#!/bin/bash
# Download all SRTM tiles for Central Federal District + Chuvashia
# Using curl with retry on connection errors

SRTM_DIR="/home/slin/enduro-trails/data/srtm"
mkdir -p "$SRTM_DIR"
cd "$SRTM_DIR"
BASE_URL="https://s3.amazonaws.com/elevation-tiles-prod/skadi"

TILES=(
  N55E037 N55E038 N55E039 N55E040
  N54E037 N54E038 N54E039 N54E040
  N53E038 N53E039 N53E040 N53E041
  N52E038 N52E039 N52E040 N52E041
  N56E037 N56E038 N56E039 N56E040
  N57E037 N57E038 N57E039 N57E040
  N58E037 N58E038 N58E039 N58E040
  N59E038 N59E039 N59E040 N59E041
  N60E040 N60E041 N60E042
  N54E042 N54E043 N54E044 N54E045
  N53E042 N53E043 N53E044 N53E045
  N52E042 N52E043 N52E044 N52E045
  N51E038 N51E039 N51E040 N51E041
  N50E038 N50E039 N50E040 N50E041
  N55E047 N55E048 N55E049 N55E050
  N54E047 N54E048 N54E049 N54E050
  N56E047 N56E048 N56E049 N56E050
)

for tile in "${TILES[@]}"; do
  lat="${tile:1:2}"
  url="${BASE_URL}/${lat}/${tile}.hgt.gz"
  
  if [ -f "${tile}.hgt" ]; then
    echo "SKIP ${tile}"
    continue
  fi
  
  echo "DL ${tile}"
  # Download with retry
  HTTP_CODE=$(curl -s -o "${tile}.hgt.gz" -w "%{http_code}" --max-time 90 --retry 3 --retry-delay 2 "$url")
  if [ "$HTTP_CODE" = "200" ] && [ -s "${tile}.hgt.gz" ]; then
    gunzip -f "${tile}.hgt.gz"
    if [ -f "${tile}.hgt" ]; then
      echo "OK ${tile}"
    else
      echo "FAIL ${tile} (gunzip failed)"
    fi
  else
    echo "FAIL ${tile} (HTTP ${HTTP_CODE})"
    rm -f "${tile}.hgt.gz"
  fi
done

echo ""
echo "Total .hgt files: $(ls *.hgt 2>/dev/null | wc -l)"