client.go

// package client provides functionality for building HTTP clients.
//
// Recommended Usage:
//
//	type MyClient struct {
//		Client *client.Client
//	}
//
//	type ThingInput struct {
//	}
//
//	type ThingOutput struct {
//	}
//
//	func(c MyClient) Thing(input *ThingInput) (*ThingOutput, err) {
//		var output ThingOutput
//		req := c.Client.NewRequest("GET", "/thing", input, output)
//		err := req.Send()
//		return output, err
//	}
package client

import (
	"context"
	"net"
	"net/http"
	"net/url"
	"time"

	"github.com/remind101/pkg/client/metadata"
	"github.com/remind101/pkg/client/request"
)

// Client is a request builder.
type Client struct {
	Info       metadata.ClientInfo // Metadata about this client.
	HTTPClient *http.Client        // Underlying http.Client used to make requests.
	Handlers   request.Handlers    // Handlers to use with requests generated by this client.
}

// ClientOpt represents a function that will alter the configuration of a Client.
type ClientOpt func(*Client)

// Timeout specifies a time limit for requests made by this Client.
func Timeout(t time.Duration) ClientOpt {
	return func(c *Client) {
		c.HTTPClient.Timeout = t
	}
}

// RoundTripper sets a custom transport on the underlying http Client.
func RoundTripper(r http.RoundTripper) ClientOpt {
	return func(c *Client) {
		c.HTTPClient.Transport = r
	}
}

// BasicAuth adds basic auth to every request made by this client.
func BasicAuth(username, password string) ClientOpt {
	return func(c *Client) {
		c.Handlers.Build.Append(request.BasicAuther(username, password))
	}
}

// RequestSigning adds a handler to sign requests.
func RequestSigning(id, key string) ClientOpt {
	return func(c *Client) {
		c.Handlers.Sign.Append(request.RequestSigner(id, key))
	}
}

// DebugLogging adds logging of the enitre request and response.
func DebugLogging(c *Client) {
	c.Handlers.Send.Prepend(request.RequestLogger)
	c.Handlers.Send.Append(request.ResponseLogger)
}

// New returns a new client with default Handlers and http client.
func New(info metadata.ClientInfo, options ...ClientOpt) *Client {
	c := &Client{
		Info:     info,
		Handlers: request.DefaultHandlers(),
		HTTPClient: &http.Client{
			Timeout: 60 * time.Second,
			Transport: &http.Transport{
				Proxy: http.ProxyFromEnvironment,
				DialContext: (&net.Dialer{
					Timeout:   1 * time.Second,
					KeepAlive: 90 * time.Second,
				}).DialContext,
				TLSHandshakeTimeout: 3 * time.Second,
				MaxIdleConns:        100,
				MaxIdleConnsPerHost: 8,
				IdleConnTimeout:     90 * time.Second,
			},
		},
	}

	// Apply options
	for _, option := range options {
		option(c)
	}

	return c
}

// NewRequest builds a request from the client configuration.
// An http.Request will be initialized with the given context, method and path.
// A request.Request will be initialized with the http.Request, Handlers,
// params and data.
func (c *Client) NewRequest(ctx context.Context, method, path string, params interface{}, data interface{}) *request.Request {
	httpReq, _ := http.NewRequest(method, path, nil)
	httpReq = httpReq.WithContext(ctx)
	httpReq.URL, _ = url.Parse(c.Info.Endpoint + path)

	r := request.New(httpReq, c.Info, c.Handlers.Copy(), params, data)
	r.HTTPClient = c.HTTPClient
	return r
}