package toolsrv

import (
	"context"
	"fmt"
)

// Addr describes how to reach a tool server.
type Addr struct {
	// Network is the transport: "local", "ssh", or (future) "unix".
	Network string
	// Host is the SSH target (user@host or user@host:port). Empty for local.
	Host string
	// CWD is the working directory on the target.
	CWD string
}

// LocalAddr returns an Addr for an in-process tool server.
func LocalAddr(cwd string) Addr {
	return Addr{Network: "local", CWD: cwd}
}

// SSHAddr returns an Addr for a remote tool server over SSH.
func SSHAddr(host, cwd string) Addr {
	return Addr{Network: "ssh", Host: host, CWD: cwd}
}

// Dial connects to a tool server at the given address.
// Options (WithStrict, WithBuiltins, etc.) are applied to local servers.
//
// TODO: Unify local and remote behind a single protocol. Local execution
// should eventually go through a Unix socket (same JSON-RPC as remote),
// making the agent always a client. The elevation broker already proves
// this pattern. Benefits: process isolation, shared tool server across
// sessions, independent lifecycle. Transport becomes the only difference:
//   - Network "local" → unix socket to co-located toolsrv process
//   - Network "ssh"   → SSH tunnel to remote toolsrv process
//   - Network "unix"  → pre-existing unix socket
func Dial(ctx context.Context, addr Addr, opts ...Option) (Runner, error) {
	switch addr.Network {
	case "", "local":
		srv := New(addr.CWD)
		for _, o := range opts {
			o(srv)
		}
		return srv, nil
	case "ssh":
		return RemoteDial(ctx, RemoteConfig{
			SSHTarget: addr.Host,
			CWD:       addr.CWD,
		})
	default:
		return nil, fmt.Errorf("toolsrv.Dial: unsupported network %q", addr.Network)
	}
}