package client

import (
	"context"
	"errors"
	"fmt"
	"github.com/docker/compose/v2/pkg/progress"
	"github.com/docker/docker/api/types/container"
	"github.com/docker/docker/api/types/filters"
	"github.com/psviderski/uncloud/internal/machine/api/pb"
	"github.com/psviderski/uncloud/pkg/api"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/status"
	"slices"
	"sync"
)

func (cli *Client) PrepareDeploymentSpec(ctx context.Context, spec api.ServiceSpec) (api.ServiceSpec, error) {
	domain, err := cli.GetDomain(ctx)
	if err != nil && !errors.Is(err, ErrNotFound) {
		return spec, fmt.Errorf("get cluster domain: %w", err)
	}

	resolver := ServiceSpecResolver{
		// If the domain is not found (not reserved), an empty domain is used for the resolver.
		ClusterDomain: domain,
		// TODO: provide an image resolver.
	}

	if err = resolver.Resolve(&spec); err != nil {
		return spec, err
	}

	return spec, nil
}

type RunServiceResponse struct {
	ID   string
	Name string
}

func (cli *Client) RunService(
	ctx context.Context, spec api.ServiceSpec, filter MachineFilter,
) (RunServiceResponse, error) {
	var resp RunServiceResponse

	if err := spec.Validate(); err != nil {
		return resp, fmt.Errorf("invalid service spec: %w", err)
	}

	if spec.Name != "" {
		// Optimistically check if a service with the specified name already exists.
		_, err := cli.InspectService(ctx, spec.Name)
		if err == nil {
			return resp, fmt.Errorf("service with name '%s' already exists", spec.Name)
		}
		if !errors.Is(err, ErrNotFound) {
			return resp, fmt.Errorf("inspect service: %w", err)
		}
	}

	var err error
	if spec, err = cli.PrepareDeploymentSpec(ctx, spec); err != nil {
		return resp, fmt.Errorf("prepare service spec ready for deployment: %w", err)
	}

	err = progress.RunWithTitle(ctx, func(ctx context.Context) error {
		deploy, err := cli.NewDeployment(spec, &RollingStrategy{MachineFilter: filter})
		if err != nil {
			return fmt.Errorf("create deployment: %w", err)
		}

		plan, err := deploy.Run(ctx)
		if err != nil {
			return err
		}

		resp.ID = plan.ServiceID
		resp.Name = plan.ServiceName

		return nil
	}, cli.progressOut(), fmt.Sprintf("Running service %s (%s mode)", spec.Name, spec.Mode))

	return resp, err
}

// InspectService returns detailed information about a service and its containers.
// The id parameter can be either a service ID or name.
func (cli *Client) InspectService(ctx context.Context, id string) (api.Service, error) {
	var svc api.Service

	machines, err := cli.ListMachines(ctx)
	if err != nil {
		return svc, fmt.Errorf("list machines: %w", err)
	}

	// Broadcast the container list request to all available machines.
	machineIDByManagementIP := make(map[string]string)
	md := metadata.New(nil)
	for _, m := range machines {
		if m.State == pb.MachineMember_UP || m.State == pb.MachineMember_SUSPECT {
			machineIP, _ := m.Machine.Network.ManagementIp.ToAddr()
			md.Append("machines", machineIP.String())

			machineIDByManagementIP[machineIP.String()] = m.Machine.Id
		}
		// TODO: warning about machines that are DOWN.
	}
	listCtx := metadata.NewOutgoingContext(ctx, md)

	// List only uncloud-managed containers that belong to some service.
	opts := container.ListOptions{
		All: true,
		Filters: filters.NewArgs(
			filters.Arg("label", api.LabelServiceID),
			filters.Arg("label", api.LabelManaged),
		),
	}
	machineContainers, err := cli.Docker.ListContainers(listCtx, opts)
	if err != nil {
		return svc, fmt.Errorf("list containers: %w", err)
	}

	// Collect all containers on all machines that belong to the specified service.
	foundByID := false
	var containers []api.MachineContainer
	for _, mc := range machineContainers {
		// Metadata can be nil if the request was broadcasted to only one machine.
		if mc.Metadata == nil && len(machineContainers) > 1 {
			return svc, errors.New("something went wrong with gRPC proxy: metadata is missing for a machine response")
		}
		if mc.Metadata != nil && mc.Metadata.Error != "" {
			// TODO: return failed machines in the response.
			fmt.Printf("WARNING: failed to list containers on machine '%s': %s\n",
				mc.Metadata.Machine, mc.Metadata.Error)
			continue
		}

		machineID := ""
		if mc.Metadata == nil {
			// ListContainers was proxied to only one machine.
			for _, v := range machineIDByManagementIP {
				machineID = v
				break
			}
		} else {
			var ok bool
			machineID, ok = machineIDByManagementIP[mc.Metadata.Machine]
			if !ok {
				return svc, fmt.Errorf("machine name not found for management IP: %s", mc.Metadata.Machine)
			}
		}

		for _, c := range mc.Containers {
			ctr := api.Container{ContainerJSON: c}
			if ctr.ServiceID() == id || ctr.ServiceName() == id {
				containers = append(containers, api.MachineContainer{
					MachineID: machineID,
					Container: ctr,
				})

				if ctr.ServiceID() == id {
					foundByID = true
				}
			}
		}
	}

	if len(containers) == 0 {
		return svc, ErrNotFound
	}

	// Containers from different services may share the same service name (distributed and eventually consistent store
	// may not prevent this), or a service name might match another service's ID. In these cases, matching by ID takes
	// priority over matching by name.
	if foundByID {
		containers = slices.DeleteFunc(containers, func(mc api.MachineContainer) bool {
			return mc.Container.ServiceID() != id
		})
	} else {
		// Matched only by name but there could be multiple services with the same name.
		serviceID := containers[0].Container.ServiceID()
		for _, mc := range containers[1:] {
			if mc.Container.ServiceID() != serviceID {
				return svc, fmt.Errorf("multiple services found with name '%s', use the service ID instead", id)
			}
		}
	}

	svc = api.Service{
		ID:         containers[0].Container.ServiceID(),
		Name:       containers[0].Container.ServiceName(),
		Mode:       containers[0].Container.ServiceMode(),
		Containers: containers,
	}
	if svc.Mode == "" {
		svc.Mode = api.ServiceModeReplicated
	}

	return svc, nil
}

// InspectServiceFromStore returns detailed information about a service and its containers from the distributed store.
// Due to eventual consistency of the store, the returned information may not reflect the most recent changes.
// The id parameter can be either a service ID or name.
func (cli *Client) InspectServiceFromStore(ctx context.Context, id string) (api.Service, error) {
	var svc api.Service

	resp, err := cli.MachineClient.InspectService(ctx, &pb.InspectServiceRequest{Id: id})
	if err != nil {
		if s, ok := status.FromError(err); ok {
			if s.Code() == codes.NotFound {
				return svc, ErrNotFound
			}
		}
		return svc, err
	}

	svc, err = api.ServiceFromProto(resp.Service)
	if err != nil {
		return svc, fmt.Errorf("from proto: %w", err)
	}
	return svc, nil
}

// RemoveService removes all containers on all machines that belong to the specified service.
// The id parameter can be either a service ID or name.
func (cli *Client) RemoveService(ctx context.Context, id string) error {
	svc, err := cli.InspectService(ctx, id)
	if err != nil {
		return err
	}

	machines, err := cli.ListMachines(ctx)
	if err != nil {
		return fmt.Errorf("list machines: %w", err)
	}
	machineManagementIPByID := make(map[string]string)
	for _, m := range machines {
		machineIP, _ := m.Machine.Network.ManagementIp.ToAddr()
		machineManagementIPByID[m.Machine.Id] = machineIP.String()
	}

	wg := sync.WaitGroup{}
	errCh := make(chan error)

	// Remove all containers on all machines that belong to the service.
	for _, mc := range svc.Containers {
		wg.Add(1)

		go func() {
			defer wg.Done()

			err := cli.StopContainer(ctx, svc.ID, mc.Container.ID, container.StopOptions{})
			if err != nil {
				errCh <- fmt.Errorf("stop container '%s': %w", mc.Container.ID, err)
				return
			}

			err = cli.RemoveContainer(ctx, svc.ID, mc.Container.ID, container.RemoveOptions{})
			if err != nil && !errors.Is(err, ErrNotFound) {
				errCh <- fmt.Errorf("remove container '%s': %w", mc.Container.ID, err)
			}
		}()
	}

	go func() {
		wg.Wait()
		close(errCh)
	}()

	err = nil
	for e := range errCh {
		err = errors.Join(err, e)
	}
	return err
}

// ListServices returns a list of all services and their containers.
func (cli *Client) ListServices(ctx context.Context) ([]api.Service, error) {
	machines, err := cli.ListMachines(ctx)
	if err != nil {
		return nil, fmt.Errorf("list machines: %w", err)
	}

	// Broadcast the container list request to all available machines.
	md := metadata.New(nil)
	for _, m := range machines {
		if m.State == pb.MachineMember_UP || m.State == pb.MachineMember_SUSPECT {
			machineIP, _ := m.Machine.Network.ManagementIp.ToAddr()
			md.Append("machines", machineIP.String())
		}
		// TODO: warning about machines that are DOWN.
	}
	listCtx := metadata.NewOutgoingContext(ctx, md)

	// List only uncloud-managed containers that belong to some service.
	opts := container.ListOptions{
		All: true,
		Filters: filters.NewArgs(
			filters.Arg("label", api.LabelServiceID),
			filters.Arg("label", api.LabelManaged),
		),
	}
	machineContainers, err := cli.Docker.ListContainers(listCtx, opts)
	if err != nil {
		return nil, fmt.Errorf("list containers: %w", err)
	}

	// TODO: optimise by extracting services from the list of all containers instead of inspecting each service.
	//  Most of the code can be reused in both InspectService and ListServices.
	servicesByID := make(map[string]api.Service)
	for _, mc := range machineContainers {
		if mc.Metadata != nil && mc.Metadata.Error != "" {
			// TODO: return failed machines in the response.
			fmt.Printf("WARNING: failed to list containers on machine '%s': %s\n",
				mc.Metadata.Machine, mc.Metadata.Error)
			continue
		}

		for _, c := range mc.Containers {
			ctr := api.Container{ContainerJSON: c}
			if _, ok := servicesByID[ctr.ServiceID()]; ok {
				continue
			}

			svc, err := cli.InspectService(ctx, ctr.ServiceID())
			if err != nil {
				if errors.Is(err, ErrNotFound) {
					continue
				}
				return nil, fmt.Errorf("inspect service: %w", err)
			}

			servicesByID[ctr.ServiceID()] = svc
		}
	}

	services := make([]api.Service, 0, len(servicesByID))
	for _, svc := range servicesByID {
		services = append(services, svc)
	}
	return services, nil
}