client.go

package httpclient

import (
	"io"
	"net/http"
	"time"

	"github.com/gojek/heimdall/v7"
	"github.com/gojek/heimdall/v7/internal"
	"github.com/pkg/errors"
)

// Client is the http client implementation
type Client struct {
	client     heimdall.Doer
	retrier    heimdall.Retriable
	plugins    []heimdall.Plugin
	timeout    *time.Duration
	retryCount int
}

const (
	defaultRetryCount  = 0
	defaultHTTPTimeout = 30 * time.Second
)

var _ heimdall.Client = (*Client)(nil)

// NewClient returns a new instance of http Client
func NewClient(opts ...Option) *Client {
	client := Client{
		client:     new(http.Client),
		retryCount: defaultRetryCount,
		retrier:    heimdall.NewNoRetrier(),
	}

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

	client.updateHTTPTimeout()

	return &client
}

// AddPlugin Adds plugin to client
func (c *Client) AddPlugin(p heimdall.Plugin) {
	c.plugins = append(c.plugins, p)
}

// Get makes a HTTP GET request to provided URL
func (c *Client) Get(url string, headers http.Header) (*http.Response, error) {
	var response *http.Response
	request, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return response, errors.Wrap(err, "GET - request creation failed")
	}

	request.Header = headers

	return c.Do(request)
}

// Post makes a HTTP POST request to provided URL and requestBody
func (c *Client) Post(url string, body io.Reader, headers http.Header) (*http.Response, error) {
	var response *http.Response
	request, err := http.NewRequest(http.MethodPost, url, body)
	if err != nil {
		return response, errors.Wrap(err, "POST - request creation failed")
	}

	request.Header = headers

	return c.Do(request)
}

// Put makes a HTTP PUT request to provided URL and requestBody
func (c *Client) Put(url string, body io.Reader, headers http.Header) (*http.Response, error) {
	var response *http.Response
	request, err := http.NewRequest(http.MethodPut, url, body)
	if err != nil {
		return response, errors.Wrap(err, "PUT - request creation failed")
	}

	request.Header = headers

	return c.Do(request)
}

// Patch makes a HTTP PATCH request to provided URL and requestBody
func (c *Client) Patch(url string, body io.Reader, headers http.Header) (*http.Response, error) {
	var response *http.Response
	request, err := http.NewRequest(http.MethodPatch, url, body)
	if err != nil {
		return response, errors.Wrap(err, "PATCH - request creation failed")
	}

	request.Header = headers

	return c.Do(request)
}

// Delete makes a HTTP DELETE request with provided URL
func (c *Client) Delete(url string, headers http.Header) (*http.Response, error) {
	var response *http.Response
	request, err := http.NewRequest(http.MethodDelete, url, nil)
	if err != nil {
		return response, errors.Wrap(err, "DELETE - request creation failed")
	}

	request.Header = headers

	return c.Do(request)
}

// Do makes an HTTP request with the native `http.Do` interface
func (c *Client) Do(request *http.Request) (*http.Response, error) {
	if origReqBody := request.Body; origReqBody != nil {
		defer func() {
			// close the original request body as internal.SetRequestGetBody wraps body with noop closer.
			_ = origReqBody.Close()
		}()
	}

	var reqGetBody internal.RequestGetBody
	var err error
	// Only SetRequestGetBody if retry is enabled to avoid unnecessary overhead for non-retry requests
	if c.retryCount > 0 {
		if err = internal.SetRequestGetBody(request); err != nil {
			return nil, err
		}
		// keeping a local variable just in case request.GetBody gets overridden by some plugins/middlewares
		reqGetBody = request.GetBody
	}

	var errs []error
	var response *http.Response

	for i := 0; i <= c.retryCount; i++ {
		if response != nil {
			_, _ = io.Copy(io.Discard, response.Body)
			_ = response.Body.Close()
		}
		if i > 0 {
			if err := internal.SleepInterruptible(request.Context(), c.retrier.NextInterval(i-1)); err != nil {
				errs = append(errs, err)
				c.reportError(request, err)
				// no point of retrying after context has been cancelled
				break
			}

			request, err = internal.CloneRequest(request, reqGetBody) // Clone the request to reset the body for retry
			if err != nil {
				errs = append(errs, err)
				c.reportError(request, err)
				break
			}
		}

		c.reportRequestStart(request)
		var err error
		response, err = c.client.Do(request)

		if err != nil {
			errs = append(errs, err)
			c.reportError(request, err)
			if internal.IsCtxDone(request.Context()) {
				break
			}
			continue
		}
		c.reportRequestEnd(request, response)

		if response.StatusCode >= http.StatusInternalServerError {
			if internal.IsCtxDone(request.Context()) {
				break
			}

			continue
		}

		errs = nil // Clear errors if any iteration succeeds
		break
	}

	return response, internal.BuildMultiError(errs)
}

func (c *Client) reportRequestStart(request *http.Request) {
	for _, plugin := range c.plugins {
		plugin.OnRequestStart(request)
	}
}

func (c *Client) reportError(request *http.Request, err error) {
	for _, plugin := range c.plugins {
		plugin.OnError(request, err)
	}
}

func (c *Client) reportRequestEnd(request *http.Request, response *http.Response) {
	for _, plugin := range c.plugins {
		plugin.OnRequestEnd(request, response)
	}
}

func (c *Client) updateHTTPTimeout() {
	timeout := defaultHTTPTimeout
	if c.timeout != nil {
		timeout = *c.timeout
	}

	if client, ok := c.client.(*http.Client); ok && client != nil {
		client.Timeout = timeout
	}
}