#!/bin/bash
# Desc: Aligns path elements with spaces
# Usage: palign.sh [path]
#        find . -type f | palign.sh
# Input: stdin   paths  newline-delimited paths (forward-slash delimited)
#        psargs  paths  word-delimited paths (forward-slash delimited)
# Output: stdout
# Depends: Bash 5.1.16
# Version: 0.0.1

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
read_stdin() {
    # Desc: Consumes stdin; outputs as stdout lines
    # Input: stdin (consumes)
    # Output: stdout  (newline delimited)
    #         return  0  stdin read
    #         return  1  stdin not present
    # Example: printf "foo\nbar\n" | read_stdin
    # Depends: GNU bash (version 5.1.16), GNU Coreutils 8.32 (cat)
    # Version: 0.1.1
    # Attrib: Steven Baltakatei Sandoval (2024-01-29). reboil.com
    local input_stdin output;

    # Store stdin
    if [[ -p /dev/stdin ]]; then
        input_stdin="$(cat -)" || {
            echo "FATAL:Error reading stdin." 1>&2; return 1; };
    else
        return 1;
    fi; 
    
    # Store as output array elements
    ## Read in stdin
    if [[ -n $input_stdin ]]; then
        while read -r line; do
            output+=("$line");
        done < <(printf "%s\n" "$input_stdin") || {
            echo "FATAL:Error parsing stdin."; return 1; };
    fi;

    # Print to stdout
    printf "%s\n" "${output[@]}";

    return 0;
}; # read stdin to stdout lines
read_psarg() {
    # Desc: Reads arguments; outputs as stdout lines
    # Input: args
    # Output: stdout (newline delimited)
    # Example: read_psarg "$@"
    # Depends: GNU bash (version 5.1.16)
    # Version: 0.0.1
    local input_psarg output;
    
    # Store arguments
    if [[ $# -gt 0 ]]; then
        input_psarg="$*";
    fi;
    
    # Store as output array elements
    ## Read in positional arguments
    if [[ -n $input_psarg ]]; then
        for arg in "$@"; do
            output+=("$arg");
        done;
    fi;

    # Print to stdout
    printf "%s\n" "${output[@]}";
}; # read positional argument to stdout lines
calculate_max_lengths() {
    # Calculate maximum lengths of each hierarchical level
    # Input:   psargs  paths  
    # Output:  stdout  ints  path element lengths (single line of space-separated ints)
    local -a paths=("$@");
    local lengths;
    
    for path in "${paths[@]}"; do
        IFS='/' read -r -a parts <<< "$path";
        # Analyze path element lengths
        for i in "${!parts[@]}"; do
            # Save max path element lengths for previously analyzed paths
            #   Note: $(( condition ? value_true : value_false ))
            #     condition:  ${#parts[$i]} > ${lengths[$i]:-0}  is path element longer than previously seen corresponding paths?
            #     value_true: ${#parts[$i]}                      save new max length
            #     value_false ${lengths[$i]:-0}                  use previous value (or init with 0 if never seen before)
            lengths[$i]=$(( ${#parts[$i]} > ${lengths[$i]:-0} ? ${#parts[$i]} : ${lengths[$i]:-0} ));
        done;
    done;
    echo "${lengths[@]}";
}; # Get maximum lengths of path elements as space-separated ints
align_paths() {
    # Align paths
    # Input:  stdin
    # Output: stdout
    # Depends: calculate_max_lengths()
    local -a paths lengths;

    # Read stdin
    while read -r line; do
        paths+=("$line");
    done < <(read_stdin);

    IFS=" " read -r -a lengths <<< "$(calculate_max_lengths "${paths[@]}")";

    for path in "${paths[@]}"; do
        IFS='/' read -r -a parts <<< "$path";
        formatted_path="";
        for i in "${!parts[@]}"; do
            if [[ $i -gt 0 ]]; then
                formatted_path+="/";
            fi;
            formatted_path+="${parts[$i]}";
            if [[ $i -lt $((${#parts[@]} - 1)) ]]; then
                formatted_path+=$(printf "%*s" $((${lengths[$i]} - ${#parts[$i]} + 1)) "");
            fi;
        done;
        echo "$formatted_path";
    done;
}; # Function to format and align paths
main() {
    { read_stdin; read_psarg "$@"; } | align_paths;
}; # Call the function with the file paths
main "$@";

# Author: Steven Baltakatei Sandoval
# License; GPLv3+