package main

import (
	"context"
	"errors"
	"io"
	"strings"

	"github.com/containers/image/transports/alltransports"
	"github.com/containers/image/types"
	"github.com/urfave/cli"
)

// errorShouldDisplayUsage is a subtype of error used by command handlers to indicate that cli.ShowSubcommandHelp should be called.
type errorShouldDisplayUsage struct {
	error
}

// commandAction intermediates between the cli.ActionFunc interface and the real handler,
// primarily to ensure that cli.Context is not available to the handler, which in turn
// makes sure that the cli.String() etc. flag access functions are not used,
// and everything is done using the *Options structures and the Destination: members of cli.Flag.
// handler may return errorShouldDisplayUsage to cause cli.ShowSubcommandHelp to be called.
func commandAction(handler func(args []string, stdout io.Writer) error) cli.ActionFunc {
	return func(c *cli.Context) error {
		err := handler(([]string)(c.Args()), c.App.Writer)
		if _, ok := err.(errorShouldDisplayUsage); ok {
			cli.ShowSubcommandHelp(c)
		}
		return err
	}
}

// sharedImageOptions collects CLI flags which are image-related, but do not change across images.
// This really should be a part of globalOptions, but that would break existing users of (skopeo copy --authfile=).
type sharedImageOptions struct {
	authFilePath string // Path to a */containers/auth.json
}

// imageFlags prepares a collection of CLI flags writing into sharedImageOptions, and the managed sharedImageOptions structure.
func sharedImageFlags() ([]cli.Flag, *sharedImageOptions) {
	opts := sharedImageOptions{}
	return []cli.Flag{
		cli.StringFlag{
			Name:        "authfile",
			Usage:       "path of the authentication file. Default is ${XDG_RUNTIME_DIR}/containers/auth.json",
			Destination: &opts.authFilePath,
		},
	}, &opts
}

// imageOptions collects CLI flags which are the same across subcommands, but may be different for each image
// (e.g. may differ between the source and destination of a copy)
type imageOptions struct {
	global           *globalOptions      // May be shared across several imageOptions instances.
	shared           *sharedImageOptions // May be shared across several imageOptions instances.
	credsOption      optionalString      // username[:password] for accessing a registry
	dockerCertPath   string              // A directory using Docker-like *.{crt,cert,key} files for connecting to a registry or a daemon
	tlsVerify        optionalBool        // Require HTTPS and verify certificates (for docker: and docker-daemon:)
	sharedBlobDir    string              // A directory to use for OCI blobs, shared across repositories
	dockerDaemonHost string              // docker-daemon: host to connect to
	noCreds          bool                // Access the registry anonymously
}

// imageFlags prepares a collection of CLI flags writing into imageOptions, and the managed imageOptions structure.
func imageFlags(global *globalOptions, shared *sharedImageOptions, flagPrefix, credsOptionAlias string) ([]cli.Flag, *imageOptions) {
	opts := imageOptions{
		global: global,
		shared: shared,
	}

	// This is horribly ugly, but we need to support the old option forms of (skopeo copy) for compatibility.
	// Don't add any more cases like this.
	credsOptionExtra := ""
	if credsOptionAlias != "" {
		credsOptionExtra += "," + credsOptionAlias
	}

	return []cli.Flag{
		cli.GenericFlag{
			Name:  flagPrefix + "creds" + credsOptionExtra,
			Usage: "Use `USERNAME[:PASSWORD]` for accessing the registry",
			Value: newOptionalStringValue(&opts.credsOption),
		},
		cli.StringFlag{
			Name:        flagPrefix + "cert-dir",
			Usage:       "use certificates at `PATH` (*.crt, *.cert, *.key) to connect to the registry or daemon",
			Destination: &opts.dockerCertPath,
		},
		cli.GenericFlag{
			Name:  flagPrefix + "tls-verify",
			Usage: "require HTTPS and verify certificates when talking to the container registry or daemon (defaults to true)",
			Value: newOptionalBoolValue(&opts.tlsVerify),
		},
		cli.StringFlag{
			Name:        flagPrefix + "shared-blob-dir",
			Usage:       "`DIRECTORY` to use to share blobs across OCI repositories",
			Destination: &opts.sharedBlobDir,
		},
		cli.StringFlag{
			Name:        flagPrefix + "daemon-host",
			Usage:       "use docker daemon host at `HOST` (docker-daemon: only)",
			Destination: &opts.dockerDaemonHost,
		},
		cli.BoolFlag{
			Name:        flagPrefix + "no-creds",
			Usage:       "Access the registry anonymously",
			Destination: &opts.noCreds,
		},
	}, &opts
}

// newSystemContext returns a *types.SystemContext corresponding to opts.
// It is guaranteed to return a fresh instance, so it is safe to make additional updates to it.
func (opts *imageOptions) newSystemContext() (*types.SystemContext, error) {
	ctx := &types.SystemContext{
		RegistriesDirPath:        opts.global.registriesDirPath,
		ArchitectureChoice:       opts.global.overrideArch,
		OSChoice:                 opts.global.overrideOS,
		DockerCertPath:           opts.dockerCertPath,
		OCISharedBlobDirPath:     opts.sharedBlobDir,
		AuthFilePath:             opts.shared.authFilePath,
		DockerDaemonHost:         opts.dockerDaemonHost,
		DockerDaemonCertPath:     opts.dockerCertPath,
		SystemRegistriesConfPath: opts.global.registriesConfPath,
	}
	if opts.tlsVerify.present {
		ctx.DockerDaemonInsecureSkipTLSVerify = !opts.tlsVerify.value
	}
	// DEPRECATED: We support this for backward compatibility, but override it if a per-image flag is provided.
	if opts.global.tlsVerify.present {
		ctx.DockerInsecureSkipTLSVerify = types.NewOptionalBool(!opts.global.tlsVerify.value)
	}
	if opts.tlsVerify.present {
		ctx.DockerInsecureSkipTLSVerify = types.NewOptionalBool(!opts.tlsVerify.value)
	}
	if opts.credsOption.present && opts.noCreds {
		return nil, errors.New("creds and no-creds cannot be specified at the same time")
	}
	if opts.credsOption.present {
		var err error
		ctx.DockerAuthConfig, err = getDockerAuth(opts.credsOption.value)
		if err != nil {
			return nil, err
		}
	}
	if opts.noCreds {
		ctx.DockerAuthConfig = &types.DockerAuthConfig{}
	}
	return ctx, nil
}

// imageDestOptions is a superset of imageOptions specialized for iamge destinations.
type imageDestOptions struct {
	*imageOptions
	osTreeTmpDir        string // A directory to use for OSTree temporary files
	dirForceCompression bool   // Compress layers when saving to the dir: transport
}

// imageDestFlags prepares a collection of CLI flags writing into imageDestOptions, and the managed imageDestOptions structure.
func imageDestFlags(global *globalOptions, shared *sharedImageOptions, flagPrefix, credsOptionAlias string) ([]cli.Flag, *imageDestOptions) {
	genericFlags, genericOptions := imageFlags(global, shared, flagPrefix, credsOptionAlias)
	opts := imageDestOptions{imageOptions: genericOptions}

	return append(genericFlags, []cli.Flag{
		cli.StringFlag{
			Name:        flagPrefix + "ostree-tmp-dir",
			Usage:       "`DIRECTORY` to use for OSTree temporary files",
			Destination: &opts.osTreeTmpDir,
		},
		cli.BoolFlag{
			Name:        flagPrefix + "compress",
			Usage:       "Compress tarball image layers when saving to directory using the 'dir' transport. (default is same compression type as source)",
			Destination: &opts.dirForceCompression,
		},
	}...), &opts
}

// newSystemContext returns a *types.SystemContext corresponding to opts.
// It is guaranteed to return a fresh instance, so it is safe to make additional updates to it.
func (opts *imageDestOptions) newSystemContext() (*types.SystemContext, error) {
	ctx, err := opts.imageOptions.newSystemContext()
	if err != nil {
		return nil, err
	}

	ctx.OSTreeTmpDirPath = opts.osTreeTmpDir
	ctx.DirForceCompress = opts.dirForceCompression
	return ctx, err
}

func parseCreds(creds string) (string, string, error) {
	if creds == "" {
		return "", "", errors.New("credentials can't be empty")
	}
	up := strings.SplitN(creds, ":", 2)
	if len(up) == 1 {
		return up[0], "", nil
	}
	if up[0] == "" {
		return "", "", errors.New("username can't be empty")
	}
	return up[0], up[1], nil
}

func getDockerAuth(creds string) (*types.DockerAuthConfig, error) {
	username, password, err := parseCreds(creds)
	if err != nil {
		return nil, err
	}
	return &types.DockerAuthConfig{
		Username: username,
		Password: password,
	}, nil
}

// parseImage converts image URL-like string to an initialized handler for that image.
// The caller must call .Close() on the returned ImageCloser.
func parseImage(ctx context.Context, opts *imageOptions, name string) (types.ImageCloser, error) {
	ref, err := alltransports.ParseImageName(name)
	if err != nil {
		return nil, err
	}
	sys, err := opts.newSystemContext()
	if err != nil {
		return nil, err
	}
	return ref.NewImage(ctx, sys)
}

// parseImageSource converts image URL-like string to an ImageSource.
// The caller must call .Close() on the returned ImageSource.
func parseImageSource(ctx context.Context, opts *imageOptions, name string) (types.ImageSource, error) {
	ref, err := alltransports.ParseImageName(name)
	if err != nil {
		return nil, err
	}
	sys, err := opts.newSystemContext()
	if err != nil {
		return nil, err
	}
	return ref.NewImageSource(ctx, sys)
}
