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package main
import (
"context"
"encoding/json"
"fmt"
"net/http"
"os"
"path/filepath"
"strconv"
"strings"
"time"
"within.website/x/web"
)
// All of these types match descriptions in the Hacker News API documentation.
//
// https://github.com/HackerNews/API
// UnixTime is a type that represents a Unix timestamp.
type UnixTime time.Time
func (u UnixTime) String() string {
return time.Time(u).Format(time.RFC3339)
}
// UnmarshalJSON converts the unix timestamp into a time.Time.
func (u *UnixTime) UnmarshalJSON(data []byte) error {
s := strings.Trim(string(data), "\"")
unix, err := strconv.ParseInt(s, 10, 64)
if err != nil {
return err
}
*u = UnixTime(time.Unix(unix, 0))
return nil
}
// MarshalJSON converts the time.Time into a unix timestamp.
func (u UnixTime) MarshalJSON() ([]byte, error) {
return []byte(strconv.FormatInt(time.Time(u).Unix(), 10)), nil
}
// HNUser is a type that represents a Hacker News user.
type HNUser struct {
ID string `json:"id"`
Created UnixTime `json:"created"`
Karma int `json:"karma"`
About string `json:"about"` // HTML
Submitted []int `json:"submitted"`
}
// HNItem is a type that represents a Hacker News item. This is a superset of all other types of items.
type HNItem struct {
ID int `json:"id"`
Deleted *bool `json:"deleted,omitempty"`
Type string `json:"type"`
By string `json:"by"`
Time UnixTime `json:"time"`
Text string `json:"text,omitempty"` // HTML
Dead *bool `json:"dead,omitempty"`
Parent *int `json:"parent,omitempty"`
Poll *int `json:"poll,omitempty"`
Kids []int `json:"kids,omitempty"`
URL string `json:"url,omitempty"`
Score int `json:"score,omitempty"`
Title string `json:"title,omitempty"` // HTML
Parts []int `json:"parts,omitempty"`
Descendants *int `json:"descendants,omitempty"`
}
type HNClient struct {
t *time.Ticker // for rate limiting requests based on --scrape-delay
cli *http.Client
cacheFolder *string
}
func NewHNClient(delay time.Duration) *HNClient {
return &HNClient{
t: time.NewTicker(delay),
cli: &http.Client{},
}
}
func (h *HNClient) Close() {
h.t.Stop()
}
func (h *HNClient) WithClient(c *http.Client) *HNClient {
h.cli = c
return h
}
func (h *HNClient) WithCacheFolder(f string) *HNClient {
h.cacheFolder = &f
return h
}
func (h *HNClient) GetItem(ctx context.Context, id int) (*HNItem, error) {
if h.cacheFolder != nil {
item, err := h.getItemFromCache(id)
if err == nil {
return item, nil
}
}
item, err := h.getItem(ctx, id)
if err != nil {
return nil, err
}
if h.cacheFolder != nil {
err = h.saveItemToCache(item)
if err != nil {
return nil, err
}
}
return item, nil
}
func (h *HNClient) saveItemToCache(item *HNItem) error {
if h.cacheFolder == nil {
return nil
}
folder := *h.cacheFolder
fname := filepath.Join(folder, "items", strconv.Itoa(item.ID)+".json")
f, err := os.Create(fname)
if err != nil {
return fmt.Errorf("failed to create cache file: %w", err)
}
defer f.Close()
if err = json.NewEncoder(f).Encode(item); err != nil {
return fmt.Errorf("failed to write item to cache: %w", err)
}
return nil
}
func (h *HNClient) getItemFromCache(id int) (*HNItem, error) {
if h.cacheFolder == nil {
return nil, nil
}
folder := *h.cacheFolder
fname := filepath.Join(folder, "items", strconv.Itoa(id)+".json")
f, err := os.Open(fname)
if err != nil {
return nil, fmt.Errorf("failed to open cache file: %w", err)
}
defer f.Close()
var item HNItem
if err = json.NewDecoder(f).Decode(&item); err != nil {
return nil, fmt.Errorf("failed to read item from cache: %w", err)
}
return &item, nil
}
func (h *HNClient) GetUser(ctx context.Context, id string) (*HNUser, error) {
<-h.t.C
req, err := http.NewRequestWithContext(ctx, "GET", "https://hacker-news.firebaseio.com/v0/user/"+id+".json", nil)
if err != nil {
return nil, err
}
resp, err := h.cli.Do(req)
if err != nil {
return nil, err
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return nil, web.NewError(http.StatusOK, resp)
}
var user HNUser
err = json.NewDecoder(resp.Body).Decode(&user)
if err != nil {
return nil, err
}
return &user, nil
}
func (h *HNClient) getItem(ctx context.Context, id int) (*HNItem, error) {
<-h.t.C
req, err := http.NewRequestWithContext(ctx, "GET", "https://hacker-news.firebaseio.com/v0/item/"+strconv.Itoa(id)+".json", nil)
if err != nil {
return nil, err
}
resp, err := h.cli.Do(req)
if err != nil {
return nil, err
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return nil, web.NewError(http.StatusOK, resp)
}
var item HNItem
err = json.NewDecoder(resp.Body).Decode(&item)
if err != nil {
return nil, err
}
return &item, nil
}
func (h *HNClient) PathToRoot(ctx context.Context, id int) ([]int, error) {
item, err := h.GetItem(ctx, id)
if err != nil {
return nil, err
}
if item.Parent == nil {
return []int{id}, nil
}
parents, err := h.PathToRoot(ctx, *item.Parent)
if err != nil {
return nil, err
}
return append(parents, id), nil
}
func (h *HNClient) GetUltimateParent(ctx context.Context, id int) (*HNItem, error) {
item, err := h.GetItem(ctx, id)
if err != nil {
return nil, err
}
if item.Parent == nil {
return item, nil
}
return h.GetUltimateParent(ctx, *item.Parent)
}
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