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/webhook_edit.go

@@ -0,0 +1,245 @@
+package handlers
+
+import (
+	"errors"
+	"net/http"
+	"strconv"
+
+	"github.com/go-chi/chi"
+	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/delivery"
+)
+
+// HandleSourceEdit shows the form to edit a webhook.
+func (h *Handlers) HandleSourceEdit() 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
+		}
+
+		h.renderWebhookEdit(
+			w, r, &webhook,
+			webhook.Name, webhook.Description,
+			strconv.Itoa(webhook.RetentionDays),
+			"", http.StatusOK,
+		)
+	}
+}
+
+// HandleSourceEditSubmit handles the webhook edit form
+// submission.
+func (h *Handlers) HandleSourceEditSubmit() 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")
+
+		h.renameMu.Lock()
+		defer h.renameMu.Unlock()
+
+		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
+		}
+
+		h.applyWebhookEdit(w, r, &webhook)
+	}
+}
+
+// applyWebhookEdit validates and saves webhook edits. A refused save
+// shows the edit form again with the values submitted and the reason.
+func (h *Handlers) applyWebhookEdit(
+	w http.ResponseWriter,
+	r *http.Request,
+	webhook *database.Webhook,
+) {
+	// The body size cap is enforced by the MaxBodySize middleware,
+	// which runs before CSRF parses the form.
+	name := r.PostFormValue("name")
+	description := r.PostFormValue("description")
+	retention := r.PostFormValue("retention_days")
+
+	if name == "" {
+		h.renderWebhookEdit(
+			w, r, webhook, name, description, retention,
+			"Name is required", http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	// An empty field falls back to the stored value, so submitting the
+	// form without touching retention leaves the policy alone.
+	retentionDays, errMsg := parseRetentionDays(
+		retention, webhook.RetentionDays,
+	)
+	if errMsg != "" {
+		h.renderWebhookEdit(
+			w, r, webhook, name, description, retention,
+			errMsg, http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	// edited is the webhook as the submission leaves it; webhook stays
+	// as stored, for the page shown again when the save is refused.
+	edited := *webhook
+	edited.Name = name
+	edited.Description = description
+	edited.RetentionDays = retentionDays
+
+	// A new name renames the archive files before it is saved (see
+	// delivery.Engine.Rename). If either step fails, the same targets'
+	// archives go back to the name that is still stored, without
+	// reading the main database again.
+	targets, err := h.renameWebhookArchives(
+		webhook.ID, webhook.Name, edited.Name,
+	)
+	if err == nil {
+		err = h.db.DB().Save(&edited).Error
+	}
+
+	if err != nil {
+		restoreErr := h.renameArchives(targets, webhook.Name)
+		if restoreErr != nil {
+			h.log.Error(
+				"failed to rename archives back",
+				"webhook_id", webhook.ID,
+				"error", restoreErr,
+			)
+		}
+
+		if errors.Is(err, delivery.ErrArchiveNameTaken) {
+			h.renderWebhookEdit(
+				w, r, webhook, name, description, retention,
+				"Not saved: "+err.Error()+
+					". Move that archive out of the data directory, "+
+					"its .db together with any -wal and -shm beside "+
+					"it, then save again.",
+				http.StatusConflict,
+			)
+
+			return
+		}
+
+		h.serverError(w, r, "failed to update webhook", err)
+
+		return
+	}
+
+	http.Redirect(
+		w, r, withNotice("/hook/"+webhook.ID, webhookSaved),
+		http.StatusSeeOther,
+	)
+}
+
+// renderWebhookEdit renders the webhook edit page for the webhook as
+// stored, its form showing name, description and retentionDays, with
+// an optional error message above it.
+func (h *Handlers) renderWebhookEdit(
+	w http.ResponseWriter,
+	r *http.Request,
+	webhook *database.Webhook,
+	name, description, retentionDays, errMsg string,
+	status int,
+) {
+	data := map[string]any{
+		tmplKeyWebhook:  webhook,
+		tmplKeyError:    errMsg,
+		"Name":          name,
+		"Description":   description,
+		"RetentionDays": retentionDays,
+	}
+
+	h.renderTemplateStatus(w, r, "source_edit.html", data, status)
+}
+
+// renameWebhookArchives renames the archive file of every database
+// target of a webhook from the webhook name oldName to newName,
+// keeping each target's own name. It does nothing when the name is
+// unchanged. It returns the targets it read, so that a failed edit can
+// move those same archives back with renameArchives.
+func (h *Handlers) renameWebhookArchives(
+	webhookID, oldName, newName string,
+) ([]database.Target, error) {
+	if h.archives == nil || oldName == newName {
+		return nil, nil
+	}
+
+	var targets []database.Target
+
+	err := h.db.DB().
+		Where(
+			"webhook_id = ? AND type = ?",
+			webhookID, database.TargetTypeDatabase,
+		).
+		Find(&targets).Error
+	if err != nil {
+		return nil, err
+	}
+
+	return targets, h.renameArchives(targets, newName)
+}
+
+// renameArchives renames the archive file of each of the given
+// database targets to the webhook name webhookName, keeping each
+// target's own name. It tries every target even after one fails, so
+// that moving the archives back after a failed edit leaves none under
+// the new name, and returns every failure joined.
+func (h *Handlers) renameArchives(
+	targets []database.Target, webhookName string,
+) error {
+	var errs []error
+
+	for i := range targets {
+		err := h.archives.Rename(
+			targets[i].ID, webhookName, targets[i].Name,
+		)
+		if err != nil {
+			errs = append(errs, err)
+		}
+	}
+
+	return errors.Join(errs...)
+}