/*
 * .============.
 * // M A K E / \
 * // C++ DEV / \
 * // E A S Y / \/ \
 * ++ ----------. \/\ .
 * \\ \ \ /\ /
 * \\ \ \ /
 * \\ \ \ /
 * -============'
 *
 * Copyright (c) 2026 Hevake and contributors, all rights reserved.
 *
 * This file is part of cpp-tbox (https://github.com/cpp-main/cpp-tbox)
 * Use of this source code is governed by MIT license that can be found
 * in the LICENSE file in the root of the source tree. All contributing
 * project authors may be found in the CONTRIBUTORS.md file in the root
 * of the source tree.
 */
#include "ws_frame_builder.h"

#include <cstring>
#include <cstdlib>

namespace tbox {
namespace websocket {

//! === 服务端帧(不掩码) ===

std::vector<uint8_t> WsFrameBuilder::BuildTextFrame(const std::string &text)
{
 return BuildFrame(WsFrame::OpCode::kText, true, text.data(), text.size());
}

std::vector<uint8_t> WsFrameBuilder::BuildBinaryFrame(const void *data, size_t len)
{
 return BuildFrame(WsFrame::OpCode::kBinary, true, data, len);
}

std::vector<uint8_t> WsFrameBuilder::BuildBinaryFrame(const std::vector<uint8_t> &data)
{
 return BuildFrame(WsFrame::OpCode::kBinary, true, data.data(), data.size());
}

std::vector<uint8_t> WsFrameBuilder::BuildCloseFrame(uint16_t code, const std::string &reason)
{
 //! Close 帧的 payload: 2字节关闭码(大端序) + 可选的原因字符串
 std::vector<uint8_t> payload;
 payload.push_back(static_cast<uint8_t>((code >> 8) & 0xFF));
 payload.push_back(static_cast<uint8_t>(code & 0xFF));
 if (!reason.empty())
 payload.insert(payload.end(), reason.begin(), reason.end());

 return BuildFrame(WsFrame::OpCode::kClose, true, payload.data(), payload.size());
}

std::vector<uint8_t> WsFrameBuilder::BuildPingFrame(const std::string &data)
{
 return BuildFrame(WsFrame::OpCode::kPing, true, data.data(), data.size());
}

std::vector<uint8_t> WsFrameBuilder::BuildPongFrame(const std::string &data)
{
 return BuildFrame(WsFrame::OpCode::kPong, true, data.data(), data.size());
}

std::vector<uint8_t> WsFrameBuilder::BuildFrame(WsFrame::OpCode opcode, bool fin, const void *payload_ptr, size_t payload_len)
{
 std::vector<uint8_t> frame;

 //! 第1字节:FIN + RSV1-3(0) + Opcode
 uint8_t byte0 = static_cast<uint8_t>(opcode);
 if (fin)
 byte0 |= 0x80;
 frame.push_back(byte0);

 //! 第2字节:MASK=0(服务端不掩码) + Payload length
 //! 服务端发送的帧不使用掩码(RFC 6455 Section 5.3)
 if (payload_len < 125) {
 frame.push_back(static_cast<uint8_t>(payload_len));
 } else if (payload_len <= 65535) {
 frame.push_back(126);
 frame.push_back(static_cast<uint8_t>((payload_len >> 8) & 0xFF));
 frame.push_back(static_cast<uint8_t>(payload_len & 0xFF));
 } else {
 frame.push_back(127);
 for (int i = 7; i >= 0; --i)
 frame.push_back(static_cast<uint8_t>((payload_len >> (i * 8)) & 0xFF));
 }

 //! Payload 数据(无掩码)
 if (payload_ptr != nullptr && payload_len > 0) {
 const uint8_t *p = static_cast<const uint8_t*>(payload_ptr);
 frame.insert(frame.end(), p, p + payload_len);
 }

 return frame;
}

//! === 客户端帧(掩码) ===

std::vector<uint8_t> WsFrameBuilder::BuildMaskedTextFrame(const std::string &text)
{
 return BuildMaskedFrame(WsFrame::OpCode::kText, true, text.data(), text.size());
}

std::vector<uint8_t> WsFrameBuilder::BuildMaskedBinaryFrame(const void *data, size_t len)
{
 return BuildMaskedFrame(WsFrame::OpCode::kBinary, true, data, len);
}

std::vector<uint8_t> WsFrameBuilder::BuildMaskedBinaryFrame(const std::vector<uint8_t> &data)
{
 return BuildMaskedFrame(WsFrame::OpCode::kBinary, true, data.data(), data.size());
}

std::vector<uint8_t> WsFrameBuilder::BuildMaskedCloseFrame(uint16_t code, const std::string &reason)
{
 std::vector<uint8_t> payload;
 payload.push_back(static_cast<uint8_t>((code >> 8) & 0xFF));
 payload.push_back(static_cast<uint8_t>(code & 0xFF));
 if (!reason.empty())
 payload.insert(payload.end(), reason.begin(), reason.end());

 return BuildMaskedFrame(WsFrame::OpCode::kClose, true, payload.data(), payload.size());
}

std::vector<uint8_t> WsFrameBuilder::BuildMaskedPingFrame(const std::string &data)
{
 return BuildMaskedFrame(WsFrame::OpCode::kPing, true, data.data(), data.size());
}

std::vector<uint8_t> WsFrameBuilder::BuildMaskedPongFrame(const std::string &data)
{
 return BuildMaskedFrame(WsFrame::OpCode::kPong, true, data.data(), data.size());
}

std::vector<uint8_t> WsFrameBuilder::BuildMaskedFrame(WsFrame::OpCode opcode, bool fin,
 const void *payload_ptr, size_t payload_len,
 const uint8_t *mask_key)
{
 std::vector<uint8_t> frame;

 //! 生成或使用提供的掩码密钥
 uint8_t mk[4];
 if (mask_key != nullptr) {
 memcpy(mk, mask_key, 4);
 } else {
 //! 随机生成掩码密钥
 mk[0] = static_cast<uint8_t>(rand() & 0xFF);
 mk[1] = static_cast<uint8_t>(rand() & 0xFF);
 mk[2] = static_cast<uint8_t>(rand() & 0xFF);
 mk[3] = static_cast<uint8_t>(rand() & 0xFF);
 }

 //! 第1字节:FIN + RSV1-3(0) + Opcode
 uint8_t byte0 = static_cast<uint8_t>(opcode);
 if (fin)
 byte0 |= 0x80;
 frame.push_back(byte0);

 //! 第2字节:MASK=1(客户端必须掩码) + Payload length
 if (payload_len < 125) {
 frame.push_back(static_cast<uint8_t>(0x80 | payload_len));
 } else if (payload_len <= 65535) {
 frame.push_back(0x80 | 126);
 frame.push_back(static_cast<uint8_t>((payload_len >> 8) & 0xFF));
 frame.push_back(static_cast<uint8_t>(payload_len & 0xFF));
 } else {
 frame.push_back(0x80 | 127);
 for (int i = 7; i >= 0; --i)
 frame.push_back(static_cast<uint8_t>((payload_len >> (i * 8)) & 0xFF));
 }

 //! 掩码密钥(4字节)
 frame.insert(frame.end(), mk, mk + 4);

 //! Payload 数据(掩码后)
 if (payload_ptr != nullptr && payload_len > 0) {
 const uint8_t *p = static_cast<const uint8_t*>(payload_ptr);
 for (size_t i = 0; i < payload_len; ++i)
 frame.push_back(p[i] ^ mk[i % 4]);
 }

 return frame;
}

}
}