#!/bin/bash

## Change Log format as logfmt (refactoring)
# ddns.sh -d domain [-t <ttl>] [-p] [-r] [-c]

# Default Information
DOMAIN=""
TTL=180
C_TTL=86400
PROXIED="false"
DELETE_FLAG="false"
CURRENT_IP=""

# These will be injected by systemd
# ZONE_ID='.secret'
# API_KEY='.secret'

# usage() function
usage() {
        echo "Usage: $0 -d \"domain\" [-t \"ttl\"] [-p] [-r] [-c]"
        echo "-d <domain>: Specify the domain to update"
        echo "-t <ttl>: Specify the TTL(Time to live)"
        echo "-p: Specify the cloudflare proxy to use"
        echo "-r: Delete the DNS record"
        exit 1
}

# Log function
log() {
    local timestamp=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
    local level="$1"
    local msg="$2"
    echo "time=\"$timestamp\" level=\"$level\" msg=\"$msg\" source=\"ddns.sh\"">&2
}

# getopts to get arguments
while getopts "d:t:pr" opt; do
    case $opt in
        d)
            DOMAIN="$OPTARG"
            ;;
        t)
            TTL="$OPTARG"
            ;;
        p)
            PROXIED="true"
            ;;
        r)
            DELETE_FLAG="true"
            ;;
        \?) # unknown options
            log "error" "Invalid option: -$OPTARG"
            usage
            ;;
        :) # parameter required option
            log "error" "Option -$OPTARG requires an argument."
            usage
            ;;
    esac
done

# Get option and move to parameters - This has no functional thing, because it only use arguments with parameters
shift $((OPTIND - 1))

# Check necessary options
if [ -z "$DOMAIN" ]; then
    log "error" "-d option is required"
    usage
fi

if ! [[ "$TTL" =~ ^[0-9]+$ ]] || [ "$TTL" -le 0 ]; then
    log "error" "-t option (ttl) requires a number above 0."
    usage
fi

# Check necessary environment variables (Injected by systemd or shell)
if [ -z "$ZONE_ID" ]; then
    log "error" "ZONE_ID is required via environment variable."
    exit 1
fi

if [ -z "$API_KEY" ]; then
    log "error" "API_KEY is required via environment variable."
    exit 1
fi

# Check package
if ! command -v curl >/dev/null; then
    log "error" "curl is required"
    exit 1
fi
if ! command -v jq >/dev/null; then
    log "error" "jq is required"
    exit 1
fi

# API options
URL="https://api.cloudflare.com/client/v4/zones/$ZONE_ID/dns_records"
CONTENT_TYPE="Content-Type: application/json"
AUTHORIZATION="Authorization: Bearer $API_KEY"

# Current IP
CURRENT_IP=$( ip address show dev wan | grep 'inet ' | awk '{print $2}' | cut -d'/' -f1 )
# Get current IP from external server when IP is private IP
if [[ -z "$CURRENT_IP" || "$CURRENT_IP" =~ ^(10\.|172\.(1[6-9]|2[0-9]|3[0-1])\.|192\.168\.|127\.) ]]; then
    log "info" "IP from interface is private or empty. Fetching public IP..."
    CURRENT_IP=$(curl -sf "https://ifconfig.me") ||\
    CURRENT_IP=$(curl -sf "https://ifconfig.kr") ||\
    CURRENT_IP=$(curl -sf "https://api.ipify.org")
fi
if [ "$CURRENT_IP" == "" ]; then
    log "Error" "Can't get an IP"
    exit 1
fi

# DNS functions

# get_dns_record() function
get_dns_record()
{
    local type="$1"
    local name="$2"

    local response="$(
        curl -s "$URL?type=$type&name=$name"\
            -H "$CONTENT_TYPE"\
            -H "$AUTHORIZATION")"
    if [ "$(echo "$response" | jq -r '.success')" == "false" ]; then
        log "error" "Can't get dns record by $response"
        exit 1
    else
        # return
        echo "$response"
    fi
}

# create_dns_record() function
create_dns_record()
{
    local type="$1"
    local name="$2"
    local ttl="$3"
    local comment="$4"
    local content="$5"
    local response="$(
        curl -s "$URL"\
            -X POST\
            -H "$CONTENT_TYPE"\
            -H "$AUTHORIZATION"\
            -d "{
            \"name\": \"$name\",
            \"ttl\": $ttl,
            \"type\": \"$type\",
            \"comment\": \"$comment\",
            \"content\": \"$content\",
            \"proxied\": $PROXIED
            }")"
    if [ "$(echo "$response" | jq -r '.success')" == "false" ]; then
        log "error" "Can't create dns record by $response"
        exit 1
    else
        # return
        echo "$response"
    fi
}

# update_dns_record() function
update_dns_record()
{
    local type="$1"
    local name="$2"
    local ttl="$3"
    local comment="$4"
    local content="$5"
    local id="$6"
    local response=$(
        curl -s "$URL/$id"\
            -X PUT\
            -H "$CONTENT_TYPE"\
            -H "$AUTHORIZATION"\
            -d "{
            \"name\": \"$name\",
            \"ttl\": $ttl,
            \"type\": \"$type\",
            \"comment\": \"$comment\",
            \"content\": \"$content\",
            \"proxied\": $PROXIED
            }")
    if [ "$(echo "$response" | jq -r '.success')" == "false" ]; then
        log "error" "Can't update dns record by $response"
        exit 1
    else
        #return
        echo "$response"
    fi
}

# delete_dns_record() function
delete_dns_record()
{
    local type="$1"
    local id="$2"

    local response=$(
        curl -s "$URL/$id"\
            -X DELETE\
            -H "$CONTENT_TYPE"\
            -H "$AUTHORIZATION"
    )
    if [ "$(echo "$response" | jq -r '.success')" == "false" ]; then
        log "error" "Can't delete dns record by $response"
        exit 1
    else
        # return
        echo "$response"
    fi
}

# Get DNS A, and CNAME record
A_DNS_RECORD=$(get_dns_record "A" "$DOMAIN")
S_DNS_RECORD=$(get_dns_record "cname" "*.$DOMAIN")
W_DNS_RECORD=$(get_dns_record "cname" "www.$DOMAIN")

# Delete DNS record with Delete flag
if [ "$DELETE_FLAG" == "true" ]; then
    FLAG="false"
    if [ "$(echo $A_DNS_RECORD | jq -r '.result | length')" -eq 1 ]; then
        A_DNS_ID="$(echo $A_DNS_RECORD | jq -r '.result[0].id')"
        delete_dns_record "A" "$A_DNS_ID"
        log "info" "root DNS record is deleted"
        FLAG="true"
    fi
    if [ "$(echo $S_DNS_RECORD | jq -r '.result | length')" -eq 1 ]; then
        S_DNS_ID="$(echo $S_DNS_RECORD | jq -r '.result[0].id')"
        delete_dns_record "cname" "$S_DNS_ID"
        log "info" "sub DNS record is deleted"
        FLAG="true"
    fi
    if [ "$(echo $W_DNS_RECORD | jq -r '.result | length')" -eq 1 ]; then
        W_DNS_ID="$(echo $W_DNS_RECORD | jq -r '.result[0].id')"
        delete_dns_record "cname" "$W_DNS_ID"
        log "info" "www DNS record is deleted"
        FLAG="true"
    fi
    if [ "$FLAG" == "false" ]; then
        log "info" "Nothing is Deleted. There are no DNS records"
    fi
    exit
fi

# Create or update DNS A record
if [ "$(echo $A_DNS_RECORD | jq -r '.result | length')" -eq 1 ]; then # root DNS record exist
    A_DNS_ID="$(echo $A_DNS_RECORD | jq -r '.result[0].id')"
    A_DNS_CONTENT="$(echo $A_DNS_RECORD | jq -r '.result[0].content')"
    A_DNS_TTL="$(echo $A_DNS_RECORD | jq -r '.result[0].ttl')"
    A_DNS_PROXIED="$(echo $A_DNS_RECORD | jq -r '.result[0].proxied')"
    if [ "$A_DNS_CONTENT" != $CURRENT_IP -o "$A_DNS_TTL" != "$TTL" -o "$A_DNS_PROXIED" != "$PROXIED" ]; then
        update_dns_record "A" "$DOMAIN" "$TTL" "$(date "+%Y-%m-%d %H:%M:%S"): root domain from ddns.sh" "$CURRENT_IP" "$A_DNS_ID"
        log "info" "Root DNS record is successfully changed Domain: $DOMAIN IP: $A_DNS_CONTENT to $CURRENT_IP TTL: $A_DNS_TTL to $TTL proxied: $A_DNS_PROXIED to $PROXIED"
    else
        log "info" "Root DNS record is not changed Domain: $DOMAIN IP: $CURRENT_IP TTL: $TTL proxied: $PROXIED"
    fi
else # root DNS record does not exist
    create_dns_record "A" "$DOMAIN" "$TTL" "$(date "+%Y-%m-%d %H:%M:%S"): root domain from ddns.sh" "$CURRENT_IP"
    log "info" "Root DNS record is successfully created Domain: $DOMAIN IP: $CURRENT_IP TTL: $TTL proxied: $PROXIED"
fi

# Create or update DNS CNAME records
if [ "$(echo $S_DNS_RECORD | jq -r '.result | length')" -eq 1 ]; then # sub DNS record exist
    S_DNS_ID="$(echo $S_DNS_RECORD | jq -r '.result[0].id')"
    S_DNS_CONTENT="$(echo $S_DNS_RECORD | jq -r '.result[0].content')"
    S_DNS_TTL="$(echo $S_DNS_RECORD | jq -r '.result[0].ttl')"
    S_DNS_PROXIED="$(echo $S_DNS_RECORD | jq -r '.result[0].proxied')"
    if [ "$S_DNS_CONTENT" != "$DOMAIN" -o "$S_DNS_TTL" != "$C_TTL" -o "$S_DNS_PROXIED" != "$PROXIED" ]; then
        update_dns_record "cname" "*.$DOMAIN" "$C_TTL" "$(date "+%Y-%m-%d %H:%M:%S"): sub domain from ddns.sh" "$DOMAIN" "$S_DNS_ID"
        log "info" "Sub DNS record is successfully changed Domain: $S_DNS_CONTENT to *.$DOMAIN cname: $DOMAIN  TTL: $S_DNS_TTL to $C_TTL proxied: $S_DNS_PROXIED to $PROXIED"
    else
        log "info" "Sub DNS record is not changed Domain: *.$DOMAIN cname: $DOMAIN TTL: $C_TTL proxied: $PROXIED"
    fi
else # sub DNS record does not exist
    create_dns_record "cname" "*.$DOMAIN" "$C_TTL" "$(date "+%Y-%m-%d %H:%M:%S"): sub domain from ddns.sh" "$DOMAIN"
    log "info" "Sub DNS record is successfully created Domain: *.$DOMAIN cname: $DOMAIN TTL: $C_TTL proxied: $PROXIED"
fi

if [ "$(echo $W_DNS_RECORD | jq -r '.result | length')" -eq 1 ]; then # www DNS record exist
    W_DNS_ID="$(echo $W_DNS_RECORD | jq -r '.result[0].id')"
    W_DNS_CONTENT="$(echo $W_DNS_RECORD | jq -r '.result[0].content')"
    W_DNS_TTL="$(echo $W_DNS_RECORD | jq -r '.result[0].ttl')"
    W_DNS_PROXIED="$(echo $W_DNS_RECORD | jq -r '.result[0].proxied')"
    if [ "$W_DNS_CONTENT" != "$DOMAIN" -o "$W_DNS_TTL" != "$C_TTL" -o "$W_DNS_PROXIED" != "$PROXIED" ]; then
        update_dns_record "cname" "www.$DOMAIN" "$C_TTL" "$(date "+%Y-%m-%d %H:%M:%S"): www domain from ddns.sh" "$DOMAIN" "$W_DNS_ID"
        log "info" "www DNS record is successfully changed Domain: $W_DNS_CONTENT to www.$DOMAIN cname: $DOMAIN TTL: $W_DNS_TTL to $C_TTL proxied: $W_DNS_PROXIED to $PROXIED"
    else
        log "info" "www DNS record is not changed Domain: www.$DOMAIN cname: $DOMAIN TTL: $C_TTL proxied: $PROXIED"
    fi
else # www DNS record does not exist
    create_dns_record "cname" "www.$DOMAIN" "$C_TTL" "$(date "+%Y-%m-%d %H:%M:%S"): www domain from ddns.sh" "$DOMAIN"
    log "info" "www DNS record is successfully created Domain: www.$DOMAIN cname: $DOMAIN TTL: $C_TTL proxied: $PROXIED"
fi