#!/bin/bash
# ------------------------------------------------------------------------------
# Copyright (c) 2013-2022 Geoffray Levasseur <fatalerrors@geoffray-levasseur.org>
# Protected by the BSD3 license. Please read bellow for details.
#
# * Redistribution and use in source and binary forms,
# * with or without modification, are permitted provided
# * that the following conditions are met:
# *
# *   Redistributions of source code must retain the above
# *   copyright notice, this list of conditions and the
# *   following disclaimer.
# *
# *   Redistributions in binary form must reproduce the above
# *   copyright notice, this list of conditions and the following
# *   disclaimer in the documentation and/or other materials
# *   provided with the distribution.
# *
# *   Neither the name of the copyright holder nor the names
# *   of any other contributors may be used to endorse or
# *   promote products derived from this software without
# *   specific prior written permission.
# *
# * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
# * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
# * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
# * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# * OF SUCH DAMAGE.
# ------------------------------------------------------------------------------

# ------------------------------------------------------------------------------
# Download a resource using curl, wget, or fetch.
# Usage: dwl <url> [output_file]
dwl()
{
    case "$1" in
        --help|-h)
            echo "Usage: dwl <url> [output_file]"
            echo "Downloads a resource using curl, wget, or fetch."
            echo ""
            echo "Arguments:"
            echo "  url          The full URL to download (http/https/ftp)."
            echo "  output_file  (Optional) Path to save the file. If omitted, prints to stdout."
            return 0
            ;;
        "")
            echo "Error: URL argument is missing." >&2
            echo "Try 'get_resource --help' for usage." >&2
            return 1
            ;;
    esac

    case "$1" in
        http://*|https://*|ftp://*) ;;
        *)
            echo "Error: '$1' does not look like a valid URL. Must start with http://, https://, or ftp://" >&2
            return 1
            ;;
    esac

    local url="$1"
    local output="$2"

    if command -v curl >/dev/null 2>&1; then
        [ -z "$output" ] && curl -sL "$url" || curl -sL -o "$output" "$url"
    elif command -v wget >/dev/null 2>&1; then
        [ -z "$output" ] && wget -qO- "$url" || wget -q -O "$output" "$url"
    elif command -v fetch >/dev/null 2>&1; then
        [ -z "$output" ] && fetch -o - "$url" || fetch -o "$output" "$url"
    else
        echo "Error: No download utility (curl, wget, or fetch) found." >&2
        return 1
    fi
}
export -f dwl
# ------------------------------------------------------------------------------


# ------------------------------------------------------------------------------
# Determine if parameter is a valid IPv4 address
# Usage: isipv4 <ip_address>
isipv4()
{
    # Set up local variables
    local ip=$1
    [[ -z $ip ]] && return 1

    # Start with a regex format test (four octets)
    if [[ $ip =~ ^([0-9]{1,3}\.){3}[0-9]{1,3}$ ]]; then
        local old_ifs=$IFS
        IFS='.'
        read -r -a ip_arr <<< "$ip"
        IFS=$old_ifs

        # Ensure each octet is between 0 and 255
        local oct
        for oct in "${ip_arr[@]}"; do
            # Reject leading plus/minus or empty entries
            if [[ -z $oct || $oct =~ [^0-9] ]]; then
                [[ -t 1 ]] && disp "The given parameter is NOT a valid IPv4."
                return 1
            fi
            if (( oct > 255 )); then
                [[ -t 1 ]] && disp "The given parameter is NOT a valid IPv4."
                return 1
            fi
        done

        [[ -t 1 ]] && disp "The given IPv4 is valid."
        return 0
    fi

    [[ -t 1 ]] && disp "The given parameter is NOT a valid IPv4."
    return 1
}
export -f isipv4
# ------------------------------------------------------------------------------


# ------------------------------------------------------------------------------
# Determine if parameter is a valid IPv6 address
# Usage: isipv6 <ip_address>
isipv6()
{
    local ip="$1"
    local regex='^([0-9a-fA-F]{0,4}:){1,7}[0-9a-fA-F]{0,4}$'
    if [[ $ip =~ $regex ]]; then
        if [[ -t 1 ]]; then
            disp "The given IPv6 is valid."
        fi
        return 0
    fi
    if [[ -t 1 ]]; then
        disp "The given parameter is not a valid IPv6."
    fi
    return 1
}
export -f isipv6
# ------------------------------------------------------------------------------


# ------------------------------------------------------------------------------
# Encode a string so it can be used as a URL parameter
# Usage: urlencode <string>
urlencode() {
    local LANG=C
    local str="$*"
    local length="${#str}"
    for (( i = 0; i < length; i++ )); do
        local c="${str:i:1}"
        case "$c" in
            [a-zA-Z0-9.~_-]) printf '%s' "$c" ;;
            ' ') printf '+' ;;
            *) printf '%%%02X' "'$c" #| cut -d' ' -f2 ;;
        esac
    done
}
export -f urlencode
# ------------------------------------------------------------------------------


# ------------------------------------------------------------------------------
# Fetch and display external IP information
# Usage: myextip [-i|--ip] [-s|--isp] [-l|--loc] [-c|--coord]
# If no option is provided, all information will be displayed.
# Options:
#   -h, --help    Display help screen
#   -i, --ip      Display only the external IP address
#   -s, --isp     Display only the ISP name
#   -l, --loc     Display only the location (city, region, country)
#   -c, --coord   Display only the coordinates (latitude, longitude)
#   -a, --as      Display only the Autonomous System (AS) information
#   -R, --raw     Display raw JSON response
myextip() {
    local show_ip=false show_isp=false show_loc=false
    local show_coord=false show_as=false show_raw=false
    local all=true

    # Parse arguments
    while [[ "$#" -gt 0 ]]; do
        case "$1" in
            -i|--ip)
                show_ip=true
                all=false
                ;;
            -s|--isp)
                show_isp=true
                all=false
                ;;
            -l|--loc)
                show_loc=true
                all=false
                ;;
            -c|--coord)
                show_coord=true
                all=false
                ;;
            -a|--as)
                show_as=true
                all=false
                ;;
            -R|--raw)
                all=false
                show_raw=true
                ;;
            -h|--help)
                printf "Fetch and display external IP information.\n\n"
                printf "Usage: myextip [-i|--ip] [-s|--isp] [-l|--loc] [-c|--coord] [-a|--as]  [-R|--raw]\n\n"
                printf "Options:\n"
                printf "\t-h, --help\tDisplay this help screen\n"
                printf "\t-i, --ip\tDisplay only the external IP address\n"
                printf "\t-s, --isp\tDisplay only the ISP name\n"
                printf "\t-l, --loc\tDisplay only the location (city, region, country)\n"
                printf "\t-c, --coord\tDisplay only the coordinates (latitude, longitude)\n"
                printf "\t-a, --as\tDisplay only the Autonomous System (AS) information\n"
                printf "\t-R, --raw\tDisplay raw JSON response\n"
                return 0
                ;;
            --)
                shift
                break
                ;;
            *)
                disp E "Unknown option: $1, use \"myextip --help\" to display usage."
                return 1
                ;;
        esac
        shift
    done

    # Fetch data. Allow overriding endpoint via env var MYEXTIP_URL
    local MYEXTIP_URL
    MYEXTIP_URL=${MYEXTIP_URL:-http://ip-api.com/json/}

    local response
    if ! response=$(dwl "$MYEXTIP_URL"); then
        disp E "Failed to fetch external IP information from $MYEXTIP_URL"
        return 2
    fi

    # Parse with jq when available and when raw wasn't requested. The jq filter
    # is tolerant to field-name differences between providers (ip-api / ipinfo).
    if command -v jq >/dev/null 2>&1 && [[ "$show_raw" != true ]]; then
        echo "$response" | jq -r --argjson all "$all" --argjson ip "$show_ip" \
            --argjson isp "$show_isp" --argjson loc "$show_loc" \
            --argjson coord "$show_coord" --argjson as "$show_as" '
                [
                    (if $all or $ip then "IP Address : \(.query // .ip)" else empty end),
                    (if $all or $isp then "ISP        : \(.isp // .org)" else empty end),
                    (if $all or $loc then
                        ("Location   : " + ((.city // "") + (if .city then ", " else "" end) + (if .regionName then .regionName else .region end) + (if .country then ", " + .country else "" end)))
                    else empty end),
                    (if $all or $coord then (if (.lat and .lon) then "Coordinates: \(.lat), \(.lon)" elif .loc then "Coordinates: \(.loc)" else empty end) else empty end),
                    (if $all or $as then "AS         : \(.as // .org)" else empty end)
                ] | .[]'
    else
        [[ "$show_raw" != true ]] && disp W "jq is not installed, displaying raw JSON response."
        echo "$response"
    fi
}
export -f myextip
# ------------------------------------------------------------------------------


# ------------------------------------------------------------------------------
# EOF