#!/bin/bash

# Desc: Outputs to stdout the current iso-8601 timestamp (second accuracy)
# Usage: tick_second.sh
# Example tick_second.sh

#==BEGIN Define script parameters==
#===BEGIN Declare variables===
declare -Ag appRollCall # Associative array for storing app status
declare -Ag fileRollCall # Associative array for storing file status
declare -Ag dirRollCall # Associative array for storing dir status
declare exitFlag
#===END Declare variables===


#===BEGIN Declare local script functions===
yell() { echo "$0: $*" >&2; } # Yell, Die, Try Three-Fingered Claw technique; # Ref/Attrib: https://stackoverflow.com/a/25515370
die() { yell "$*"; exit 111; }
try() { "$@" || die "cannot $*"; }
checkapp() {
    # Desc: If arg is a command, save result in assoc array 'appRollCall'
    # Usage: checkapp arg1 arg2 arg3 ...
    # Version: 0.1.1
    # Input: global assoc. array 'appRollCall'
    # Output: adds/updates key(value) to global assoc array 'appRollCall'
    # Depends: bash 5.0.3
    local returnState    

    #===Process Args===
    for arg in "$@"; do
	if command -v "$arg" 1>/dev/null 2>&1; then # Check if arg is a valid command
	    appRollCall[$arg]="true";
	    if ! [ "$returnState" = "false" ]; then returnState="true"; fi;
	else
	    appRollCall[$arg]="false"; returnState="false";
	fi;
    done;

    #===Determine function return code===
    if [ "$returnState" = "true" ]; then
	return 0;
    else
	return 1;
    fi;
} # Check that app exists
displayMissing() {
    # Desc: Displays missing apps, files, and dirs
    # Usage: displayMissing
    # Version 0.1.1
    # Input: associative arrays: appRollCall, fileRollCall, dirRollCall
    # Output: stderr: messages indicating missing apps, file, or dirs
    # Depends: bash 5, checkAppFileDir()
    local missingApps value appMissing missingFiles fileMissing
    local missingDirs dirMissing
    
    #==BEGIN Display errors==
    #===BEGIN Display Missing Apps===
    missingApps="Missing apps  :";
    #for key in "${!appRollCall[@]}"; do echo "DEBUG:$key => ${appRollCall[$key]}"; done
    for key in "${!appRollCall[@]}"; do
	value="${appRollCall[$key]}";
	if [ "$value" = "false" ]; then
	    #echo "DEBUG:Missing apps: $key => $value";
	    missingApps="$missingApps""$key ";
	    appMissing="true";
	fi;
    done;
    if [ "$appMissing" = "true" ]; then  # Only indicate if an app is missing.
	echo "$missingApps" 1>&2;
    fi;
    unset value;
    #===END Display Missing Apps===

    #===BEGIN Display Missing Files===
    missingFiles="Missing files:";
    #for key in "${!fileRollCall[@]}"; do echo "DEBUG:$key => ${fileRollCall[$key]}"; done
    for key in "${!fileRollCall[@]}"; do
	value="${fileRollCall[$key]}";
	if [ "$value" = "false" ]; then
	    #echo "DEBUG:Missing files: $key => $value";
	    missingFiles="$missingFiles""$key ";
	    fileMissing="true";
	fi;
    done;
    if [ "$fileMissing" = "true" ]; then  # Only indicate if an app is missing.
	echo "$missingFiles" 1>&2;
    fi;
    unset value;
    #===END Display Missing Files===

    #===BEGIN Display Missing Directories===
    missingDirs="Missing dirs:";
    #for key in "${!dirRollCall[@]}"; do echo "DEBUG:$key => ${dirRollCall[$key]}"; done
    for key in "${!dirRollCall[@]}"; do
	value="${dirRollCall[$key]}";
	if [ "$value" = "false" ]; then
	    #echo "DEBUG:Missing dirs: $key => $value";
	    missingDirs="$missingDirs""$key ";
	    dirMissing="true";
	fi;
    done;
    if [ "$dirMissing" = "true" ]; then  # Only indicate if an dir is missing.
	echo "$missingDirs" 1>&2;
    fi;
    unset value;
    #===END Display Missing Directories===

    #==END Display errors==
} # Display missing apps, files, dirsw
main() {
    # Desc: main program
    # Input: var: arg1:        path
    #        var: appRollCall  checkapp() dependency
    #        var: exitFlag     indicates to script if exit required
    # Output: stdout: iso-8601 date string
    # Depends: try()
    
    # Validate input
    ## Check argument count (must be 0)
    if [[ $# -gt 0 ]]; then yell "ERROR:Too many arguments:$#"; exitFlag="true"; fi;
    
    ## Check Apps
    if ! checkapp date echo; then yell "ERROR:Missing App"; exitFlag="true"; fi;

    ## Report errors
    displayMissing;
    if [[ $exitFlag == "true" ]]; then exit 1; fi;

    # Form output
    output="$(date +%Y-%m-%dT%H:%M:%S%z)"; #iso-8601 string (e.g. 2021-05-28T19:30:57+0000)

    # Write output
    echo "$output";
}

#===END Declare local script functions===
#==END Define script parameters==

try main "$@";