#include "touch.h"

#include <algorithm>

#include <windows.h>
#include <versionhelpers.h>

#include "util/logging.h"
#include "util/time.h"
#include "touch/touch.h"

// std::min
#ifdef min
#undef min
#endif

// std::max
#ifdef max
#undef max
#endif

namespace rawinput::touch {

    // settings
    bool DISABLED = false;
    bool INVERTED = false;
    AspectMode ASPECT_COMPENSATION_MODE = AspectMode::Auto;
    bool ASPECT_COMPENSATION_GAME = false;

    // state
    DWORD DISPLAY_ORIENTATION = DMDO_DEFAULT;
    long DISPLAY_SIZE_X = 1920L;
    long DISPLAY_SIZE_Y = 1080L;
    long DISPLAY_NATIVE_X = 0L;
    long DISPLAY_NATIVE_Y = 0L;
    bool DISPLAY_INITIALIZED = false;

    static void update_current_display_mode();

    bool aspect_compensation_enabled() {
        switch (ASPECT_COMPENSATION_MODE) {
            case AspectMode::On:
                return true;
            case AspectMode::Off:
                return false;
            default:
                return ASPECT_COMPENSATION_GAME;
        }
    }

    // compute the centered letterbox inset (fraction cropped from each side) that results
    // from showing the current display mode on a panel with a different native aspect
    // ratio. only one of inset_x / inset_y is ever non-zero.
    static void compute_letterbox_inset(double &inset_x, double &inset_y) {
        inset_x = 0.0;
        inset_y = 0.0;

        // native resolution in the current display orientation
        long native_x = DISPLAY_NATIVE_X;
        long native_y = DISPLAY_NATIVE_Y;
        if ((DISPLAY_SIZE_Y >= DISPLAY_SIZE_X) != (native_y >= native_x)) {
            long tmp = native_x;
            native_x = native_y;
            native_y = tmp;
        }

        // compare the displayed aspect ratio against the panel's native one; ignore
        // tiny mismatches (e.g. 1366x768 vs true 16:9) that would only add a sub-pixel
        // inset, so near-matched panels stay an exact no-op
        double current_aspect = (double) DISPLAY_SIZE_X / (double) DISPLAY_SIZE_Y;
        double native_aspect = (double) native_x / (double) native_y;
        constexpr double aspect_epsilon = 0.01;
        if (current_aspect < native_aspect - aspect_epsilon) {

            // image is narrower than the panel -> bars on left/right
            inset_x = (1.0 - current_aspect / native_aspect) / 2.0;
        } else if (current_aspect > native_aspect + aspect_epsilon) {

            // image is wider than the panel -> bars on top/bottom
            inset_y = (1.0 - native_aspect / current_aspect) / 2.0;
        }
    }

    // undo letterboxing: remap the normalized (0.0 - 1.0) digitizer coordinates, which span
    // the whole physical panel, into the displayed image region. returns false when the
    // touch lands in the black bars (outside the image) and should be ignored.
    static bool remap_aspect_compensation(double &norm_x, double &norm_y) {
        if (DISPLAY_NATIVE_X <= 0 || DISPLAY_NATIVE_Y <= 0) {
            return true;
        }

        double inset_x, inset_y;
        compute_letterbox_inset(inset_x, inset_y);

        // log once the first time the compensation actually engages (non-zero inset)
        static bool logged_active = false;
        if (!logged_active && (inset_x > 0.0 || inset_y > 0.0)) {
            logged_active = true;
            log_info("rawinput", "aspect compensation active: display {}x{}, native {}x{}, inset x={:.4f} y={:.4f}",
                     (int) DISPLAY_SIZE_X, (int) DISPLAY_SIZE_Y,
                     (int) DISPLAY_NATIVE_X, (int) DISPLAY_NATIVE_Y,
                     inset_x, inset_y);
        }

        // ignore touches inside the black bars (outside the displayed image)
        if ((inset_x > 0.0 && (norm_x < inset_x || norm_x > 1.0 - inset_x)) ||
            (inset_y > 0.0 && (norm_y < inset_y || norm_y > 1.0 - inset_y))) {
            return false;
        }

        // remap the displayed image region back to the full 0.0 - 1.0 range
        if (inset_x > 0.0) {
            norm_x = (norm_x - inset_x) / (1.0 - 2.0 * inset_x);
        }
        if (inset_y > 0.0) {
            norm_y = (norm_y - inset_y) / (1.0 - 2.0 * inset_y);
        }
        return true;
    }

    // determine the native (maximum) resolution advertised by the primary display device.
    // used to detect and undo letterboxing when a non-native display mode is in use.
    // falls back to the current display size if enumeration yields nothing larger.
    static void detect_native_resolution() {
        DISPLAY_NATIVE_X = DISPLAY_SIZE_X;
        DISPLAY_NATIVE_Y = DISPLAY_SIZE_Y;

        DEVMODE native_mode{};
        native_mode.dmSize = sizeof(native_mode);
        for (int i = 0; EnumDisplaySettings(nullptr, i, &native_mode); i++) {
            if ((long) native_mode.dmPelsWidth * (long) native_mode.dmPelsHeight >
                DISPLAY_NATIVE_X * DISPLAY_NATIVE_Y) {
                DISPLAY_NATIVE_X = (long) native_mode.dmPelsWidth;
                DISPLAY_NATIVE_Y = (long) native_mode.dmPelsHeight;
            }
        }
    }

    bool is_touchscreen(Device *device) {

        // check if disabled
        if (DISABLED) {
            return false;
        }

        // check device type
        if (device->type != HID) {
            return false;
        }

        auto *hid = device->hidInfo;
        auto &attributes = hid->attributes;

        // filter by VID/PID
        if (attributes.VendorID > 0) {

            // P2418HT
            // touch points apparently aren't released and will stay
            if (attributes.VendorID == 0x1FD2 && attributes.ProductID == 0x6103) {
                return false;
            }
        }

        // ignore the "Touch Pad" (0x05) usage under the "Digitizers" (0x0d) usage page
        if (hid->caps.UsagePage == 0x0d && hid->caps.Usage == 0x05) {
            return false;
        }

        // check description
        if (device->desc == "HID-compliant touch screen") {
            // TODO: this only works on english OS (?)
            return true;
        }

        // we can also check if there's touch point values inside
        for (const auto &value_name : hid->value_caps_names) {
            if (value_name == "Contact identifier") {
                return true;
            }
        }

        // nope this one probably not
        return false;
    }

    void enable(Device *device) {
        if (device->type == HID) {
            device->hidInfo->touch.valid = true;
            log_info("rawinput", "enabled touchscreen device: {} ({})", device->desc, device->name);
        } else {
            log_fatal("rawinput", "tried to enable touch functionality on non HID device");
        }
    }

    void disable(Device *device) {
        if (device->type == HID) {
            device->hidInfo->touch.valid = false;
            log_info("rawinput", "disabled touchscreen device: {} ({})", device->desc, device->name);
        } else
            log_fatal("rawinput", "tried to disable touch functionality on non HID device");
    }

    void update_input(Device *device) {

        // check type
        if (device->type != HID) {
            log_warning("rawinput", "touch update called on non HID device");
            return;
        }

        // get touch info
        auto hid = device->hidInfo;
        auto &touch = hid->touch;
        if (!touch.valid) {

            // not a registered touchscreen
            return;
        }

        // parse elements
        if (!touch.parsed_elements) {
            log_info("rawinput", "parsing touch elements");

            // clear lists first
            touch.elements_contact_count.clear();
            touch.elements_contact_identifier.clear();
            touch.elements_x.clear();
            touch.elements_y.clear();
            touch.elements_width.clear();
            touch.elements_height.clear();
            touch.elements_pressed.clear();
            touch.elements_pressure.clear();

            // get value indices
            for (int i = 0; i < (int) hid->value_caps_names.size(); i++) {
                auto &name = hid->value_caps_names[i];
                if (name == "Contact count") {
                    touch.elements_contact_count.push_back(i);
                } else if (name == "X") {
                    touch.elements_x.push_back(i);
                } else if (name == "Y") {
                    touch.elements_y.push_back(i);
                } else if (name == "Width") {
                    touch.elements_width.push_back(i);
                } else if (name == "Height") {
                    touch.elements_height.push_back(i);
                } else if (name == "Contact identifier") {
                    touch.elements_contact_identifier.push_back(i);
                } else if (name == "Pressure") {
                    touch.elements_pressure.push_back(i);
                }
            }

            // get button indices
            for (int i = 0; i < (int) hid->button_caps_names.size(); i++) {
                auto &name = hid->button_caps_names[i];
                if (name == "Tip Switch") {
                    touch.elements_pressed.push_back(i);
                }
            }

            // check sizes
            auto touch_size = touch.elements_contact_identifier.size();
            if (touch_size != touch.elements_x.size() ||
                touch_size != touch.elements_y.size() ||
                touch_size != touch.elements_pressed.size())
            {
                log_info("rawinput", "touch element size mismatch: {}:contacts, {}:x, {}:y, {}:pressed",
                         touch.elements_contact_identifier.size(),
                         touch.elements_x.size(),
                         touch.elements_y.size(),
                         touch.elements_pressed.size());
                disable(device);
                return;
            }

            // mark as parsed
            touch.parsed_elements = true;
            log_info("rawinput", "touch elements parsed: {} status fields", touch.elements_x.size());
        }

        // check if display is initialized
        if (!DISPLAY_INITIALIZED) {
            update_current_display_mode();
        }

        // update timeouts here as well so events are in the right order
        update_timeouts(device);

        // determine the number of touches contained in this report, defaulting to the size of `elements_x`
        size_t touch_report_count = touch.elements_x.size();
        if (!touch.elements_contact_count.empty()) {

            // support devices that have multiple "Contact count" fields, for some reason
            size_t contact_count = 0;
            for (auto &index : touch.elements_contact_count) {
                contact_count = std::max(contact_count, (size_t) hid->value_states_raw[index]);
            }

            // https://learn.microsoft.com/en-us/windows-hardware/design/component-guidelines/touchscreen-packet-reporting-modes
            // hybrid mode devices will report a contact count of 0 for subsequent reports that are
            // part of the same initial frame
            // most laptops and touchscreens are like this - they have the contact count set to 5 but can actually report up to 10 fingers
            if (contact_count > 0) {
                if (contact_count > touch_report_count) {
                    touch.remaining_contact_count = contact_count - touch_report_count;
                } else {
                    touch_report_count = contact_count;
                    touch.remaining_contact_count = 0;
                }
            } else if (touch.remaining_contact_count > 0) {
                if (touch.remaining_contact_count > touch_report_count) {
                    touch.remaining_contact_count -= touch_report_count;
                } else {
                    touch_report_count = touch.remaining_contact_count;
                    touch.remaining_contact_count = 0;
                }
            }
        }

        // iterate all input data and get touch points
        thread_local std::vector<HIDTouchPoint> touch_points;
        touch_points.clear();
        touch_points.reserve(touch.elements_x.size());
        for (size_t i = 0; i < touch.elements_x.size(); i++) {

            // if there are no more touch events to handle, exit out early
            if (touch_report_count == 0) {
                break;
            }
            touch_report_count--;

            // build touch point
            HIDTouchPoint hid_tp{};
            auto pos_x = hid->value_states[touch.elements_x[i]];
            auto pos_y = hid->value_states[touch.elements_y[i]];
            switch (DISPLAY_ORIENTATION) {
                case DMDO_DEFAULT:
                    hid_tp.x = pos_x;
                    hid_tp.y = pos_y;
                    break;
                case DMDO_90:
                    hid_tp.x = 1.f - pos_y;
                    hid_tp.y = pos_x;
                    break;
                case DMDO_180:
                    hid_tp.x = 1.f - pos_x;
                    hid_tp.y = 1.f - pos_y;
                    break;
                case DMDO_270:
                    hid_tp.x = pos_y;
                    hid_tp.y = 1.f - pos_x;
                    break;
                default:
                    break;
            }

            // optionally invert
            if (INVERTED) {
                hid_tp.x = 1.f - hid_tp.x;
                hid_tp.y = 1.f - hid_tp.y;
            }

            // generate ID (hopefully unique)
            hid_tp.id = (DWORD) hid->value_states_raw[touch.elements_contact_identifier[i]];
            hid_tp.id += (DWORD) (0xFFFFFF + device->id * 512);

            //std::string src = "(none)";

            // check if tip switch is down
            size_t index_pressed = touch.elements_pressed[i];
            for (auto &button_states : hid->button_states) {
                if (index_pressed < button_states.size()) {
                    hid_tp.down = button_states[index_pressed];

                    /*
                    if (hid_tp.down)
                        src = "pressed (index: " + to_string(touch.elements_pressed[i]) + ", state: " + to_string(button_states[index_pressed]) +")";
                        */

                    break;
                } else
                    index_pressed -= button_states.size();
            }

            // check width/height of touch point to see if pressed
            float width = 0.f, height = 0.f;
            if (!hid_tp.down && i < touch.elements_width.size() && i < touch.elements_height.size()) {
                width = hid->value_states[touch.elements_width[i]];
                height = hid->value_states[touch.elements_height[i]];
                hid_tp.down = width > 0.f && height > 0.f;

                /*
                if (hid_tp.down)
                    src = "width_height (width index: " + to_string(touch.elements_width[i]) + ", height index: " + to_string(touch.elements_height[i]) + ")";
                    */
            }

            // so last thing we can check is the pressure
            if (!hid_tp.down && i < touch.elements_pressure.size()) {
                auto pressure = hid->value_states[touch.elements_pressure[i]];
                hid_tp.down = pressure > 0.f;

                /*
                if (hid_tp.down)
                    src = "pressure (index: " + to_string(touch.elements_pressure[i]) + ")";
                    */
            }

            /*
            log_info("rawinput",
                "touch i: " + to_string(i) +
                " (id: " + to_string(hid_tp.id) +
                "), ci: " + to_string(hid->value_states_raw[touch.elements_contact_identifier[i]]) +
                ", x: " + to_string(pos_x) +
                ", y: " + to_string(pos_y) +
                ", width: " + to_string(width) +
                ", height: " + to_string(height) +
                ", down: " + to_string(hid_tp.down) +
                ", src: " + src);
                */

            // add to touch points
            touch_points.emplace_back(hid_tp);
        }

        // process touch points
        thread_local std::vector<DWORD> touch_removes;
        thread_local std::vector<TouchPoint> touch_writes;
        thread_local std::vector<DWORD> touch_modifications;
        touch_removes.clear();
        touch_writes.clear();
        touch_modifications.clear();
        touch_removes.reserve(touch.touch_points.size() + touch_points.size());
        touch_writes.reserve(touch_points.size());
        touch_modifications.reserve(touch_points.size());

        // drop every touch point with the given id (marking it as released)
        auto remove_touch_point = [&] (DWORD id) {
            touch_removes.push_back(id);
            touch.touch_points.erase(std::remove_if(
                    touch.touch_points.begin(),
                    touch.touch_points.end(),
                    [id] (const HIDTouchPoint &x) {
                        return x.id == id;
                    }), touch.touch_points.end());
        };

        for (auto &hid_tp : touch_points) {

            // check if existing
            auto existing = std::find_if(
                    touch.touch_points.begin(),
                    touch.touch_points.end(),
                    [hid_tp] (const HIDTouchPoint &x) {
                        return x.id == hid_tp.id;
                    });

            /*
            ssize_t ttl = -1;
            int64_t last_report = -1;
            if (existing != touch.touch_points.end()) {
                ttl = existing->ttl;
                last_report = existing->last_report;
            }

            log_info("rawinput",
                "id: " + to_string(hid_tp.id) +
                ", existing: " + to_string(existing != touch.touch_points.end()) +
                ", ttl: " + to_string(ttl) +
                ", last_report: " + to_string(last_report) +
                ", down: " + to_string(hid_tp.down));
                */

            // check if pressed
            if (!hid_tp.down) {

                // only remove if it exists
                if (existing != touch.touch_points.end()) {
                    remove_touch_point(hid_tp.id);
                }
            } else {

                // start from the normalized (0.0 - 1.0) digitizer coordinates
                double norm_x = hid_tp.x;
                double norm_y = hid_tp.y;

                // undo letterboxing so raw input touches line up with the displayed
                // image; touches that land in the black bars are treated as released
                if (aspect_compensation_enabled() && !remap_aspect_compensation(norm_x, norm_y)) {
                    if (existing != touch.touch_points.end()) {
                        remove_touch_point(hid_tp.id);
                    }
                    continue;
                }

                // scale the normalized coordinates to the monitor to obtain the
                // physical screen position of the touch
                TouchPoint tp {
                        .id = hid_tp.id,
                        .x = (long) (norm_x * DISPLAY_SIZE_X),
                        .y = (long) (norm_y * DISPLAY_SIZE_Y),
                        .mouse = false,
                };
                touch_writes.push_back(tp);
                touch_modifications.push_back(hid_tp.id);

                // check if existing
                if (existing == touch.touch_points.end()) {

                    // add new touch point
                    touch.touch_points.push_back(hid_tp);

                } else {

                    // update existing touch point
                    *existing = hid_tp;
                }
            }
        }

        // set TTL and last report time
        if (!touch.elements_x.empty()) {

            // a HID digitizer reports only a fixed number of contacts per report and
            // cycles the remaining ones through following reports, so a contact can be
            // absent for up to this many reports before it comes back around
            auto ttl = touch.touch_points.size() / touch.elements_x.size() + 1;
            auto system_time_ms = get_system_milliseconds();

            // extend every tracked contact to the current cycle length without ever
            // shrinking it; otherwise a rising contact count (e.g. rapid taps) lengthens
            // the cycle and can starve a stationary held contact into being reaped before
            // it is reported again. the 50ms last-report timeout remains the hard backstop
            for (auto &hid_tp : touch.touch_points) {
                if (hid_tp.ttl < ttl) {
                    hid_tp.ttl = ttl;
                }
            }

            // only contacts actually seen this report refresh their last-report time
            for (auto &hid_tp_id : touch_modifications) {
                for (auto &hid_tp : touch.touch_points) {
                    if (hid_tp.id == hid_tp_id) {
                        hid_tp.last_report = system_time_ms;
                    }
                }
            }
        }

        // remove dead touch points
        auto ttl_it = touch.touch_points.begin();
        while (ttl_it != touch.touch_points.end()) {
            auto &tp = *ttl_it;
            if (tp.ttl == 0) {
                touch_removes.push_back(tp.id);
                ttl_it = touch.touch_points.erase(ttl_it);
            } else {
                tp.ttl--;
                ttl_it++;
            }
        }

#ifndef SPICETOOLS_SPICECFG_STANDALONE

        // update touch module
        touch_remove_points(&touch_removes);
        touch_write_points(&touch_writes);
#endif
    }

    void update_timeouts(Device *device) {

        // check type
        if (device->type != HID) {
            log_fatal("rawinput", "touch timeout update called on non HID device");
            return;
        }

        // get touch info
        auto hid = device->hidInfo;
        auto &touch = hid->touch;
        if (!touch.valid) {
            return; // not a registered touchscreen
        }

        // calculate deadline - we allow the devices 50ms of not sending shit
        auto deadline = get_system_milliseconds() - 50;

        // check touch points
        thread_local std::vector<DWORD> touch_removes;
        touch_removes.clear();
        touch_removes.reserve(touch.touch_points.size());
        auto touch_it = touch.touch_points.begin();
        while (touch_it != touch.touch_points.end()) {
            auto &hid_tp = *touch_it;

            // see if it's behind the deadline
            if (hid_tp.last_report < deadline) {

                // oops it's gone
                touch_removes.push_back(hid_tp.id);
                touch_it = touch.touch_points.erase(touch_it);

            } else {

                // check the next device
                touch_it++;
            }
        }

#ifndef SPICETOOLS_SPICECFG_STANDALONE

        // remove from touch module
        touch_remove_points(&touch_removes);
#endif
    }

    void update_timeouts(RawInputManager *manager) {

        // iterate all devices
        for (auto &device : manager->devices_get()) {

            // check if it's a valid touchscreen
            if (device.type == HID && device.hidInfo->touch.valid) {

                // lock n' load
                device.mutex->lock();
                update_timeouts(&device);
                device.mutex->unlock();
            }
        }
    }

    bool is_enabled(RawInputManager *manager) {

        // check if disabled or manager is null
        if (DISABLED || manager == nullptr)
            return false;

        // check if at least one device is marked as valid touchscreen
        for (auto &device : manager->devices_get()) {
            if (device.type == HID && device.hidInfo->touch.valid) {
                return true;
            }
        }

        // no valid touch screen found
        return false;
    }

    static void update_current_display_mode() {
        // determine monitor size
        static RECT display_rect;
        GetWindowRect(GetDesktopWindow(), &display_rect);
        DISPLAY_SIZE_X = display_rect.right - display_rect.left;
        DISPLAY_SIZE_Y = display_rect.bottom - display_rect.top;
        log_info("rawinput", "primary display size: {}x{}", (int) DISPLAY_SIZE_X, (int) DISPLAY_SIZE_Y);

        // determine monitor orientation
        DEVMODE display_mode{};
        display_mode.dmSize = sizeof(DEVMODE);
        if (!EnumDisplaySettingsEx(nullptr, ENUM_CURRENT_SETTINGS, &display_mode, EDS_RAWMODE)) {
            log_info("rawinput", "failed to determine monitor mode");
        } else if (display_mode.dmFields & DM_DISPLAYORIENTATION) {
            DISPLAY_ORIENTATION = display_mode.dmDisplayOrientation;
            switch (DISPLAY_ORIENTATION) {
                case DMDO_DEFAULT:
                    log_info("rawinput", "display rotation: 0");
                    break;
                case DMDO_90:
                    log_info("rawinput", "display rotation: 90");
                    break;
                case DMDO_180:
                    log_info("rawinput", "display rotation: 180");
                    break;
                case DMDO_270:
                    log_info("rawinput", "display rotation: 270");
                    break;
                default:
                    break;
            }

            // another XP fix
            if (!IsWindowsVistaOrGreater()) {
                switch (DISPLAY_ORIENTATION) {
                    case DMDO_90:
                        DISPLAY_ORIENTATION = DMDO_180;
                        log_info("rawinput", "flipping to 180");
                        break;
                    case DMDO_270:
                        DISPLAY_ORIENTATION = DMDO_90;
                        log_info("rawinput", "flipping to 90");
                        break;
                    default:
                        break;
                }
            }
        } else {
            log_info("rawinput", "failed to determine monitor orientation");
        }

        // mark as initialized
        DISPLAY_INITIALIZED = true;
    }

    void display_update() {

        // check if disabled
        if (DISABLED)
            return;

        update_current_display_mode();

        if (aspect_compensation_enabled()) {
            // determine the native (maximum) resolution of the primary display; used to
            // detect and undo letterboxing when a non-native display mode is in use
            detect_native_resolution();
            log_info("rawinput", "primary display native size: {}x{}",
                     (int) DISPLAY_NATIVE_X, (int) DISPLAY_NATIVE_Y);
        }
    }
}