package meter

import (
	"context"
)

var DefaultQuantiles = []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10}

// Option powers the configuration for metrics implementations:
type Option func(*Options)

// Options for metrics implementations
type Options struct {
	// Context holds external options
	Context context.Context
	// Name holds the meter name
	Name string
	// Address holds the address that serves metrics
	Address string
	// Path holds the path for metrics
	Path string
	// Labels holds the default labels
	Labels []string
	// WriteProcessMetrics flag to write process metrics
	WriteProcessMetrics bool
	// WriteFDMetrics flag to write fd metrics
	WriteFDMetrics bool
	// Quantiles specifies buckets for histogram
	Quantiles []float64
}

// NewOptions prepares a set of options:
func NewOptions(opt ...Option) Options {
	opts := Options{
		Address: DefaultAddress,
		Path:    DefaultPath,
		Context: context.Background(),
	}

	for _, o := range opt {
		o(&opts)
	}

	return opts
}

// Context sets the metrics context
func Context(ctx context.Context) Option {
	return func(o *Options) {
		o.Context = ctx
	}
}

// Path used to serve metrics over HTTP
func Path(value string) Option {
	return func(o *Options) {
		o.Path = value
	}
}

// Address is the listen address to serve metrics
func Address(value string) Option {
	return func(o *Options) {
		o.Address = value
	}
}

// Quantiles defines the desired spread of statistics for histogram metrics:
func Quantiles(quantiles []float64) Option {
	return func(o *Options) {
		o.Quantiles = quantiles
	}
}

// Labels add the meter labels
func Labels(ls ...string) Option {
	return func(o *Options) {
		o.Labels = append(o.Labels, ls...)
	}
}

// Name sets the name
func Name(n string) Option {
	return func(o *Options) {
		o.Name = n
	}
}

// WriteProcessMetrics enable process metrics output for write
func WriteProcessMetrics(b bool) Option {
	return func(o *Options) {
		o.WriteProcessMetrics = b
	}
}

// WriteFDMetrics enable fd metrics output for write
func WriteFDMetrics(b bool) Option {
	return func(o *Options) {
		o.WriteFDMetrics = b
	}
}