Show an event's entrypoint and request headers (closes #389)

An expanded event in the event log and the event's own page now show
the entrypoint the event arrived at (its description, "Entrypoint"
when it has none, or "deleted entrypoint"; never its URL) and the
full request headers, one per line, sorted by name. Both pages draw
them through one shared template, event_request.html. The event
columns now load entrypoint_id and headers, and the webhook's
entrypoints are read once per page.

Model: opus-5-5

internal/handlers/event_log_view.go

@@ -1,8 +1,13 @@
 package handlers
 
 import (
+	"encoding/json"
+	"net/http"
+	"slices"
 	"time"
 	"unicode/utf8"
+
+	"sneak.berlin/go/webhooker/internal/database"
 )
 
 // eventLogColumns is the event log's projection. The casts to
@@ -12,14 +17,14 @@ import (
 // rather than in Go is the point of the projection — an
 // oversized body never becomes a Go string at all.
 const eventLogColumns = "id, created_at, method, content_type, " +
-	"resubmitted_from_id, " +
+	"resubmitted_from_id, entrypoint_id, headers, " +
 	"substr(cast(body as blob), 1, ?) AS body, " +
 	"length(cast(body as blob)) AS body_bytes"
 
 // eventColumns is eventLogColumns for the event's own page, which
 // shows the whole body.
 const eventColumns = "id, created_at, method, content_type, " +
-	"resubmitted_from_id, " +
+	"resubmitted_from_id, entrypoint_id, headers, " +
 	"cast(body as blob) AS body, " +
 	"length(cast(body as blob)) AS body_bytes"
 
@@ -34,6 +39,15 @@ type EventLogView struct {
 
 	Body BodyView
 
+	// Entrypoint names the entrypoint the event arrived at: its
+	// description, "Entrypoint" when it has none, or "deleted
+	// entrypoint". Never its URL, which is the entrypoint's secret.
+	Entrypoint string
+
+	// Headers is the event's request headers, one "Name: value"
+	// per value, sorted by name.
+	Headers []string
+
 	// ResubmittedFromID names the event this one was copied
 	// from, empty for an event that arrived on the receiver.
 	ResubmittedFromID string
@@ -63,6 +77,8 @@ type eventLogRow struct {
 	Method            string
 	ContentType       string
 	ResubmittedFromID *string
+	EntrypointID      string
+	Headers           string
 	Body              []byte
 	BodyBytes         int64
 }
@@ -83,10 +99,69 @@ func (r *eventLogRow) view(webhookID string) EventLogView {
 		Body: newBodyView(
 			"/hook/"+webhookID+"/events/"+r.ID, r.Body, r.BodyBytes,
 		),
+		Headers:           requestHeaderLines(r.Headers),
 		ResubmittedFromID: from,
 	}
 }
 
+// requestHeaderLines turns an event's stored request headers, the
+// JSON the receiver writes, into one "Name: value" line per value,
+// sorted by name. Headers that do not parse show as none.
+func requestHeaderLines(headersJSON string) []string {
+	var headers http.Header
+
+	if json.Unmarshal([]byte(headersJSON), &headers) != nil {
+		return nil
+	}
+
+	names := make([]string, 0, len(headers))
+	for name := range headers {
+		names = append(names, name)
+	}
+
+	slices.Sort(names)
+
+	var lines []string
+
+	for _, name := range names {
+		for _, value := range headers[name] {
+			lines = append(lines, name+": "+value)
+		}
+	}
+
+	return lines
+}
+
+// entrypointNames maps each of the webhook's entrypoints to the name
+// an event that arrived at it shows: its description, or "Entrypoint"
+// when it has none, as the webhook page names it. A deleted
+// entrypoint is left out.
+func (h *Handlers) entrypointNames(
+	webhookID string,
+) (map[string]string, error) {
+	var entrypoints []database.Entrypoint
+
+	err := h.db.DB().Where(
+		"webhook_id = ?", webhookID,
+	).Find(&entrypoints).Error
+	if err != nil {
+		return nil, err
+	}
+
+	names := make(map[string]string, len(entrypoints))
+
+	for i := range entrypoints {
+		name := entrypoints[i].Description
+		if name == "" {
+			name = "Entrypoint"
+		}
+
+		names[entrypoints[i].ID] = name
+	}
+
+	return names, nil
+}
+
 // trimPartialRune drops a trailing UTF-8 sequence that the
 // byte-wise cut left incomplete, so a multi-byte rune severed
 // at the cap does not surface as a mojibake tail.