package commands

import (
	"context"
	"os"
	"path/filepath"

	"github.com/docker/cli/cli/command"
	"github.com/docker/cli/cli/context/docker"
	dopts "github.com/docker/cli/opts"
	dockerclient "github.com/docker/docker/client"
	"github.com/pkg/errors"
	"github.com/tonistiigi/buildx/build"
	"github.com/tonistiigi/buildx/driver"
	"github.com/tonistiigi/buildx/store"
	"golang.org/x/sync/errgroup"
)

// getStore returns current builder instance store
func getStore(dockerCli command.Cli) (*store.Txn, func(), error) {
	dir := filepath.Dir(dockerCli.ConfigFile().Filename)
	s, err := store.New(dir)
	if err != nil {
		return nil, nil, err
	}
	return s.Txn()
}

// getCurrentEndpoint returns the current default endpoint value
func getCurrentEndpoint(dockerCli command.Cli) (string, error) {
	name := dockerCli.CurrentContext()
	if name != "default" {
		return name, nil
	}
	de, err := getDockerEndpoint(dockerCli, name)
	if err != nil {
		return "", errors.Errorf("docker endpoint for %q not found", name)
	}
	return de, nil
}

// getDockerEndpoint returns docker endpoint string for given context
func getDockerEndpoint(dockerCli command.Cli, name string) (string, error) {
	list, err := dockerCli.ContextStore().ListContexts()
	if err != nil {
		return "", err
	}
	for _, l := range list {
		if l.Name == name {
			ep, ok := l.Endpoints["docker"]
			if !ok {
				return "", errors.Errorf("context %q does not have a Docker endpoint", name)
			}
			typed, ok := ep.(docker.EndpointMeta)
			if !ok {
				return "", errors.Errorf("endpoint %q is not of type EndpointMeta, %T", ep, ep)
			}
			return typed.Host, nil
		}
	}
	return "", nil
}

// validateEndpoint validates that endpoint is either a context or a docker host
func validateEndpoint(dockerCli command.Cli, ep string) (string, error) {
	de, err := getDockerEndpoint(dockerCli, ep)
	if err == nil && de != "" {
		if ep == "default" {
			return de, nil
		}
		return ep, nil
	}
	h, err := dopts.ParseHost(true, ep)
	if err != nil {
		return "", errors.Wrapf(err, "failed to parse endpoint %s", ep)
	}
	return h, nil
}

// getCurrentInstance finds the current builder instance
func getCurrentInstance(txn *store.Txn, dockerCli command.Cli) (*store.NodeGroup, error) {
	ep, err := getCurrentEndpoint(dockerCli)
	if err != nil {
		return nil, err
	}
	ng, err := txn.Current(ep)
	if err != nil {
		return nil, err
	}
	return ng, nil
}

// getNodeGroup returns nodegroup based on the name
func getNodeGroup(txn *store.Txn, dockerCli command.Cli, name string) (*store.NodeGroup, error) {
	ng, err := txn.NodeGroupByName(name)
	if err != nil {
		if !os.IsNotExist(errors.Cause(err)) {
			return nil, err
		}
	}
	if ng != nil {
		return ng, nil
	}

	if name == "default" {
		name = dockerCli.CurrentContext()
	}

	list, err := dockerCli.ContextStore().ListContexts()
	if err != nil {
		return nil, err
	}
	for _, l := range list {
		if l.Name == name {
			return &store.NodeGroup{
				Name: "default",
				Nodes: []store.Node{
					{
						Name:     "default",
						Endpoint: name,
					},
				},
			}, nil
		}
	}

	return nil, errors.Errorf("no builder %q found", name)
}

// driversForNodeGroup returns drivers for a nodegroup instance
func driversForNodeGroup(ctx context.Context, dockerCli command.Cli, ng *store.NodeGroup) ([]build.DriverInfo, error) {
	eg, _ := errgroup.WithContext(ctx)

	dis := make([]build.DriverInfo, len(ng.Nodes))

	var f driver.Factory
	if ng.Driver != "" {
		f = driver.GetFactory(ng.Driver, true)
		if f == nil {
			return nil, errors.Errorf("failed to find driver %q", f)
		}
	} else {
		dockerapi, err := clientForEndpoint(dockerCli, ng.Nodes[0].Endpoint)
		if err != nil {
			return nil, err
		}
		f, err = driver.GetDefaultFactory(ctx, dockerapi, false)
		if err != nil {
			return nil, err
		}
	}

	for i, n := range ng.Nodes {
		func(i int, n store.Node) {
			eg.Go(func() error {
				di := build.DriverInfo{
					Name:     n.Name,
					Platform: n.Platforms,
				}
				defer func() {
					dis[i] = di
				}()
				dockerapi, err := clientForEndpoint(dockerCli, n.Endpoint)
				if err != nil {
					di.Err = err
					return nil
				}

				d, err := driver.GetDriver(ctx, "buildx_buildkit_"+n.Name, f, dockerapi)
				if err != nil {
					di.Err = err
					return nil
				}
				di.Driver = d
				return nil
			})
		}(i, n)
	}

	if err := eg.Wait(); err != nil {
		return nil, err
	}

	return dis, nil
}

// clientForEndpoint returns a docker client for an endpoint
func clientForEndpoint(dockerCli command.Cli, name string) (dockerclient.APIClient, error) {
	list, err := dockerCli.ContextStore().ListContexts()
	if err != nil {
		return nil, err
	}
	for _, l := range list {
		if l.Name == name {
			dep, ok := l.Endpoints["docker"]
			if !ok {
				return nil, errors.Errorf("context %q does not have a Docker endpoint", name)
			}
			epm, ok := dep.(docker.EndpointMeta)
			if !ok {
				return nil, errors.Errorf("endpoint %q is not of type EndpointMeta, %T", dep, dep)
			}
			ep, err := docker.WithTLSData(dockerCli.ContextStore(), name, epm)
			if err != nil {
				return nil, err
			}
			clientOpts, err := ep.ClientOpts()
			if err != nil {
				return nil, err
			}
			return dockerclient.NewClientWithOpts(clientOpts...)
		}
	}
	return dockerclient.NewClientWithOpts(dockerclient.WithHost(name))
}

// getDefaultDrivers returns drivers based on current cli config
func getDefaultDrivers(ctx context.Context, dockerCli command.Cli) ([]build.DriverInfo, error) {
	txn, release, err := getStore(dockerCli)
	if err != nil {
		return nil, err
	}
	defer release()

	ng, err := getCurrentInstance(txn, dockerCli)
	if err != nil {
		return nil, err
	}

	if ng != nil {
		return driversForNodeGroup(ctx, dockerCli, ng)
	}

	d, err := driver.GetDriver(ctx, "buildx_buildkit_default", nil, dockerCli.Client())
	if err != nil {
		return nil, err
	}
	return []build.DriverInfo{
		{
			Name:   "default",
			Driver: d,
		},
	}, nil
}

// type ngInfo struct {
// 	ng *store.NodeGroup
// }
//
// func (i *ngInfo) init(ctx context.Context, boot bool) {
//
// }