// Copyright 2023 The Gitea Authors. All rights reserved.
// Copyright 2023 The nektos/act Authors. All rights reserved.
// SPDX-License-Identifier: MIT

//go:build !(WITHOUT_DOCKER || !(linux || darwin || windows || netbsd || freebsd))

package container

import (
	"context"
	"errors"
	"fmt"
	"net/netip"
	"strings"
	"time"

	"gitea.com/gitea/runner/act/common"

	cerrdefs "github.com/containerd/errdefs"
	"github.com/moby/moby/api/types/network"
	"github.com/moby/moby/client"
)

const (
	networkCreateAttempts   = 3
	networkCreateRetryDelay = time.Second
)

// RemoveOrphanNetworks removes the networks this runner created for jobs whose teardown did
// not get to them: the runner died with the job, the teardown timed out, or the network still
// had an endpoint on it at the time. Each one holds a subnet of the daemon's address pool
// until it is removed. Networks created after createdBefore are left alone, so a job starting
// while this runs cannot lose the network it has created but not yet attached a container to.
func RemoveOrphanNetworks(ctx context.Context, runnerUUID, detach string, createdBefore time.Time) error {
	cli, err := GetDockerClient(ctx)
	if err != nil {
		return fmt.Errorf("failed to connect to the docker daemon: %w", err)
	}
	defer cli.Close()

	return removeOrphanNetworks(ctx, cli, runnerUUID, detach, createdBefore)
}

func removeOrphanNetworks(ctx context.Context, cli client.APIClient, runnerUUID, detach string, createdBefore time.Time) error {
	networks, err := cli.NetworkList(ctx, client.NetworkListOptions{
		Filters: make(client.Filters).Add("label", runnerUUIDLabel+"="+runnerUUID),
	})
	if err != nil {
		return err
	}

	var errs []error
networks:
	for _, n := range networks.Items {
		result, err := cli.NetworkInspect(ctx, n.ID, client.NetworkInspectOptions{})
		if cerrdefs.IsNotFound(err) {
			continue
		} else if err != nil {
			errs = append(errs, fmt.Errorf("failed to inspect network %s: %w", n.Name, err))
			continue
		}
		// the emptiness check, not the label, is what keeps a live job of another process
		// sharing this registration safe
		if len(result.Network.Containers) > 1 || result.Network.Created.After(createdBefore) {
			continue
		}
		for containerID := range result.Network.Containers {
			if detach == "" || !strings.HasPrefix(containerID, detach) {
				continue networks
			}
			if err := disconnectNetwork(ctx, cli, n.ID, containerID); err != nil {
				errs = append(errs, fmt.Errorf("failed to disconnect container from network %s: %w", n.Name, err))
				continue networks
			}
		}
		if _, err := cli.NetworkRemove(ctx, n.ID, client.NetworkRemoveOptions{}); cerrdefs.IsNotFound(err) {
			continue
		} else if err != nil {
			errs = append(errs, fmt.Errorf("failed to remove network %s: %w", n.Name, err))
			continue
		}
		common.Logger(ctx).Infof("removed docker network %s left behind by an earlier job", n.Name)
	}
	return errors.Join(errs...)
}

func NewDockerNetworkCreateExecutor(name string, opts NewDockerNetworkCreateExecutorInput) common.Executor {
	return common.Executor(func(ctx context.Context) error {
		cli, err := GetDockerClient(ctx)
		if err != nil {
			return err
		}
		defer cli.Close()
		return createDockerNetwork(ctx, cli, name, opts)
	}).IfNot(common.Dryrun)
}

func createDockerNetwork(ctx context.Context, cli client.APIClient, name string, opts NewDockerNetworkCreateExecutorInput) error {
	// Only create the network if it doesn't exist
	networks, err := cli.NetworkList(ctx, client.NetworkListOptions{})
	if err != nil {
		return err
	}
	var options map[string]string
	// For Gitea, reduce log noise
	// common.Logger(ctx).Debugf("%v", networks)
	for _, n := range networks.Items {
		if n.Name == name {
			common.Logger(ctx).Debugf("Network %v exists", name)
			return nil
		}
		// the daemon's mtu only reaches its default bridge, Docker's default is left out to keep default-network-opts
		if mtu := n.Options["com.docker.network.driver.mtu"]; n.Name == network.NetworkBridge && mtu != "" && mtu != "1500" {
			options = map[string]string{"com.docker.network.driver.mtu": mtu}
		}
	}

	for i := range networkCreateAttempts {
		if i > 0 {
			common.Logger(ctx).Infof("Waiting for a free docker address pool to create network %s", name)
			select {
			case <-ctx.Done():
				return ctx.Err()
			case <-time.After(time.Duration(i) * networkCreateRetryDelay):
			}
		}
		if _, err = cli.NetworkCreate(ctx, name, client.NetworkCreateOptions{
			Driver:     "bridge",
			Scope:      "local",
			EnableIPv4: opts.EnableIPv4,
			EnableIPv6: opts.EnableIPv6,
			Options:    options,
			Labels:     runnerLabels(opts.RunnerUUID),
		}); err == nil {
			return nil
		}
		if !isAddressPoolExhausted(err) {
			return err
		}
	}
	return fmt.Errorf("docker has no address pool left for this job's network, lower runner.capacity or widen default-address-pools in the docker daemon config: %w", err)
}

func runnerLabels(runnerUUID string) map[string]string {
	if runnerUUID == "" {
		return nil
	}
	return map[string]string{runnerUUIDLabel: runnerUUID}
}

// The daemon reports this as a plain invalid-parameter error, the same kind it uses for every
// malformed request, so the message is the only discriminator.
func isAddressPoolExhausted(err error) bool {
	msg := err.Error()
	return strings.Contains(msg, "all predefined address pools have been fully subnetted") ||
		strings.Contains(msg, "could not find an available, non-overlapping IPv4 address pool among the defaults") // docker 24 and older
}

func NewDockerNetworkConnectExecutor(networkName, container string) common.Executor {
	return common.Executor(func(ctx context.Context) error {
		cli, err := GetDockerClient(ctx)
		if err != nil {
			return err
		}
		defer cli.Close()
		if err := connectNetwork(ctx, cli, networkName, container); err != nil {
			common.Logger(ctx).Warnf("cannot connect %s to network %s, so jobs on it cannot reach the cache: %v", container, networkName, err)
		}
		return nil
	}).IfNot(common.Dryrun)
}

func connectNetwork(ctx context.Context, cli client.APIClient, networkName, container string) error {
	_, err := cli.NetworkConnect(ctx, networkName, client.NetworkConnectOptions{
		Container:      container,
		EndpointConfig: &network.EndpointSettings{Aliases: []string{container}},
	})
	if err != nil && (strings.Contains(err.Error(), "already exists in network") || strings.Contains(err.Error(), "already connected")) {
		return nil
	}
	return err
}

func NewDockerNetworkDisconnectExecutor(networkName, container string) common.Executor {
	return common.Executor(func(ctx context.Context) error {
		cli, err := GetDockerClient(ctx)
		if err != nil {
			return err
		}
		defer cli.Close()
		return disconnectNetwork(ctx, cli, networkName, container)
	}).IfNot(common.Dryrun)
}

func disconnectNetwork(ctx context.Context, cli client.APIClient, networkName, container string) error {
	_, err := cli.NetworkDisconnect(ctx, networkName, client.NetworkDisconnectOptions{Container: container, Force: true})
	if cerrdefs.IsNotFound(err) || (err != nil && strings.Contains(err.Error(), "is not connected")) {
		return nil
	}
	return err
}

func NewDockerNetworkRemoveExecutor(name string) common.Executor {
	return common.Executor(func(ctx context.Context) error {
		cli, err := GetDockerClient(ctx)
		if err != nil {
			return err
		}
		defer cli.Close()
		return removeNetwork(ctx, cli, name)
	}).IfNot(common.Dryrun)
}

func removeNetwork(ctx context.Context, cli client.APIClient, name string) error {
	networks, err := cli.NetworkList(ctx, client.NetworkListOptions{}) // NetworkRemove by name refuses duplicates, so remove each by ID
	if err != nil {
		return err
	}
	var errs []error
	for _, n := range networks.Items {
		if n.Name != name {
			continue
		}
		result, err := cli.NetworkInspect(ctx, n.ID, client.NetworkInspectOptions{})
		if cerrdefs.IsNotFound(err) {
			continue
		} else if err != nil {
			return err
		}
		if len(result.Network.Containers) != 0 {
			common.Logger(ctx).Warnf("Refusing to remove network %s because it still has active endpoints, the orphan cleanup reclaims it once they are gone", name)
			continue
		}
		if _, err = cli.NetworkRemove(ctx, n.ID, client.NetworkRemoveOptions{}); err != nil && !cerrdefs.IsNotFound(err) {
			errs = append(errs, fmt.Errorf("failed to remove network %s: %w", name, err))
		}
	}
	return errors.Join(errs...)
}

// IsolatedCacheContainer returns the container holding addr, when jobs on jobNetwork cannot reach it there.
func IsolatedCacheContainer(ctx context.Context, addr netip.Addr, jobNetwork string) (string, error) {
	cli, err := GetDockerClient(ctx)
	if err != nil {
		return "", err
	}
	defer cli.Close()
	return isolatedCacheContainer(ctx, cli, addr, jobNetwork)
}

func isolatedCacheContainer(ctx context.Context, cli client.APIClient, addr netip.Addr, jobNetwork string) (string, error) {
	if jobNetwork == "host" || strings.HasPrefix(jobNetwork, "container:") {
		return "", nil
	}
	containers, err := cli.ContainerList(ctx, client.ContainerListOptions{})
	if err != nil {
		return "", err
	}
	var holderID, holderContainer string
	for _, summary := range containers.Items {
		if summary.NetworkSettings == nil {
			continue
		}
		for _, endpoint := range summary.NetworkSettings.Networks {
			if endpoint != nil && (endpoint.IPAddress == addr || endpoint.GlobalIPv6Address == addr) {
				holderID = endpoint.NetworkID
				holderContainer = summary.ID[:12]
			}
		}
	}
	if holderID == "" {
		return "", nil
	}
	holder, err := cli.NetworkInspect(ctx, holderID, client.NetworkInspectOptions{})
	if err != nil || holder.Network.Driver != "bridge" {
		return "", err
	}
	if jobNetwork != "" {
		job, err := cli.NetworkInspect(ctx, jobNetwork, client.NetworkInspectOptions{})
		if err != nil || job.Network.ID == holderID {
			return "", err
		}
	}
	return holderContainer, nil
}