path: root/radarFetch.sh

#!/bin/bashset -euo pipefailshopt -s nullglob# SJP 2026-06-09# Fetch BOM radar layers via anonymous FTP, alpha-composite them,# publish the last FRAME_COUNT frames as an APNG loop.# Parameterised on product code; default IDR713 (Sydney 128 km).# Deployed to /opt/radar/radarFetch.sh on cremonde for radar.pestrel.com.RADAR_ID="${1:-IDR713}"FRAME_COUNT="${FRAME_COUNT:-6}"FRAME_DELAY="${FRAME_DELAY:-50}"           # centiseconds per frameEND_PAUSE="${END_PAUSE:-150}"              # centiseconds, pause on last frameTRANSPARENCY_TTL_HOURS="${TRANSPARENCY_TTL_HOURS:-24}"DATA_ROOT="/var/lib/radar/${RADAR_ID,,}"TRANS_DIR="${DATA_ROOT}/transparencies"FRAMES_DIR="${DATA_ROOT}/frames"PLATES_DIR="${DATA_ROOT}/plates"OUT_DIR="${DATA_ROOT}/out"PUBLISH_DIR="/srv/www/radar"PUBLISH_PATH="${PUBLISH_DIR}/${RADAR_ID,,}-loop.apng"FTP_DYNAMIC="ftp://ftp.bom.gov.au/anon/gen/radar/"FTP_STATIC="ftp://ftp.bom.gov.au/anon/gen/radar_transparencies/"require_cmd() {    command -v "$1" >/dev/null 2>&1 || { echo "Required command not found: $1" >&2; exit 127; }}require_cmd curlrequire_cmd magickrequire_cmd ffmpegmkdir -p "$TRANS_DIR" "$FRAMES_DIR" "$PLATES_DIR" "$OUT_DIR"fetch_validated() {    # $1 url  $2 dest    local url="$1" dest="$2" tmp="${2}.tmp"    curl -q -fs -o "$tmp" "$url" || { rm -f "$tmp"; return 1; }    if magick identify "$tmp" >/dev/null 2>&1; then        mv "$tmp" "$dest"    else        rm -f "$tmp"        return 1    fi}# --- 1. Refresh transparencies if stale ----------------------------------TRANS_MARKER="${TRANS_DIR}/.last_refreshed"needs_refresh=1if [ -f "$TRANS_MARKER" ]; then    age_h=$(( ( $(date +%s) - $(stat -c %Y "$TRANS_MARKER") ) / 3600 ))    [ "$age_h" -lt "$TRANSPARENCY_TTL_HOURS" ] && needs_refresh=0fiif [ "$needs_refresh" -eq 1 ]; then    echo "Refreshing transparencies for ${RADAR_ID}..."    if listing=$(curl -q -fs "$FTP_STATIC"); then        # ls -l style listing; filename is the last whitespace-delimited field        while read -r fname; do            [ -n "$fname" ] || continue            fetch_validated "${FTP_STATIC}${fname}" "${TRANS_DIR}/${fname}" \                || echo "  failed: ${fname}" >&2        done < <(echo "$listing" | awk '{print $NF}' | grep "^${RADAR_ID}\." || true)        touch "$TRANS_MARKER"        # invalidate precomposited plates        rm -f "${PLATES_DIR}/lower.png" "${PLATES_DIR}/upper.png"    else        echo "Transparency listing failed; keeping cached copies." >&2    fifi# --- 2. Build precomposited plates ---------------------------------------BACKGROUND="${TRANS_DIR}/${RADAR_ID}.background.png"if [ ! -f "$BACKGROUND" ]; then    echo "No background transparency cached; cannot composite." >&2    exit 1fiexisting_layers() {    # echo paths that exist, in given order    local base p    for base in "$@"; do        p="${TRANS_DIR}/${RADAR_ID}.${base}.png"        [ -f "$p" ] && echo "$p"    done}if [ ! -f "${PLATES_DIR}/lower.png" ]; then    # background (opaque) + topography + optional feature overlays under the echo    readarray -t lower_layers < <(existing_layers \        background topography catchments waterways wthrDistricts roads rail)    magick "${lower_layers[@]}" -background none -layers flatten "${PLATES_DIR}/lower.png"fiif [ ! -f "${PLATES_DIR}/upper.png" ]; then    # range rings + place labels go over the echo so they stay legible    readarray -t upper_layers < <(existing_layers range locations)    if [ "${#upper_layers[@]}" -gt 0 ]; then        magick "${upper_layers[@]}" -background none -layers flatten "${PLATES_DIR}/upper.png"    fifi# --- 3. Determine current top-N frames on the FTP ------------------------echo "Listing dynamic frames..."if ! listing=$(curl -q -fs "$FTP_DYNAMIC"); then    echo "Dynamic listing failed; serving last good loop." >&2    exit 0fimapfile -t remote_frames < <(echo "$listing" \    | awk '{print $NF}' \    | grep "^${RADAR_ID}\.T\.[0-9]\{12\}\.png$" \    | sort \    | tail -n "$FRAME_COUNT")if [ "${#remote_frames[@]}" -eq 0 ]; then    echo "No remote frames for ${RADAR_ID}; serving last good loop." >&2    exit 0fi# --- 4. Fetch missing frames; evict frames outside the rolling buffer ----for fname in "${remote_frames[@]}"; do    if [ ! -f "${FRAMES_DIR}/${fname}" ]; then        echo "  fetching ${fname}"        fetch_validated "${FTP_DYNAMIC}${fname}" "${FRAMES_DIR}/${fname}" \            || echo "  failed: ${fname}" >&2    fidonekeep_set=" $(printf '%s ' "${remote_frames[@]}")"for existing in "$FRAMES_DIR"/${RADAR_ID}.T.*.png; do    bn=$(basename "$existing")    case "$keep_set" in        *" $bn "*) ;;        *) rm -f "$existing" ;;    esacdone# --- 5. Composite each held frame ----------------------------------------LEGEND="${TRANS_DIR}/${RADAR_ID}.legend.0.png"HAVE_UPPER=0; [ -f "${PLATES_DIR}/upper.png" ] && HAVE_UPPER=1HAVE_LEGEND=0; [ -f "$LEGEND" ] && HAVE_LEGEND=1# clear stale composited framesrm -f "${OUT_DIR}"/frame.*.pngcomposited=()seq=0for fname in "${remote_frames[@]}"; do    src="${FRAMES_DIR}/${fname}"    [ -f "$src" ] || continue    out="${OUT_DIR}/frame.$(printf '%02d' "$seq").png"    cmd=(magick "${PLATES_DIR}/lower.png" "$src" -composite)    [ "$HAVE_UPPER" -eq 1 ]  && cmd+=("${PLATES_DIR}/upper.png" -composite)    [ "$HAVE_LEGEND" -eq 1 ] && cmd+=(-gravity southeast "$LEGEND" -composite +gravity)    cmd+=("$out")    "${cmd[@]}"    composited+=("$out")    seq=$((seq + 1))doneif [ "${#composited[@]}" -eq 0 ]; then    echo "No frames composited; serving last good loop." >&2    exit 0fi# --- 6. Assemble APNG loop via ffmpeg concat demuxer ---------------------# ImageMagick's PNG writer on Arch lacks APNG support; ffmpeg's apng muxer# handles it. Per-frame durations: last frame gets END_PAUSE.mkdir -p "$PUBLISH_DIR"TMP_APNG="${OUT_DIR}/loop.apng.tmp"LIST_FILE="${OUT_DIR}/concat.txt": > "$LIST_FILE"last_idx=$(( ${#composited[@]} - 1 ))for i in "${!composited[@]}"; do    printf "file '%s'\n" "${composited[$i]}" >> "$LIST_FILE"    if [ "$i" -eq "$last_idx" ]; then        printf "duration %s\n" "$(awk "BEGIN{print $END_PAUSE/100}")" >> "$LIST_FILE"    else        printf "duration %s\n" "$(awk "BEGIN{print $FRAME_DELAY/100}")" >> "$LIST_FILE"    fidone# ffmpeg concat quirk: last file must be repeated without a duration lineprintf "file '%s'\n" "${composited[$last_idx]}" >> "$LIST_FILE"ffmpeg -y -hide_banner -loglevel error \    -f concat -safe 0 -i "$LIST_FILE" \    -plays 0 -vf format=rgba -f apng "$TMP_APNG"install -m 644 "$TMP_APNG" "$PUBLISH_PATH"rm -f "$TMP_APNG"echo "Published ${PUBLISH_PATH} (frames=${#composited[@]}, latest=${remote_frames[-1]})"