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package api
import (
"bytes"
"container/heap"
"encoding/json"
"fmt"
"io"
"log/slog"
"net/http"
"net/url"
"strconv"
"time"
)
type APIError struct {
Code int `json:"code"`
Data json.RawMessage `json:"data"`
Message string `json:"message"`
}
func (e *APIError) Error() string {
return fmt.Sprintf("unhandled APIError code %d, message \"%s\", data: %s", e.Code, e.Message, string(e.Data))
}
type APIMessage struct {
Data json.RawMessage `json:"data"`
Error *APIError `json:"error"`
Meta *Meta `json:"meta"`
}
type Meta struct {
Limit int `json:"limit"`
Page int `json:"page"`
Total int `json:"total"`
}
type Request struct {
index int
priority int
method string
uri *url.URL
payload any
responseChannel chan *Response
}
type Response struct {
Message *APIMessage
Err error
}
func (c *Client) Send(method string, uriRef *url.URL, payload any, response any) error {
responseChannel := make(chan *Response)
uri := c.baseURI.ResolveReference(uriRef)
query := uri.Query()
query.Add("limit", "20")
page := 1
var rawResponses []json.RawMessage
for {
query.Set("page", strconv.Itoa(page))
uri.RawQuery = query.Encode()
c.requestsChannel <- &Request{
method: method,
payload: payload,
priority: 10,
responseChannel: responseChannel,
uri: uri,
}
res := <-responseChannel
if res.Err != nil {
return res.Err
}
if err := res.Message.Error; err != nil {
return err
}
err := res.Message.Error
if err != nil {
switch err.Code {
case 4214:
e := decodeShipInTransitError(err.Data)
time.Sleep(e.SecondsToArrival.Duration() * time.Second)
return c.Send(method, uriRef, payload, response)
default:
return err
}
}
if res.Message.Meta == nil {
// This is not a paginated request, we are done
if err := json.Unmarshal(res.Message.Data, &response); err != nil {
return fmt.Errorf("failed to unmarshal message: %w", err)
}
return nil
}
var oneResponse []json.RawMessage
if err := json.Unmarshal(res.Message.Data, &oneResponse); err != nil {
return fmt.Errorf("failed to unmarshal message: %w", err)
}
rawResponses = append(rawResponses, oneResponse...)
if res.Message.Meta.Limit*res.Message.Meta.Page >= res.Message.Meta.Total {
break
}
page++
}
responses, err := json.Marshal(rawResponses)
if err != nil {
return fmt.Errorf("failed to marshal raw responses to paginated request: %w", err)
}
if err := json.Unmarshal(responses, &response); err != nil {
return fmt.Errorf("failed to unmarshal paginated request responses: %w", err)
}
return nil
}
func queueProcessor(client *Client) {
var (
req *Request
ok bool
)
for {
// The queue is empty so we do this blocking call
select {
case <-client.ctx.Done():
return
case req, ok = <-client.requestsChannel:
if !ok {
return
}
heap.Push(client.pq, req)
}
// we enqueue all values read from the channel and process the queue's
// contents until empty. We keep reading the channel as long as this
// emptying goes on
for {
select {
case <-client.ctx.Done():
return
case req, ok = <-client.requestsChannel:
if !ok {
return
}
heap.Push(client.pq, req)
default:
if client.pq.Len() == 0 {
break
}
// we process one
if req, ok = heap.Pop(client.pq).(*Request); !ok {
panic("queueProcessor got something other than a Request on its channel")
}
msg, err := client.sendOne(req.method, req.uri, req.payload)
req.responseChannel <- &Response{
Message: msg,
Err: err,
}
}
}
}
}
func (c *Client) sendOne(method string, uri *url.URL, payload any) (*APIMessage, error) {
slog.Debug("request", "method", method, "path", uri.Path, "payload", payload)
var payloadReader io.Reader
if payload != nil {
if body, err := json.Marshal(payload); err != nil {
return nil, fmt.Errorf("failed to marshal payload: %w", err)
} else {
payloadReader = bytes.NewReader(body)
}
}
req, err := http.NewRequestWithContext(c.ctx, method, uri.String(), payloadReader)
if err != nil {
return nil, fmt.Errorf("failed to create request: %w", err)
}
req.Header = *c.headers
resp, err := c.httpClient.Do(req)
if err != nil {
return nil, fmt.Errorf("failed to do request: %w", err)
}
defer resp.Body.Close()
body, err := io.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("failed to read response body: %w", err)
}
var msg APIMessage
if err = json.Unmarshal(body, &msg); err != nil {
return nil, fmt.Errorf("failed to unmarshal response body: %w", err)
}
slog.Debug("response", "code", resp.StatusCode, "message", msg)
switch resp.StatusCode {
case 429:
e := decodeRateLimitError(msg.Error.Data)
time.Sleep(e.RetryAfter.Duration() * time.Second)
return c.sendOne(method, uri, payload)
}
return &msg, nil
}
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