package daemon

import (
	"context"
	"fmt"
	"isle/bootstrap"
	"isle/yamlutil"
	"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"
)

// 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,
		"Creating UDP socket from nebula addr",
		func(context.Context) error {
			conn, err := net.DialUDP("udp", lUDPAddr, rUDPAddr)
			if err != nil {
				return err
			}
			conn.Close()
			return nil
		},
	)

	return ctx.Err()
}

func nebulaConfig(
	daemonConfig Config,
	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": daemonConfig.VPN.Tun.Device,
		},
		"firewall": daemonConfig.VPN.Firewall,
	}

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

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

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

	} else {

		_, port, err := net.SplitHostPort(publicAddr)

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

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

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

	return config, nil
}

func nebulaWriteConfig(
	runtimeDirPath string,
	daemonConfig Config,
	hostBootstrap bootstrap.Bootstrap,
) (
	string, error,
) {
	config, err := nebulaConfig(daemonConfig, hostBootstrap)
	if err != nil {
		return "", fmt.Errorf("creating nebula config: %w", err)
	}

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

	if err := yamlutil.WriteYamlFile(config, nebulaYmlPath, 0600); err != nil {
		return "", fmt.Errorf("writing nebula.yml to %q: %w", nebulaYmlPath, err)
	}

	return nebulaYmlPath, nil
}

func nebulaPmuxProcConfig(
	runtimeDirPath, binDirPath string,
	daemonConfig Config,
	hostBootstrap bootstrap.Bootstrap,
) (
	pmuxlib.ProcessConfig, error,
) {
	config, err := nebulaConfig(daemonConfig, hostBootstrap)
	if err != nil {
		return pmuxlib.ProcessConfig{}, fmt.Errorf(
			"creating nebula config: %w", err,
		)
	}

	nebulaYmlPath := filepath.Join(runtimeDirPath, "nebula.yml")
	if err := yamlutil.WriteYamlFile(config, nebulaYmlPath, 0600); err != nil {
		return pmuxlib.ProcessConfig{}, fmt.Errorf(
			"writing nebula.yml to %q: %w", nebulaYmlPath, err,
		)
	}

	return pmuxlib.ProcessConfig{
		Cmd:   filepath.Join(binDirPath, "nebula"),
		Args:  []string{"-config", nebulaYmlPath},
		Group: -1, // Make sure nebula is shut down last.
	}, nil
}