provider "aws" {
  region = "us-west-1"
}

locals {

  nat_gws_only_if_igw = {for k, v in local.subnets:
  k => [
  for igw in aws_internet_gateway.gw-vpc:
  v if igw.tags.Name == "gw-${regex("^(.*).$",v.az)[0]}-${v.vpc_name}" // "gw-us-west-1-vpc1"
  ]
  }

  flattened_nat_gws_only_if_igw = {for k, v in local.nat_gws_only_if_igw:
  k => v[0] if can(v[0])
  }

  vpcs = {
    vpc0 = {
      cidr_block = "10.0.0.0/16"
    },
    vpc1 = {
      cidr_block = "10.1.0.0/16"
      create_igw = false
    }
  }

  subnets = {
    0 = {
      vpc_name = "vpc0"
      az = "us-west-1a"
      name = "1A"
      public = "10.0.32.0/20"
      private = "10.0.0.0/19"
    }
    1 = {
      vpc_name = "vpc0"
      az = "us-west-1b"
      name = "1B"
      public = "10.0.96.0/20"
      private = "10.0.64.0/19"
    }
    2 = {
      vpc_name = "vpc1"
      az = "us-west-1a"
      name = "1A"
      public = "10.1.32.0/20"
      private = "10.1.0.0/19"
    }
    3 = {
      vpc_name = "vpc1"
      az = "us-west-1b"
      name = "1B"
      public = "10.1.96.0/20"
      private = "10.1.64.0/19"
    }
  }

  created_private_subnets = {
  for v in aws_subnet.vpc-private:
  v.tags.Name => v
  }

  created_nat_gws = {
  for v in aws_nat_gateway.natgw-vpc:
  v.tags.Name => v
  }

  nat_gws = {
    us-west-1 = {for k, v in local.created_nat_gws:
    k=>v
    }
  }

  subnet_info = {
    us-west-1 = {for v in local.subnets:
    ("${v.vpc_name}-private-${v.name}") => {
      az = v.az
      short_name = v.name
      vpc_name = v.vpc_name
    }
    }
  }

}

resource aws_vpc the_vpcs {
  for_each = local.vpcs
  cidr_block = each.value.cidr_block
  instance_tenancy = "default"
  tags = {
    Name = "us-west-1-${each.key}"
  }
}

resource aws_internet_gateway gw-vpc {
  for_each = {for k, v in aws_vpc.the_vpcs: k=> v if try(local.vpcs[k].create_igw, true)==true}
  vpc_id = aws_vpc.the_vpcs[each.key].id

  tags = {
    Name = "gw-us-west-1-${each.key}"
  }
}

resource aws_eip natgw-eip-vpc {
  for_each = {for k, v in local.subnets: k=>v if try(local.vpcs[v.vpc_name].create_igw, true)==true}
  vpc = true
  tags = {
    Name = "${each.value.vpc_name}-nat-${each.value.az}"
  }
}

resource aws_nat_gateway natgw-vpc {
  for_each = local.flattened_nat_gws_only_if_igw
  allocation_id = aws_eip.natgw-eip-vpc[each.key].id
  subnet_id = aws_subnet.vpc-private[each.key].id
  tags = {
    Name = "${each.value.vpc_name}-natgw-${each.value.name}"
  }
}

resource aws_subnet vpc-private {
  for_each = local.subnets
  vpc_id = aws_vpc.the_vpcs[each.value.vpc_name].id
  availability_zone = local.subnets[each.key].az
  cidr_block = local.subnets[each.key].private
  tags = {
    Name = "${each.value.vpc_name}-private-${each.value.name}"
  }
}

resource aws_route_table the_private_route_table {
  for_each = {for k, v in local.created_private_subnets: k=>v if length(regexall("-private-", k))>0}
  vpc_id = each.value.vpc_id

  // default route
  dynamic route {
    for_each = {for k, v in local.nat_gws["us-west-1"]: k=>v if try(k == local.nat_gws["us-west-1"]["${local.subnet_info["us-west-1"][each.key].vpc_name}-natgw-${local.subnet_info["us-west-1"][each.key].short_name}"].tags.Name, false)!=false}
    content {
      cidr_block = "0.0.0.0/0"
      nat_gateway_id = local.nat_gws["us-west-1"]["${local.subnet_info["us-west-1"][each.key].vpc_name}-natgw-${local.subnet_info["us-west-1"][each.key].short_name}"].id
    }
  }
}

resource aws_route_table_association src-ra-vpc-private {
  for_each = {for k, v in aws_route_table.the_private_route_table: k=>v}
  subnet_id = local.created_private_subnets[each.key].id
  route_table_id = each.value.id
}

output test {
  value = local.nat_gws["us-west-1"]
}

output test2 {
  value = {
    private_subnets = local.created_private_subnets
    routes = aws_route_table.the_private_route_table
    subnet_info = local.subnet_info
  }
}

output test3 {
  value = {for key, val in local.created_private_subnets:
  key=>
  {for k, v in local.nat_gws["us-west-1"]:
  k=>v if can(local.nat_gws["us-west-1"]["${local.subnet_info["us-west-1"][key].vpc_name}-natgw-${local.subnet_info["us-west-1"][key].short_name}"].tags) && k == local.nat_gws["us-west-1"]["${local.subnet_info["us-west-1"][key].vpc_name}-natgw-${local.subnet_info["us-west-1"][key].short_name}"].tags.Name
  }
  if length(regexall("-private-", key))>0 && try(key==local.nat_gws["us-west-1"]["${local.subnet_info["us-west-1"][key].vpc_name}-natgw-${local.subnet_info["us-west-1"][key].short_name}"].tags.Name, false)!=false
  }
}