resource "aws_vpc" "cluster-vpc" {
    cidr_block = "${var.aws_vpc_cidr_block}"

    #DNS Related Entries
    enable_dns_support = true
    enable_dns_hostnames = true

    tags {
        Name = "kubernetes-${var.aws_cluster_name}-vpc"
    }
}


resource "aws_eip" "cluster-nat-eip" {
  count    = "${length(var.aws_cidr_subnets_public)}"
  vpc      = true
}



resource "aws_internet_gateway" "cluster-vpc-internetgw" {
  vpc_id = "${aws_vpc.cluster-vpc.id}"

  tags {
      Name = "kubernetes-${var.aws_cluster_name}-internetgw"
  }
}

resource "aws_subnet" "cluster-vpc-subnets-public" {
    vpc_id = "${aws_vpc.cluster-vpc.id}"
    count="${length(var.aws_avail_zones)}"
    availability_zone = "${element(var.aws_avail_zones, count.index)}"
    cidr_block = "${element(var.aws_cidr_subnets_public, count.index)}"

    tags {
        Name = "kubernetes-${var.aws_cluster_name}-${element(var.aws_avail_zones, count.index)}-public"
    }
}

resource "aws_nat_gateway" "cluster-nat-gateway" {
    count = "${length(var.aws_cidr_subnets_public)}"
    allocation_id = "${element(aws_eip.cluster-nat-eip.*.id, count.index)}"
    subnet_id = "${element(aws_subnet.cluster-vpc-subnets-public.*.id, count.index)}"

}

resource "aws_subnet" "cluster-vpc-subnets-private" {
    vpc_id = "${aws_vpc.cluster-vpc.id}"
    count="${length(var.aws_avail_zones)}"
    availability_zone = "${element(var.aws_avail_zones, count.index)}"
    cidr_block = "${element(var.aws_cidr_subnets_private, count.index)}"

    tags {
        Name = "kubernetes-${var.aws_cluster_name}-${element(var.aws_avail_zones, count.index)}-private"
    }
}

#Routing in VPC

#TODO: Do we need two routing tables for each subnet for redundancy or is one enough?

resource "aws_route_table" "kubernetes-public" {
    vpc_id = "${aws_vpc.cluster-vpc.id}"
    route {
        cidr_block = "0.0.0.0/0"
        gateway_id = "${aws_internet_gateway.cluster-vpc-internetgw.id}"
    }
    tags {
        Name = "kubernetes-${var.aws_cluster_name}-routetable-public"
    }
}

resource "aws_route_table" "kubernetes-private" {
    count = "${length(var.aws_cidr_subnets_private)}"
    vpc_id = "${aws_vpc.cluster-vpc.id}"
    route {
        cidr_block = "0.0.0.0/0"
        gateway_id = "${element(aws_nat_gateway.cluster-nat-gateway.*.id, count.index)}"
    }
    tags {
        Name = "kubernetes-${var.aws_cluster_name}-routetable-private-${count.index}"
    }
}

resource "aws_route_table_association" "kubernetes-public" {
    count = "${length(var.aws_cidr_subnets_public)}"
    subnet_id = "${element(aws_subnet.cluster-vpc-subnets-public.*.id,count.index)}"
    route_table_id = "${aws_route_table.kubernetes-public.id}"

}

resource "aws_route_table_association" "kubernetes-private" {
    count = "${length(var.aws_cidr_subnets_private)}"
    subnet_id = "${element(aws_subnet.cluster-vpc-subnets-private.*.id,count.index)}"
    route_table_id = "${element(aws_route_table.kubernetes-private.*.id,count.index)}"

}


#Kubernetes Security Groups

resource "aws_security_group" "kubernetes" {
    name = "kubernetes-${var.aws_cluster_name}-securitygroup"
    vpc_id = "${aws_vpc.cluster-vpc.id}"

    tags {
        Name = "kubernetes-${var.aws_cluster_name}-securitygroup"
    }
}

resource "aws_security_group_rule" "allow-all-ingress" {
    type = "ingress"
    from_port = 0
    to_port = 65535
    protocol = "-1"
    cidr_blocks= ["${var.aws_vpc_cidr_block}"]
    security_group_id = "${aws_security_group.kubernetes.id}"
}

resource "aws_security_group_rule" "allow-all-egress" {
    type = "egress"
    from_port = 0
    to_port = 65535
    protocol = "-1"
    cidr_blocks = ["0.0.0.0/0"]
    security_group_id = "${aws_security_group.kubernetes.id}"
}


resource "aws_security_group_rule" "allow-ssh-connections" {
    type = "ingress"
    from_port = 22
    to_port = 22
    protocol = "TCP"
    cidr_blocks = ["0.0.0.0/0"]
    security_group_id = "${aws_security_group.kubernetes.id}"
}