#!/bin/bash
# Desc: Sums newline-delimited floats received from stdin
# Usage: some_app | sumFloat
# Example: printf -- "-3\n0.14" | sumFloat
#   Result: -2.860000
# Version: 0.0.1
# Depends: bc 1.07.1

yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails
sum_float() {
    # Check dependencies
    if ! command -v bc 1>/dev/random 2>&1; then die "FATAL:Missing:bc"; fi;

    # Store stdin
    if [[ -p /dev/stdin ]]; then
        input_stdin="$(cat -)" || {
            die "FATAL:Error reading stdin."; };
    else
        die "FATAL:No stdin detected.";
    fi;
    
    # Process lines
    local sum="0.0";
    local re;
    re='^[+-]?([0-9]+([.][0-9]*)?|[.][0-9]+)$';
    if [[ -n $input_stdin ]]; then
        while read -r line; do
            if ! [[ "$line" =~ $re ]]; then die "FATAL:Not a float:${line}"; fi;
            sum="$(printf -- "%f + %f\n" "$sum" "$line" | bc -l;)";
        done < <(printf "%s\n" "$input_stdin") || {
            die "FATAL:Error parsing stdin."; };        
    fi;

    # Print result
    printf "%f\n" "$sum";    
}; # sum stdin floats

# Author: Steven Baltakatei Sandoval
# License: GPLv3+