#define AL_LOG_SECTION "glfw"
#include <al/log.h>
#include <al/lib.h>

#include "window_glfw.h"
#include "common.h"
#ifdef STELA_API_OPENGL
#include "gl_common.h"
#endif

#ifdef STELA_API_OPENGL
#define STELA_GL_API GLFW_OPENGL_API
#define STELA_GLES_API GLFW_OPENGL_ES_API

// Unused.
#define STELA_GL_BIT 0
#define STELA_GLES2_BIT 0
#define STELA_GLES3_BIT 0

#define STELA_GL_CORE_PROFILE_BIT GLFW_OPENGL_CORE_PROFILE

#include "gl_versions.h"

PASTE_GL_VERSIONS()
#endif

f64 stl_scale_scroll(f64 v, f64 factor)
{
    return v / (1.5 * factor);
}

static struct stl_glfw_global global = { 0 };

void stl_set_output_discovered_callback(void (*output_discovered)(void *, struct stl_monitor *), void *userdata)
{
    (void)output_discovered;
    (void)userdata;
}

static void error_callback(s32 error_code, const char *description)
{
    log_error("GLFW Error %d: %s.", error_code, description);
}

bool stl_global_init(bool skip_graphics)
{
    (void)skip_graphics;

    glfwSetErrorCallback(error_callback);
    if (!glfwInit()) {
        log_error("Failed to initialize GLFW.");
        return false;
    }

    global.master_window = NULL;

    global.cursors[STELA_CURSOR_NORMAL] = NULL;
    global.cursors[STELA_CURSOR_MOVE] = glfwCreateStandardCursor(GLFW_HAND_CURSOR);
    global.cursors[STELA_CURSOR_CROSSHAIR] = glfwCreateStandardCursor(GLFW_CROSSHAIR_CURSOR);

    return true;
}

s32 stl_global_get_poll_fd(void)
{
    al_assert_and_return(-1);
}

void stl_global_process_events(void)
{
    al_assert(false);
}

s32 stl_swallow_main(u32 argc, str *argv, s32 (*main)(u32, str *, void *), void *extra)
{
    return main(argc, argv, extra);
}

void stl_global_close(void)
{
    if (global.cursors[STELA_CURSOR_MOVE]) {
        glfwDestroyCursor(global.cursors[STELA_CURSOR_MOVE]);
    }
    if (global.cursors[STELA_CURSOR_CROSSHAIR]) {
        glfwDestroyCursor(global.cursors[STELA_CURSOR_CROSSHAIR]);
    }
    glfwTerminate();
}

static void resize_callback(GLFWwindow *window, s32 event_width, s32 event_height)
{
    struct stl_window_glfw *glfw = glfwGetWindowUserPointer(window);
    if (event_width <= 0 || event_height <= 0) {
        // This happens on Windows when minimizing.
        return;
    }

    u32 width = (u32)event_width;
    u32 height = (u32)event_height;
    if (width == glfw->w.width && height == glfw->w.height) {
        return;
    }

    glfw->w.width = (u32)width;
    glfw->w.height = (u32)height;

    stl_window_send_resize_event(&glfw->w, glfw->w.width, glfw->w.height);
}

static void content_scale_callback(GLFWwindow *window, f32 xscale, f32 yscale)
{
    struct stl_window_glfw *glfw = glfwGetWindowUserPointer(window);
    glfw->scale_x = xscale;
    glfw->scale_y = yscale;
}

static void cursor_position_callback(GLFWwindow *window, f64 xpos, f64 ypos)
{
    struct stl_window_glfw *glfw = glfwGetWindowUserPointer(window);
    xpos *= glfw->scale_x;
    ypos *= glfw->scale_y;
    stl_window_send_pointer_pos_event(&glfw->w, xpos, ypos);
}

// @TODO: Test behavior on x11, Windows?
static void cursor_enter_callback(GLFWwindow *window, s32 entered)
{
    struct stl_window_glfw *glfw = glfwGetWindowUserPointer(window);
    if (entered) {
        if (glfwGetKey(glfw->window, GLFW_KEY_LEFT_CONTROL)) {
        }
    }
}

static void scroll_callback(GLFWwindow *window, f64 xoffset, f64 yoffset)
{
    struct stl_window_glfw *glfw = glfwGetWindowUserPointer(window);
    (void)xoffset;
    stl_window_send_scroll_event(&glfw->w, yoffset);
}

static void mouse_button_callback(GLFWwindow *window, s32 button, s32 action, s32 mods)
{
    struct stl_window_glfw *glfw = glfwGetWindowUserPointer(window);
    (void)mods;
    switch (button) {
    case GLFW_MOUSE_BUTTON_1:
        if (action == GLFW_PRESS) {
            stl_window_send_mouse_button_event(&glfw->w, STELA_BUTTON_PRESSED, STELA_MOUSE1);
        } else if (action == GLFW_RELEASE) {
            stl_window_send_mouse_button_event(&glfw->w, STELA_BUTTON_RELEASED, STELA_MOUSE1);
        }
        break;
    case GLFW_MOUSE_BUTTON_2:
        if (action == GLFW_PRESS) {
            stl_window_send_mouse_button_event(&glfw->w, STELA_BUTTON_PRESSED, STELA_MOUSE2);
        } else if (action == GLFW_RELEASE) {
            stl_window_send_mouse_button_event(&glfw->w, STELA_BUTTON_RELEASED, STELA_MOUSE2);
        }
        break;
    case GLFW_MOUSE_BUTTON_3:
        if (action == GLFW_PRESS) {
            stl_window_send_mouse_button_event(&glfw->w, STELA_BUTTON_PRESSED, STELA_MOUSE3);
        } else if (action == GLFW_RELEASE) {
            stl_window_send_mouse_button_event(&glfw->w, STELA_BUTTON_RELEASED, STELA_MOUSE3);
        }
        break;
    }
}

static void key_callback(GLFWwindow *window, s32 key, s32 scancode, s32 action, s32 mods)
{
    struct stl_window_glfw *glfw = glfwGetWindowUserPointer(window);
    (void)scancode;
    (void)mods;
    al_assert(key >= 0 && key <= UINT16_MAX);
    if (key == GLFW_KEY_F25 || key == GLFW_KEY_WORLD_1 || key == GLFW_KEY_WORLD_2) {
        log_warn("Unmapped GLFW key pressed (%hu).", (u16)key);
        return;
    }
    u8 mapped_state = action == GLFW_PRESS ? STELA_BUTTON_PRESSED : STELA_BUTTON_RELEASED;
    stl_window_send_key_immediate_event(&glfw->w, mapped_state, (u16)key);
    stl_window_send_key_event(&glfw->w, mapped_state, (u16)key);
}

static void close_callback(GLFWwindow *window)
{
    struct stl_window_glfw *glfw = glfwGetWindowUserPointer(window);
    stl_window_send_should_close_event(&glfw->w);
}

static bool window_glfw_create_window(struct stl_window *window, u32 width, u32 height, u32 flags,
    const char *monitor, const char *name, const char *app_id)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)window;
    (void)monitor;

#if GLFW_VERSION_MAJOR > 3 || (GLFW_VERSION_MAJOR == 3 && GLFW_VERSION_MINOR >= 4)
    glfwWindowHintString(GLFW_WAYLAND_APP_ID, app_id);
#endif
    glfwWindowHintString(GLFW_X11_CLASS_NAME, app_id);

#if defined STELA_API_VULKAN
    if (!glfwVulkanSupported()) {
        log_error("Vulkan not supported.");
        return false;
    }
    glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
#elif defined STELA_API_DX11
    glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
#elif defined STELA_API_OPENGL
#ifdef STELA_USE_EGL
    glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_EGL_CONTEXT_API);
#else
    glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_NATIVE_CONTEXT_API);
#endif
    for (u32 i = 0; i < ARRAY_SIZE(stl_gl_vers); i++) {
        glfwWindowHint(GLFW_CLIENT_API, stl_gl_vers[i].api);
        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, stl_gl_vers[i].major);
        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, stl_gl_vers[i].minor);
        if (stl_gl_vers[i].api == STELA_GL_API) {
            glfwWindowHint(GLFW_OPENGL_PROFILE, stl_gl_vers[i].profile);
        }
        if (stl_gl_vers[i].major >= 3) {
            glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
        }
        log_debug("Attempting to create a %s context of version %d.%d (GLSL %d).",
            stl_gl_vers[i].api == STELA_GL_API ? "GL" : "GLES",
            stl_gl_vers[i].major, stl_gl_vers[i].minor, stl_gl_vers[i].glsl_ver);
#endif
        al_assert(width >= STELA_MIN_WIDTH && height >= STELA_MIN_HEIGHT);
        glfw->window = glfwCreateWindow(width, height, name, NULL, global.master_window);
#ifdef STELA_API_OPENGL
        if (glfw->window) break;
    }
#endif

    if (!glfw->window) {
        log_info("Failed to create window/context.");
        return false;
    }

    if (!global.master_window) {
        // This doesn't work right, at least on wayland.
        global.master_window = glfw->window;
    }

    /*
    if (glfwRawMouseMotionSupported()) {
        glfwSetInputMode(glfw->window, GLFW_RAW_MOUSE_MOTION, GLFW_TRUE);
    }
    */

#if defined STELA_API_VULKAN
    (void)flags;
#elif defined STELA_API_DX11
    (void)flags;
    glfw->w.win32_window = glfwGetWin32Window(glfw->window);
#elif defined STELA_API_OPENGL
#ifdef STELA_USE_EGL
    glfw->w.egl_display = glfwGetEGLDisplay();
    glfw->w.egl_context = glfwGetEGLContext(glfw->window);
#endif
    glfwMakeContextCurrent(glfw->window);
    glfwSwapInterval((flags & STELA_WINDOW_VSYNC) ? 1 : 0);
    glfwMakeContextCurrent(NULL);
#else
    (void)flags;
#endif

    s32 buffer_width, buffer_height;
    //glfwGetFramebufferSize(glfw->window, &buffer_width, &buffer_height);
    glfwGetWindowSize(glfw->window, &buffer_width, &buffer_height);
    al_assert(buffer_width > 0 && buffer_height > 0);
    stl_window_created(&glfw->w, (u32)buffer_width, (u32)buffer_height, flags);
    glfwSetWindowSizeLimits(glfw->window, STELA_MIN_WIDTH, STELA_MIN_HEIGHT, GLFW_DONT_CARE, GLFW_DONT_CARE);

    glfw->scale_x = 1.f;
    glfw->scale_y = 1.f;
    glfw->prev.x = 0;
    glfw->prev.y = 0;
    glfw->prev.width = 0;
    glfw->prev.height = 0;

    glfwSetWindowUserPointer(glfw->window, glfw);

    //glfwSetFramebufferSizeCallback(glfw->window, resize_callback);
    glfwSetWindowSizeCallback(glfw->window, resize_callback);
    glfwSetWindowContentScaleCallback(glfw->window, content_scale_callback);
    glfwSetCursorPosCallback(glfw->window, cursor_position_callback);
    glfwSetCursorEnterCallback(glfw->window, cursor_enter_callback);
    glfwSetScrollCallback(glfw->window, scroll_callback);
    glfwSetMouseButtonCallback(glfw->window, mouse_button_callback);
    glfwSetKeyCallback(glfw->window, key_callback);
    // A Wayland window will trigger CloseCallback if it's lagging too hard.
    glfwSetWindowCloseCallback(glfw->window, close_callback);

    return true;
}

static void window_glfw_resize_internal(struct stl_window *window, u32 width, u32 height)
{
    (void)window;
    (void)width;
    (void)height;
}

static void window_glfw_resize(struct stl_window *window, u32 width, u32 height)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)window;
    glfwSetWindowAspectRatio(glfw->window, width, height);
    glfwSetWindowSize(glfw->window, width, height);
}

// https://stackoverflow.com/a/31526753
static GLFWmonitor *get_current_monitor(GLFWwindow *window, s32 wx, s32 wy)
{
#if GLFW_VERSION_MAJOR > 3 || (GLFW_VERSION_MAJOR == 3 && GLFW_VERSION_MINOR >= 4)
    if (glfwGetPlatform() == GLFW_PLATFORM_WAYLAND) {
        // Calculating the current monitor doesn't work on Wayland because
        // we can't know the position of the window.
        return glfwGetPrimaryMonitor();
    }
#endif

    s32 monitor_count;
    GLFWmonitor **monitors = glfwGetMonitors(&monitor_count);
    if (monitor_count == 0) return NULL;

    GLFWmonitor *best_monitor = monitors[0];

    s32 ww, wh;
    glfwGetWindowSize(window, &ww, &wh);

    const GLFWvidmode *mode;

    s32 mx, my;
    s32 mw, mh;
    s32 overlap;
    s32 best_overlap = 0;

    for (s32 i = 0; i < monitor_count; i++) {
        mode = glfwGetVideoMode(monitors[i]);

        glfwGetMonitorPos(monitors[i], &mx, &my);
        mw = mode->width;
        mh = mode->height;

        s32 dx = MIN(wx + ww, mx + mw) - MAX(wx, mx);
        s32 dy = MIN(wy + wh, my + mh) - MAX(wy, my);
        overlap = MAX(0, dx) * MAX(0, dy);

        if (best_overlap < overlap) {
            best_overlap = overlap;
            best_monitor = monitors[i];
        }
    }

    return best_monitor;
}

static void window_glfw_toggle_fullscreen(struct stl_window *window)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)window;
    if (!glfw->w.fullscreen) {
#if GLFW_VERSION_MAJOR > 3 || (GLFW_VERSION_MAJOR == 3 && GLFW_VERSION_MINOR >= 4)
        if (glfwGetPlatform() != GLFW_PLATFORM_WAYLAND) {
            glfwGetWindowPos(glfw->window, &glfw->prev.x, &glfw->prev.y);
        }
#endif
        GLFWmonitor *monitor = get_current_monitor(glfw->window, glfw->prev.x, glfw->prev.y);
        if (!monitor) return;
        const GLFWvidmode *mode = glfwGetVideoMode(monitor);
        glfw->prev.width = glfw->w.width;
        glfw->prev.height = glfw->w.height;
        glfwSetWindowMonitor(glfw->window, monitor, 0, 0,
            mode->width, mode->height, GLFW_DONT_CARE);
    } else {
        glfwSetWindowMonitor(glfw->window, NULL, glfw->prev.x, glfw->prev.y,
            glfw->prev.width, glfw->prev.height, GLFW_DONT_CARE);
    }
    glfw->w.fullscreen = !glfw->w.fullscreen;
}

static void window_glfw_set_cursor(struct stl_window *window, u8 shape)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)window;
    if (shape == STELA_CURSOR_HIDDEN) {
        glfwSetCursor(glfw->window, NULL);
        glfwSetInputMode(glfw->window, GLFW_CURSOR, GLFW_CURSOR_HIDDEN);
        return;
    }
    glfwSetInputMode(glfw->window, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
    glfwSetCursor(glfw->window, global.cursors[shape]);
}

static void window_glfw_set_decorations(struct stl_window *window, bool enabled)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)window;
    glfwSetWindowAttrib(glfw->window, GLFW_DECORATED, enabled ? GLFW_TRUE : GLFW_FALSE);
}

#ifdef STELA_POLL_INLINE
#ifdef STELA_EVENT_BUFFER
#error "window_glfw_poll() is incompatible with event buffer mode."
#endif
static bool window_glfw_poll(struct stl_window *window, bool block)
{
    (void)window;
    if (block) glfwWaitEvents();
    else glfwPollEvents();
    return true;
}

#ifdef STELA_PAUSE
static void window_glfw_wake(struct stl_window *window)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)window;
    glfw->w.pending_refresh = true;
    glfwPostEmptyEvent();
}
#endif
#endif

static void window_glfw_process_events(struct stl_window *window)
{
    (void)window;
}

#ifdef STELA_PAUSE
static bool window_glfw_should_refresh(struct stl_window *window)
{
    return stl_should_refresh_common(window);
}
#endif

static void window_glfw_free(struct stl_window **window)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)*window;
    if (glfw->window) {
        glfwDestroyWindow(glfw->window);
    }
    al_free(glfw);
    *window = NULL;
}

#if defined STELA_API_VULKAN
static VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL window_glfw_get_vk_proc_address(VkInstance inst, const char *name)
{
    return (PFN_vkVoidFunction)glfwGetInstanceProcAddress(inst, name);
}

static VkResult window_glfw_vk_create_surface(void *window, VkInstance inst, VkSurfaceKHR *surface)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)window;
    return glfwCreateWindowSurface(inst, glfw->window, NULL, surface);
}

static VkResult window_glfw_vk_destroy_surface(VkInstance inst, VkSurfaceKHR surface)
{
    return stl_vk_destroy_surface(inst, surface);
}

static const char *const *window_glfw_vk_get_extensions(u32 *num)
{
    return glfwGetRequiredInstanceExtensions(num);
}
#elif defined STELA_API_OPENGL
static bool window_glfw_gl_loader_load(void *window)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)window;
    return stl_gl_loader_load(glfw->w.get_gl_proc_address);
}

static bool window_glfw_gl_make_current(void *window)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)window;
    glfwMakeContextCurrent(glfw->window);
    return true;
}

static void window_glfw_gl_release_current(void *window)
{
    (void)window;
    glfwMakeContextCurrent(NULL);
}

static void window_glfw_gl_swap_buffers(void *window)
{
    struct stl_window_glfw *glfw = (struct stl_window_glfw *)window;
    glfwSwapBuffers(glfw->window);
}
#endif

struct stl_window *stl_window_create(void)
{
    log_info("Creating GLFW3 window.");
    struct stl_window_glfw *glfw = al_alloc_object(struct stl_window_glfw);
    stl_window_init(&glfw->w);
    glfw->w.fullscreen = false;
    glfw->w.create_window = window_glfw_create_window;
    glfw->w.resize_internal = window_glfw_resize_internal;
    glfw->w.resize = window_glfw_resize;
    glfw->w.toggle_fullscreen = window_glfw_toggle_fullscreen;
    glfw->w.set_cursor = window_glfw_set_cursor;
    glfw->w.set_decorations = window_glfw_set_decorations;
#ifdef STELA_POLL_INLINE
    glfw->w.poll = window_glfw_poll;
#ifdef STELA_PAUSE
    glfw->w.wake = window_glfw_wake;
#endif
#endif
    glfw->w.process_events = window_glfw_process_events;
#ifdef STELA_PAUSE
    glfw->w.should_refresh = window_glfw_should_refresh;
#endif
    glfw->w.free = window_glfw_free;
#if defined STELA_API_VULKAN
    glfw->w.get_vk_proc_address = window_glfw_get_vk_proc_address;
    glfw->w.vk_create_surface = window_glfw_vk_create_surface;
    glfw->w.vk_destroy_surface = window_glfw_vk_destroy_surface;
    glfw->w.vk_get_extensions = window_glfw_vk_get_extensions;
#elif defined STELA_API_OPENGL
    glfw->w.get_gl_proc_address = glfwGetProcAddress;
    glfw->w.gl_loader_load = window_glfw_gl_loader_load;
    glfw->w.gl_make_current = window_glfw_gl_make_current;
    glfw->w.gl_release_current = window_glfw_gl_release_current;
    glfw->w.gl_swap_buffers = window_glfw_gl_swap_buffers;
#endif
    return (struct stl_window *)glfw;
}