package envoy

// BootstrapTplArgs is the set of arguments that may be interpolated into the
// Envoy bootstrap template.
type BootstrapTplArgs struct {
	// ProxyCluster is the cluster name for the the Envoy `node` specification and
	// is typically the same as the ProxyID.
	ProxyCluster string

	// ProxyID is the ID of the proxy service instance as registered with the
	// local Consul agent. This must be used as the Envoy `node.id` in order for
	// the agent to deliver the correct configuration.
	ProxyID string

	// AgentAddress is the IP address of the local agent where the proxy instance
	// is registered.
	AgentAddress string

	// AgentPort is the gRPC port exposed on the local agent.
	AgentPort string

	// AgentTLS is true of the local agent gRPC service should be accessed over
	// TLS.
	AgentTLS bool

	// AgentCAFile is the CA file to use to verify the local agent gRPC service if
	// TLS is enabled.
	AgentCAFile string

	// AdminBindAddress is the address the Envoy admin server should bind to.
	AdminBindAddress string

	// AdminBindPort is the port the Envoy admin server should bind to.
	AdminBindPort string

	// LocalAgentClusterName is the name reserved for the local Consul agent gRPC
	// service and is expected to be used for that purpose.
	LocalAgentClusterName string

	// Token is the Consul ACL token provided which is required to make gRPC
	// discovery requests. If non-empty, this must be configured as the gRPC
	// service "initial_metadata" with the key "x-consul-token" in order to
	// authorize the discovery streaming RPCs.
	Token string

	// StaticClustersJSON is JSON string, each is expected to be a valid Cluster
	// definition. They are appended to the "static_resources.clusters" list. Note
	// that cluster names should be chosen in such a way that they won't collide
	// with service names since we use plain service names as cluster names in xDS
	// to make metrics population simpler and cluster names mush be unique. See
	// https://www.envoyproxy.io/docs/envoy/v1.9.0/api-v2/api/v2/cds.proto.
	StaticClustersJSON string

	// StaticListenersJSON is a JSON string containing zero or more Listener
	// definitions. They are appended to the "static_resources.listeners" list. A
	// single listener should be given as a plain object, if more than one is to
	// be added, they should be separated by a comma suitable for direct injection
	// into a JSON array.
	// See https://www.envoyproxy.io/docs/envoy/v1.9.0/api-v2/api/v2/lds.proto.
	StaticListenersJSON string

	// StatsSinksJSON is a JSON string containing an array in the right format
	// to be rendered as the body of the `stats_sinks` field at the top level of
	// the bootstrap config. It's format may vary based on Envoy version used. See
	// https://www.envoyproxy.io/docs/envoy/v1.9.0/api-v2/config/metrics/v2/stats.proto#config-metrics-v2-statssink.
	StatsSinksJSON string

	// StatsConfigJSON is a JSON string containing an object in the right format
	// to be rendered as the body of the `stats_config` field at the top level of
	// the bootstrap config. It's format may vary based on Envoy version used. See
	// https://www.envoyproxy.io/docs/envoy/v1.9.0/api-v2/config/metrics/v2/stats.proto#envoy-api-msg-config-metrics-v2-statsconfig.
	StatsConfigJSON string

	// StatsFlushInterval is the time duration between Envoy stats flushes. It is
	// in proto3 "duration" string format for example "1.12s" See
	// https://developers.google.com/protocol-buffers/docs/proto3#json and
	// https://www.envoyproxy.io/docs/envoy/v1.9.0/api-v2/config/bootstrap/v2/bootstrap.proto#bootstrap
	StatsFlushInterval string

	// TracingConfigJSON is a JSON string containing an object in the right format
	// to be rendered as the body of the `tracing` field at the top level of
	// the bootstrap config. It's format may vary based on Envoy version used.
	// See https://www.envoyproxy.io/docs/envoy/v1.9.0/api-v2/config/trace/v2/trace.proto.
	TracingConfigJSON string
}

const bootstrapTemplate = `{
  "admin": {
    "access_log_path": "/dev/null",
    "address": {
      "socket_address": {
        "address": "{{ .AdminBindAddress }}",
        "port_value": {{ .AdminBindPort }}
      }
    }
  },
  "node": {
    "cluster": "{{ .ProxyCluster }}",
    "id": "{{ .ProxyID }}"
  },
  "static_resources": {
    "clusters": [
      {
        "name": "{{ .LocalAgentClusterName }}",
        "connect_timeout": "1s",
        "type": "STATIC",
        {{- if .AgentTLS -}}
        "tls_context": {
          "common_tls_context": {
            "validation_context": {
              "trusted_ca": {
                "filename": "{{ .AgentCAFile }}"
              }
            }
          }
        },
        {{- end }}
        "http2_protocol_options": {},
        "hosts": [
          {
            "socket_address": {
              "address": "{{ .AgentAddress }}",
              "port_value": {{ .AgentPort }}
            }
          }
        ]
      }
      {{- if .StaticClustersJSON -}}
      ,
      {{ .StaticClustersJSON }}
      {{- end }}
    ]{{- if .StaticListenersJSON -}}
    ,
    "listeners": [
      {{ .StaticListenersJSON }}
    ]
    {{- end }}
  },
  {{- if .StatsSinksJSON }}
  "stats_sinks": {{ .StatsSinksJSON }},
  {{- end }}
  {{- if .StatsConfigJSON }}
  "stats_config": {{ .StatsConfigJSON }},
  {{- end }}
  {{- if .StatsFlushInterval }}
  "stats_flush_interval": "{{ .StatsFlushInterval }}",
  {{- end }}
  {{- if .TracingConfigJSON }}
  "tracing": {{ .TracingConfigJSON }},
  {{- end }}
  "dynamic_resources": {
    "lds_config": { "ads": {} },
    "cds_config": { "ads": {} },
    "ads_config": {
      "api_type": "GRPC",
      "grpc_services": {
        "initial_metadata": [
          {
            "key": "x-consul-token",
            "value": "{{ .Token }}"
          }
        ],
        "envoy_grpc": {
          "cluster_name": "{{ .LocalAgentClusterName }}"
        }
      }
    }
  }
}
`