#!/bin/bash

# This script reads the aliases of all ML results
# indices and generates the body of the request
# needed to recreate those aliases (POST _aliases).
# The script helps with restoring ML results indices
# after reindexing them to a temporary place and
# back in order to ensure the correct mappings are in place.
#
# Usage:
#   With CURL:
#     curl --user:es_user http://host:port/_aliases | ./gen_post_aliases_body.sh
#   With the response of GET .ml-anomalies-*/_alias stored in a file:
#     ./gen_post_aliases_body.sh < file_containing_response.txt

GET_ALIASES_RESPONSE=$(cat)
INDICES=$(echo $GET_ALIASES_RESPONSE | jq keys)

ACTIONS=()

for ((i=0;i<$(echo $INDICES | jq length);i++)); do
  INDEX=$(echo $INDICES | jq ".[$i]")
  INDEX_ALIASES=$(echo $GET_ALIASES_RESPONSE | jq '.['"$INDEX"']')
  ALIASES=$(echo $INDEX_ALIASES | jq '.aliases | keys')
  for ((j=0;j<$(echo $ALIASES | jq length);j++)); do
    ACTION=""
    ALIAS=$(echo $ALIASES | jq ".[$j]")
    FILTER=$(echo $INDEX_ALIASES | jq '.["aliases"]['"$ALIAS"']["filter"]')
    ACTION="add$i$j"
    ACTION='{"add": {"index":'"$INDEX"',"alias":'"$ALIAS"
    if [ "$FILTER" != "null" ]; then
      ACTION="$ACTION"',"filter":'"$FILTER"
    fi
    ACTION="$ACTION}}"
    ACTIONS+=("$ACTION")
  done
done

echo '{"actions":['
( IFS=$','; echo "${ACTIONS[*]}" )
echo ']}'