convert duration string like: 2d3h5m30s into seconds only (bash)

duration_string_to_seconds.sh

#!/usr/bin/env bash
test_str="1h5m"
test_str="5d3h2m50v" #bad
test_str="5d3h2m50s"

declare -A keys
keys[d]=$((60 * 60 * 24))
keys[h]=$((60 * 60))
keys[m]=60
keys[s]=1

alphas=($(echo "${test_str}" | tr 'A-Z' 'a-z' | sed 's/[0-9]\+/\n/g' | sed '/^$/d'))
nums=($(echo "${test_str}" | tr 'A-Z' 'a-z' | sed 's/[a-z]\+/\n/g' | sed '/^$/d'))
val=0


for i in "${!alphas[@]}"; do
    metric=${alphas[${i}]}
    echo ${!keys[@]} | grep -q "${metric}" || {
        echo "Error, invalid metric: ${metric}, need ${!keys[@]}"
        exit -1
    }
    kv=${keys[${metric}]}
    nv=${nums[${i}]}
    val=$((${val} + (${kv} * ${nv})))
done

echo "${val}"