#include "app_base.h"

#include "imgui.h"
#include "imgui_impl_glfw.h"
#include "imgui_impl_opengl3.h"
#include "implot.h"
#include "implot3d.h"
#include "core/tokens.h"
#include "core/icon_font.h"
#include "core/app_settings.h"
#include "core/app_about.h"
#include "core/app_menubar.h"
#include "core/fps_overlay.h"
#include "core/logger.h"
#include "core/log_window.h"
#include "gfx/gl_loader.h"

#include <GLFW/glfw3.h>
#include <cstdio>
#include <cstring>
#include <filesystem>
#include <string>
#include <sys/stat.h>

#ifdef _WIN32
  #ifndef WIN32_LEAN_AND_MEAN
    #define WIN32_LEAN_AND_MEAN
  #endif
  #include <windows.h>
#else
  #include <unistd.h>
#endif

#ifdef TRACY_ENABLE
#include "tracy/Tracy.hpp"
#endif

static void glfw_error_callback(int error, const char* description) {
    fprintf(stderr, "GLFW Error %d: %s\n", error, description);
}

namespace fn {

// ============================================================================
// Local files
// ============================================================================
namespace {

std::string compute_exe_dir() {
#ifdef _WIN32
    wchar_t buf[MAX_PATH * 2];
    DWORD n = GetModuleFileNameW(nullptr, buf,
        (DWORD)(sizeof(buf) / sizeof(buf[0])));
    if (n == 0 || n >= sizeof(buf)/sizeof(buf[0])) return "";
    int u8n = WideCharToMultiByte(CP_UTF8, 0, buf, (int)n,
                                   nullptr, 0, nullptr, nullptr);
    std::string out(u8n, 0);
    WideCharToMultiByte(CP_UTF8, 0, buf, (int)n, out.data(), u8n,
                         nullptr, nullptr);
    size_t slash = out.find_last_of("/\\");
    return (slash == std::string::npos) ? "" : out.substr(0, slash);
#else
    char buf[4096];
    ssize_t n = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
    if (n <= 0) return "";
    buf[n] = 0;
    std::string out(buf);
    size_t slash = out.find_last_of('/');
    return (slash == std::string::npos) ? "" : out.substr(0, slash);
#endif
}

const std::string& exe_dir_ref() {
    static std::string cached = compute_exe_dir();
    return cached;
}

const std::string& local_dir_ref() {
    static std::string cached;
    static bool inited = false;
    if (inited) return cached;
    const std::string& edir = exe_dir_ref();
    if (edir.empty()) {
        cached = "local_files";   // fallback: relativo al cwd
    } else {
        cached = edir + "/local_files";
    }
    std::error_code ec;
    std::filesystem::create_directories(cached, ec);
    inited = true;
    return cached;
}

} // namespace

const char* exe_dir() { return exe_dir_ref().c_str(); }
const char* local_dir() { return local_dir_ref().c_str(); }

const char* local_path(const char* name) {
    static thread_local std::string buf;
    buf = local_dir_ref();
    if (name && *name) {
        if (!buf.empty() && buf.back() != '/' && buf.back() != '\\') buf += '/';
        buf += name;
    }
    return buf.c_str();
}

void migrate_to_local_files(const char* const* names, std::size_t n) {
    if (!names || n == 0) return;
    const std::string& ldir = local_dir_ref();
    const std::string& edir = exe_dir_ref();
    for (std::size_t i = 0; i < n; ++i) {
        const char* name = names[i];
        if (!name || !*name) continue;
        std::string dst = ldir + "/" + name;
        struct stat st{};
        if (::stat(dst.c_str(), &st) == 0) continue;   // ya existe en local

        // Buscar en exe_dir y en cwd. Mover el primero que aparezca.
        std::string cands[] = {
            edir.empty() ? std::string() : (edir + "/" + name),
            std::string(name),
        };
        for (const auto& src : cands) {
            if (src.empty() || src == dst) continue;
            if (::stat(src.c_str(), &st) != 0) continue;
            std::error_code ec;
            std::filesystem::rename(src, dst, ec);
            if (ec) {
                // Cross-device o permisos — fallback a copy + remove.
                std::filesystem::copy(src, dst,
                    std::filesystem::copy_options::recursive |
                    std::filesystem::copy_options::overwrite_existing, ec);
                if (!ec) std::filesystem::remove_all(src, ec);
            }
            std::fprintf(stdout,
                "[local_files] migrado: %s -> %s\n",
                src.c_str(), dst.c_str());
            break;
        }
    }
}

int run_app(AppConfig config, std::function<void()> render_fn) {
    // Logger primero para capturar fallos del propio init (GLFW, ventana, GL).
    if (config.log.file_path != nullptr) {
        fn_log::logger_init(
            config.log.file_path,
            static_cast<fn_log::Level>(config.log.level));
        fn_log::log_info("app start: %s", config.title ? config.title : "(no title)");
    }

    glfwSetErrorCallback(glfw_error_callback);
    if (!glfwInit()) {
        fprintf(stderr, "Failed to initialize GLFW\n");
        fn_log::log_error("GLFW init failed");
        if (config.log.file_path != nullptr) fn_log::logger_close();
        return 1;
    }

    // OpenGL 4.3 core (issue 0049b) — habilita compute shaders, SSBOs, image
    // load/store, atomic counters y debug output. Backward-compatible con
    // shaders #version 330 y con todo lo escrito para 3.3 core.
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);

    GLFWwindow* window = glfwCreateWindow(config.width, config.height, config.title, nullptr, nullptr);
    if (!window) {
        fprintf(stderr, "Failed to create GLFW window\n");
        fn_log::log_error("GLFW createWindow failed (%dx%d)", config.width, config.height);
        if (config.log.file_path != nullptr) fn_log::logger_close();
        glfwTerminate();
        return 1;
    }

    glfwMakeContextCurrent(window);
    glfwSwapInterval(config.vsync ? 1 : 0);

    // Carga punteros a funciones GL >= 2.0 si la app lo pide. En Linux es
    // no-op; en Windows usa wglGetProcAddress (requiere ctx GL activo).
    if (config.init_gl_loader) {
        if (!fn::gfx::gl_loader_init()) {
            fprintf(stderr, "Failed to initialize GL function loader\n");
            fn_log::log_error("gl_loader_init failed");
            if (config.log.file_path != nullptr) fn_log::logger_close();
            glfwDestroyWindow(window);
            glfwTerminate();
            return 1;
        }
    }

    // Setup ImGui
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImPlot::CreateContext();
    ImPlot3D::CreateContext();

    ImGuiIO& io = ImGui::GetIO();
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;

    // Convencion local_files: imgui.ini y app_settings.ini viven en
    // <exe_dir>/local_files/. Migra automaticamente desde el cwd o
    // exe_dir si vienen de una version previa.
    {
        static const char* legacy_names[] = {"imgui.ini", "app_settings.ini"};
        migrate_to_local_files(legacy_names,
            sizeof(legacy_names) / sizeof(legacy_names[0]));
    }
    static std::string s_imgui_ini = local_path("imgui.ini");
    io.IniFilename = s_imgui_ini.c_str();

    // Lee app_settings.ini (font_id, font_size_px, show_fps) antes de cargar
    // fuentes. Si no existe el .ini, los defaults se aplican.
    fn_ui::settings_load();

    // Registra info de la ventana About si la app la proveyo en AppConfig.
    if (config.about.name != nullptr) {
        fn_ui::about_window_set_info(
            config.about.name,
            config.about.version    ? config.about.version    : "",
            config.about.description ? config.about.description : "");
    }

    // Texto vectorial (Karla / Roboto / DroidSans / Cousine, segun settings)
    // + iconos Tabler mergeados al mismo tamaño en el mismo ImFont.
    fn_ui::load_fonts_from_settings();

    // ImGui 1.92+ usa style.FontSizeBase como tamaño activo (escalable sin
    // rebuild de atlas). Inicializa al valor del .ini para que el primer
    // frame ya respete el setting.
    {
        ImGuiStyle& style = ImGui::GetStyle();
        style.FontSizeBase            = fn_ui::settings().font_size_px;
        style._NextFrameFontSizeBase  = style.FontSizeBase;
    }

    if (config.viewports) {
        io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;
    }

    // Identidad visual — ver cpp/DESIGN_SYSTEM.md
    switch (config.theme) {
        case ThemeMode::FnDark:     fn_tokens::apply_dark_theme(); break;
        case ThemeMode::ImGuiDark:  ImGui::StyleColorsDark();      break;
        case ThemeMode::ImGuiLight: ImGui::StyleColorsLight();     break;
        case ThemeMode::None:                                      break;
    }

    // When viewports are enabled, tweak WindowRounding/WindowBg so
    // platform windows look consistent with the main window
    if (config.viewports) {
        ImGuiStyle& style = ImGui::GetStyle();
        style.WindowRounding = 0.0f;
        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
    }

    ImGui_ImplGlfw_InitForOpenGL(window, true);
    ImGui_ImplOpenGL3_Init("#version 330");

    // Main loop
    while (!glfwWindowShouldClose(window)) {
        glfwPollEvents();

        if (glfwGetWindowAttrib(window, GLFW_ICONIFIED)) {
            glfwWaitEvents();
            continue;
        }

        // Tamaño de fuente: aplica via style.FontSizeBase cada frame. Cambios
        // se ven al instante (ImGui 1.92+ escala el atlas dinamicamente, no
        // hace falta rebuild).
        ImGuiStyle& style = ImGui::GetStyle();
        if (style.FontSizeBase != fn_ui::settings().font_size_px) {
            style.FontSizeBase            = fn_ui::settings().font_size_px;
            style._NextFrameFontSizeBase  = style.FontSizeBase;  // FIXME-ImGui hack
        }

        // Cambio de fuente (font_id): rebuild atlas. ImGui_ImplOpenGL3
        // refresca la GPU texture via UpdateTexture en RenderDrawData.
        if (fn_ui::settings_consume_font_dirty()) {
            fn_ui::load_fonts_from_settings();
        }

        ImGui_ImplOpenGL3_NewFrame();
        ImGui_ImplGlfw_NewFrame();
        ImGui::NewFrame();

        // Menubar canonica (View / Layouts / Settings / About) si la app la
        // configuro en AppConfig. Se renderiza ANTES del render_fn para que
        // el render_fn pueda hacer DockSpaceOverViewport debajo.
        if (config.panels != nullptr || config.layouts_cb != nullptr) {
            fn_ui::app_menubar(config.panels, config.panel_count, config.layouts_cb);
        }

        render_fn();

        // Ventana de Settings (no-op si esta cerrada).
        fn_ui::settings_window_render();

        // Ventana de Logs (no-op si esta cerrada).
        fn_ui::log_window_render();

        // Ventana About (no-op si esta cerrada).
        fn_ui::about_window_render();

        // FPS overlay si esta activado en Settings.
        if (fn_ui::settings().show_fps) {
            fps_overlay();
        }

        ImGui::Render();
        int display_w, display_h;
        glfwGetFramebufferSize(window, &display_w, &display_h);
        glViewport(0, 0, display_w, display_h);
        glClearColor(config.bg_r, config.bg_g, config.bg_b, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);
        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

        // Multi-viewport: update and render platform windows
        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) {
            GLFWwindow* backup_ctx = glfwGetCurrentContext();
            ImGui::UpdatePlatformWindows();
            ImGui::RenderPlatformWindowsDefault();
            glfwMakeContextCurrent(backup_ctx);
        }

        glfwSwapBuffers(window);

#ifdef TRACY_ENABLE
        FrameMark;
#endif
    }

    // Persiste settings al exit (idempotente con auto-saves del menu).
    fn_ui::settings_save();

    // Cierra el archivo de log (si la app lo abrio).
    if (config.log.file_path != nullptr) {
        fn_log::log_info("app exit");
        fn_log::logger_close();
    }

    // Cleanup
    ImGui_ImplOpenGL3_Shutdown();
    ImGui_ImplGlfw_Shutdown();
    ImPlot3D::DestroyContext();
    ImPlot::DestroyContext();
    ImGui::DestroyContext();
    glfwDestroyWindow(window);
    glfwTerminate();

    return 0;
}

int run_app(std::function<void()> render_fn) {
    return run_app(AppConfig{}, render_fn);
}

} // namespace fn