#!/bin/bash
# Desc: Updates all ots files in $HOME and /mnt/ directories recursively.
# Depends: bash 5.1.16, GNU Findutils 4.8.0, GNU Coreutils 8.32
# Version: 0.1.3
# Depends: GNU Coreutils (nproc)

main() {
    # Specify find targets
    declare -a find_targets;
    
    ## User home directory
    find_targets+=("$HOME");
    
    ## Subdirectories of /mnt/
    mapfile -t -O "${#find_targets[@]}" find_targets < <(find /mnt/ -mindepth 1 -maxdepth 1 -type d; );

    # Specify options
    find_depth=12;                     # find directory depth
    cpu_count="$(nproc)";              # get logical CPU count
    batch_size_xargs=100;              # xargs batch size
    cpu_duty="$((cpu_count / 4 + 1))"; # logical CPU cores to use
    
    # Remove OTS backup files
    find "${find_targets[@]}" -maxdepth "$find_depth" -type f -name "*.ots.bak" -exec rm '{}' \; 2>/dev/random;

    # Upgrade OTS files
    find "${find_targets[@]}" -maxdepth "$find_depth" -type f -name "*.ots" -print0 2>/dev/random | \
        sort -uz | \
        shuf -z | \
        xargs -0 -n "$batch_size_xargs" -P "$cpu_duty" ots u;
}; # main program

time { main "$@"; };