/*
   Copyright 2020 Docker Compose CLI authors

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package compose

import (
	"context"
	"errors"
	"fmt"
	"slices"
	"strings"
	"time"

	cerrdefs "github.com/containerd/errdefs"
	"github.com/docker/compose/v2/pkg/api"
	"github.com/docker/compose/v2/pkg/progress"
	"github.com/docker/compose/v2/pkg/utils"
	containerType "github.com/docker/docker/api/types/container"

	"github.com/compose-spec/compose-go/v2/types"
	"github.com/docker/docker/api/types/filters"
	"golang.org/x/sync/errgroup"
)

func (s *composeService) Start(ctx context.Context, projectName string, options api.StartOptions) error {
	return progress.Run(ctx, func(ctx context.Context) error {
		return s.start(ctx, strings.ToLower(projectName), options, nil)
	}, s.stdinfo())
}

func (s *composeService) start(ctx context.Context, projectName string, options api.StartOptions, listener api.ContainerEventListener) error {
	project := options.Project
	if project == nil {
		var containers Containers
		containers, err := s.getContainers(ctx, projectName, oneOffExclude, true)
		if err != nil {
			return err
		}

		project, err = s.projectFromName(containers, projectName, options.AttachTo...)
		if err != nil {
			return err
		}
	}

	// use an independent context tied to the errgroup for background attach operations
	// the primary context is still used for other operations
	// this means that once any attach operation fails, all other attaches are cancelled,
	// but an attach failing won't interfere with the rest of the start
	eg, attachCtx := errgroup.WithContext(ctx)
	if listener != nil {
		_, err := s.attach(attachCtx, project, listener, options.AttachTo)
		if err != nil {
			return err
		}

		eg.Go(func() error {
			// it's possible to have a required service whose log output is not desired
			// (i.e. it's not in the attach set), so watch everything and then filter
			// calls to attach; this ensures that `watchContainers` blocks until all
			// required containers have exited, even if their output is not being shown
			attachTo := utils.NewSet[string](options.AttachTo...)
			required := utils.NewSet[string](options.Services...)
			toWatch := attachTo.Union(required).Elements()

			containers, err := s.getContainers(ctx, projectName, oneOffExclude, true, toWatch...)
			if err != nil {
				return err
			}

			// N.B. this uses the parent context (instead of attachCtx) so that the watch itself can
			// continue even if one of the log streams fails
			return s.watchContainers(ctx, project.Name, toWatch, required.Elements(), listener, containers,
				func(ctr containerType.Summary, _ time.Time) error {
					svc := ctr.Labels[api.ServiceLabel]
					if attachTo.Has(svc) {
						return s.attachContainer(attachCtx, ctr, listener)
					}

					// HACK: simulate an "attach" event
					listener(api.ContainerEvent{
						Type:      api.ContainerEventAttach,
						Container: getContainerNameWithoutProject(ctr),
						ID:        ctr.ID,
						Service:   svc,
					})
					return nil
				}, func(ctr containerType.Summary, _ time.Time) error {
					listener(api.ContainerEvent{
						Type:      api.ContainerEventAttach,
						Container: "", // actual name will be set by start event
						ID:        ctr.ID,
						Service:   ctr.Labels[api.ServiceLabel],
					})
					return nil
				})
		})
	}

	var containers Containers
	containers, err := s.apiClient().ContainerList(ctx, containerType.ListOptions{
		Filters: filters.NewArgs(
			projectFilter(project.Name),
			oneOffFilter(false),
		),
		All: true,
	})
	if err != nil {
		return err
	}

	err = InDependencyOrder(ctx, project, func(c context.Context, name string) error {
		service, err := project.GetService(name)
		if err != nil {
			return err
		}

		return s.startService(ctx, project, service, containers, listener, options.WaitTimeout)
	})
	if err != nil {
		return err
	}

	if options.Wait {
		depends := types.DependsOnConfig{}
		for _, s := range project.Services {
			depends[s.Name] = types.ServiceDependency{
				Condition: getDependencyCondition(s, project),
				Required:  true,
			}
		}
		if options.WaitTimeout > 0 {
			withTimeout, cancel := context.WithTimeout(ctx, options.WaitTimeout)
			ctx = withTimeout
			defer cancel()
		}

		err = s.waitDependencies(ctx, project, project.Name, depends, containers, 0)
		if err != nil {
			if errors.Is(ctx.Err(), context.DeadlineExceeded) {
				return fmt.Errorf("application not healthy after %s", options.WaitTimeout)
			}
			return err
		}
	}

	return eg.Wait()
}

// getDependencyCondition checks if service is depended on by other services
// with service_completed_successfully condition, and applies that condition
// instead, or --wait will never finish waiting for one-shot containers
func getDependencyCondition(service types.ServiceConfig, project *types.Project) string {
	for _, services := range project.Services {
		for dependencyService, dependencyConfig := range services.DependsOn {
			if dependencyService == service.Name && dependencyConfig.Condition == types.ServiceConditionCompletedSuccessfully {
				return types.ServiceConditionCompletedSuccessfully
			}
		}
	}
	return ServiceConditionRunningOrHealthy
}

type containerWatchFn func(ctr containerType.Summary, t time.Time) error

// watchContainers uses engine events to capture container start/die and notify ContainerEventListener
func (s *composeService) watchContainers(ctx context.Context, //nolint:gocyclo
	projectName string, services, required []string,
	listener api.ContainerEventListener, containers Containers, onStart, onRecreate containerWatchFn,
) error {
	if len(containers) == 0 {
		return nil
	}
	if len(required) == 0 {
		required = services
	}

	unexpected := utils.NewSet[string](required...).Diff(utils.NewSet[string](services...))
	if len(unexpected) != 0 {
		return fmt.Errorf(`required service(s) "%s" not present in watched service(s) "%s"`,
			strings.Join(unexpected.Elements(), ", "),
			strings.Join(services, ", "))
	}

	// predicate to tell if a container we receive event for should be considered or ignored
	ofInterest := func(c containerType.Summary) bool {
		if len(services) > 0 {
			// we only watch some services
			return slices.Contains(services, c.Labels[api.ServiceLabel])
		}
		return true
	}

	// predicate to tell if a container we receive event for should be watched until termination
	isRequired := func(c containerType.Summary) bool {
		if len(services) > 0 && len(required) > 0 {
			// we only watch some services
			return slices.Contains(required, c.Labels[api.ServiceLabel])
		}
		return true
	}

	var (
		expected = utils.NewSet[string]()
		watched  = map[string]int{}
		replaced []string
	)
	for _, c := range containers {
		if isRequired(c) {
			expected.Add(c.ID)
		}
		watched[c.ID] = 0
	}

	ctx, stop := context.WithCancel(ctx)
	err := s.Events(ctx, projectName, api.EventsOptions{
		Services: services,
		Consumer: func(event api.Event) error {
			defer func() {
				// after consuming each event, check to see if we're done
				if len(expected) == 0 {
					stop()
				}
			}()
			inspected, err := s.apiClient().ContainerInspect(ctx, event.Container)
			if err != nil {
				if cerrdefs.IsNotFound(err) {
					// it's possible to get "destroy" or "kill" events but not
					// be able to inspect in time before they're gone from the
					// API, so just remove the watch without erroring
					delete(watched, event.Container)
					expected.Remove(event.Container)
					return nil
				}
				return err
			}
			container := containerType.Summary{
				ID:     inspected.ID,
				Names:  []string{inspected.Name},
				Labels: inspected.Config.Labels,
			}
			name := getContainerNameWithoutProject(container)
			service := container.Labels[api.ServiceLabel]
			switch event.Status {
			case "stop":
				if inspected.State.Running {
					// on sync+restart action the container stops -> dies -> start -> restart
					// we do not want to stop the current container, we want to restart it
					return nil
				}
				if _, ok := watched[container.ID]; ok {
					eType := api.ContainerEventStopped
					if slices.Contains(replaced, container.ID) {
						replaced = slices.DeleteFunc(replaced, func(e string) bool { return e == container.ID })
						eType = api.ContainerEventRecreated
					}
					listener(api.ContainerEvent{
						Type:      eType,
						Container: name,
						ID:        container.ID,
						Service:   service,
						ExitCode:  inspected.State.ExitCode,
					})
				}

				delete(watched, container.ID)
				expected.Remove(container.ID)
			case "die":
				restarted := watched[container.ID]
				watched[container.ID] = restarted + 1
				// Container terminated.
				willRestart := inspected.State.Restarting
				if inspected.State.Running {
					// on sync+restart action inspected.State.Restarting is false,
					// however the container is already running before it restarts
					willRestart = true
				}

				eType := api.ContainerEventExit
				if slices.Contains(replaced, container.ID) {
					replaced = slices.DeleteFunc(replaced, func(e string) bool { return e == container.ID })
					eType = api.ContainerEventRecreated
				}

				listener(api.ContainerEvent{
					Type:       eType,
					Container:  name,
					ID:         container.ID,
					Service:    service,
					ExitCode:   inspected.State.ExitCode,
					Restarting: willRestart,
				})

				if !willRestart {
					// we're done with this one
					delete(watched, container.ID)
					expected.Remove(container.ID)
				}
			case "start":
				count, ok := watched[container.ID]
				mustAttach := ok && count > 0 // Container restarted, need to re-attach
				if !ok {
					// A new container has just been added to service by scale
					watched[container.ID] = 0
					expected.Add(container.ID)
					mustAttach = true
				}
				if mustAttach {
					// Container restarted, need to re-attach
					err := onStart(container, event.Timestamp)
					if err != nil {
						return err
					}
				}
			case "create":
				if id, ok := container.Labels[api.ContainerReplaceLabel]; ok {
					replaced = append(replaced, id)
					err = onRecreate(container, event.Timestamp)
					if err != nil {
						return err
					}
					if expected.Has(id) {
						expected.Add(inspected.ID)
						expected.Add(container.ID)
					}
					watched[container.ID] = 1
				} else if ofInterest(container) {
					watched[container.ID] = 1
					if isRequired(container) {
						expected.Add(container.ID)
					}
				}
			}
			return nil
		},
	})
	if errors.Is(ctx.Err(), context.Canceled) {
		return nil
	}
	return err
}