Split source_management.go along its CRUD seams (closes #274)

Pure code movement. Every declaration of
internal/handlers/source_management.go moves unchanged into one of:
webhook_list.go, webhook_create.go, webhook_detail.go, webhook_edit.go
and webhook_delete.go for the webhook pages; event_log.go for the event
log; entrypoint.go for the entrypoint handlers; target_create.go,
target_delete.go and target_toggle.go for the target handlers; and
shared.go for the helpers several of them use. Only each file's package
line and imports are new. The README and a middleware comment that
named the removed file now name the new ones.

Model: opus-5-5

internal/handlers/entrypoint.go

@@ -0,0 +1,169 @@
+package handlers
+
+import (
+	"net/http"
+
+	"github.com/go-chi/chi"
+	"github.com/google/uuid"
+	"sneak.berlin/go/webhooker/internal/database"
+)
+
+// HandleEntrypointCreate handles adding a new entrypoint.
+func (h *Handlers) HandleEntrypointCreate() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		userID, ok := h.getUserID(r)
+		if !ok {
+			http.Redirect(
+				w, r, "/pages/login", http.StatusSeeOther,
+			)
+
+			return
+		}
+
+		sourceID := chi.URLParam(r, "sourceID")
+
+		var webhook database.Webhook
+
+		err := h.db.DB().Where(
+			"id = ? AND user_id = ?", sourceID, userID,
+		).First(&webhook).Error
+		if err != nil {
+			h.renderError(w, r, http.StatusNotFound)
+
+			return
+		}
+
+		// The body size cap is enforced by the MaxBodySize
+		// middleware, which runs before CSRF parses the form.
+		err = r.ParseForm()
+		if err != nil {
+			h.renderError(w, r, http.StatusBadRequest)
+
+			return
+		}
+
+		description := r.PostFormValue("description")
+
+		entrypoint := &database.Entrypoint{
+			WebhookID:   webhook.ID,
+			Path:        uuid.New().String(),
+			Description: description,
+			Active:      true,
+		}
+
+		err = h.db.DB().Create(entrypoint).Error
+		if err != nil {
+			h.serverError(w, r, "failed to create entrypoint", err)
+
+			return
+		}
+
+		http.Redirect(
+			w, r, withNotice("/hook/"+webhook.ID, entrypointAdded),
+			http.StatusSeeOther,
+		)
+	}
+}
+
+// HandleEntrypointEdit handles changing an entrypoint's description.
+// It writes only the description column, so the entrypoint keeps its
+// URL, and an activate or deactivate saved since the page was shown
+// is not undone.
+func (h *Handlers) HandleEntrypointEdit() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		userID, ok := h.getUserID(r)
+		if !ok {
+			http.Redirect(
+				w, r, "/pages/login", http.StatusSeeOther,
+			)
+
+			return
+		}
+
+		sourceID := chi.URLParam(r, "sourceID")
+		entrypointID := chi.URLParam(r, "entrypointID")
+
+		var webhook database.Webhook
+
+		err := h.db.DB().Where(
+			"id = ? AND user_id = ?", sourceID, userID,
+		).First(&webhook).Error
+		if err != nil {
+			h.renderError(w, r, http.StatusNotFound)
+
+			return
+		}
+
+		// The body size cap is enforced by the MaxBodySize
+		// middleware, which runs before CSRF parses the form.
+		err = r.ParseForm()
+		if err != nil {
+			h.renderError(w, r, http.StatusBadRequest)
+
+			return
+		}
+
+		result := h.db.DB().Model(&database.Entrypoint{}).Where(
+			"id = ? AND webhook_id = ?", entrypointID, webhook.ID,
+		).Update("description", r.PostFormValue("description"))
+		if result.Error != nil {
+			h.serverError(
+				w, r, "failed to edit entrypoint", result.Error,
+			)
+
+			return
+		}
+
+		// The id came from the URL and may name another webhook's
+		// entrypoint, which this webhook does not have.
+		if result.RowsAffected == 0 {
+			h.renderError(w, r, http.StatusNotFound)
+
+			return
+		}
+
+		http.Redirect(
+			w, r, withNotice("/hook/"+webhook.ID, entrypointSaved),
+			http.StatusSeeOther,
+		)
+	}
+}
+
+// HandleEntrypointDelete handles deleting an entrypoint.
+func (h *Handlers) HandleEntrypointDelete() http.HandlerFunc {
+	return h.deleteChildResource(
+		"entrypointID", &database.Entrypoint{},
+		"failed to delete entrypoint",
+		nil,
+		entrypointDeleted,
+	)
+}
+
+// HandleEntrypointToggle handles toggling an entrypoint's
+// active state.
+func (h *Handlers) HandleEntrypointToggle() http.HandlerFunc {
+	return h.toggleChildResource(
+		"entrypointID",
+		func(webhookID, childID string) (bool, error) {
+			var ep database.Entrypoint
+
+			err := h.db.DB().Where(
+				"id = ? AND webhook_id = ?",
+				childID, webhookID,
+			).First(&ep).Error
+			if err != nil {
+				return false, err
+			}
+
+			// Only the active column: saving the whole row would
+			// write back the description read above over an edit
+			// saved since.
+			active := !ep.Active
+
+			return active, h.db.DB().Model(&ep).
+				Update("active", active).Error
+		},
+		"failed to toggle entrypoint",
+		entrypointActivated, entrypointDeactivated,
+	)
+}