#!/bin/bash
set -e
GDALCOPYPROJ="/usr/share/doc/python-gdal/examples/gdalcopyproj.py"

# Expected directory names: 2010-04, 2010-11, ... 2016-04
OSSV_EDITIONS=($(ls -d 201*|sort -n))
OSSV_EDITIONS_LENGTH=${#OSSV_EDITIONS[@]}

OSSV_EDITIONS_TMP=$(mktemp -d --suffix=osstvw_edit)
function cleanup {
  rm -rf "${OSSV_EDITIONS_TMP}"
}
trap cleanup EXIT

# Create OSSTVW ocean blue to compare new files against
convert -size 5000x5000 xc:'#e6f6ff' -depth 8 ${OSSV_EDITIONS_TMP}/blue.png

# Outer loop (compare from)
for (( i=0; i<${OSSV_EDITIONS_LENGTH}; i++ )); do
  # Inner loop (compare to)
  for (( o=${i}; o<${OSSV_EDITIONS_LENGTH}; o++ )); do
    # Skip when outer == inner edition
    if [ "$i" != "$o" ]; then
      OSSV_DIFF_NAME="diff-${OSSV_EDITIONS[$i]}-${OSSV_EDITIONS[$o]}"
      mkdir -p "${OSSV_DIFF_NAME}"
      # TIF file loop for edition - see end of loop for find
      while IFS= read -r -d $'\0' FILE; do
        FILE_1="${OSSV_EDITIONS[$i]}/${FILE}"
        FILE_2="${OSSV_EDITIONS[$o]}/${FILE}"
        if [ ! -f "${FILE_1}" ]; then
          FILE_1="${OSSV_EDITIONS_TMP}/blue.png"
        fi
        # Skip existing files or excluded files
        if [ ! -f "${OSSV_DIFF_NAME}/${FILE}" ] && [ ! -f "${OSSV_DIFF_NAME}/${FILE}.skip" ]; then
          echo Creating diff ${OSSV_EDITIONS[$i]} ${OSSV_EDITIONS[$o]} "${FILE_1}" "${OSSV_DIFF_NAME}/${FILE}"
          # Background compare + gdalcopyproj
          ((compare -quiet "${FILE_1}" "${FILE_2}" -compose Src -highlight-color Red -lowlight-color 'rgba(255,255,255,0)' -define tiff:tile-geometry=512x512 "${OSSV_DIFF_NAME}/${FILE}" || true) && python ${GDALCOPYPROJ} "${FILE_2}" "${OSSV_DIFF_NAME}/${FILE}" ) &

          # Check how many background processes and wait if exceed
          running=($(jobs -rp))
          while [ ${#running[@]} -ge 16 ] ; do
            sleep 1   # this is not optimal, but you can't use wait here
            running=($(jobs -rp))
          done
        fi
      done < <(find "${OSSV_EDITIONS[$o]}" -maxdepth 1 -name '*.tif' -printf '%f\0')

      # Wait for background jobs to finish
      wait

      # TIF cleanup loop for images which have no diff
      while IFS= read -r -d $'\0' FILE; do
        ( FILE_COLOURS=$(identify -quiet -format '%k' "${OSSV_DIFF_NAME}/${FILE}")
        if [ "$FILE_COLOURS" -lt "2" ]; then
          rm -f "${OSSV_DIFF_NAME}/${FILE}"
          touch "${OSSV_DIFF_NAME}/${FILE}.skip"
        fi ) &

        # Check how many background processes and wait if exceed
        running=($(jobs -rp))
        while [ ${#running[@]} -ge 16 ] ; do
          sleep 1   # this is not optimal, but you can't use wait here
          running=($(jobs -rp))
        done
      done < <(find "${OSSV_DIFF_NAME}" -maxdepth 1 -name '*.tif' -size -180000c -printf '%f\0')
    fi
  done
done
echo Now create the VRT and external overview layers
echo 1: gdalbuildvrt -resolution highest -hidenodata diffXYZ.vrt diff/*.tif
echo 2: gdaladdo --config GDAL_CACHEMAX=16000 -ro --config COMPRESS DEFLATE --config COMPRESS_OVERVIEW DEFLATE --config ZLEVEL 9 --config BIGTIFF_OVERVIEW IF_SAFER --config GDAL_TIFF_OVR_BLOCKSIZE 512 -r average ossv-2016-04-combined.vrt 4 16 64 256 1024 4096