/*
 * @file toml_parse.h
 * @brief Lightweight single-header TOML parser (subset: flat key-value pairs).
 * 轻量级单头文件 TOML 解析器（子集：扁平键值对）。
 * Copyright (c) 2026 dstalk contributors. GPLv3.
 */

#pragma once
// 共享 TOML 解析器 —— 由 ConfigStore（核心）和 config 插件共同使用 / Shared TOML parser — used by both ConfigStore (core) and config plugin.
// W12.2: Extracted from config_store.cpp:23-61 and config_plugin.cpp:28-66
//        to eliminate the 74-line code duplication (W11.2 audit Finding 1).
// Does NOT support: inline tables, arrays, multi-line strings, escape sequences.
// 不支持：内联表、数组、多行字符串、转义序列。

#include <string>

namespace dstalk {
namespace toml {

/// 解析 TOML 字符串，对每个键值对调用 on_kv(full_key, value) / Parse a TOML string, calling on_kv(full_key, value) for each key-value pair.
/// 支持 [section] 标题、key = "value" 键值对、# 注释、空行 / Supports [section] headers, key = "value" pairs, # comments, blank lines.
template<typename F>
inline void parse(const std::string& content, F&& on_kv)
{
    std::string current_section;
    size_t pos = 0;

    while (pos < content.size()) {
        // 去除左侧空白 / Trim left whitespace
        while (pos < content.size() && (content[pos] == ' ' || content[pos] == '\t'))
            pos++;
        if (pos >= content.size()) break;

        // 提取下一行 / Extract next line
        size_t nl = content.find('\n', pos);
        std::string line = (nl != std::string::npos)
            ? content.substr(pos, nl - pos) : content.substr(pos);
        pos = (nl != std::string::npos) ? nl + 1 : content.size();

        // 去除右侧空白（包括 \r） / Trim right whitespace (including \r)
        while (!line.empty() && (line.back() == '\r' || line.back() == ' '))
            line.pop_back();

        // 跳过空行和注释 / Skip empty lines and comments
        if (line.empty() || line[0] == '#') continue;

        // 节标题: [section_name] / Section header: [section_name]
        if (line[0] == '[' && line.back() == ']') {
            current_section = line.substr(1, line.size() - 2);
            continue;
        }

        // 键 = 值 / Key = value
        size_t eq = line.find('=');
        if (eq == std::string::npos) continue;

        std::string key = line.substr(0, eq);
        while (!key.empty() && key.back() == ' ') key.pop_back();
        if (key.empty()) continue;

        std::string val = line.substr(eq + 1);
        while (!val.empty() && (val.front() == ' ' || val.front() == '\t'))
            val.erase(0, 1);
        if (val.size() >= 2 && val.front() == '"' && val.back() == '"')
            val = val.substr(1, val.size() - 2);

        std::string full_key = current_section.empty()
            ? key : current_section + "." + key;

        on_kv(full_key, val);
    }
}

} // namespace toml
} // namespace dstalk