#!/bin/bash
set -e

cd /home/slin/enduro-trails/data/srtm

echo 'Downloading missing SRTM tiles from multiple mirrors...'

download_tile() {
  local tile=$1
  local f="${tile}.hgt"
  
  if [ -f "$f" ]; then
    echo "  EXISTS: $f"
    return 0
  fi
  
  # Mirror 1: USGS via e4ftl01 (SRTMGL3 - 3 arc-second, no auth for v003)
  # Mirror 2: OpenData AWS terrain tiles
  # Mirror 3: viewfinderpanoramas.org
  
  local lat_num=${tile:1:2}
  local lon_num=${tile:4:3}
  
  # Try viewfinderpanoramas (grouped by lat band in zip)
  # Individual files available at: http://viewfinderpanoramas.org/dem3/N55/N55E041.hgt.zip
  local vfp_url="http://viewfinderpanoramas.org/dem3/${tile:0:3}/${tile}.hgt.zip"
  wget -q --timeout=30 "$vfp_url" -O "/tmp/${tile}.zip" 2>/dev/null
  if [ -s "/tmp/${tile}.zip" ]; then
    unzip -o -q "/tmp/${tile}.zip" -d . 2>/dev/null
    if [ -f "$f" ]; then
      echo "  OK (viewfinder): $f ($(du -h $f | cut -f1))"
      rm -f "/tmp/${tile}.zip"
      return 0
    fi
  fi
  rm -f "/tmp/${tile}.zip"
  
  # Try CGIAR SRTM v4 (5x5 degree tiles, different naming)
  # Try direct NASA mirror
  local nasa_url="https://e4ftl01.cr.usgs.gov/MEASURES/SRTMGL3.003/2000.02.11/${tile}.SRTMGL3.hgt.zip"
  wget -q --timeout=30 "$nasa_url" -O "/tmp/${tile}.zip" 2>/dev/null
  if [ -s "/tmp/${tile}.zip" ]; then
    unzip -o -q "/tmp/${tile}.zip" -d . 2>/dev/null
    if [ -f "$f" ]; then
      echo "  OK (nasa): $f ($(du -h $f | cut -f1))"
      rm -f "/tmp/${tile}.zip"
      return 0
    fi
  fi
  rm -f "/tmp/${tile}.zip"
  
  # Try sonny's mirror (reliable for SRTM3)
  local sonny_url="https://srtm.kurviger.de/SRTM3/Eurasia/${tile}.hgt.zip"
  wget -q --timeout=30 "$sonny_url" -O "/tmp/${tile}.zip" 2>/dev/null
  if [ -s "/tmp/${tile}.zip" ]; then
    unzip -o -q "/tmp/${tile}.zip" -d . 2>/dev/null
    if [ -f "$f" ]; then
      echo "  OK (kurviger): $f ($(du -h $f | cut -f1))"
      rm -f "/tmp/${tile}.zip"
      return 0
    fi
  fi
  rm -f "/tmp/${tile}.zip"
  
  echo "  FAIL: $tile (all mirrors failed)"
  return 1
}

# Clean up stale downloads
rm -f /tmp/N*.hgt.zip

for lat in 54 55 56; do
  for lon in 041 042 043 044 045 046; do
    download_tile "N${lat}E${lon}"
  done
done

echo ''
echo "Total HGT files: $(ls *.hgt | wc -l)"
echo "E041-E046 coverage:"
ls *E04[1-6]* 2>/dev/null | grep -E "N5[456]" | sort