package utils

import (
	"bufio"
	"bytes"
	"context"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"github.com/fluxcd/pkg/ssa"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"sigs.k8s.io/cli-utils/pkg/kstatus/polling"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/client/apiutil"
	"sigs.k8s.io/kustomize/api/konfig"

	"github.com/fluxcd/flux2/pkg/manifestgen/kustomization"
)

// Apply is the equivalent of 'kubectl apply --server-side -f'.
// If the given manifest is a kustomization.yaml, then apply performs the equivalent of 'kubectl apply --server-side -k'.
func Apply(ctx context.Context, kubeConfigPath string, kubeContext string, manifestPath string) (string, error) {
	cfg, err := KubeConfig(kubeConfigPath, kubeContext)
	if err != nil {
		return "", err
	}
	restMapper, err := apiutil.NewDynamicRESTMapper(cfg)
	if err != nil {
		return "", err
	}
	kubeClient, err := client.New(cfg, client.Options{Mapper: restMapper})
	if err != nil {
		return "", err
	}
	kubePoller := polling.NewStatusPoller(kubeClient, restMapper)

	resourceManager := ssa.NewResourceManager(kubeClient, kubePoller, ssa.Owner{
		Field: "flux",
		Group: "fluxcd.io",
	})

	objs, err := readObjects(manifestPath)
	if err != nil {
		return "", err
	}

	if len(objs) < 1 {
		return "", fmt.Errorf("no Kubernetes objects found at: %s", manifestPath)
	}

	if err := ssa.SetNativeKindsDefaults(objs); err != nil {
		return "", err
	}

	changeSet, err := resourceManager.ApplyAllStaged(ctx, objs, false, time.Minute)
	if err != nil {
		return "", err
	}

	return changeSet.String(), nil
}

func readObjects(manifestPath string) ([]*unstructured.Unstructured, error) {
	if _, err := os.Stat(manifestPath); err != nil {
		return nil, err
	}

	if filepath.Base(manifestPath) == konfig.DefaultKustomizationFileName() {
		resources, err := kustomization.Build(filepath.Dir(manifestPath))
		if err != nil {
			return nil, err
		}
		return ssa.ReadObjects(bytes.NewReader(resources))
	}

	ms, err := os.Open(manifestPath)
	if err != nil {
		return nil, err
	}
	defer ms.Close()

	return ssa.ReadObjects(bufio.NewReader(ms))
}