package helm

import (
	"bytes"
	"io"
	"net/url"
	"regexp"
	"strings"

	"github.com/aws/aws-sdk-go/aws/arn"
	"github.com/porter-dev/porter/internal/kubernetes"
	"github.com/porter-dev/porter/internal/models"
	"github.com/porter-dev/porter/internal/models/integrations"
	"github.com/porter-dev/porter/internal/repository"
	"golang.org/x/oauth2"
	"gopkg.in/yaml.v2"
	"helm.sh/helm/v3/pkg/postrender"

	"github.com/docker/distribution/reference"
)

// DockerSecretsPostRenderer is a Helm post-renderer that adds image pull secrets to
// pod specs that would otherwise be unable to pull an image.
//
// The post-renderer currently looks for two types of registries: GCR and ECR (TODO: DOCR
// and Dockerhub). It also detects if the image pull secret is necessary: if GCR image pulls
// occur in a GKE cluster in the same project, or if ECR image pulls exist in an EKS cluster
// in the same organization + region, an image pull is not necessary.
type DockerSecretsPostRenderer struct {
	Cluster   *models.Cluster
	Repo      repository.Repository
	Agent     *kubernetes.Agent
	Namespace string
	DOAuth    *oauth2.Config

	registries map[string]*models.Registry

	podSpecs  []resource
	resources []resource
}

// while manifests are map[string]interface{} at the top level,
// nested keys will be of type map[interface{}]interface{}
type resource map[interface{}]interface{}

func NewDockerSecretsPostRenderer(
	cluster *models.Cluster,
	repo repository.Repository,
	agent *kubernetes.Agent,
	namespace string,
	regs []*models.Registry,
	doAuth *oauth2.Config,
) (postrender.PostRenderer, error) {
	// Registries is a map of registry URLs to registry ids
	registries := make(map[string]*models.Registry)

	for _, reg := range regs {
		regURL := reg.URL

		if !strings.Contains(regURL, "http") {
			regURL = "https://" + regURL
		}

		parsedRegURL, err := url.Parse(regURL)

		if err != nil {
			continue
		}

		addReg := parsedRegURL.Host

		if parsedRegURL.Path != "" {
			addReg += "/" + strings.Trim(parsedRegURL.Path, "/")
		}

		registries[addReg] = reg
	}

	return &DockerSecretsPostRenderer{
		Cluster:    cluster,
		Repo:       repo,
		Agent:      agent,
		Namespace:  namespace,
		DOAuth:     doAuth,
		registries: registries,
		podSpecs:   make([]resource, 0),
		resources:  make([]resource, 0),
	}, nil
}

func (d *DockerSecretsPostRenderer) Run(
	renderedManifests *bytes.Buffer,
) (modifiedManifests *bytes.Buffer, err error) {
	bufCopy := bytes.NewBuffer(renderedManifests.Bytes())

	linkedRegs, err := d.getRegistriesToLink(bufCopy)

	// if we encountered an error here, we'll render the manifests anyway
	// without modification
	if err != nil {
		return renderedManifests, nil
	}

	// create the necessary secrets
	secrets, err := d.Agent.CreateImagePullSecrets(
		d.Repo,
		d.Namespace,
		linkedRegs,
		d.DOAuth,
	)

	if err != nil {
		return renderedManifests, nil
	}

	d.updatePodSpecs(secrets)

	modifiedManifests = bytes.NewBuffer([]byte{})
	encoder := yaml.NewEncoder(modifiedManifests)
	defer encoder.Close()

	for _, resource := range d.resources {
		err = encoder.Encode(resource)

		if err != nil {
			return nil, err
		}
	}

	return modifiedManifests, nil
}

func (d *DockerSecretsPostRenderer) getRegistriesToLink(renderedManifests *bytes.Buffer) (map[string]*models.Registry, error) {
	// create a map of registry names to registries: these are the registries
	// that a secret will be generated for, if it does not exist
	linkedRegs := make(map[string]*models.Registry)

	err := d.decodeRenderedManifests(renderedManifests)

	if err != nil {
		return linkedRegs, err
	}

	// read the pod specs into the post-renderer object
	d.getPodSpecs(d.resources)

	for _, podSpec := range d.podSpecs {
		// get all images
		images := d.getImageList(podSpec)

		// read the image url
		for _, image := range images {
			named, err := reference.ParseNormalizedNamed(image)

			if err != nil {
				continue
			}

			domain := reference.Domain(named)
			path := reference.Path(named)

			regName := domain

			if pathArr := strings.Split(path, "/"); len(pathArr) > 1 {
				regName += "/" + strings.Join(pathArr[:len(pathArr)-1], "/")
			}

			// check if the integration is native to the cluster/registry combination
			isNative := d.isRegistryNative(regName)

			if isNative {
				continue
			}

			reg, exists := d.registries[regName]

			if !exists {
				continue
			}

			// if the registry exists, add it to the map
			linkedRegs[regName] = reg
		}
	}

	return linkedRegs, nil
}

func (d *DockerSecretsPostRenderer) decodeRenderedManifests(
	renderedManifests *bytes.Buffer,
) error {
	// use the yaml decoder to parse the multi-document yaml.
	decoder := yaml.NewDecoder(renderedManifests)

	for {
		res := make(resource)
		err := decoder.Decode(&res)
		if err == io.EOF {
			break
		}

		if err != nil {
			return err
		}

		d.resources = append(d.resources, res)
	}

	return nil
}

func (d *DockerSecretsPostRenderer) getPodSpecs(resources []resource) {
	for _, res := range resources {
		kindVal, hasKind := res["kind"]
		if !hasKind {
			continue
		}

		kind, ok := kindVal.(string)
		if !ok {
			continue
		}

		// manifests of list type will have an items field, items should
		// be recursively parsed
		if itemsVal, isList := res["items"]; isList {
			if items, ok := itemsVal.([]interface{}); ok {
				// convert items to resource
				resArr := make([]resource, 0)
				for _, item := range items {
					if arrVal, ok := item.(resource); ok {
						resArr = append(resArr, arrVal)
					}
				}

				d.getPodSpecs(resArr)
			}

			continue
		}

		// otherwise, get the pod spec based on the type of resource
		podSpec := getPodSpecFromResource(kind, res)

		if podSpec == nil {
			continue
		}

		d.podSpecs = append(d.podSpecs, podSpec)
	}

	return
}

func (d *DockerSecretsPostRenderer) updatePodSpecs(secrets map[string]string) {
	for _, podSpec := range d.podSpecs {
		containersVal, hasContainers := podSpec["containers"]

		if !hasContainers {
			continue
		}

		containers, ok := containersVal.([]interface{})

		if !ok {
			continue
		}

		imagePullSecrets := make([]map[string]interface{}, 0)

		if existingPullSecrets, ok := podSpec["imagePullSecrets"]; ok {
			if existing, ok := existingPullSecrets.([]map[string]interface{}); ok {
				imagePullSecrets = existing
			}
		}

		for _, container := range containers {
			_container, ok := container.(resource)

			if !ok {
				continue
			}

			image, ok := _container["image"].(string)

			if !ok {
				continue
			}

			named, err := reference.ParseNormalizedNamed(image)

			if err != nil {
				continue
			}

			domain := reference.Domain(named)
			path := reference.Path(named)

			regName := domain

			if pathArr := strings.Split(path, "/"); len(pathArr) > 1 {
				regName += "/" + strings.Join(pathArr[:len(pathArr)-1], "/")
			}

			if secretName, ok := secrets[regName]; ok && secretName != "" {
				imagePullSecrets = append(imagePullSecrets, map[string]interface{}{
					"name": secretName,
				})
			}
		}

		if len(imagePullSecrets) > 0 {
			podSpec["imagePullSecrets"] = imagePullSecrets
		}
	}
}

func (d *DockerSecretsPostRenderer) getImageList(podSpec resource) []string {
	images := make([]string, 0)

	containersVal, hasContainers := podSpec["containers"]

	if !hasContainers {
		return images
	}

	containers, ok := containersVal.([]interface{})

	if !ok {
		return images
	}

	for _, container := range containers {
		_container, ok := container.(resource)

		if !ok {
			continue
		}

		image, ok := _container["image"].(string)

		if !ok {
			continue
		}

		images = append(images, image)
	}

	return images
}

var ecrPattern = regexp.MustCompile(`(^[a-zA-Z0-9][a-zA-Z0-9-_]*)\.dkr\.ecr(\-fips)?\.([a-zA-Z0-9][a-zA-Z0-9-_]*)\.amazonaws\.com(\.cn)?`)

func (d *DockerSecretsPostRenderer) isRegistryNative(regName string) bool {
	isNative := false

	if strings.Contains(regName, "gcr") && d.Cluster.AuthMechanism == models.GCP {
		// get the project id of the cluster
		gcpInt, err := d.Repo.GCPIntegration.ReadGCPIntegration(d.Cluster.GCPIntegrationID)

		if err != nil {
			return false
		}

		gkeProjectID, err := integrations.GCPProjectIDFromJSON(gcpInt.GCPKeyData)

		if err != nil {
			return false
		}

		// parse the project id of the gcr url
		if regNameArr := strings.Split(regName, "/"); len(regNameArr) >= 2 {
			gcrProjectID := regNameArr[1]

			isNative = gcrProjectID == gkeProjectID
		}
	} else if strings.Contains(regName, "ecr") && d.Cluster.AuthMechanism == models.AWS {
		matches := ecrPattern.FindStringSubmatch(regName)

		if len(matches) < 3 {
			return false
		}

		eksAccountID := matches[1]
		eksRegion := matches[3]

		awsInt, err := d.Repo.AWSIntegration.ReadAWSIntegration(d.Cluster.AWSIntegrationID)

		if err != nil {
			return false
		}

		err = awsInt.PopulateAWSArn()

		if err != nil {
			return false
		}

		parsedARN, err := arn.Parse(awsInt.AWSArn)

		if err != nil {
			return false
		}

		isNative = parsedARN.AccountID == eksAccountID && parsedARN.Region == eksRegion
	}

	return isNative
}

func getPodSpecFromResource(kind string, res resource) resource {
	switch kind {
	case "Pod":
		return getNestedResource(res, "spec")
	case "DaemonSet", "Deployment", "Job", "ReplicaSet", "ReplicationController", "StatefulSet":
		return getNestedResource(res, "spec", "template", "spec")
	case "PodTemplate":
		return getNestedResource(res, "template", "spec")
	case "CronJob":
		return getNestedResource(res, "spec", "jobTemplate", "spec", "template", "spec")
	}

	return nil
}

func getNestedResource(res resource, keys ...string) resource {
	curr := res
	var ok bool

	for _, key := range keys {
		curr, ok = curr[key].(resource)

		if !ok {
			return nil
		}
	}

	return curr
}