#include "app.hpp"
#include <RmlUi/Core/Core.h>
#include <RmlUi/Core/Factory.h>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <sstream>

App::App(Rml::Context *ctx, ApplicationData *appData) 
    : ctx(ctx), appData(appData), doc(nullptr) {}


App::~App() {
    Shutdown();
}

void App::SetupListeners(std::function<void(Rml::ElementDocument*)> bindCallback) {
    onBindListeners = bindCallback;
}

void App::RegisterListener(Rml::Element* element, std::unique_ptr<Rml::EventListener> listener) {
    if (element && listener) {
        element->AddEventListener(Rml::EventId::Click, listener.get());
        listeners.push_back(std::move(listener));
    }
}

PageBase* App::GetOrCreatePage(const std::string& pageName) {
    if (auto it = pages.find(pageName); it != pages.end()) {
        return it->second.get();
    }

    std::string path = GetAssetsPath() + "/pages/" + pageName + ".rml";
    if (!std::filesystem::exists(path)) {
        return nullptr;
    }

    auto page = std::make_unique<PageBase>(pageName, this);
    PageBase* raw = page.get();
    pages.emplace(pageName, std::move(page));
    return raw;
}

bool App::ReadFile(const std::string& path, std::string& outContent) {
    std::ifstream file(path, std::ios::in | std::ios::binary);
    if (!file) return false;

    std::ostringstream ss;
    ss << file.rdbuf();
    outContent = ss.str();
    return true;
}

bool App::NavigateTo(const std::string &pageName) {

    if (!pageOutlet) {
        std::cout << "[ERROR] no page outlet - is main.rml missing id=\"page-content\"?\n";
        return false;
    }

    PageBase* page = GetOrCreatePage(pageName);
    if (!page) {
        std::cout << "[ERROR] no page registered or found on disk for '" << pageName << "'\n";
        return false;
    }

    std::string path = GetAssetsPath() + "/pages/" + pageName + ".rml";
    std::string content;
    if (!ReadFile(path, content)) {
        std::cout << "[ERROR] could not read page file: " << path << "\n";
        return false;
    }

    TeardownCurrentPage();

    if (Rml::DataModelConstructor constructor = ctx->CreateDataModel(pageName)) {
        page->SetupDataModel(constructor);
        page->model = constructor.GetModelHandle();
        page->hasModel = true;
    } else {
        std::cout << "[WARN] failed to create data model for page '" << pageName << "'\n";
    }

    pageOutlet->SetInnerRML(content);

    page->root = pageOutlet->GetElementById("page-root");
    if (!page->root) {
        std::cout << "[WARN] page '" << pageName << "' has no element with id=\"page-root\"\n";
    }

    currentPage = page;
    page->OnEnter(page->root);

    return true;
}

bool App::LoadUi() {
    if (!ctx) return false;

    doc = ctx->LoadDocument(GetAssetsPath() + "/main.rml");
    if (!doc) return false;

    doc->Show();

    pageOutlet = doc->GetElementById("page-content");
    if (!pageOutlet) {
        std::cout << "[WARN] main.rml has no element with id=\"page-content\"\n";
    }

    listeners.clear();
    if (onBindListeners) {
        onBindListeners(doc);
    }

    return true;
}

void App::Reload() {
    Rml::Factory::ClearStyleSheetCache();
    Rml::Factory::ClearTemplateCache();

    std::string previousPage = currentPage ? currentPage->GetName() : "";

    TeardownCurrentPage();

    if (doc) {
        doc->Close();
        doc = nullptr;
        pageOutlet = nullptr;
    }

    LoadUi();

    if (!previousPage.empty()) {
        NavigateTo(previousPage);
    }
}

std::string App::GetAssetsPath() {
    std::string install_path = std::string(ASSETS_DIR) + "/main.rml";
    if (std::filesystem::exists(install_path)) {
        return std::string(ASSETS_DIR);
    }
    if (std::filesystem::exists("./assets/main.rml")) {
        return "./assets";
    }
    return ".";
}

void App::TeardownCurrentPage() {
    if (!currentPage) return;

    currentPage->OnExit();

    if (currentPage->hasModel) {
        ctx->RemoveDataModel(currentPage->GetName());
        currentPage->hasModel = false;
    }

    currentPage->root = nullptr;

    if (pageOutlet) {
        pageOutlet->SetInnerRML(""); 
    }

    currentPage->pageListeners.clear();
    currentPage = nullptr;
}

void App::Shutdown() {
    if (hasShutdown) return;
    hasShutdown = true;

    TeardownCurrentPage(); // uses ctx->RemoveDataModel - must run while ctx is still valid

    if (doc) {
        doc->Close();   // deferred destruction, but marks it for cleanup on next Update/Shutdown
        doc = nullptr;
        pageOutlet = nullptr;
    }
}