# ── Vault LB — GCP Global HTTPS LB ───────────────────────────────────────────
#
# LB frontend is unchanged: forwarding rule → target HTTPS proxy → url map → backend.
# Backend uses GKE container-native NEGs (cut over from GCE instance groups).
#
# Architecture (GKE):
#   - Vault Helm chart runs 3 pods in namespace: vault on GKE neuron-platform cluster
#   - GKE auto-creates zonal container-native NEGs via Service annotation:
#       cloud.google.com/neg: '{"exposed_ports":{"8200":{}}}'
#   - NEG backends replace GCE instance group backends in the Global HTTPS LB
#   - DNS unchanged: vault.neuralplatform.ai → 34.54.164.21 (same GCP Global LB IP)
#
# GCE nodes (vault-node-1/2/3) and their instance groups have been removed.
# GKE Vault (via Workload Identity + vault-unseal SA) is the sole Vault backend.

locals {
  # Container-native NEG names created by GKE from the Vault Service annotation:
  #   cloud.google.com/neg: '{"exposed_ports":{"8200":{}}}'
  # GKE creates one NEG per zone where Vault pods are scheduled.
  # Confirmed with: gcloud compute network-endpoint-groups list --project neuron-785695
  vault_neg_names = {
    "us-central1-b" = "k8s1-bfbeff02-vault-vault-helm-gke-8200-db1a474f"
    "us-central1-c" = "k8s1-bfbeff02-vault-vault-helm-gke-8200-db1a474f"
    "us-central1-f" = "k8s1-bfbeff02-vault-vault-helm-gke-8200-db1a474f"
  }
}

# ── GKE container-native NEG data sources ────────────────────────────────────
# GKE auto-creates these when the Vault Service annotation is applied.

data "google_compute_network_endpoint_group" "vault_gke" {
  for_each = local.vault_neg_names
  name     = each.value
  zone     = each.key
  project  = var.project_id
}

# ── Firewall — GKE health checks ─────────────────────────────────────────────
# Allow GCP health check probers to reach pod IPs on port 8200.
# Container-native NEGs direct health checks to pod IPs (not node IPs).
# GKE Autopilot pod CIDR: 10.45.128.0/22 (from cluster ip_allocation_policy).
# Without this rule, GCP LB health checks fail → "no healthy upstream".
# No target_tags — applies to all instances/pods in the default network.
# Safe: GCP health check ranges (130.211.0.0/22, 35.191.0.0/16) are GCP-internal only.
resource "google_compute_firewall" "vault_api_gke" {
  name      = "vault-api-from-lb-gke"
  network   = "default"
  project   = var.project_id
  direction = "INGRESS"
  priority  = 1000

  allow {
    protocol = "tcp"
    ports    = ["8200"]
  }

  # GCP health check source ranges only — restricted port, low risk
  source_ranges = ["130.211.0.0/22", "35.191.0.0/16"]
}

# ── Regional HTTPS LB for vault.neuralplatform.ai ─────────────────────────────
# Global external HTTPS LB with a Google-managed cert for vault.neuralplatform.ai.
#
# TLS is terminated at the LB. Vault listens on plain 8200 internally.
# Cloudflare DNS A record for vault.neuralplatform.ai → vault_lb_ip output below.

resource "google_compute_global_address" "vault" {
  name    = "vault-ip"
  project = var.project_id
}

resource "google_compute_managed_ssl_certificate" "vault" {
  name    = "vault-cert"
  project = var.project_id

  managed {
    domains = ["vault.neuralplatform.ai"]
  }
}

resource "google_compute_health_check" "vault" {
  name    = "vault-health"
  project = var.project_id

  # Vault listens on plain HTTP (tls_disable = true) — TLS is terminated at the LB
  http_health_check {
    port         = 8200
    request_path = "/v1/sys/health?standbyok=true&sealedok=true&uninitcode=200"
  }

  check_interval_sec  = 15
  timeout_sec         = 5
  healthy_threshold   = 2
  unhealthy_threshold = 3
}

resource "google_compute_backend_service" "vault" {
  name                  = "vault-backend"
  project               = var.project_id
  load_balancing_scheme = "EXTERNAL_MANAGED"
  protocol              = "HTTP"   # Vault serves plain HTTP; TLS terminates at the LB
  timeout_sec           = 30

  health_checks = [google_compute_health_check.vault.self_link]

  # GKE container-native NEG backends — one per zone where Vault pods are scheduled.
  # RATE balancing mode is required for NEGs with EXTERNAL_MANAGED load balancers.
  dynamic "backend" {
    for_each = data.google_compute_network_endpoint_group.vault_gke
    content {
      group                 = backend.value.self_link
      balancing_mode        = "RATE"
      max_rate_per_endpoint = 100
    }
  }

  log_config {
    enable      = true
    sample_rate = 1.0
  }
}

resource "google_compute_url_map" "vault" {
  name            = "vault-urlmap"
  project         = var.project_id
  default_service = google_compute_backend_service.vault.self_link
}

resource "google_compute_target_https_proxy" "vault" {
  name             = "vault-https-proxy"
  project          = var.project_id
  url_map          = google_compute_url_map.vault.self_link
  ssl_certificates = [google_compute_managed_ssl_certificate.vault.self_link]
}

resource "google_compute_target_http_proxy" "vault_redirect" {
  name    = "vault-http-proxy"
  project = var.project_id
  url_map = google_compute_url_map.vault_redirect.self_link
}

resource "google_compute_url_map" "vault_redirect" {
  name    = "vault-urlmap-http-redirect"
  project = var.project_id

  default_url_redirect {
    https_redirect         = true
    redirect_response_code = "MOVED_PERMANENTLY_DEFAULT"
    strip_query            = false
  }
}

resource "google_compute_global_forwarding_rule" "vault_https" {
  name                  = "vault-fwd-https"
  project               = var.project_id
  target                = google_compute_target_https_proxy.vault.self_link
  ip_address            = google_compute_global_address.vault.address
  port_range            = "443"
  load_balancing_scheme = "EXTERNAL_MANAGED"
}

resource "google_compute_global_forwarding_rule" "vault_http" {
  name                  = "vault-fwd-http"
  project               = var.project_id
  target                = google_compute_target_http_proxy.vault_redirect.self_link
  ip_address            = google_compute_global_address.vault.address
  port_range            = "80"
  load_balancing_scheme = "EXTERNAL_MANAGED"
}

# ── Outputs ───────────────────────────────────────────────────────────────────

output "vault_lb_ip" {
  description = "Global IP for vault.neuralplatform.ai — set as DNS A record in Cloudflare (neuralplatform.ai zone)"
  value       = google_compute_global_address.vault.address
}