package asterisk

import (
	"encoding/hex"
	"errors"
	"fmt"
	"os"
	"path/filepath"

	"github.com/CyCoreSystems/ari/v5"
	"github.com/CyCoreSystems/ari/v5/client/native"
)

// ariOptions uses the credential issued to the Agent on the same Cell as
// native Asterisk. It never reads a historical local test credential.
func (l Loader) ariOptions() (*native.Options, error) {
	if l.ConfigDir == "" {
		return nil, errors.New("native Asterisk configuration directory required")
	}
	path := filepath.Join(l.ConfigDir, "ari-secret")
	info, err := os.Lstat(path)
	if err != nil {
		return nil, fmt.Errorf("inspect issued Agent ARI credential: %T", err)
	}
	if !info.Mode().IsRegular() || info.Mode().Perm() != 0600 {
		return nil, errors.New("issued Agent ARI credential must be a private regular file (0600)")
	}
	secret, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read issued Agent ARI credential: %T", err)
	}
	if len(secret) != 64 {
		return nil, errors.New("issued Agent ARI credential has an invalid length")
	}
	if _, err := hex.DecodeString(string(secret)); err != nil {
		return nil, errors.New("issued Agent ARI credential has an invalid format")
	}
	return &native.Options{
		URL: "http://127.0.0.1:8088/ari", WebsocketURL: "ws://127.0.0.1:8088/ari/events",
		Application: "go-sip-agent", Username: "go-sip-agent", Password: string(secret),
	}, nil
}

// OpenARI proves that the native server accepts this Agent credential without
// creating a channel or dialing. The caller owns and must close the client.
func (l Loader) OpenARI() (ari.Client, error) {
	options, err := l.ariOptions()
	if err != nil {
		return nil, err
	}
	client, err := native.Connect(options)
	if err != nil {
		return nil, fmt.Errorf("connect native Agent ARI: %T", err)
	}
	info, err := client.Asterisk().Info(nil)
	if err != nil {
		client.Close()
		return nil, fmt.Errorf("read native Agent ARI status: %T", err)
	}
	if info == nil {
		client.Close()
		return nil, errors.New("native Agent ARI returned an empty status")
	}
	return client, nil
}