How to generate a map from two disjoint datastructures in Terraform?

Terraform
1

I have a list and a map like so:

locals {

  traffic_rules = [
    {
      name         = "eu-pool"
      geo_mappings = ["GEO-EU"]
      failover     = [local.endpoint_pools.a, local.endpoint_pools.b, local.endpoint_pools.c]
    },
    {
      name         = "world-pool"
      geo_mappings = ["WORLD"]
      failover     = [local.endpoint_pools.a]
    },
  ]

  endpoint_pools = {
    a = [
      {
        fqdn   = "endpoint_pool.a.com."
        weight = 1
    }]
    b = [
      {
        fqdn   = "endpoint_pool.b1.com."
        weight = 1
      },
      {
        fqdn   = "endpoint_pool.b2.com."
        weight = 1
    }]
    c = [
      {
        fqdn   = "endpoint_pool.c.com."
        weight = 1
    }]
  }

Basically, I want to gather:

  1. the index of failover[item] in traffic_rules when I iterate through it
  2. the name of the traffic_rule, eg “eu-pool”
  3. the string “a/b.c” from local.endpoint_pools.a/b/c (these are also keys in endpoint_pools map)

In the end, I need to be able to generate a flattened map like below:

{
“eu-pool-a” =	{
    endpoint_pool_name = "a"
	priority = 1
	top_profile_name = “eu-pool”, 
	bottom_profile_name = “bottom-profile-a”
	}
“eu-pool-b” =	{
    endpoint_pool_name = "b"
	priority = 2
	top_profile_name = “eu-pool”, 
	bottom_profile_name = “bottom-profile-b”
	}
“eu-pool-c” =	{
    endpoint_pool_name = "c"
	priority = 3
	top_profile_name = “eu-pool”, 
	bottom_profile_name = “bottom-profile-c”
	}
“world-pool-a” =	{
    endpoint_pool_name = "a"
	priority = 1
	top_profile_name = “world-pool”, 
	bottom_profile_name = “bottom-profile-a”
	}
}

I started off trying to flatten traffic_rules, then realized that TF is substituting local.endpoint_pools.a/b/c into its actual contents, so I am completely losing the context/string of a/b/c.