hackernews.go

package opinions

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"time"
)

// HackerNewsResponse represents some interesting fields of response from
// HN Search API.
//
// See: https://hn.algolia.com/api
type HackerNewsResponse struct {
	Hits []struct {
		CreatedAt   time.Time `json:"created_at"`
		Title       string    `json:"title"`
		URL         string    `json:"url"`
		ObjectID    string    `json:"objectID"`
		NumComments int       `json:"num_comments"`
	} `json:"hits"`
}

// SearchHackerNews query HN Search API for given prompt. It returns list of
// discussions sorted by relevance, then popularity, then number of comments.
//
// See: https://hn.algolia.com/api
func SearchHackerNews(ctx context.Context, client GetRequester, query string) (discussions []Discussion, err error) {
	searchURL := "https://hn.algolia.com/api/v1/search?"

	_, err = url.Parse(query)
	switch {
	case err == nil:
		searchURL += "restrictSearchableAttributes=url&query="
	default:
		searchURL += "tags=story&query="
	}

	r, err := client.Get(ctx, searchURL+url.QueryEscape(query))
	if err != nil {
		return noDiscussions, err
	}
	defer func() {
		if closeErr := r.Body.Close(); closeErr != nil && err == nil {
			err = closeErr
		}
	}()

	if r.StatusCode != http.StatusOK {
		return noDiscussions, fmt.Errorf("GET %s` responded with unexpected status code %d", r.Request.URL, r.StatusCode)
	}

	var response HackerNewsResponse
	if err := json.NewDecoder(r.Body).Decode(&response); err != nil {
		return noDiscussions, err
	}

	discussions = make([]Discussion, 0, len(response.Hits))
	for _, entry := range response.Hits {
		discussions = append(discussions, Discussion{
			Service:  "Hacker News",
			URL:      "https://news.ycombinator.com/item?id=" + url.QueryEscape(entry.ObjectID),
			Title:    entry.Title,
			Source:   entry.URL,
			Comments: entry.NumComments,
		})
	}

	return discussions, nil
}