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package main
import (
"encoding/json"
"fmt"
"io"
"net/http"
"net/url"
"os"
"path/filepath"
"sort"
)
type httpCacheEntry struct {
Body string
Err error
}
var httpCache = map[string]httpCacheEntry{}
type httpStatusError struct {
StatusCode int
Status string
}
// Is implements the interface for [errors.Is].
func (e *httpStatusError) Is(target error) bool {
switch target {
case os.ErrNotExist:
return e.StatusCode == http.StatusNotFound
default:
return false
}
}
// Error implements [error].
func (e *httpStatusError) Error() string {
return fmt.Sprintf("unexpected HTTP status: %v", e.Status)
}
func httpGet(u string, hdr map[string]string) (string, error) {
cacheKey := url.QueryEscape(u)
hdrKeys := make([]string, 0, len(hdr))
for k := range hdr {
hdrKeys = append(hdrKeys, http.CanonicalHeaderKey(k))
}
sort.Strings(hdrKeys)
for _, k := range hdrKeys {
cacheKey += "|" + url.QueryEscape(k) + ":" + url.QueryEscape(hdr[k])
}
if cache, ok := httpCache[cacheKey]; ok {
fmt.Printf("CACHE-GET %q\n", u)
return cache.Body, cache.Err
}
if err := os.Mkdir(".http-cache", 0777); err != nil && !os.IsExist(err) {
return "", err
}
cacheFile := filepath.Join(".http-cache", cacheKey)
if bs, err := os.ReadFile(cacheFile); err == nil {
fmt.Printf("CACHE-GET %q\n", u)
httpCache[cacheKey] = httpCacheEntry{Body: string(bs)}
return httpCache[cacheKey].Body, nil
} else if !os.IsNotExist(err) {
httpCache[cacheKey] = httpCacheEntry{Err: err}
return "", err
}
fmt.Printf("GET %q...", u)
req, err := http.NewRequest(http.MethodGet, u, nil)
if err != nil {
httpCache[cacheKey] = httpCacheEntry{Err: err}
return "", err
}
for k, v := range hdr {
req.Header.Add(k, v)
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
fmt.Printf(" err\n")
httpCache[cacheKey] = httpCacheEntry{Err: err}
return "", err
}
if resp.StatusCode != http.StatusOK {
fmt.Printf(" err\n")
httpCache[cacheKey] = httpCacheEntry{Err: err}
return "", &httpStatusError{StatusCode: resp.StatusCode, Status: resp.Status}
}
bs, err := io.ReadAll(resp.Body)
if err != nil {
fmt.Printf(" err\n")
httpCache[cacheKey] = httpCacheEntry{Err: err}
httpCache[cacheKey] = httpCacheEntry{Err: err}
return "", err
}
fmt.Printf(" ok\n")
if err := os.WriteFile(cacheFile, bs, 0666); err != nil {
return "", err
}
httpCache[cacheKey] = httpCacheEntry{Body: string(bs)}
return httpCache[cacheKey].Body, nil
}
func httpGetJSON(u string, hdr map[string]string, out any) error {
str, err := httpGet(u, hdr)
if err != nil {
return err
}
return json.Unmarshal([]byte(str), out)
}
func httpGetPaginatedJSON[T any](uStr string, hdr map[string]string, out *[]T, pageFn func(i int) url.Values) error {
u, err := url.Parse(uStr)
if err != nil {
return err
}
query := u.Query()
for i := 0; true; i++ {
pageParams := pageFn(i)
for k, v := range pageParams {
query[k] = v
}
u.RawQuery = query.Encode()
var resp []T
if err := httpGetJSON(u.String(), hdr, &resp); err != nil {
return err
}
fmt.Printf(" -> %d records\n", len(resp))
if len(resp) == 0 {
break
}
*out = append(*out, resp...)
}
return nil
}
|
