package network

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

	"github.com/docker/cli/cli"
	"github.com/docker/cli/cli/command"
	"github.com/docker/cli/cli/command/completion"
	"github.com/docker/cli/opts"
	"github.com/moby/moby/api/types/network"
	"github.com/moby/moby/client"
	"github.com/spf13/cobra"
)

type connectOptions struct {
	network      string
	container    string
	ipaddress    net.IP // TODO(thaJeztah): we need a flag-type to handle netip.Addr directly
	ipv6address  net.IP // TODO(thaJeztah): we need a flag-type to handle netip.Addr directly
	links        opts.ListOpts
	aliases      []string
	linklocalips []net.IP // TODO(thaJeztah): we need a flag-type to handle []netip.Addr directly
	driverOpts   []string
	gwPriority   int
}

func newConnectCommand(dockerCLI command.Cli) *cobra.Command {
	options := connectOptions{
		links: opts.NewListOpts(opts.ValidateLink),
	}

	cmd := &cobra.Command{
		Use:   "connect [OPTIONS] NETWORK CONTAINER",
		Short: "Connect a container to a network",
		Args:  cli.ExactArgs(2),
		RunE: func(cmd *cobra.Command, args []string) error {
			options.network = args[0]
			options.container = args[1]
			return runConnect(cmd.Context(), dockerCLI.Client(), options)
		},
		ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
			if len(args) == 0 {
				return completion.NetworkNames(dockerCLI)(cmd, args, toComplete)
			}
			nw := args[0]
			return completion.ContainerNames(dockerCLI, true, not(isConnected(nw)))(cmd, args, toComplete)
		},
		DisableFlagsInUseLine: true,
	}

	flags := cmd.Flags()
	flags.IPVar(&options.ipaddress, "ip", nil, `IPv4 address (e.g., "172.30.100.104")`)
	flags.IPVar(&options.ipv6address, "ip6", nil, `IPv6 address (e.g., "2001:db8::33")`)
	flags.Var(&options.links, "link", "Add link to another container")
	flags.StringSliceVar(&options.aliases, "alias", []string{}, "Add network-scoped alias for the container")
	flags.IPSliceVar(&options.linklocalips, "link-local-ip", nil, "Add a link-local address for the container")
	flags.StringSliceVar(&options.driverOpts, "driver-opt", []string{}, "driver options for the network")
	flags.IntVar(&options.gwPriority, "gw-priority", 0, "Highest gw-priority provides the default gateway. Accepts positive and negative values.")
	return cmd
}

func runConnect(ctx context.Context, apiClient client.NetworkAPIClient, options connectOptions) error {
	driverOpts, err := convertDriverOpt(options.driverOpts)
	if err != nil {
		return err
	}
	_, err = apiClient.NetworkConnect(ctx, options.network, client.NetworkConnectOptions{
		Container: options.container,
		EndpointConfig: &network.EndpointSettings{
			IPAMConfig: &network.EndpointIPAMConfig{
				IPv4Address:  toNetipAddr(options.ipaddress),
				IPv6Address:  toNetipAddr(options.ipv6address),
				LinkLocalIPs: toNetipAddrSlice(options.linklocalips),
			},
			Links:      options.links.GetSlice(),
			Aliases:    options.aliases,
			DriverOpts: driverOpts,
			GwPriority: options.gwPriority,
		},
	})
	return err
}

func convertDriverOpt(options []string) (map[string]string, error) {
	driverOpt := make(map[string]string)
	for _, opt := range options {
		k, v, ok := strings.Cut(opt, "=")
		// TODO(thaJeztah): we should probably not accept whitespace here (both for key and value).
		k = strings.TrimSpace(k)
		if !ok || k == "" {
			return nil, errors.New("invalid key/value pair format in driver options")
		}
		driverOpt[k] = strings.TrimSpace(v)
	}
	return driverOpt, nil
}

func toNetipAddrSlice(ips []net.IP) []netip.Addr {
	if len(ips) == 0 {
		return nil
	}
	netIPs := make([]netip.Addr, 0, len(ips))
	for _, ip := range ips {
		netIPs = append(netIPs, toNetipAddr(ip))
	}
	return netIPs
}

func toNetipAddr(ip net.IP) netip.Addr {
	a, _ := netip.AddrFromSlice(ip)
	return a.Unmap()
}

// toPrefix converts n into a netip.Prefix. If n is not a valid IPv4 or IPV6
// address, ToPrefix returns netip.Prefix{}, false.
//
// TODO(thaJeztah): create internal package similar to https://github.com/moby/moby/blob/0769fe708773892d6ac399ee137e71a777b35de7/daemon/internal/netiputil/netiputil.go#L21-L42
func toPrefix(n net.IPNet) (netip.Prefix, bool) {
	if ll := len(n.Mask); ll != net.IPv4len && ll != net.IPv6len {
		return netip.Prefix{}, false
	}

	addr, ok := netip.AddrFromSlice(n.IP)
	if !ok {
		return netip.Prefix{}, false
	}

	ones, bits := n.Mask.Size()
	if ones == 0 && bits == 0 {
		return netip.Prefix{}, false
	}

	return netip.PrefixFrom(addr.Unmap(), ones), true
}