#include "config_manager.h"
#include "yaml_parser.h"

#include <cstdlib>
#include <fstream>
#include <iostream>
#include <pwd.h>
#include <sstream>
#include <unistd.h>

namespace radiantwave::config {

// ─── Constructor & Destructor ──────────────────────────────────────────

ConfigManager::ConfigManager() = default;

ConfigManager::~ConfigManager() {
    shutdown();
}

// ─── Path Resolution ───────────────────────────────────────────────────

std::string ConfigManager::resolvePath(const std::string& raw_path) const {
    std::string path = raw_path;

    if (path.empty()) {
        const char* home = std::getenv("HOME");
        if (!home) {
            struct passwd* pw = getpwuid(getuid());
            if (pw) {
                home = pw->pw_dir;
            }
        }

        if (home) {
            path = std::string(home) + "/.local/radiantwave/config.yaml";
        } else {
            path = "/tmp/radiantwave/config.yaml";
        }
    } else if (path.front() == '~') {
        const char* home = std::getenv("HOME");
        if (!home) {
            struct passwd* pw = getpwuid(getuid());
            if (pw) {
                home = pw->pw_dir;
            }
        }

        if (home) {
            path = std::string(home) + path.substr(1);
        }
    }

    return path;
}

// ─── Initialization ────────────────────────────────────────────────────

bool ConfigManager::initialize(const std::string& custom_path) {
    file_path_ = resolvePath(custom_path);

    // Create parent directories if they don't exist
    try {
        std::filesystem::path p(file_path_);
        if (p.has_parent_path()) {
            std::filesystem::create_directories(p.parent_path());
        }
    } catch (const std::exception& e) {
        std::cerr << "[Config] Failed to create directories: " << e.what() << std::endl;
        return false;
    }

    // Load and merge defaults without overwriting existing settings
    loadAndMergeDefaults();

    // Store initial modification timestamp
    try {
        if (std::filesystem::exists(file_path_)) {
            last_write_time_ = std::filesystem::last_write_time(file_path_);
        }
    } catch (...) {}

    // Start live hot-reload background watcher
    startWatcher();

    return true;
}

void ConfigManager::shutdown() {
    stopWatcher();
}

// ─── Read / Write Operations ───────────────────────────────────────────

AppConfig ConfigManager::get() const {
    std::lock_guard<std::mutex> lock(mutex_);
    return config_;
}

bool ConfigManager::update(std::function<void(AppConfig& config)> modifier) {
    std::vector<ConfigCallback> callbacks_to_notify;
    AppConfig updated_config;
    bool success = false;

    {
        std::lock_guard<std::mutex> lock(mutex_);
        modifier(config_);
        updated_config = config_;
        success = saveUnlocked();
    }

    if (success) {
        std::lock_guard<std::mutex> cb_lock(callback_mutex_);
        callbacks_to_notify = callbacks_;
    }

    for (const auto& cb : callbacks_to_notify) {
        if (cb) cb(updated_config);
    }

    return success;
}

bool ConfigManager::save() {
    std::lock_guard<std::mutex> lock(mutex_);
    return saveUnlocked();
}

bool ConfigManager::saveUnlocked() {
    std::string content = serializeConfigToYaml(config_);

    std::ofstream file(file_path_, std::ios::out | std::ios::trunc);
    if (!file.is_open()) {
        std::cerr << "[Config] Failed to open file for writing: " << file_path_ << std::endl;
        return false;
    }

    file << content;
    file.close();

    // Update timestamp so watcher doesn't trigger a duplicate hot-reload event
    try {
        if (std::filesystem::exists(file_path_)) {
            last_write_time_ = std::filesystem::last_write_time(file_path_);
        }
    } catch (...) {}

    return true;
}

bool ConfigManager::reload() {
    std::ifstream file(file_path_);
    if (!file.is_open()) {
        return false;
    }

    std::stringstream ss;
    ss << file.rdbuf();
    file.close();

    AppConfig loaded = parseConfigFromYaml(ss.str());
    
    std::vector<ConfigCallback> callbacks_to_notify;
    {
        std::lock_guard<std::mutex> lock(mutex_);
        config_ = loaded;
    }

    {
        std::lock_guard<std::mutex> cb_lock(callback_mutex_);
        callbacks_to_notify = callbacks_;
    }

    for (const auto& cb : callbacks_to_notify) {
        if (cb) cb(loaded);
    }

    return true;
}

void ConfigManager::loadAndMergeDefaults() {
    AppConfig defaults = AppConfig::defaults();

    if (!std::filesystem::exists(file_path_)) {
        // File doesn't exist: write full defaults
        std::lock_guard<std::mutex> lock(mutex_);
        config_ = defaults;
        saveUnlocked();
        return;
    }

    // Read existing file
    std::ifstream file(file_path_);
    if (!file.is_open()) {
        std::lock_guard<std::mutex> lock(mutex_);
        config_ = defaults;
        return;
    }

    std::stringstream ss;
    ss << file.rdbuf();
    file.close();

    std::string yaml_content = ss.str();
    YamlNode root = parseYaml(yaml_content);

    AppConfig merged = defaults;

    // Preserving existing values if present
    if (root.hasChild("license_key") && !root.getChild("license_key").asString().empty()) {
        merged.license_key = root.getChild("license_key").asString();
    }
    if (root.hasChild("email_address") && !root.getChild("email_address").asString().empty()) {
        merged.email_address = root.getChild("email_address").asString();
    }
    if (root.hasChild("provisioning_status") && !root.getChild("provisioning_status").asString().empty()) {
        merged.provisioning_status = root.getChild("provisioning_status").asString();
    }
    if (root.hasChild("timezone") && !root.getChild("timezone").asString().empty()) {
        merged.timezone = root.getChild("timezone").asString();
    }

    if (root.hasChild("audio")) {
        const auto& audio_node = root.getChild("audio");
        if (audio_node.hasChild("enabled")) {
            merged.audio.enabled = audio_node.getChild("enabled").asBool(defaults.audio.enabled);
        }
        if (audio_node.hasChild("volume")) {
            merged.audio.volume = audio_node.getChild("volume").asInt(defaults.audio.volume);
        }
        if (audio_node.hasChild("output_device")) {
            merged.audio.output_device = audio_node.getChild("output_device").asString(defaults.audio.output_device);
        }
        if (audio_node.hasChild("current_track")) {
            merged.audio.current_track = audio_node.getChild("current_track").asString(defaults.audio.current_track);
        }
        if (audio_node.hasChild("dynamic_audio")) {
            merged.audio.dynamic_audio = audio_node.getChild("dynamic_audio").asBool(defaults.audio.dynamic_audio);
        }
    }

    if (root.hasChild("proclamation")) {
        const auto& proc_node = root.getChild("proclamation");
        if (proc_node.hasChild("scroll_speed")) {
            merged.proclamation.scroll_speed = proc_node.getChild("scroll_speed").asFloat(defaults.proclamation.scroll_speed);
        }
        if (proc_node.hasChild("font_size")) {
            merged.proclamation.font_size = proc_node.getChild("font_size").asInt(defaults.proclamation.font_size);
        }
        if (proc_node.hasChild("current_id")) {
            merged.proclamation.current_id = proc_node.getChild("current_id").asString(defaults.proclamation.current_id);
        }
        if (proc_node.hasChild("schedule_active")) {
            merged.proclamation.schedule_active = proc_node.getChild("schedule_active").asBool(defaults.proclamation.schedule_active);
        }
        if (proc_node.hasChild("schedule_enabled")) {
            merged.proclamation.schedule_enabled = proc_node.getChild("schedule_enabled").asBool(defaults.proclamation.schedule_enabled);
        }
    }

    {
        std::lock_guard<std::mutex> lock(mutex_);
        config_ = merged;
        saveUnlocked();
    }
}

// ─── Live Hot-Reloading Watcher ───────────────────────────────────────

void ConfigManager::onChanged(ConfigCallback callback) {
    std::lock_guard<std::mutex> lock(callback_mutex_);
    callbacks_.push_back(std::move(callback));
}

std::string ConfigManager::getFilePath() const {
    return file_path_;
}

void ConfigManager::startWatcher() {
    stopWatcher();
    watcher_running_ = true;

    watcher_thread_ = std::thread([this]() {
        while (watcher_running_) {
            std::this_thread::sleep_for(std::chrono::milliseconds(500));

            if (!watcher_running_) break;

            try {
                if (std::filesystem::exists(file_path_)) {
                    auto current_time = std::filesystem::last_write_time(file_path_);
                    if (current_time != last_write_time_) {
                        last_write_time_ = current_time;
                        std::cout << "[Config] Detected live change in " << file_path_ << ", hot-reloading..." << std::endl;
                        reload();
                    }
                }
            } catch (...) {}
        }
    });
}

void ConfigManager::stopWatcher() {
    if (watcher_running_) {
        watcher_running_ = false;
        if (watcher_thread_.joinable()) {
            watcher_thread_.join();
        }
    }
}

} // namespace radiantwave::config