resource "azurerm_resource_group" "main" {
  location = var.location
  name     = var.resource_group_name
}

resource "azurerm_virtual_network" "main" {
  address_space       = var.vnet_address_space
  location            = var.location
  name                = var.vnet_name
  resource_group_name = var.resource_group_name
  depends_on = [
    azurerm_resource_group.main
  ]
}

resource "azurerm_subnet" "default" {
  address_prefixes     = var.subnet_address_prefixes
  name                 = var.subnet_name
  resource_group_name  = var.resource_group_name
  virtual_network_name = var.vnet_name
  depends_on = [
    azurerm_virtual_network.main
  ]
}

resource "azurerm_log_analytics_workspace" "main" {
  name                = "aksloganalytics${replace(var.aks_cluster_name, "_", "")}"
  location            = var.location
  resource_group_name = var.resource_group_name
  sku                 = "PerGB2018"
  retention_in_days   = 30
  depends_on = [
    azurerm_resource_group.main
  ]
}

resource "azurerm_kubernetes_cluster" "main" {
  automatic_upgrade_channel    = "patch"
  dns_prefix                   = var.aks_dns_prefix
  image_cleaner_enabled        = true
  image_cleaner_interval_hours = 168
  location                     = var.location
  name                         = var.aks_cluster_name
  oidc_issuer_enabled          = true
  resource_group_name          = var.resource_group_name
  workload_identity_enabled    = true

  default_node_pool {
    auto_scaling_enabled      = true
    max_count                 = var.aks_node_pool_max_count
    min_count                 = var.aks_node_pool_min_count
    name                      = "agentpool"
    vm_size                   = var.aks_node_vm_size
    zones                     = var.aks_node_zones
    temporary_name_for_rotation = "temppool"
    upgrade_settings {
      max_surge = "10%"
    }
  }

  identity {
    type = "SystemAssigned"
  }

  maintenance_window_auto_upgrade {
    day_of_week = "Sunday"
    duration    = 8
    frequency   = "Weekly"
    interval    = 1
    start_time  = "00:00"
    utc_offset  = "+00:00"
  }

  maintenance_window_node_os {
    day_of_week = "Sunday"
    duration    = 8
    frequency   = "Weekly"
    interval    = 1
    start_time  = "00:00"
    utc_offset  = "+00:00"
  }

  oms_agent {
    log_analytics_workspace_id      = azurerm_log_analytics_workspace.main.id
    msi_auth_for_monitoring_enabled = true
  }

  depends_on = [
    azurerm_resource_group.main,
    azurerm_log_analytics_workspace.main
  ]
}

resource "azurerm_monitor_data_collection_rule" "aks_monitoring" {
  kind                = "Linux"
  location            = var.location
  name                = "MSCI-${var.location}-${var.aks_cluster_name}"
  resource_group_name = var.resource_group_name

  data_flow {
    destinations = ["ciworkspace"]
    streams      = ["Microsoft-ContainerLog", "Microsoft-ContainerLogV2", "Microsoft-KubeEvents", "Microsoft-KubePodInventory"]
  }

  data_sources {
    extension {
      extension_json = jsonencode({
        dataCollectionSettings = {
          enableContainerLogV2   = true
          interval               = "1m"
          namespaceFilteringMode = "Off"
        }
      })
      extension_name = "ContainerInsights"
      name           = "ContainerInsightsExtension"
      streams        = ["Microsoft-ContainerLog", "Microsoft-ContainerLogV2", "Microsoft-KubeEvents", "Microsoft-KubePodInventory"]
    }
  }

  destinations {
    log_analytics {
      name                  = "ciworkspace"
      workspace_resource_id = azurerm_log_analytics_workspace.main.id
    }
  }

  depends_on = [
    azurerm_resource_group.main,
    azurerm_log_analytics_workspace.main
  ]
}

resource "azurerm_monitor_action_group" "alerts" {
  name                = "RecommendedAlertRules-AG-c92012"
  resource_group_name = var.resource_group_name
  short_name          = "alertc92012"

  email_receiver {
    email_address           = var.alert_email_address
    name                    = "Email_-EmailAction-"
    use_common_alert_schema = true
  }

  depends_on = [
    azurerm_resource_group.main
  ]
}

resource "azurerm_monitor_metric_alert" "cpu_alert" {
  auto_mitigate       = false
  frequency           = "PT5M"
  name                = "CPU Usage Percentage - ${var.aks_cluster_name}"
  resource_group_name = var.resource_group_name
  scopes              = [azurerm_kubernetes_cluster.main.id]

  action {
    action_group_id = azurerm_monitor_action_group.alerts.id
  }

  criteria {
    aggregation      = "Average"
    metric_name      = "node_cpu_usage_percentage"
    metric_namespace = "Microsoft.ContainerService/managedClusters"
    operator         = "GreaterThan"
    threshold        = 95
  }

  depends_on = [
    azurerm_resource_group.main
  ]
}

resource "azurerm_monitor_metric_alert" "memory_alert" {
  auto_mitigate       = false
  frequency           = "PT5M"
  name                = "Memory Working Set Percentage - ${var.aks_cluster_name}"
  resource_group_name = var.resource_group_name
  scopes              = [azurerm_kubernetes_cluster.main.id]

  action {
    action_group_id = azurerm_monitor_action_group.alerts.id
  }

  criteria {
    aggregation      = "Average"
    metric_name      = "node_memory_working_set_percentage"
    metric_namespace = "Microsoft.ContainerService/managedClusters"
    operator         = "GreaterThan"
    threshold        = 100
  }

  depends_on = [
    azurerm_resource_group.main
  ]
}