; then
    VFILTER="delogo=x=${X}:y=${Y}:w=${W}:h=${H}:show=0:enable='${ENABLE_EXPR}'"
  else
    VFILTER="delogo=x=${X}:y=${Y}:w=${W}:h=${H}:show=0"
  fi

fi

# Assemble ffmpeg command
# -c:v libx264 -crf 18: quality/size balance; adjust as needed
# -preset medium: speed/efficiency tradeoff
# -c:a copy: keep original audio
CMD=(ffmpeg -hide_banner -y -i "$INPUT" -vf "$VFILTER" -c:v libx264 -crf 18 -preset medium -c:a copy "$OUTPUT")

echo "Running:"
printf ' %q' "${CMD[@]}"; echo

if [[ "$DRYRUN" == "1" ]]; then
  exit 0
fi

"${CMD[@]}"

echo "Done: $OUTPUT"