Go

package pulse

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

const base = "https://api.thepulseapi.com/api/v1"

type Signal struct {
	Type  string `json:"type"`
	Value string `json:"value"`
}

type Client struct {
	apiKey string
	orgID  string
	http   *http.Client
}

func New(apiKey, orgID string) *Client {
	return &Client{
		apiKey: apiKey,
		orgID:  orgID,
		// http.DefaultClient has no timeout at all, which is a goroutine leak waiting
		// for a slow upstream. Always supply one.
		http: &http.Client{Timeout: 5 * time.Second},
	}
}

func (c *Client) post(ctx context.Context, path string, body map[string]any, out any) error {
	// organizationId is read from the body rather than from the key, and is required
	// on nearly every endpoint.
	body["organizationId"] = c.orgID

	payload, err := json.Marshal(body)
	if err != nil {
		return err
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, base+path, bytes.NewReader(payload))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("x-api-key", c.apiKey)

	res, err := c.http.Do(req)
	if err != nil {
		return err
	}
	defer res.Body.Close()

	if res.StatusCode >= 300 {
		return fmt.Errorf("pulse %s: %s", path, res.Status)
	}
	return json.NewDecoder(res.Body).Decode(out)
}

func (c *Client) Track(ctx context.Context, sessionID string, signals []Signal) (map[string]any, error) {
	var out map[string]any
	err := c.post(ctx, "/track", map[string]any{"sessionId": sessionID, "signals": signals}, &out)
	return out, err
}

func (c *Client) RankedCatalog(ctx context.Context, sessionID string, limit int) (map[string]any, error) {
	var out map[string]any
	err := c.post(ctx, "/catalog/ranked", map[string]any{"sessionId": sessionID, "limit": limit}, &out)
	return out, err
}

p := pulse.New(os.Getenv("PULSE_API_KEY"), os.Getenv("PULSE_ORG_ID"))

ranked, err := p.RankedCatalog(r.Context(), sessionID, 24)
if err != nil {
	// Serve the catalogue in its default order. Personalisation is an enhancement.
	ranked = nil
}