From f35de22d2ee0da8d24d5a541bbab14424b4e1801 Mon Sep 17 00:00:00 2001
From: Dylan Ratcliffe <dylan@overmind.tech>
Date: Thu, 26 Sep 2024 09:09:19 +0000
Subject: [PATCH] Added ability to detect Overmind instance

---
 instance_detect.go | 91 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 instance_detect.go

diff --git a/instance_detect.go b/instance_detect.go
new file mode 100644
index 0000000..caddcb0
--- /dev/null
+++ b/instance_detect.go
@@ -0,0 +1,91 @@
+package sdp
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
+)
+
+// Information about a particular instance of Overmind. This is used to
+// determine where to send requests, how to authenticate etc.
+type OvermindInstance struct {
+	FrontendUrl *url.URL
+	ApiUrl      *url.URL
+	NatsUrl     *url.URL
+	Audience    string
+	Auth0Domain string
+	CLIClientID string
+}
+
+// GatewayUrl returns the URL for the gateway for this instance.
+func (oi OvermindInstance) GatewayUrl() string {
+	return fmt.Sprintf("%v/api/gateway", oi.ApiUrl.String())
+}
+
+func (oi OvermindInstance) String() string {
+	return fmt.Sprintf("Frontend: %v, API: %v, Nats: %v, Audience: %v", oi.FrontendUrl, oi.ApiUrl, oi.NatsUrl, oi.Audience)
+}
+
+type instanceData struct {
+	Api         string `json:"api_url"`
+	Nats        string `json:"nats_url"`
+	Aud         string `json:"aud"`
+	Auth0Domain string `json:"auth0_domain"`
+	CLIClientID string `json:"auth0_cli_client_id"`
+}
+
+// NewOvermindInstance creates a new OvermindInstance from the given app URL
+// with all URLs filled in, or an error. The app URL should be the URL of the
+// frontend of the Overmind instance. e.g. https://app.overmind.tech
+func NewOvermindInstance(ctx context.Context, app string) (OvermindInstance, error) {
+	var instance OvermindInstance
+	var err error
+
+	instance.FrontendUrl, err = url.Parse(app)
+	if err != nil {
+		return instance, fmt.Errorf("invalid app value '%v', error: %w", app, err)
+	}
+
+	// Get the instance data
+	instanceDataUrl := fmt.Sprintf("%v/api/public/instance-data", instance.FrontendUrl)
+	req, err := http.NewRequest("GET", instanceDataUrl, nil)
+	if err != nil {
+		return OvermindInstance{}, fmt.Errorf("could not initialize instance-data fetch: %w", err)
+	}
+
+	req = req.WithContext(ctx)
+	res, err := otelhttp.DefaultClient.Do(req)
+	if err != nil {
+		return OvermindInstance{}, fmt.Errorf("could not fetch instance-data: %w", err)
+	}
+
+	if res.StatusCode != 200 {
+		return OvermindInstance{}, fmt.Errorf("instance-data fetch returned non-200 status: %v", res.StatusCode)
+	}
+
+	defer res.Body.Close()
+	data := instanceData{}
+	err = json.NewDecoder(res.Body).Decode(&data)
+	if err != nil {
+		return OvermindInstance{}, fmt.Errorf("could not parse instance-data: %w", err)
+	}
+
+	instance.ApiUrl, err = url.Parse(data.Api)
+	if err != nil {
+		return OvermindInstance{}, fmt.Errorf("invalid api_url value '%v' in instance-data, error: %w", data.Api, err)
+	}
+	instance.NatsUrl, err = url.Parse(data.Nats)
+	if err != nil {
+		return OvermindInstance{}, fmt.Errorf("invalid nats_url value '%v' in instance-data, error: %w", data.Nats, err)
+	}
+
+	instance.Audience = data.Aud
+	instance.CLIClientID = data.CLIClientID
+	instance.Auth0Domain = data.Auth0Domain
+
+	return instance, nil
+}