var (
	// GoSQLInstance is the SQL instance name.
	GoSQLInstance, _ = tag.NewKey("go_sql_instance")
	// GoSQLMethod is the SQL method called.
	GoSQLMethod, _ = tag.NewKey("go_sql_method")
	// GoSQLError is the error received while calling a SQL method.
	GoSQLError, _ = tag.NewKey("go_sql_error")
	// GoSQLStatus identifies success vs. error from the SQL method response.
	GoSQLStatus, _ = tag.NewKey("go_sql_status")
)

var (
	MeasureLatencyMs         = stats.Float64("go.sql/latency", "The latency of calls in milliseconds", stats.UnitMilliseconds)
	MeasureOpenConnections   = stats.Int64("go.sql/connections/open", "Count of open connections in the pool", stats.UnitDimensionless)
	MeasureIdleConnections   = stats.Int64("go.sql/connections/idle", "Count of idle connections in the pool", stats.UnitDimensionless)
	MeasureActiveConnections = stats.Int64("go.sql/connections/active", "Count of active connections in the pool", stats.UnitDimensionless)
	MeasureWaitCount         = stats.Int64("go.sql/connections/wait_count", "The total number of connections waited for", stats.UnitDimensionless)
	MeasureWaitDuration      = stats.Float64("go.sql/connections/wait_duration", "The total time blocked waiting for a new connection", stats.UnitMilliseconds)
	MeasureIdleClosed        = stats.Int64("go.sql/connections/idle_closed", "The total number of connections closed due to SetMaxIdleConns", stats.UnitDimensionless)
	MeasureLifetimeClosed    = stats.Int64("go.sql/connections/lifetime_closed", "The total number of connections closed due to SetConnMaxLifetime", stats.UnitDimensionless)
)

var (
	SQLClientLatencyView = &view.View{
		Name:        "go.sql/client/latency",
		Description: "The distribution of latencies of various calls in milliseconds",
		Measure:     MeasureLatencyMs,
		Aggregation: DefaultMillisecondsDistribution,
		TagKeys:     []tag.Key{GoSQLInstance, GoSQLMethod, GoSQLError, GoSQLStatus},
	}

	SQLClientCallsView = &view.View{
		Name:        "go.sql/client/calls",
		Description: "The number of various calls of methods",
		Measure:     MeasureLatencyMs,
		Aggregation: view.Count(),
		TagKeys:     []tag.Key{GoSQLInstance, GoSQLMethod, GoSQLError, GoSQLStatus},
	}

	SQLClientOpenConnectionsView = &view.View{
		Name:        "go.sql/db/connections/open",
		Description: "The number of open connections",
		Measure:     MeasureOpenConnections,
		Aggregation: view.LastValue(),
		TagKeys:     []tag.Key{GoSQLInstance},
	}

	SQLClientIdleConnectionsView = &view.View{
		Name:        "go.sql/db/connections/idle",
		Description: "The number of idle connections",
		Measure:     MeasureIdleConnections,
		Aggregation: view.LastValue(),
		TagKeys:     []tag.Key{GoSQLInstance},
	}

	SQLClientActiveConnectionsView = &view.View{
		Name:        "go.sql/db/connections/active",
		Description: "The number of active connections",
		Measure:     MeasureActiveConnections,
		Aggregation: view.LastValue(),
		TagKeys:     []tag.Key{GoSQLInstance},
	}

	SQLClientWaitCountView = &view.View{
		Name:        "go.sql/db/connections/wait_count",
		Description: "The total number of connections waited for",
		Measure:     MeasureWaitCount,
		Aggregation: view.LastValue(),
		TagKeys:     []tag.Key{GoSQLInstance},
	}

	SQLClientWaitDurationView = &view.View{
		Name:        "go.sql/db/connections/wait_duration",
		Description: "The total time blocked waiting for a new connection",
		Measure:     MeasureWaitDuration,
		Aggregation: view.LastValue(),
		TagKeys:     []tag.Key{GoSQLInstance},
	}

	SQLClientIdleClosedView = &view.View{
		Name:        "go.sql/db/connections/idle_closed_count",
		Description: "The total number of connections closed due to SetMaxIdleConns",
		Measure:     MeasureIdleClosed,
		Aggregation: view.LastValue(),
		TagKeys:     []tag.Key{GoSQLInstance},
	}

	SQLClientLifetimeClosedView = &view.View{
		Name:        "go.sql/db/connections/lifetime_closed_count",
		Description: "The total number of connections closed due to SetConnMaxLifetime",
		Measure:     MeasureLifetimeClosed,
		Aggregation: view.LastValue(),
		TagKeys:     []tag.Key{GoSQLInstance},
	}

	DefaultViews = []*view.View{
		SQLClientLatencyView, SQLClientCallsView, SQLClientOpenConnectionsView,
		SQLClientIdleConnectionsView, SQLClientActiveConnectionsView,
		SQLClientWaitCountView, SQLClientWaitDurationView,
		SQLClientIdleClosedView, SQLClientLifetimeClosedView,
	}
)

var AllTraceOptions = TraceOptions{
	AllowRoot:    true,
	Ping:         true,
	RowsNext:     true,
	RowsClose:    true,
	RowsAffected: true,
	LastInsertID: true,
	Query:        true,
	QueryParams:  true,
}

var (
	DefaultMillisecondsDistribution = view.Distribution(
		0.0,
		0.001,
		0.005,
		0.01,
		0.05,
		0.1,
		0.5,
		1.0,
		1.5,
		2.0,
		2.5,
		5.0,
		10.0,
		25.0,
		50.0,
		100.0,
		200.0,
		400.0,
		600.0,
		800.0,
		1000.0,
		1500.0,
		2000.0,
		2500.0,
		5000.0,
		10000.0,
		20000.0,
		40000.0,
		100000.0,
		200000.0,
		500000.0)
)

type TraceOption func(o *TraceOptions)

type TraceOptions struct {
	// AllowRoot, if set to true, will allow ocsql to create root spans in
	// absence of existing spans or even context.
	// Default is to not trace ocsql calls if no existing parent span is found
	// in context or when using methods not taking context.
	AllowRoot bool

	// Ping, if set to true, will enable the creation of spans on Ping requests.
	Ping bool

	// RowsNext, if set to true, will enable the creation of spans on RowsNext
	// calls. This can result in many spans.
	RowsNext bool

	// RowsClose, if set to true, will enable the creation of spans on RowsClose
	// calls.
	RowsClose bool

	// RowsAffected, if set to true, will enable the creation of spans on
	// RowsAffected calls.
	RowsAffected bool

	// LastInsertID, if set to true, will enable the creation of spans on
	// LastInsertId calls.
	LastInsertID bool

	// Query, if set to true, will enable recording of sql queries in spans.
	// Only allow this if it is safe to have queries recorded with respect to
	// security.
	Query bool

	// QueryParams, if set to true, will enable recording of parameters used
	// with parametrized queries. Only allow this if it is safe to have
	// parameters recorded with respect to security.
	// This setting is a noop if the Query option is set to false.
	QueryParams bool

	// DefaultAttributes will be set to each span as default.
	DefaultAttributes []trace.Attribute

	// InstanceName identifies database.
	InstanceName string

	// DisableErrSkip, if set to true, will suppress driver.ErrSkip errors in spans.
	DisableErrSkip bool

	// Sampler to use when creating spans.
	Sampler trace.Sampler
}