package children

import (
	"context"
	"fmt"
	"io"
	"isle/bootstrap"
	"isle/daemon/daecommon"
	"isle/toolkit"
	"net"
	"path/filepath"

	"code.betamike.com/micropelago/pmux/pmuxlib"
	"dev.mediocregopher.com/mediocre-go-lib.git/mctx"
	"dev.mediocregopher.com/mediocre-go-lib.git/mlog"
	"github.com/slackhq/nebula/cert"
	"gopkg.in/yaml.v3"
)

// waitForNebula waits for the nebula interface to have been started up. It does
// this by attempting to create a UDP connection which has the nebula IP set as
// its source. If this succeeds we can assume that at the very least the nebula
// interface has been initialized.
func waitForNebula(
	ctx context.Context, logger *mlog.Logger, hostBootstrap bootstrap.Bootstrap,
) error {
	var (
		ip       = net.IP(hostBootstrap.ThisHost().IP().AsSlice())
		lUDPAddr = &net.UDPAddr{IP: ip, Port: 0}
		rUDPAddr = &net.UDPAddr{IP: ip, Port: 45535}
	)

	ctx = mctx.Annotate(ctx, "lUDPAddr", lUDPAddr, "rUDPAddr", rUDPAddr)

	until(
		ctx,
		logger,
		"Checking if nebula is online by creating UDP socket from nebula IP",
		func(context.Context) error {
			conn, err := net.DialUDP("udp", lUDPAddr, rUDPAddr)
			if err != nil {
				return err
			}
			conn.Close()
			return nil
		},
	)

	return ctx.Err()
}

// TODO this needs to be produce a deterministic config value.
func nebulaConfig(
	networkConfig daecommon.NetworkConfig,
	hostBootstrap bootstrap.Bootstrap,
) (
	map[string]any, error,
) {
	var (
		lighthouseHostIPs []string
		staticHostMap     = map[string][]string{}
	)

	for _, host := range hostBootstrap.Hosts {

		if host.Nebula.PublicAddr == "" {
			continue
		}

		ip := host.IP().String()
		lighthouseHostIPs = append(lighthouseHostIPs, ip)
		staticHostMap[ip] = []string{host.Nebula.PublicAddr}
	}

	caCertPEM, err := hostBootstrap.CAPublicCredentials.Cert.Unwrap().MarshalToPEM()
	if err != nil {
		return nil, fmt.Errorf("marshaling CA cert to PEM: :%w", err)
	}

	hostCertPEM, err := hostBootstrap.PublicCredentials.Cert.Unwrap().MarshalToPEM()
	if err != nil {
		return nil, fmt.Errorf("marshaling host cert to PEM: :%w", err)
	}

	hostKeyPEM := cert.MarshalX25519PrivateKey(
		hostBootstrap.PrivateCredentials.EncryptingPrivateKey.Bytes(),
	)

	config := map[string]any{
		"pki": map[string]string{
			"ca":   string(caCertPEM),
			"cert": string(hostCertPEM),
			"key":  string(hostKeyPEM),
		},
		"static_host_map": staticHostMap,
		"punchy": map[string]bool{
			"punch":   true,
			"respond": true,
		},
		"tun": map[string]any{
			"dev": networkConfig.VPN.Tun.Device,
		},
		"firewall": networkConfig.VPN.Firewall,
	}

	if publicAddr := networkConfig.VPN.PublicAddr; publicAddr == "" {

		config["listen"] = map[string]string{
			"host": "0.0.0.0",
			"port": "0",
		}

		config["lighthouse"] = map[string]any{
			"hosts": lighthouseHostIPs,
		}

	} else {

		host, port, err := net.SplitHostPort(publicAddr)
		if err != nil {
			return nil, fmt.Errorf(
				"parsing public address %q: %w", publicAddr, err,
			)
		}

		// This helps with integration testing, so we can set a test to listen
		// on some local IP without conflicting with something else running on
		// the host.
		if hostIP := net.ParseIP(host); hostIP == nil || !hostIP.IsLoopback() {
			host = "0.0.0.0"
		}

		config["listen"] = map[string]string{
			"host": host,
			"port": port,
		}

		config["lighthouse"] = map[string]any{
			"hosts":         []string{},
			"am_lighthouse": true,
		}
	}

	return config, nil
}

func nebulaWriteConfig(
	ctx context.Context,
	logger *mlog.Logger,
	runtimeDirPath string,
	networkConfig daecommon.NetworkConfig,
	hostBootstrap bootstrap.Bootstrap,
) (
	string, bool, error,
) {
	config, err := nebulaConfig(networkConfig, hostBootstrap)
	if err != nil {
		return "", false, fmt.Errorf("creating nebula config: %w", err)
	}

	nebulaYmlPath := filepath.Join(runtimeDirPath, "nebula.yml")

	changed, err := toolkit.WriteFileCheckChanged(
		ctx, logger, nebulaYmlPath, 0600, func(w io.Writer) error {
			return yaml.NewEncoder(w).Encode(config)
		},
	)
	if err != nil {
		return "", false, fmt.Errorf(
			"writing nebula.yml to %q: %w", nebulaYmlPath, err,
		)
	}

	return nebulaYmlPath, changed, nil
}

func nebulaPmuxProc(
	ctx context.Context,
	logger *mlog.Logger,
	runtimeDirPath, binDirPath string,
	networkConfig daecommon.NetworkConfig,
	hostBootstrap bootstrap.Bootstrap,
) (
	*pmuxlib.Process, error,
) {
	nebulaYmlPath, _, err := nebulaWriteConfig(
		ctx, logger, runtimeDirPath, networkConfig, hostBootstrap,
	)
	if err != nil {
		return nil, fmt.Errorf("writing nebula config: %w", err)
	}

	cfg := pmuxlib.ProcessConfig{
		Cmd:  filepath.Join(binDirPath, "nebula"),
		Args: []string{"-config", nebulaYmlPath},
	}
	cfg = withPmuxLoggers(ctx, logger, "nebula", cfg)

	return pmuxlib.NewProcess(cfg), nil
}