// The MIT License
//
// Copyright (c) 2020 Temporal Technologies Inc.  All rights reserved.
//
// Copyright (c) 2020 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package internal

import (
	"context"
	"crypto/tls"
	"fmt"
	"io"
	"time"

	commonpb "go.temporal.io/api/common/v1"
	enumspb "go.temporal.io/api/enums/v1"
	"go.temporal.io/api/workflowservice/v1"
	"go.temporal.io/sdk/internal/common/backoff"
	"google.golang.org/grpc"
	healthpb "google.golang.org/grpc/health/grpc_health_v1"

	"go.temporal.io/sdk/converter"
	"go.temporal.io/sdk/internal/common/metrics"
	ilog "go.temporal.io/sdk/internal/log"
	"go.temporal.io/sdk/log"
)

const (
	// DefaultNamespace is the namespace name which is used if not passed with options.
	DefaultNamespace = "default"

	// QueryTypeStackTrace is the build in query type for Client.QueryWorkflow() call. Use this query type to get the call
	// stack of the workflow. The result will be a string encoded in the EncodedValue.
	QueryTypeStackTrace string = "__stack_trace"

	// QueryTypeOpenSessions is the build in query type for Client.QueryWorkflow() call. Use this query type to get all open
	// sessions in the workflow. The result will be a list of SessionInfo encoded in the EncodedValue.
	QueryTypeOpenSessions string = "__open_sessions"

	healthCheckServiceName           = "temporal.api.workflowservice.v1.WorkflowService"
	defaultHealthCheckAttemptTimeout = 5 * time.Second
	defaultHealthCheckTimeout        = 10 * time.Second
)

type (
	// Client is the client for starting and getting information about a workflow executions as well as
	// completing activities asynchronously.
	Client interface {
		// ExecuteWorkflow starts a workflow execution and return a WorkflowRun instance and error
		// The user can use this to start using a function or workflow type name.
		// Either by
		//     ExecuteWorkflow(ctx, options, "workflowTypeName", arg1, arg2, arg3)
		//     or
		//     ExecuteWorkflow(ctx, options, workflowExecuteFn, arg1, arg2, arg3)
		// The errors it can return:
		//	- serviceerror.NotFound, if namespace does not exists
		//	- serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		//
		// The current timeout resolution implementation is in seconds and uses math.Ceil(d.Seconds()) as the duration. But is
		// subjected to change in the future.
		//
		// WorkflowRun has three methods:
		//  - GetID() string: which return workflow ID (which is same as StartWorkflowOptions.ID if provided)
		//  - GetRunID() string: which return the first started workflow run ID (please see below)
		//  - Get(ctx context.Context, valuePtr interface{}) error: which will fill the workflow
		//    execution result to valuePtr, if workflow execution is a success, or return corresponding
		//    error. This is a blocking API.
		// NOTE: if the started workflow return ContinueAsNewError during the workflow execution, the
		// return result of GetRunID() will be the started workflow run ID, not the new run ID caused by ContinueAsNewError,
		// however, Get(ctx context.Context, valuePtr interface{}) will return result from the run which did not return ContinueAsNewError.
		// Say ExecuteWorkflow started a workflow, in its first run, has run ID "run ID 1", and returned ContinueAsNewError,
		// the second run has run ID "run ID 2" and return some result other than ContinueAsNewError:
		// GetRunID() will always return "run ID 1" and  Get(ctx context.Context, valuePtr interface{}) will return the result of second run.
		// NOTE: DO NOT USE THIS API INSIDE A WORKFLOW, USE workflow.ExecuteChildWorkflow instead
		ExecuteWorkflow(ctx context.Context, options StartWorkflowOptions, workflow interface{}, args ...interface{}) (WorkflowRun, error)

		// GetWorkflow retrieves a workflow execution and return a WorkflowRun instance
		// - workflow ID of the workflow.
		// - runID can be default(empty string). if empty string then it will pick the last running execution of that workflow ID.
		//
		// WorkflowRun has three methods:
		//  - GetID() string: which return workflow ID (which is same as StartWorkflowOptions.ID if provided)
		//  - GetRunID() string: which return the first started workflow run ID (please see below)
		//  - Get(ctx context.Context, valuePtr interface{}) error: which will fill the workflow
		//    execution result to valuePtr, if workflow execution is a success, or return corresponding
		//    error. This is a blocking API.
		// NOTE: if the retrieved workflow returned ContinueAsNewError during the workflow execution, the
		// return result of GetRunID() will be the retrieved workflow run ID, not the new run ID caused by ContinueAsNewError,
		// however, Get(ctx context.Context, valuePtr interface{}) will return result from the run which did not return ContinueAsNewError.
		GetWorkflow(ctx context.Context, workflowID string, runID string) WorkflowRun

		// SignalWorkflow sends a signals to a workflow in execution
		// - workflow ID of the workflow.
		// - runID can be default(empty string). if empty string then it will pick the running execution of that workflow ID.
		// - signalName name to identify the signal.
		// The errors it can return:
		//	- serviceerror.NotFound
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		SignalWorkflow(ctx context.Context, workflowID string, runID string, signalName string, arg interface{}) error

		// SignalWithStartWorkflow sends a signal to a running workflow.
		// If the workflow is not running or not found, it starts the workflow and then sends the signal in transaction.
		// - workflowID, signalName, signalArg are same as SignalWorkflow's parameters
		// - options, workflow, workflowArgs are same as StartWorkflow's parameters
		// - the workflowID parameter is used instead of options.ID. If the latter is present, it must match the workflowID.
		// Note: options.WorkflowIDReusePolicy is default to AllowDuplicate.
		// The errors it can return:
		//  - serviceerror.NotFound, if namespace does not exist
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		SignalWithStartWorkflow(ctx context.Context, workflowID string, signalName string, signalArg interface{},
			options StartWorkflowOptions, workflow interface{}, workflowArgs ...interface{}) (WorkflowRun, error)

		// CancelWorkflow cancels a workflow in execution
		// - workflow ID of the workflow.
		// - runID can be default(empty string). if empty string then it will pick the running execution of that workflow ID.
		// The errors it can return:
		//	- serviceerror.NotFound
		//	- serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		CancelWorkflow(ctx context.Context, workflowID string, runID string) error

		// TerminateWorkflow terminates a workflow execution.
		// workflowID is required, other parameters are optional.
		// - workflow ID of the workflow.
		// - runID can be default(empty string). if empty string then it will pick the running execution of that workflow ID.
		// The errors it can return:
		//	- serviceerror.NotFound
		//	- serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		TerminateWorkflow(ctx context.Context, workflowID string, runID string, reason string, details ...interface{}) error

		// GetWorkflowHistory gets history events of a particular workflow
		// - workflow ID of the workflow.
		// - runID can be default(empty string). if empty string then it will pick the last running execution of that workflow ID.
		// - whether use long poll for tracking new events: when the workflow is running, there can be new events generated during iteration
		// 	 of HistoryEventIterator, if isLongPoll == true, then iterator will do long poll, tracking new history event, i.e. the iteration
		//   will not be finished until workflow is finished; if isLongPoll == false, then iterator will only return current history events.
		// - whether return all history events or just the last event, which contains the workflow execution end result
		// Example:-
		//	To iterate all events,
		//		iter := GetWorkflowHistory(ctx, workflowID, runID, isLongPoll, filterType)
		//		events := []*shared.HistoryEvent{}
		//		for iter.HasNext() {
		//			event, err := iter.Next()
		//			if err != nil {
		//				return err
		//			}
		//			events = append(events, event)
		//		}
		GetWorkflowHistory(ctx context.Context, workflowID string, runID string, isLongPoll bool, filterType enumspb.HistoryEventFilterType) HistoryEventIterator

		// CompleteActivity reports activity completed.
		// activity Execute method can return acitivity.activity.ErrResultPending to
		// indicate the activity is not completed when it's Execute method returns. In that case, this CompleteActivity() method
		// should be called when that activity is completed with the actual result and error. If err is nil, activity task
		// completed event will be reported; if err is CanceledError, activity task canceled event will be reported; otherwise,
		// activity task failed event will be reported.
		// An activity implementation should use GetActivityInfo(ctx).TaskToken function to get task token to use for completion.
		// Example:-
		//	To complete with a result.
		//  	CompleteActivity(token, "Done", nil)
		//	To fail the activity with an error.
		//      CompleteActivity(token, nil, temporal.NewApplicationError("reason", details)
		// The activity can fail with below errors ApplicationError, TimeoutError, CanceledError.
		CompleteActivity(ctx context.Context, taskToken []byte, result interface{}, err error) error

		// CompleteActivityByID reports activity completed.
		// Similar to CompleteActivity, but may save user from keeping taskToken info.
		// activity Execute method can return activity.ErrResultPending to
		// indicate the activity is not completed when it's Execute method returns. In that case, this CompleteActivityById() method
		// should be called when that activity is completed with the actual result and error. If err is nil, activity task
		// completed event will be reported; if err is CanceledError, activity task canceled event will be reported; otherwise,
		// activity task failed event will be reported.
		// An activity implementation should use activityID provided in ActivityOption to use for completion.
		// namespace name, workflowID, activityID are required, runID is optional.
		// The errors it can return:
		//  - ApplicationError
		//  - TimeoutError
		//  - CanceledError
		CompleteActivityByID(ctx context.Context, namespace, workflowID, runID, activityID string, result interface{}, err error) error

		// RecordActivityHeartbeat records heartbeat for an activity.
		// details - is the progress you want to record along with heart beat for this activity.
		// The errors it can return:
		//	- serviceerror.NotFound
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		RecordActivityHeartbeat(ctx context.Context, taskToken []byte, details ...interface{}) error

		// RecordActivityHeartbeatByID records heartbeat for an activity.
		// details - is the progress you want to record along with heart beat for this activity.
		// The errors it can return:
		//	- serviceerror.NotFound
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		RecordActivityHeartbeatByID(ctx context.Context, namespace, workflowID, runID, activityID string, details ...interface{}) error

		// ListClosedWorkflow gets closed workflow executions based on request filters
		// The errors it can return:
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		//  - serviceerror.NotFound
		ListClosedWorkflow(ctx context.Context, request *workflowservice.ListClosedWorkflowExecutionsRequest) (*workflowservice.ListClosedWorkflowExecutionsResponse, error)

		// ListOpenWorkflow gets open workflow executions based on request filters
		// The errors it can return:
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		//  - serviceerror.NotFound
		ListOpenWorkflow(ctx context.Context, request *workflowservice.ListOpenWorkflowExecutionsRequest) (*workflowservice.ListOpenWorkflowExecutionsResponse, error)

		// ListWorkflow gets workflow executions based on query. This API only works with ElasticSearch,
		// and will return serviceerror.InvalidArgument when using Cassandra or MySQL. The query is basically the SQL WHERE clause,
		// examples:
		//  - "(WorkflowID = 'wid1' or (WorkflowType = 'type2' and WorkflowID = 'wid2'))".
		//  - "CloseTime between '2019-08-27T15:04:05+00:00' and '2019-08-28T15:04:05+00:00'".
		//  - to list only open workflow use "CloseTime = missing"
		// Retrieved workflow executions are sorted by StartTime in descending order when list open workflow,
		// and sorted by CloseTime in descending order for other queries.
		// The errors it can return:
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		ListWorkflow(ctx context.Context, request *workflowservice.ListWorkflowExecutionsRequest) (*workflowservice.ListWorkflowExecutionsResponse, error)

		// ListArchivedWorkflow gets archived workflow executions based on query. This API will return BadRequest if Temporal
		// cluster or target namespace is not configured for visibility archival or read is not enabled. The query is basically the SQL WHERE clause.
		// However, different visibility archivers have different limitations on the query. Please check the documentation of the visibility archiver used
		// by your namespace to see what kind of queries are accept and whether retrieved workflow executions are ordered or not.
		// The errors it can return:
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		ListArchivedWorkflow(ctx context.Context, request *workflowservice.ListArchivedWorkflowExecutionsRequest) (*workflowservice.ListArchivedWorkflowExecutionsResponse, error)

		// ScanWorkflow gets workflow executions based on query. This API only works with ElasticSearch,
		// and will return serviceerror.InvalidArgument when using Cassandra or MySQL. The query is basically the SQL WHERE clause
		// (see ListWorkflow for query examples).
		// ScanWorkflow should be used when retrieving large amount of workflows and order is not needed.
		// It will use more ElasticSearch resources than ListWorkflow, but will be several times faster
		// when retrieving millions of workflows.
		// The errors it can return:
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		ScanWorkflow(ctx context.Context, request *workflowservice.ScanWorkflowExecutionsRequest) (*workflowservice.ScanWorkflowExecutionsResponse, error)

		// CountWorkflow gets number of workflow executions based on query. This API only works with ElasticSearch,
		// and will return serviceerror.InvalidArgument when using Cassandra or MySQL. The query is basically the SQL WHERE clause
		// (see ListWorkflow for query examples).
		// The errors it can return:
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		CountWorkflow(ctx context.Context, request *workflowservice.CountWorkflowExecutionsRequest) (*workflowservice.CountWorkflowExecutionsResponse, error)

		// GetSearchAttributes returns valid search attributes keys and value types.
		// The search attributes can be used in query of List/Scan/Count APIs. Adding new search attributes requires temporal server
		// to update dynamic config ValidSearchAttributes.
		GetSearchAttributes(ctx context.Context) (*workflowservice.GetSearchAttributesResponse, error)

		// QueryWorkflow queries a given workflow execution and returns the query result synchronously. Parameter workflowID
		// and queryType are required, other parameters are optional. The workflowID and runID (optional) identify the
		// target workflow execution that this query will be send to. If runID is not specified (empty string), server will
		// use the currently running execution of that workflowID. The queryType specifies the type of query you want to
		// run. By default, temporal supports "__stack_trace" as a standard query type, which will return string value
		// representing the call stack of the target workflow. The target workflow could also setup different query handler
		// to handle custom query types.
		// See comments at workflow.SetQueryHandler(ctx Context, queryType string, handler interface{}) for more details
		// on how to setup query handler within the target workflow.
		// - workflowID is required.
		// - runID can be default(empty string). if empty string then it will pick the running execution of that workflow ID.
		// - queryType is the type of the query.
		// - args... are the optional query parameters.
		// The errors it can return:
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		//  - serviceerror.NotFound
		//  - serviceerror.QueryFailed
		QueryWorkflow(ctx context.Context, workflowID string, runID string, queryType string, args ...interface{}) (converter.EncodedValue, error)

		// QueryWorkflowWithOptions queries a given workflow execution and returns the query result synchronously.
		// See QueryWorkflowWithOptionsRequest and QueryWorkflowWithOptionsResponse for more information.
		// The errors it can return:
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		//  - serviceerror.NotFound
		//  - serviceerror.QueryFailed
		QueryWorkflowWithOptions(ctx context.Context, request *QueryWorkflowWithOptionsRequest) (*QueryWorkflowWithOptionsResponse, error)

		// DescribeWorkflowExecution returns information about the specified workflow execution.
		// The errors it can return:
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		//  - serviceerror.NotFound
		DescribeWorkflowExecution(ctx context.Context, workflowID, runID string) (*workflowservice.DescribeWorkflowExecutionResponse, error)

		// DescribeTaskQueue returns information about the target taskqueue, right now this API returns the
		// pollers which polled this taskqueue in last few minutes.
		// The errors it can return:
		//  - serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		//  - serviceerror.NotFound
		DescribeTaskQueue(ctx context.Context, taskqueue string, taskqueueType enumspb.TaskQueueType) (*workflowservice.DescribeTaskQueueResponse, error)

		// ResetWorkflowExecution reset an existing workflow execution to WorkflowTaskFinishEventId(exclusive).
		// And it will immediately terminating the current execution instance.
		// RequestId is used to deduplicate requests. It will be autogenerated if not set.
		ResetWorkflowExecution(ctx context.Context, request *workflowservice.ResetWorkflowExecutionRequest) (*workflowservice.ResetWorkflowExecutionResponse, error)

		// WorkflowService provides access to the underlying gRPC service. This should only be used for advanced use cases
		// that cannot be accomplished via other Client methods. Unlike calls to other Client methods, calls directly to the
		// service are not configured with internal semantics such as automatic retries.
		WorkflowService() workflowservice.WorkflowServiceClient

		// Close client and clean up underlying resources.
		Close()
	}

	// ClientOptions are optional parameters for Client creation.
	ClientOptions struct {
		// Optional: To set the host:port for this client to connect to.
		// default: localhost:7233
		//
		// This is a gRPC address and therefore can also support a special-formatted address of "<resolver>:///<value>" that
		// will use a registered resolver. By default all hosts returned from the resolver will be used in a round-robin
		// fashion.
		//
		// The "dns" resolver is registered by default. Using a "dns:///" prefixed address will periodically resolve all IPs
		// for DNS address given and round robin amongst them.
		//
		// A custom resolver can be created to provide multiple hosts in other ways. For example, to manually provide
		// multiple IPs to round-robin across, a google.golang.org/grpc/resolver/manual resolver can be created and
		// registered with google.golang.org/grpc/resolver with a custom scheme:
		//		builder := manual.NewBuilderWithScheme("myresolver")
		//		builder.InitialState(resolver.State{Addresses: []resolver.Address{{Addr: "1.2.3.4:1234"}, {Addr: "2.3.4.5:2345"}}})
		//		resolver.Register(builder)
		//		c, err := client.NewClient(client.Options{HostPort: "myresolver:///ignoredvalue"})
		// Other more advanced resolvers can also be registered.
		HostPort string

		// Optional: To set the namespace name for this client to work with.
		// default: default
		Namespace string

		// Optional: Logger framework can use to log.
		// default: default logger provided.
		Logger log.Logger

		// Optional: Metrics handler for reporting metrics.
		// default: no metrics.
		MetricsHandler metrics.Handler

		// Optional: Sets an identify that can be used to track this host for debugging.
		// default: default identity that include hostname, groupName and process ID.
		Identity string

		// Optional: Sets DataConverter to customize serialization/deserialization of arguments in Temporal
		// default: defaultDataConverter, an combination of google protobuf converter, gogo protobuf converter and json converter
		DataConverter converter.DataConverter

		// Optional: Sets ContextPropagators that allows users to control the context information passed through a workflow
		// default: nil
		ContextPropagators []ContextPropagator

		// Optional: Sets options for server connection that allow users to control features of connections such as TLS settings.
		// default: no extra options
		ConnectionOptions ConnectionOptions

		// Optional: HeadersProvider will be invoked on every outgoing gRPC request and gives user ability to
		// set custom request headers. This can be used to set auth headers for example.
		HeadersProvider HeadersProvider

		// Optional parameter that is designed to be used *in tests*. It gets invoked last in
		// the gRPC interceptor chain and can be used to induce artificial failures in test scenarios.
		TrafficController TrafficController

		// Interceptors to apply to some calls of the client. Earlier interceptors
		// wrap later interceptors.
		//
		// Any interceptors that also implement Interceptor (meaning they implement
		// WorkerInterceptor in addition to ClientInterceptor) will be used for
		// worker interception as well. When worker interceptors are here and in
		// worker options, the ones here wrap the ones in worker options. The same
		// interceptor should not be set here and in worker options.
		Interceptors []ClientInterceptor
	}

	// HeadersProvider returns a map of gRPC headers that should be used on every request.
	HeadersProvider interface {
		GetHeaders(ctx context.Context) (map[string]string, error)
	}

	// TrafficController is getting called in the interceptor chain with API invocation parameters.
	// Result is either nil if API call is allowed or an error, in which case request would be interrupted and
	// the error will be propagated back through the interceptor chain.
	TrafficController interface {
		CheckCallAllowed(ctx context.Context, method string, req, reply interface{}) error
	}

	// ConnectionOptions is provided by SDK consumers to control optional connection params.
	ConnectionOptions struct {
		// TLS configures connection level security credentials.
		TLS *tls.Config

		// Authority specifies the value to be used as the :authority pseudo-header.
		// This value only used when TLS is nil.
		Authority string

		// By default, after gRPC connection to the Server is created, client will make a request to
		// health check endpoint to make sure that the Server is accessible.
		// Set DisableHealthCheck to true to disable it.
		DisableHealthCheck bool

		// HealthCheckAttemptTimeout specifies how to long to wait for service response on each health check attempt.
		// Default: 5s.
		HealthCheckAttemptTimeout time.Duration

		// HealthCheckTimeout defines how long client should be sending health check requests to the server before concluding
		// that it is unavailable. Defaults to 10s, once this timeout is reached error will be propagated to the client.
		HealthCheckTimeout time.Duration

		// Enables keep alive ping from client to the server, which can help detect abruptly closed connections faster.
		EnableKeepAliveCheck bool

		// After a duration of this time if the client doesn't see any activity it
		// pings the server to see if the transport is still alive.
		// If set below 10s, a minimum value of 10s will be used instead.
		KeepAliveTime time.Duration

		// After having pinged for keepalive check, the client waits for a duration
		// of Timeout and if no activity is seen even after that the connection is
		// closed.
		KeepAliveTimeout time.Duration

		// If true, client sends keepalive pings even with no active RPCs. If false,
		// when there are no active RPCs, Time and Timeout will be ignored and no
		// keepalive pings will be sent.
		KeepAlivePermitWithoutStream bool

		// MaxPayloadSize is a number of bytes that gRPC would allow to travel to and from server. Defaults to 64 MB.
		MaxPayloadSize int

		// Advanced dial options for gRPC connections. These are applied after the internal default dial options are
		// applied. Therefore any dial options here may override internal ones.
		//
		// For gRPC interceptors, internal interceptors such as error handling, metrics, and retrying are done via
		// grpc.WithChainUnaryInterceptor. Therefore to add inner interceptors that are wrapped by those, a
		// grpc.WithChainUnaryInterceptor can be added as an option here. To add a single outer interceptor, a
		// grpc.WithUnaryInterceptor option can be added since grpc.WithUnaryInterceptor is prepended to chains set with
		// grpc.WithChainUnaryInterceptor.
		DialOptions []grpc.DialOption
	}

	// StartWorkflowOptions configuration parameters for starting a workflow execution.
	// The current timeout resolution implementation is in seconds and uses math.Ceil(d.Seconds()) as the duration. But is
	// subjected to change in the future.
	StartWorkflowOptions struct {
		// ID - The business identifier of the workflow execution.
		// Optional: defaulted to a uuid.
		ID string

		// TaskQueue - The workflow tasks of the workflow are scheduled on the queue with this name.
		// This is also the name of the activity task queue on which activities are scheduled.
		// The workflow author can choose to override this using activity options.
		// Mandatory: No default.
		TaskQueue string

		// WorkflowExecutionTimeout - The timeout for duration of workflow execution.
		// It includes retries and continue as new. Use WorkflowRunTimeout to limit execution time
		// of a single workflow run.
		// The resolution is seconds.
		// Optional: defaulted to unlimited.
		WorkflowExecutionTimeout time.Duration

		// WorkflowRunTimeout - The timeout for duration of a single workflow run.
		// The resolution is seconds.
		// Optional: defaulted to WorkflowExecutionTimeout.
		WorkflowRunTimeout time.Duration

		// WorkflowTaskTimeout - The timeout for processing workflow task from the time the worker
		// pulled this task. If a workflow task is lost, it is retried after this timeout.
		// The resolution is seconds.
		// Optional: defaulted to 10 secs.
		WorkflowTaskTimeout time.Duration

		// WorkflowIDReusePolicy - Whether server allow reuse of workflow ID, can be useful
		// for dedupe logic if set to RejectDuplicate.
		// Optional: defaulted to AllowDuplicate.
		WorkflowIDReusePolicy enumspb.WorkflowIdReusePolicy

		// When WorkflowExecutionErrorWhenAlreadyStarted is true, Client.ExecuteWorkflow will return an error if the
		// workflow id has already been used and WorkflowIDReusePolicy would disallow a re-run. If it is set to false,
		// rather than erroring a WorkflowRun instance representing the current or last run will be returned.
		//
		// Optional: defaults to false
		WorkflowExecutionErrorWhenAlreadyStarted bool

		// RetryPolicy - Optional retry policy for workflow. If a retry policy is specified, in case of workflow failure
		// server will start new workflow execution if needed based on the retry policy.
		RetryPolicy *RetryPolicy

		// CronSchedule - Optional cron schedule for workflow. If a cron schedule is specified, the workflow will run
		// as a cron based on the schedule. The scheduling will be based on UTC time. Schedule for next run only happen
		// after the current run is completed/failed/timeout. If a RetryPolicy is also supplied, and the workflow failed
		// or timeout, the workflow will be retried based on the retry policy. While the workflow is retrying, it won't
		// schedule its next run. If next schedule is due while workflow is running (or retrying), then it will skip that
		// schedule. Cron workflow will not stop until it is terminated or canceled (by returning temporal.CanceledError).
		// The cron spec is as following:
		// ┌───────────── minute (0 - 59)
		// │ ┌───────────── hour (0 - 23)
		// │ │ ┌───────────── day of the month (1 - 31)
		// │ │ │ ┌───────────── month (1 - 12)
		// │ │ │ │ ┌───────────── day of the week (0 - 6) (Sunday to Saturday)
		// │ │ │ │ │
		// │ │ │ │ │
		// * * * * *
		CronSchedule string

		// Memo - Optional non-indexed info that will be shown in list workflow.
		Memo map[string]interface{}

		// SearchAttributes - Optional indexed info that can be used in query of List/Scan/Count workflow APIs (only
		// supported when Temporal server is using ElasticSearch). The key and value type must be registered on Temporal server side.
		// Use GetSearchAttributes API to get valid key and corresponding value type.
		SearchAttributes map[string]interface{}
	}

	// RetryPolicy defines the retry policy.
	// Note that the history of activity with retry policy will be different: the started event will be written down into
	// history only when the activity completes or "finally" timeouts/fails. And the started event only records the last
	// started time. Because of that, to check an activity has started or not, you cannot rely on history events. Instead,
	// you can use CLI to describe the workflow to see the status of the activity:
	//     tctl --ns <namespace> wf desc -w <wf-id>
	RetryPolicy struct {
		// Backoff interval for the first retry. If BackoffCoefficient is 1.0 then it is used for all retries.
		// If not set or set to 0, a default interval of 1s will be used.
		InitialInterval time.Duration

		// Coefficient used to calculate the next retry backoff interval.
		// The next retry interval is previous interval multiplied by this coefficient.
		// Must be 1 or larger. Default is 2.0.
		BackoffCoefficient float64

		// Maximum backoff interval between retries. Exponential backoff leads to interval increase.
		// This value is the cap of the interval. Default is 100x of initial interval.
		MaximumInterval time.Duration

		// Maximum number of attempts. When exceeded the retries stop even if not expired yet.
		// If not set or set to 0, it means unlimited, and rely on activity ScheduleToCloseTimeout to stop.
		MaximumAttempts int32

		// Non-Retriable errors. This is optional. Temporal server will stop retry if error type matches this list.
		// Note:
		//  - cancellation is not a failure, so it won't be retried,
		//  - only StartToClose or Heartbeat timeouts are retryable.
		NonRetryableErrorTypes []string
	}

	// NamespaceClient is the client for managing operations on the namespace.
	// CLI, tools, ... can use this layer to manager operations on namespace.
	NamespaceClient interface {
		// Register a namespace with temporal server
		// The errors it can throw:
		//	- NamespaceAlreadyExistsError
		//	- serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		Register(ctx context.Context, request *workflowservice.RegisterNamespaceRequest) error

		// Describe a namespace. The namespace has 3 part of information
		// NamespaceInfo - Which has Name, Status, Description, Owner Email
		// NamespaceConfiguration - Configuration like Workflow Execution Retention Period In Days, Whether to emit metrics.
		// ReplicationConfiguration - replication config like clusters and active cluster name
		// The errors it can throw:
		//	- serviceerror.NotFound
		//	- serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		Describe(ctx context.Context, name string) (*workflowservice.DescribeNamespaceResponse, error)

		// Update a namespace.
		// The errors it can throw:
		//	- serviceerror.NotFound
		//	- serviceerror.InvalidArgument
		//	- serviceerror.Internal
		//	- serviceerror.Unavailable
		Update(ctx context.Context, request *workflowservice.UpdateNamespaceRequest) error

		// Close client and clean up underlying resources.
		Close()
	}
)

// NewClient creates an instance of a workflow client
func NewClient(options ClientOptions) (Client, error) {
	if options.Namespace == "" {
		options.Namespace = DefaultNamespace
	}

	// Initialize root tags
	if options.MetricsHandler == nil {
		options.MetricsHandler = metrics.NopHandler
	}
	options.MetricsHandler = options.MetricsHandler.WithTags(metrics.RootTags(options.Namespace))

	if options.HostPort == "" {
		options.HostPort = LocalHostPort
	}

	if options.Logger == nil {
		options.Logger = ilog.NewDefaultLogger()
		options.Logger.Info("No logger configured for temporal client. Created default one.")
	}

	connection, err := dial(newDialParameters(&options))
	if err != nil {
		return nil, err
	}

	if err = checkHealth(connection, options.ConnectionOptions); err != nil {
		if err := connection.Close(); err != nil {
			options.Logger.Warn("Unable to close connection on health check failure.", "error", err)
		}
		return nil, err
	}

	return NewServiceClient(workflowservice.NewWorkflowServiceClient(connection), connection, options), nil
}

func newDialParameters(options *ClientOptions) dialParameters {
	return dialParameters{
		UserConnectionOptions: options.ConnectionOptions,
		HostPort:              options.HostPort,
		RequiredInterceptors:  requiredInterceptors(options.MetricsHandler, options.HeadersProvider, options.TrafficController),
		DefaultServiceConfig:  defaultServiceConfig,
	}
}

// NewServiceClient creates workflow client from workflowservice.WorkflowServiceClient. Must be used internally in unit tests only.
func NewServiceClient(workflowServiceClient workflowservice.WorkflowServiceClient, connectionCloser io.Closer, options ClientOptions) *WorkflowClient {
	// Namespace can be empty in unit tests.
	if options.Namespace == "" {
		options.Namespace = DefaultNamespace
	}

	if options.Identity == "" {
		options.Identity = getWorkerIdentity("")
	}

	if options.DataConverter == nil {
		options.DataConverter = converter.GetDefaultDataConverter()
	}

	if options.MetricsHandler == nil {
		options.MetricsHandler = metrics.NopHandler
	}

	// Collect set of applicable worker interceptors
	var workerInterceptors []WorkerInterceptor
	for _, interceptor := range options.Interceptors {
		if workerInterceptor, _ := interceptor.(WorkerInterceptor); workerInterceptor != nil {
			workerInterceptors = append(workerInterceptors, workerInterceptor)
		}
	}

	client := &WorkflowClient{
		workflowService:    workflowServiceClient,
		connectionCloser:   connectionCloser,
		namespace:          options.Namespace,
		registry:           newRegistry(),
		metricsHandler:     options.MetricsHandler,
		logger:             options.Logger,
		identity:           options.Identity,
		dataConverter:      options.DataConverter,
		contextPropagators: options.ContextPropagators,
		workerInterceptors: workerInterceptors,
	}

	// Create outbound interceptor by wrapping backwards through chain
	client.interceptor = &workflowClientInterceptor{client: client}
	for i := len(options.Interceptors) - 1; i >= 0; i-- {
		client.interceptor = options.Interceptors[i].InterceptClient(client.interceptor)
	}

	return client
}

// NewNamespaceClient creates an instance of a namespace client, to manager lifecycle of namespaces.
func NewNamespaceClient(options ClientOptions) (NamespaceClient, error) {
	// Initialize root tags
	if options.MetricsHandler == nil {
		options.MetricsHandler = metrics.NopHandler
	}
	options.MetricsHandler = options.MetricsHandler.WithTags(metrics.RootTags(metrics.NoneTagValue))

	if options.HostPort == "" {
		options.HostPort = LocalHostPort
	}

	connection, err := dial(newDialParameters(&options))
	if err != nil {
		return nil, err
	}

	if err = checkHealth(connection, options.ConnectionOptions); err != nil {
		if err := connection.Close(); err != nil {
			options.Logger.Warn("Unable to close connection on health check failure.", "error", err)
		}
		return nil, err
	}

	return newNamespaceServiceClient(workflowservice.NewWorkflowServiceClient(connection), connection, options), nil
}

func newNamespaceServiceClient(workflowServiceClient workflowservice.WorkflowServiceClient, clientConn *grpc.ClientConn, options ClientOptions) NamespaceClient {
	if options.Identity == "" {
		options.Identity = getWorkerIdentity("")
	}

	return &namespaceClient{
		workflowService:  workflowServiceClient,
		connectionCloser: clientConn,
		metricsHandler:   options.MetricsHandler,
		logger:           options.Logger,
		identity:         options.Identity,
	}
}

// NewValue creates a new converter.EncodedValue which can be used to decode binary data returned by Temporal.  For example:
// User had Activity.RecordHeartbeat(ctx, "my-heartbeat") and then got response from calling Client.DescribeWorkflowExecution.
// The response contains binary field PendingActivityInfo.HeartbeatDetails,
// which can be decoded by using:
//   var result string // This need to be same type as the one passed to RecordHeartbeat
//   NewValue(data).Get(&result)
func NewValue(data *commonpb.Payloads) converter.EncodedValue {
	return newEncodedValue(data, nil)
}

// NewValues creates a new converter.EncodedValues which can be used to decode binary data returned by Temporal. For example:
// User had Activity.RecordHeartbeat(ctx, "my-heartbeat", 123) and then got response from calling Client.DescribeWorkflowExecution.
// The response contains binary field PendingActivityInfo.HeartbeatDetails,
// which can be decoded by using:
//   var result1 string
//   var result2 int // These need to be same type as those arguments passed to RecordHeartbeat
//   NewValues(data).Get(&result1, &result2)
func NewValues(data *commonpb.Payloads) converter.EncodedValues {
	return newEncodedValues(data, nil)
}

// checkHealth checks service health using gRPC health check:
// https://github.com/grpc/grpc/blob/master/doc/health-checking.md
func checkHealth(connection grpc.ClientConnInterface, options ConnectionOptions) error {
	if options.DisableHealthCheck {
		return nil
	}

	healthClient := healthpb.NewHealthClient(connection)

	request := &healthpb.HealthCheckRequest{
		Service: healthCheckServiceName,
	}

	attemptTimeout := options.HealthCheckAttemptTimeout
	if attemptTimeout == 0 {
		attemptTimeout = defaultHealthCheckAttemptTimeout
	}
	timeout := options.HealthCheckTimeout
	if timeout == 0 {
		timeout = defaultHealthCheckTimeout
	}
	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()
	policy := createDynamicServiceRetryPolicy(ctx)
	// TODO: refactor using grpc retry interceptor
	return backoff.Retry(ctx, func() error {
		healthCheckCtx, cancel := context.WithTimeout(context.Background(), attemptTimeout)
		defer cancel()
		resp, err := healthClient.Check(healthCheckCtx, request)
		if err != nil {
			return fmt.Errorf("health check error: %w", err)
		}
		if resp.Status != healthpb.HealthCheckResponse_SERVING {
			return fmt.Errorf("health check returned unhealthy status: %v", resp.Status)
		}
		return nil
	}, policy, nil)
}