/*
 * blebus.hpp — BLEBus v1.1.0
 * Pure C++17 BLE L2CAP IPC library.
 * Dual-listener broker: local unix socket + BLE L2CAP CoC.
 * Length-prefixed framing (wire-compatible with sockbus).
 * Bytes in, bytes out, broadcast to all readers including sender.
 *
 * Copyright (c) 2026 Are Bjørby <are.bjorby@langsyn.org>
 * SPDX-License-Identifier: MIT
 */

#pragma once

#include <cstddef>
#include <cstdint>
#include <memory>
#include <string_view>

namespace blebus {

// ── Constants ────────────────────────────────────────────────────────

inline constexpr size_t DEFAULT_SIZE    = 64 * 1024;
inline constexpr size_t MAX_NAME        = 256;
inline constexpr size_t MAX_READERS     = 8;
inline constexpr size_t READER_NAME_LEN = 32;
inline constexpr size_t MAX_MSG_SIZE    = DEFAULT_SIZE - 4;
inline constexpr uint16_t PSM           = 0x0080;

// ── Bus lifecycle (no handle) ────────────────────────────────────────

/**
 * Create a new BLE bus.
 * Starts BLE advertising, L2CAP listener (PSM 0x0080), and local
 * unix socket listener. Spawns broker thread.
 * @throws std::system_error on failure
 */
void create(std::string_view name, size_t size = 0);

/**
 * Destroy bus (stop advertising, disconnect all clients).
 * @throws std::system_error(ENOENT) if no broker for name
 */
void destroy(std::string_view name);

// ── Bus handle (RAII) ────────────────────────────────────────────────

class Bus {
public:
    /**
     * Connect to an existing blebus via local unix socket.
     * @throws std::system_error on connection failure
     */
    explicit Bus(std::string_view name);

    ~Bus();

    Bus(const Bus&) = delete;
    Bus& operator=(const Bus&) = delete;

    Bus(Bus&&) noexcept;
    Bus& operator=(Bus&&) noexcept;

    // ── Write ────────────────────────────────────────────────────────

    /**
     * Write data to bus (broadcast to all connected peers).
     * @return Payload bytes written
     * @throws std::system_error(EMSGSIZE) if len > MAX_MSG_SIZE
     * @throws std::system_error on send failure
     */
    size_t write(const uint8_t* data, size_t len);
    size_t write(std::string_view sv);

    // ── Read ─────────────────────────────────────────────────────────

    /**
     * Non-blocking read. Returns one complete message per call.
     * @return Bytes read, 0 if no message available
     */
    size_t read(uint8_t* buf, size_t len);

    /**
     * Blocking read with timeout.
     * @param timeout_ms  -1 = block forever, 0 = poll, >0 = ms
     * @return Bytes read, 0 on timeout
     */
    size_t read_wait(uint8_t* buf, size_t len, int timeout_ms = -1);

    // ── Metadata ─────────────────────────────────────────────────────

    void set_reader_name(std::string_view label);
    std::string_view name() const;

private:
    struct Impl;
    std::unique_ptr<Impl> impl_;
};

} // namespace blebus