package main

import (
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"

	"github.com/joho/godotenv"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	"github.com/urfave/cli"

	kaniko "github.com/drone/drone-kaniko"
	"github.com/drone/drone-kaniko/pkg/artifact"
	"github.com/drone/drone-kaniko/pkg/docker"
	"github.com/google/go-containerregistry/pkg/authn"
	"github.com/google/go-containerregistry/pkg/crane"
	"github.com/drone/drone-kaniko/pkg/utils"

)

const (
	dockerConfigPath string = "/kaniko/.docker"
	// GAR JSON key file path
	garKeyPath     string = "/kaniko/config.json"
	garEnvVariable string = "GOOGLE_APPLICATION_CREDENTIALS"

	defaultDigestFile string = "/kaniko/digest-file"
)

var (
	version = "unknown"
)

func main() {
	// Load env-file if it exists first
	if env := os.Getenv("PLUGIN_ENV_FILE"); env != "" {
		if err := godotenv.Load(env); err != nil {
			logrus.Fatal(err)
		}
	}

	app := cli.NewApp()
	app.Name = "kaniko gar plugin"
	app.Usage = "kaniko gar plugin"
	app.Action = run
	app.Version = version
	app.Flags = []cli.Flag{
		cli.StringFlag{
			Name:   "dockerfile",
			Usage:  "build dockerfile",
			Value:  "Dockerfile",
			EnvVar: "PLUGIN_DOCKERFILE",
		},
		cli.StringFlag{
			Name:   "context",
			Usage:  "build context",
			Value:  ".",
			EnvVar: "PLUGIN_CONTEXT",
		},
		cli.StringFlag{
			Name:   "drone-commit-ref",
			Usage:  "git commit ref passed by Drone",
			EnvVar: "DRONE_COMMIT_REF",
		},
		cli.StringFlag{
			Name:   "drone-repo-branch",
			Usage:  "git repository default branch passed by Drone",
			EnvVar: "DRONE_REPO_BRANCH",
		},
		cli.StringSliceFlag{
			Name:     "tags",
			Usage:    "build tags",
			Value:    &cli.StringSlice{"latest"},
			EnvVar:   "PLUGIN_TAGS",
			FilePath: ".tags",
		},
		cli.BoolFlag{
			Name:   "expand-tag",
			Usage:  "enable for semver tagging",
			EnvVar: "PLUGIN_EXPAND_TAG",
		},
		cli.BoolFlag{
			Name:   "auto-tag",
			Usage:  "enable auto generation of build tags",
			EnvVar: "PLUGIN_AUTO_TAG",
		},
		cli.StringFlag{
			Name:   "auto-tag-suffix",
			Usage:  "the suffix of auto build tags",
			EnvVar: "PLUGIN_AUTO_TAG_SUFFIX",
		},
		cli.StringSliceFlag{
			Name:   "args",
			Usage:  "build args",
			EnvVar: "PLUGIN_BUILD_ARGS",
		},
		cli.GenericFlag{
			Name:   "args-new",
			Usage:  "build args new",
			EnvVar: "PLUGIN_BUILD_ARGS_NEW",
			Value:  new(utils.CustomStringSliceFlag),
		},
		cli.BoolFlag{
			Name:   "plugin-multiple-build-agrs",
			Usage:  "plugin multiple build agrs",
			EnvVar: "PLUGIN_MULTIPLE_BUILD_ARGS",
		},
		cli.StringFlag{
			Name:   "target",
			Usage:  "build target",
			EnvVar: "PLUGIN_TARGET",
		},
		cli.StringFlag{
			Name:   "repo",
			Usage:  "gar repository",
			EnvVar: "PLUGIN_REPO",
		},
		cli.StringSliceFlag{
			Name:   "custom-labels",
			Usage:  "additional k=v labels",
			EnvVar: "PLUGIN_CUSTOM_LABELS",
		},
		cli.StringFlag{
			Name:   "registry",
			Usage:  "gar registry",
			EnvVar: "PLUGIN_REGISTRY",
		},
		cli.StringFlag{
			Name:   "base-image-username",
			Usage:  "Docker username for base image registry",
			EnvVar: "PLUGIN_DOCKER_USERNAME,PLUGIN_BASE_IMAGE_USERNAME,DOCKER_USERNAME",
		},
		cli.StringFlag{
			Name:   "base-image-password",
			Usage:  "Docker password for base image registry",
			EnvVar: "PLUGIN_DOCKER_PASSWORD,PLUGIN_BASE_IMAGE_PASSWORD,DOCKER_PASSWORD",
		},
		cli.StringFlag{
			Name:   "base-image-registry",
			Usage:  "Docker registry for base image registry",
			EnvVar: "PLUGIN_DOCKER_REGISTRY,PLUGIN_BASE_IMAGE_REGISTRY,DOCKER_REGISTRY",
		},
		cli.StringSliceFlag{
			Name:   "registry-mirrors",
			Usage:  "docker registry mirrors",
			EnvVar: "PLUGIN_REGISTRY_MIRRORS",
		},
		cli.StringFlag{
			Name:   "json-key",
			Usage:  "docker username",
			EnvVar: "PLUGIN_JSON_KEY",
		},
		cli.StringFlag{
			Name:   "snapshot-mode",
			Usage:  "Specify one of full, redo or time as snapshot mode",
			EnvVar: "PLUGIN_SNAPSHOT_MODE",
		},
		cli.BoolFlag{
			Name:   "enable-cache",
			Usage:  "Set this flag to opt into caching with kaniko",
			EnvVar: "PLUGIN_ENABLE_CACHE",
		},
		cli.StringFlag{
			Name:   "cache-repo",
			Usage:  "Remote repository that will be used to store cached layers. Cache repo should be present in specified registry. enable-cache needs to be set to use this flag",
			EnvVar: "PLUGIN_CACHE_REPO",
		},
		cli.IntFlag{
			Name:   "cache-ttl",
			Usage:  "Cache timeout in hours. Defaults to two weeks.",
			EnvVar: "PLUGIN_CACHE_TTL",
		},
		cli.StringFlag{
			Name:   "artifact-file",
			Usage:  "Artifact file location that will be generated by the plugin. This file will include information of docker images that are uploaded by the plugin.",
			EnvVar: "PLUGIN_ARTIFACT_FILE",
		},
		cli.BoolFlag{
			Name:   "no-push",
			Usage:  "Set this flag if you only want to build the image, without pushing to a registry",
			EnvVar: "PLUGIN_NO_PUSH",
		},
		cli.BoolFlag{
			Name:   "push-only",
			Usage:  "Set this flag if you only want to push a pre-built image from a tarball",
			EnvVar: "PLUGIN_PUSH_ONLY",
		},
		cli.StringFlag{
			Name:   "source-tar-path",
			Usage:  "Path to the local tarball to be pushed when push-only is set",
			EnvVar: "PLUGIN_SOURCE_TAR_PATH",
		},
		cli.StringFlag{
			Name:   "tar-path",
			Usage:  "Set this flag to save the image as a tarball at path",
			EnvVar: "PLUGIN_TAR_PATH,PLUGIN_DESTINATION_TAR_PATH",
		},
		cli.StringFlag{
			Name:   "verbosity",
			Usage:  "Set this flag as --verbosity=<panic|fatal|error|warn|info|debug|trace> to set the logging level for kaniko. Defaults to info.",
			EnvVar: "PLUGIN_VERBOSITY",
		},
		cli.StringFlag{
			Name:   "platform",
			Usage:  "Allows to build with another default platform than the host, similarly to docker build --platform",
			EnvVar: "PLUGIN_PLATFORM,PLUGIN_CUSTOM_PLATFORM",
		},
		cli.BoolFlag{
			Name:   "skip-unused-stages",
			Usage:  "build only used stages",
			EnvVar: "PLUGIN_SKIP_UNUSED_STAGES",
		},
		cli.StringFlag{
			Name:   "cache-dir",
			Usage:  "Set this flag to specify a local directory cache for base images",
			EnvVar: "PLUGIN_CACHE_DIR",
		},

		cli.BoolFlag{
			Name:   "cache-copy-layers",
			Usage:  "Enable or disable copying layers from the cache.",
			EnvVar: "PLUGIN_CACHE_COPY_LAYERS",
		},
		cli.BoolFlag{
			Name:   "cache-run-layers",
			Usage:  "Enable or disable running layers from the cache.",
			EnvVar: "PLUGIN_CACHE_RUN_LAYERS",
		},
		cli.BoolFlag{
			Name:   "cleanup",
			Usage:  "Enable or disable cleanup of temporary files.",
			EnvVar: "PLUGIN_CLEANUP",
		},
		cli.BoolFlag{
			Name:   "compressed-caching",
			Usage:  "Enable or disable compressed caching.",
			EnvVar: "PLUGIN_COMPRESSED_CACHING",
		},
		cli.StringFlag{
			Name:   "context-sub-path",
			Usage:  "Sub-path within the context to build.",
			EnvVar: "PLUGIN_CONTEXT_SUB_PATH",
		},
		cli.BoolFlag{
			Name:   "force",
			Usage:  "Force building the image even if it already exists.",
			EnvVar: "PLUGIN_FORCE",
		},
		cli.StringFlag{
			Name:   "image-name-with-digest-file",
			Usage:  "Write image name with digest to a file.",
			EnvVar: "PLUGIN_IMAGE_NAME_WITH_DIGEST_FILE",
		},
		cli.StringFlag{
			Name:   "image-name-tag-with-digest-file",
			Usage:  "Write image name with tag and digest to a file.",
			EnvVar: "PLUGIN_IMAGE_NAME_TAG_WITH_DIGEST_FILE",
		},
		cli.BoolFlag{
			Name:   "insecure",
			Usage:  "Allow connecting to registries without TLS.",
			EnvVar: "PLUGIN_INSECURE",
		},
		cli.BoolFlag{
			Name:   "insecure-pull",
			Usage:  "Allow insecure pulls from the registry.",
			EnvVar: "PLUGIN_INSECURE_PULL",
		},
		cli.StringFlag{
			Name:   "insecure-registry",
			Usage:  "Use plain HTTP for registry communication.",
			EnvVar: "PLUGIN_INSECURE_REGISTRY",
		},
		cli.StringFlag{
			Name:   "log-format",
			Usage:  "Set the log format for build output.",
			EnvVar: "PLUGIN_LOG_FORMAT",
		},
		cli.BoolFlag{
			Name:   "log-timestamp",
			Usage:  "Show timestamps in build output.",
			EnvVar: "PLUGIN_LOG_TIMESTAMP",
		},
		cli.StringFlag{
			Name:   "oci-layout-path",
			Usage:  "Directory to store OCI layout.",
			EnvVar: "PLUGIN_OCI_LAYOUT_PATH",
		},
		cli.IntFlag{
			Name:   "push-retry",
			Usage:  "Number of times to retry pushing an image.",
			EnvVar: "PLUGIN_PUSH_RETRY",
		},
		cli.StringFlag{
			Name:   "registry-certificate",
			Usage:  "Path to a file containing a registry certificate.",
			EnvVar: "PLUGIN_REGISTRY_CERTIFICATE",
		},
		cli.StringFlag{
			Name:   "registry-client-cert",
			Usage:  "Path to a file containing a registry client certificate.",
			EnvVar: "PLUGIN_REGISTRY_CLIENT_CERT",
		},
		cli.BoolFlag{
			Name:   "skip-default-registry-fallback",
			Usage:  "Skip Docker Hub and default registry fallback.",
			EnvVar: "PLUGIN_SKIP_DEFAULT_REGISTRY_FALLBACK",
		},
		cli.BoolFlag{
			Name:   "reproducible",
			Usage:  "Create a reproducible image.",
			EnvVar: "PLUGIN_REPRODUCIBLE",
		},
		cli.BoolFlag{
			Name:   "single-snapshot",
			Usage:  "Only create a single snapshot of the image.",
			EnvVar: "PLUGIN_SINGLE_SNAPSHOT",
		},
		cli.BoolFlag{
			Name:   "skip-push-permission-check",
			Usage:  "Skip permission check when pushing.",
			EnvVar: "PLUGIN_SKIP_PUSH_PERMISSION_CHECK",
		},
		cli.BoolFlag{
			Name:   "skip-tls-verify-pull",
			Usage:  "Skip TLS verification when pulling.",
			EnvVar: "PLUGIN_SKIP_TLS_VERIFY_PULL",
		},
		cli.BoolFlag{
			Name:   "skip-tls-verify-registry",
			Usage:  "Skip TLS verification when connecting to a registry.",
			EnvVar: "PLUGIN_SKIP_TLS_VERIFY_REGISTRY",
		},
		cli.BoolFlag{
			Name:   "use-new-run",
			Usage:  "Skip TLS verification when connecting to a registry.",
			EnvVar: "PLUGIN_USE_NEW_RUN",
		},
		cli.BoolFlag{
			Name:   "ignore-var-run",
			Usage:  "Ignore the /var/run directory during build.",
			EnvVar: "PLUGIN_IGNORE_VAR_RUN",
		},
		cli.StringFlag{
			Name:   "ignore-path",
			Usage:  "Path to ignore during the build.",
			EnvVar: "PLUGIN_IGNORE_PATH",
		},
		cli.IntFlag{
			Name:   "image-fs-extract-retry",
			Usage:  "Number of retries for extracting filesystem layers.",
			EnvVar: "PLUGIN_IMAGE_FS_EXTRACT_RETRY",
		},
		cli.IntFlag{
			Name:   "image-download-retry",
			Usage:  "Number of retries for downloading base images.",
			EnvVar: "PLUGIN_IMAGE_DOWNLOAD_RETRY",
		},
	}

	if err := app.Run(os.Args); err != nil {
		logrus.Fatal(err)
	}
}

func run(c *cli.Context) error {
	// Check if this is a push-only operation
	if c.Bool("push-only") {
		return handlePushOnly(c)
	}

	noPush := c.Bool("no-push")
	jsonKey := c.String("json-key")
	// JSON key may not be set in the following cases:
	// 1. Image does not need to be pushed to GAR.
	// 2. Workload identity is set on GKE in which pod will inherit the credentials via service account.
	if jsonKey != "" {
		if err := setupGARAuth(jsonKey); err != nil {
			return err
		}

		// setup docker config only when base image registry is specified
		if c.String("base-image-registry") != "" {
			if err := setDockerAuth(
				c.String("base-image-username"),
				c.String("base-image-password"),
				c.String("base-image-registry"),
			); err != nil {
				return errors.Wrap(err, "failed to create docker config")
			}
		} else {
			fmt.Println("\033[33mTo ensure consistent and reliable pipeline execution, we recommend setting up a Base Image Connector.\033[0m\n" +
				"\033[33mWhile optional at this time, configuring it helps prevent failures caused by Docker Hub's rate limits.\033[0m")
		}
	}

	plugin := kaniko.Plugin{
		Build: kaniko.Build{
			DroneCommitRef:              c.String("drone-commit-ref"),
			DroneRepoBranch:             c.String("drone-repo-branch"),
			Dockerfile:                  c.String("dockerfile"),
			Context:                     c.String("context"),
			Tags:                        c.StringSlice("tags"),
			AutoTag:                     c.Bool("auto-tag"),
			AutoTagSuffix:               c.String("auto-tag-suffix"),
			ExpandTag:                   c.Bool("expand-tag"),
			Args:                        c.StringSlice("args"),
			ArgsNew:                     c.Generic("args-new").(*utils.CustomStringSliceFlag).GetValue(),
			IsMultipleBuildArgs:         c.Bool("plugin-multiple-build-agrs"),
			Target:                      c.String("target"),
			Repo:                        fmt.Sprintf("%s/%s", c.String("registry"), c.String("repo")),
			Mirrors:                     c.StringSlice("registry-mirrors"),
			Labels:                      c.StringSlice("custom-labels"),
			SnapshotMode:                c.String("snapshot-mode"),
			EnableCache:                 c.Bool("enable-cache"),
			CacheRepo:                   fmt.Sprintf("%s/%s", c.String("registry"), c.String("cache-repo")),
			CacheTTL:                    c.Int("cache-ttl"),
			DigestFile:                  defaultDigestFile,
			NoPush:                      noPush,
			PushOnly:                    c.Bool("push-only"),
			SourceTarPath:               c.String("source-tar-path"),
			TarPath:                     c.String("tar-path"),
			Verbosity:                   c.String("verbosity"),
			CustomPlatform:              c.String("platform"),
			SkipUnusedStages:            c.Bool("skip-unused-stages"),
			CacheDir:                    c.String("cache-dir"),
			CacheCopyLayers:             c.Bool("cache-copy-layers"),
			CacheRunLayers:              c.Bool("cache-run-layers"),
			Cleanup:                     c.Bool("cleanup"),
			ContextSubPath:              c.String("context-sub-path"),
			Force:                       c.Bool("force"),
			ImageNameWithDigestFile:     c.String("image-name-with-digest-file"),
			ImageNameTagWithDigestFile:  c.String("image-name-tag-with-digest-file"),
			Insecure:                    c.Bool("insecure"),
			InsecurePull:                c.Bool("insecure-pull"),
			InsecureRegistry:            c.String("insecure-registry"),
			Label:                       c.String("label"),
			LogFormat:                   c.String("log-format"),
			LogTimestamp:                c.Bool("log-timestamp"),
			OCILayoutPath:               c.String("oci-layout-path"),
			PushRetry:                   c.Int("push-retry"),
			RegistryCertificate:         c.String("registry-certificate"),
			RegistryClientCert:          c.String("registry-client-cert"),
			SkipDefaultRegistryFallback: c.Bool("skip-default-registry-fallback"),
			Reproducible:                c.Bool("reproducible"),
			SingleSnapshot:              c.Bool("single-snapshot"),
			SkipTLSVerify:               c.Bool("skip-tls-verify"),
			SkipPushPermissionCheck:     c.Bool("skip-push-permission-check"),
			SkipTLSVerifyPull:           c.Bool("skip-tls-verify-pull"),
			SkipTLSVerifyRegistry:       c.Bool("skip-tls-verify-registry"),
			UseNewRun:                   c.Bool("use-new-run"),
			IgnorePath:                  c.String("ignore-path"),
			IgnorePaths:                 c.StringSlice("ignore-paths"),
			ImageFSExtractRetry:         c.Int("image-fs-extract-retry"),
			ImageDownloadRetry:          c.Int("image-download-retry"),
		},
		Artifact: kaniko.Artifact{
			Tags:         c.StringSlice("tags"),
			Repo:         c.String("repo"),
			Registry:     c.String("registry"),
			ArtifactFile: c.String("artifact-file"),
			RegistryType: artifact.GAR,
		},
	}
	if c.IsSet("compressed-caching") {
		flag := c.Bool("compressed-caching")
		plugin.Build.CompressedCaching = &flag
	}
	if c.IsSet("ignore-var-run") {
		flag := c.Bool("ignore-var-run")
		plugin.Build.IgnoreVarRun = &flag
	}
	return plugin.Exec()
}

func setDockerAuth(dockerUsername, dockerPassword, dockerRegistry string) error {
	dockerConfig := docker.NewConfig()
	dockerRegistryCreds := docker.RegistryCredentials{
		Registry: dockerRegistry,
		Username: dockerUsername,
		Password: dockerPassword,
	}
	credentials := []docker.RegistryCredentials{dockerRegistryCreds}

	return dockerConfig.CreateDockerConfig(credentials, dockerConfigPath)
}

func setupGARAuth(jsonKey string) error {
	err := ioutil.WriteFile(garKeyPath, []byte(jsonKey), 0644)
	if err != nil {
		return errors.Wrap(err, "failed to write GAR JSON key")
	}

	err = os.Setenv(garEnvVariable, garKeyPath)
	if err != nil {
		return errors.Wrap(err, fmt.Sprintf("failed to set %s environment variable", garEnvVariable))
	}
	return nil
}

func handlePushOnly(c *cli.Context) error {
	// Validate inputs for push-only operation
	sourceTarPath := c.String("source-tar-path")
	if sourceTarPath == "" {
		return fmt.Errorf("source_tar_path is required when push_only is set")
	}

	if _, err := os.Stat(sourceTarPath); os.IsNotExist(err) {
		return fmt.Errorf("image tarball does not exist at path: %s", sourceTarPath)
	}

	repo := c.String("repo")
	registry := c.String("registry")
	if repo == "" || registry == "" {
		return fmt.Errorf("repository and registry must be specified for push-only operation")
	}

	// Authentication options for crane
	var opts []crane.Option

	// Setup GAR authentication
	jsonKey := c.String("json-key")
	if jsonKey != "" {
		if err := setupGARAuth(jsonKey); err != nil {
			return err
		}

		logrus.Info("Setting up authentication for GAR")

		// Create Docker config directory if it doesn't exist
		dockerConfigDir := "/kaniko/.docker"
		if err := os.MkdirAll(dockerConfigDir, 0755); err != nil {
			return fmt.Errorf("failed to create Docker config directory: %v", err)
		}

		// Generate a Docker config with GAR auth
		type DockerAuth struct {
			Username string `json:"username"`
			Password string `json:"password"`
			Auth     string `json:"auth"`
		}

		type DockerConfig struct {
			Auths map[string]DockerAuth `json:"auths"`
		}

		// Create proper Auth field (base64 encoded username:password)
		username := "_json_key"
		authString := base64.StdEncoding.EncodeToString([]byte(username + ":" + jsonKey))

		// Use _json_key as username and the key content as password for GAR
		config := DockerConfig{
			Auths: map[string]DockerAuth{
				registry: {
					Username: username,
					Password: jsonKey,
					Auth:     authString,
				},
			},
		}

		// Write the Docker config
		configBytes, err := json.Marshal(config)
		if err != nil {
			return fmt.Errorf("failed to marshal Docker config: %v", err)
		}

		dockerConfigPath := filepath.Join(dockerConfigDir, "config.json")
		if err := ioutil.WriteFile(dockerConfigPath, configBytes, 0644); err != nil {
			return fmt.Errorf("failed to write Docker config: %v", err)
		}

		// Explicitly set DOCKER_CONFIG environment variable to ensure crane finds the config
		if err := os.Setenv("DOCKER_CONFIG", dockerConfigDir); err != nil {
			return fmt.Errorf("failed to set DOCKER_CONFIG environment variable: %v", err)
		}

		// Set up crane to use basic auth with docker config
		opts = append(opts, crane.WithAuthFromKeychain(authn.DefaultKeychain))
	} else {
		logrus.Warn("No JSON key provided, authentication may fail if not running with workload identity")
	}

	// Load the image from the tarball
	logrus.Infof("Loading image from tarball: %s", sourceTarPath)
	img, err := crane.Load(sourceTarPath)
	if err != nil {
		return fmt.Errorf("failed to load image from tarball: %v", err)
	}

	// Push for each tag
	tags := c.StringSlice("tags")
	if len(tags) == 0 {
		tags = []string{"latest"}
	}

	for _, tag := range tags {
		dest := fmt.Sprintf("%s/%s:%s", registry, repo, tag)
		logrus.Infof("Pushing image to: %s", dest)

		if err := crane.Push(img, dest, opts...); err != nil {
			return fmt.Errorf("failed to push image to %s: %v", dest, err)
		}

		logrus.Infof("Successfully pushed image to %s", dest)
	}

	return nil
}