feat(coderd): add support for presets to the coder API (#16526)

This pull request builds on the existing migrations and queries to add
support for presets to the coder API.

coderd/presets.go

@@ -0,0 +1,57 @@
+package coderd
+
+import (
+	"net/http"
+
+	"github.com/coder/coder/v2/coderd/httpapi"
+	"github.com/coder/coder/v2/coderd/httpmw"
+	"github.com/coder/coder/v2/codersdk"
+)
+
+// @Summary Get template version presets
+// @ID get-template-version-presets
+// @Security CoderSessionToken
+// @Produce json
+// @Tags Templates
+// @Param templateversion path string true "Template version ID" format(uuid)
+// @Success 200 {array} codersdk.Preset
+// @Router /templateversions/{templateversion}/presets [get]
+func (api *API) templateVersionPresets(rw http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	templateVersion := httpmw.TemplateVersionParam(r)
+
+	presets, err := api.Database.GetPresetsByTemplateVersionID(ctx, templateVersion.ID)
+	if err != nil {
+		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
+			Message: "Internal error fetching template version presets.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+
+	presetParams, err := api.Database.GetPresetParametersByTemplateVersionID(ctx, templateVersion.ID)
+	if err != nil {
+		httpapi.Write(ctx, rw, http.StatusInternalServerError, codersdk.Response{
+			Message: "Internal error fetching template version presets.",
+			Detail:  err.Error(),
+		})
+		return
+	}
+
+	var res []codersdk.Preset
+	for _, preset := range presets {
+		sdkPreset := codersdk.Preset{
+			ID:   preset.ID,
+			Name: preset.Name,
+		}
+		for _, presetParam := range presetParams {
+			sdkPreset.Parameters = append(sdkPreset.Parameters, codersdk.PresetParameter{
+				Name:  presetParam.Name,
+				Value: presetParam.Value,
+			})
+		}
+		res = append(res, sdkPreset)
+	}
+
+	httpapi.Write(ctx, rw, http.StatusOK, res)
+}