# Version: 1.0.2
# Usage:
# oci-curl <host> <method> [file-to-send-as-body] <request-target> [extra-curl-args]
#
# ex:
# oci-curl iaas.us-ashburn-1.oraclecloud.com get "/20160918/instances?compartmentId=some-compartment-ocid"
# oci-curl iaas.us-ashburn-1.oraclecloud.com post ./request.json "/20160918/vcns"

function oci-curl {
    # TODO: update these values to your own
	local tenancyId="ocid1.tenancy.oc1..aaaaaaaaba3pv6wkcr4jqae5f15p2b2m2yt2j6rx32uzr4h25vqstifsfdsq";
	local authUserId="ocid1.user.oc1..aaaaaaaat5nvwcna5j6aqzjcaty5eqbb6qt2jvpkanghtgdaqedqw3rynjq";
	local keyFingerprint="20:3b:97:13:55:1c:5b:0d:d3:37:d8:50:4e:c5:3a:34";
	local privateKeyPath="/Users/someuser/.oci/oci_api_key.pem";

    local alg=rsa-sha256
    local sigVersion="1"
    local now="$(LC_ALL=C \date -u "+%a, %d %h %Y %H:%M:%S GMT")"
    local host=$1
    local method=$2
    local extra_args
    local keyId="$tenancyId/$authUserId/$keyFingerprint"

    case $method in

        "get" | "GET")
            local target=$3
            extra_args=("${@: 4}")
            local curl_method="GET";
            local request_method="get";
            ;;

        "delete" | "DELETE")
            local target=$3
            extra_args=("${@: 4}")
            local curl_method="DELETE";
            local request_method="delete";
            ;;

        "head" | "HEAD")
            local target=$3
            extra_args=("--head" "${@: 4}")
            local curl_method="HEAD";
            local request_method="head";
            ;;

        "post" | "POST")
            local body=$3
            local target=$4
            extra_args=("${@: 5}")
            local curl_method="POST";
            local request_method="post";
            local content_sha256="$(openssl dgst -binary -sha256 < $body | openssl enc -e -base64)";
            local content_type="application/json";
            local content_length="$(wc -c < $body | xargs)";
            ;;

        "put" | "PUT")
            local body=$3
            local target=$4
            extra_args=("${@: 5}")
            local curl_method="PUT"
            local request_method="put"
            local content_sha256="$(openssl dgst -binary -sha256 < $body | openssl enc -e -base64)";
            local content_type="application/json";
            local content_length="$(wc -c < $body | xargs)";
            ;;

        *) echo "invalid method"; return;;
    esac

    # This line will url encode all special characters in the request target except "/", "?", "=", and "&", since those characters are used 
    # in the request target to indicate path and query string structure. If you need to encode any of "/", "?", "=", or "&", such as when
    # used as part of a path value or query string key or value, you will need to do that yourself in the request target you pass in.
    local escaped_target="$(echo $( rawurlencode "$target" ))"
    
    local request_target="(request-target): $request_method $escaped_target"
    local date_header="date: $now"
    local host_header="host: $host"
    local content_sha256_header="x-content-sha256: $content_sha256"
    local content_type_header="content-type: $content_type"
    local content_length_header="content-length: $content_length"
    local signing_string="$request_target\n$date_header\n$host_header"
    local headers="(request-target) date host"
    local curl_header_args
    curl_header_args=(-H "$date_header")
    local body_arg
    body_arg=()

    if [ "$curl_method" = "PUT" -o "$curl_method" = "POST" ]; then
        signing_string="$signing_string\n$content_sha256_header\n$content_type_header\n$content_length_header"
        headers=$headers" x-content-sha256 content-type content-length"
        curl_header_args=("${curl_header_args[@]}" -H "$content_sha256_header" -H "$content_type_header" -H "$content_length_header")
        body_arg=(--data-binary @${body})
    fi

    local sig=$(printf '%b' "$signing_string" | \
                openssl dgst -sha256 -sign $privateKeyPath | \
                openssl enc -e -base64 | tr -d '\n')

    curl "${extra_args[@]}" "${body_arg[@]}" -X $curl_method -sS https://${host}${escaped_target} "${curl_header_args[@]}" \
        -H "Authorization: Signature version=\"$sigVersion\",keyId=\"$keyId\",algorithm=\"$alg\",headers=\"${headers}\",signature=\"$sig\""
}

# url encode all special characters except "/", "?", "=", and "&"
function rawurlencode {
  local string="${1}"
  local strlen=${#string}
  local encoded=""
  local pos c o

  for (( pos=0 ; pos<strlen ; pos++ )); do
     c=${string:$pos:1}
     case "$c" in
        [-_.~a-zA-Z0-9] | "/" | "?" | "=" | "&" ) o="${c}" ;;
        * )               printf -v o '%%%02x' "'$c"
     esac
     encoded+="${o}"
  done

  echo "${encoded}"
}