#!/bin/bash
## change to "bin/sh" when necessary

display_help(){
  logger "Usage: $0 [local|file|pass]"
  logger "  local - Load variables from this script"
  logger "  file  - Load variables from a file"
  logger "  pass  - Load variables from pass"
}

load_variables(){
  case "$1" in
    "local")
        ##############  CLOUDFLARE CREDENTIALS  ##############
        # @auth_email           - The email used to login 'https://dash.cloudflare.com'
        # @auth_method          - Set to "global" for Global API Key or "token" for Scoped API Token
        # @auth_key             - Your API Token or Global API Key
        # @zone_identifier      - Can be found in the "Overview" tab of your domain
        # -------------------------------------------------- #
        auth_email=""
        auth_method="token"
        auth_key=""
        zone_identifier=""

        #############  DNS RECORD CONFIGURATION  #############
        # @record_name          - Which record you want to be synced
        # @ttl                  - DNS TTL (seconds), can be set between (30 if enterprise) 60 and 86400 seconds, or 1 for Automatic
        # @proxy                - Set the proxy to true or false
        # -------------------------------------------------- #
        record_name=""
        ttl="3600"
        proxy="false"

        ###############  SCRIPT CONFIGURATION  ###############
        # @static_IPv6_mode     - Useful if you are using EUI-64 IPv6 address with SLAAC IPv6 suffix token. (Privacy Extensions)
        #                       + Or some kind of static IPv6 assignment from DHCP server configuration, etc
        #                       + If set to false, the IPv6 address will be acquired from external services
        # @last_notable_hexes   - Used with `static_IPv6_mode`. Configure this to target what specific IPv6 address to search for
        #                       + E.g. Your global primary IPv6 address is 2404:6800:4001:80e::59ec:ab12:34cd, then
        #                       + You can put values (i.e. static suffixes) such as "34cd", "ab12:34cd" and etc
        # @log_header_name      - Header name used for logs
        # -------------------------------------------------- #
        static_IPv6_mode="false"
        last_notable_hexes="ffff:ffff"
        log_header_name="DDNS Updater_v6"

        #############  WEBHOOKS CONFIGURATION  ###############
        # @sitename             - Title of site "Example Site"
        # @slackchannel         - Slack Channel #example
        # @slackuri             - URI for Slack WebHook "https://hooks.slack.com/services/xxxxx"
        # @discorduri           - URI for Discord WebHook "https://discordapp.com/api/webhooks/xxxxx"
        # -------------------------------------------------- #
        sitename=""
        slackchannel=""
        slackuri=""
        discorduri=""
      ;;
    "file")
        # Load variables from file
        CONFIG_FILE="$HOME/.cloudflare/config6.ini"

        # Check if the configuration file exists
        if [ -f "$CONFIG_FILE" ]; then
            # Load configuration from the file
            source "$CONFIG_FILE"
        else
            logger "Error: Configuration file '$CONFIG_FILE' not found."
            exit 1
        fi
        ;;
    "pass")
        # Load variables from pass
        source <(pass credentials/cloudflare)
        ;;
    *)
        logger "Invalid load_variables option"
        exit 1
        ;;
  esac
}

validate_variables(){
  # Validate required variables
  if [[ -z $auth_email || -z $auth_key || -z $zone_identifier || -z $record_name ]]; then
    logger "Missing required variables. Please provide values for 'auth_email', 'auth_key', 'zone_identifier', and 'record_name'."
    exit 1
  fi
}


check_ipv6_is_available(){
    if ! { curl -6 -s --head --fail https://ipv6.google.com >/dev/null; }; then
        logger -s "$log_header_name: Unable to establish a valid IPv6 connection to a known host."
        exit 1
    fi

    # Regex credits to https://stackoverflow.com/a/17871737
    ipv6_regex="(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))"

    if $static_IPv6_mode; then
        # Test whether 'ip' command is available
        if { command -v "ip" &>/dev/null; }; then
            ip=$(ip -6 -o addr show scope global primary -deprecated | grep -oE "$ipv6_regex" | grep -oE ".*($last_notable_hexes)$")
        else
            # Fall back to 'ifconfig' command
            ip=$(ifconfig | grep -oE "$ipv6_regex" | grep -oE ".*($last_notable_hexes)$")
        fi
    else
        # Use external services to discover our system's preferred IPv6 address
        ip=$(curl -s -6 https://cloudflare.com/cdn-cgi/trace | grep -E '^ip')
        ret=$?
        if [[ ! $ret == 0 ]]; then # In the case that cloudflare failed to return an ip.
            # Attempt to get the ip from other websites.
            ip=$(curl -s -6 https://api64.ipify.org || curl -s -6 https://ipv6.icanhazip.com)
        else
            # Extract just the ip from the ip line from cloudflare.
            ip=$(echo $ip | sed -E "s/^ip=($ipv6_regex)$/\1/")
        fi
    fi

    # Check point: Make sure the collected IPv6 address is valid
    if [[ ! $ip =~ ^$ipv6_regex$ ]]; then
        logger -s "$log_header_name: Failed to find a valid IPv6 address."
        exit 1
    fi
}

set_auth_headers(){
    if [[ "${auth_method}" == "global" ]]; then
        auth_header="X-Auth-Key:"
    else
        auth_header="Authorization: Bearer"
    fi
}

check_if_aaaa_record_exists(){
    logger "$log_header_name: Check Initiated"
    record=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records?type=AAAA&name=$record_name" \
        -H "X-Auth-Email: $auth_email" \
        -H "$auth_header $auth_key" \
        -H "Content-Type: application/json")
    if [[ $record == *"\"count\":0"* ]]; then
        logger -s "$log_header_name: Record does not exist, perhaps create one first? (${ip} for ${record_name})"
        exit 1
    fi
}

get_current_ip_from_cloudflare(){
    old_ip=$(echo "$record" | sed -E 's/.*"content":"'${ipv6_regex}'".*/\1/')

    # Make sure the extracted IPv6 address is valid
    if [[ ! $old_ip =~ ^$ipv6_regex$ ]]; then
        logger -s "$log_header_name: Unable to extract existing IPv6 address from DNS record."
        exit 1
    fi

    # Compare if they're the same
    if [[ $ip == $old_ip ]]; then
        logger "$log_header_name: IP ($ip) for ${record_name} has not changed."
        exit 0
    fi
}

update_ip_on_cloudflare(){
    record_identifier=$(echo "$record" | sed -E 's/.*"id":"([A-Za-z0-9_]+)".*/\1/')
    update=$(curl -s -X PATCH "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records/$record_identifier" \
        -H "X-Auth-Email: $auth_email" \
        -H "$auth_header $auth_key" \
        -H "Content-Type: application/json" \
        --data "{\"content\":\"$ip\",\"ttl\":\"$ttl\",\"proxied\":$proxy}")
}

send_webhooks(){
    case "$update" in
    *"\"success\":false"*)
        echo -e "$log_header_name: $ip $record_name DDNS failed for $record_identifier ($ip). DUMPING RESULTS:\n$update" | logger -s
        if [[ $slackuri != "" ]]; then
            curl -L -X POST $slackuri \
                --data-raw "{
                    \"channel\": \"$slackchannel\",
                    \"text\": \"$sitename DDNS Update Failed: $record_name: $record_identifier ($ip).\"
                }"
        fi
        if [[ $discorduri != "" ]]; then
            curl -i -H "Accept: application/json" -H "Content-Type:application/json" -X POST \
                --data-raw "{
                    \"content\": \"$sitename DDNS Update Failed: $record_name: $record_identifier ($ip).\"
                }" $discorduri
        fi
        exit 1
        ;;
    *)
        logger "$log_header_name: $ip $record_name DDNS updated."
        if [[ $slackuri != "" ]]; then
            curl -L -X POST $slackuri \
                --data-raw "{
                    \"channel\": \"$slackchannel\",
                    \"text\": \"$sitename Updated: $record_name's new IPv6 Address is $ip\"
                }"
        fi
        if [[ $discorduri != "" ]]; then
            curl -i -H "Accept: application/json" -H "Content-Type:application/json" -X POST \
                --data-raw "{
                    \"content\": \"$sitename Updated: $record_name's new IPv6 Address is $ip\"
                }" $discorduri
        fi
        exit 0
        ;;
    esac
}

main(){
    validate_variables
    check_ipv6_is_available
    set_auth_headers
    check_if_aaaa_record_exists
    get_current_ip_from_cloudflare
    update_ip_on_cloudflare
    send_webhooks
}

# switch for environment variables loading
case "$1" in
    "local"|"file"|"pass")
        load_variables "$1"
        main
        ;;
    *)
        display_help
        exit 1
        ;;
esac