#ifdef ESP_PLATFORM

#include <Tactility/service/displayidle/DisplayIdleService.h>
#include <Tactility/service/ServiceManifest.h>
#include <Tactility/service/ServiceRegistration.h>
#include <Tactility/mcp/McpSystem.h>

#include <app/manager.h>
#include <app/start.h>

#include "BouncingBallsScreensaver.h"
#include "MatrixRainScreensaver.h"
#include "MystifyScreensaver.h"
#include "McpScreensaver.h"
#include "Screensaver.h"
#include "StackChanScreensaver.h"

#include <cstdlib>
#include <ctime>

#include <tactility/delay.h>
#include <tactility/log.h>
#include <tactility/drivers/display.h>
#include <tactility/drivers/backlight.h>

#include <lvgl/lvgl.h>

namespace tt::service::displayidle {

constexpr auto* TAG = "DisplayIdle";

constexpr uint32_t kWakeActivityThresholdMs = 100;

void DisplayIdleService::stopScreensaverCb(lv_event_t* e) {
    auto* self = static_cast<DisplayIdleService*>(lv_event_get_user_data(e));
    lv_event_stop_bubbling(e);
    self->stopScreensaverRequested.store(true, std::memory_order_release);
    lv_display_trigger_activity(nullptr);
}

static void setBacklightBrightness(uint8_t brightness) {
    ::Device* display;
    if (device_get_first_active_by_type(&DISPLAY_TYPE, &display) == ERROR_NONE) {
        ::Device* backlight;
        if (display_get_backlight(display, &backlight) == ERROR_NONE) {
            backlight_set_brightness(backlight, brightness);
            device_put(backlight);
        }
        device_put(display);
    }
}

static bool hasDisplayWithBacklight() {
    ::Device* display;
    bool result = false;
    if (device_get_first_active_by_type(&DISPLAY_TYPE, &display) == ERROR_NONE) {
        ::Device* backlight;
        if (display_get_backlight(display, &backlight) == ERROR_NONE) {
            result = true;
            device_put(backlight);
        }
        device_put(display);
    }
    return result;
}

/**
 * Effective backlight duty for the screensaver: the dimmed night level when
 * night dim is enabled and the local hour is inside the configured window,
 * otherwise the regular duty. A start == end window covers the whole day.
 */
static uint8_t screensaverBacklightDuty(const settings::display::DisplaySettings& displaySettings) {
    if (!displaySettings.nightDimEnabled) {
        return displaySettings.backlightDuty;
    }
    const std::time_t now = std::time(nullptr);
    std::tm local_time {};
    if (localtime_r(&now, &local_time) == nullptr || local_time.tm_year < 125) {
        return displaySettings.backlightDuty;
    }
    const uint8_t hour = static_cast<uint8_t>(local_time.tm_hour);
    const uint8_t start = displaySettings.nightDimStartHour;
    const uint8_t end = displaySettings.nightDimEndHour;
    bool in_window;
    if (start == end) {
        in_window = true;
    } else if (start < end) {
        in_window = hour >= start && hour < end;
    } else {
        in_window = hour >= start || hour < end;
    }
    return in_window ? displaySettings.nightDimDuty : displaySettings.backlightDuty;
}

void DisplayIdleService::stopScreensaver() {
    if (!lvgl_try_lock(100)) {
        // Lock failed - keep flag set to retry on next tick
        return;
    }

    const auto restoreDuty = cachedDisplaySettings.backlightDuty;
    const bool wasDimmed = displayDimmed;

    if (screensaverOverlay) {
        if (screensaver) {
            screensaver->stop();
            screensaver.reset();
        }
        lv_obj_delete(screensaverOverlay);
        screensaverOverlay = nullptr;
    }
    lvgl_unlock();

    // Stop an app launched as screensaver (e.g. Bible Verse): on wake the
    // device returns to the launcher. Stopping is safe when the user already
    // closed it (unknown ids report STOPPED / stop is a no-op for them).
    if (screensaverAppActive) {
        screensaverAppActive = false;
        if (screensaverAppInstanceId != 0) {
            app_manager_stop(screensaverAppInstanceId);
            screensaverAppInstanceId = 0;
        }
    }
    stopScreensaverRequested.store(false, std::memory_order_relaxed);

    // Reset auto-off state
    screensaverActiveCounter = 0;
    backlightOff = false;

    // Restore backlight if display was dimmed
    if (wasDimmed) {
        setBacklightBrightness(restoreDuty);
    }

    displayDimmed = wasDimmed ? false : displayDimmed;
}

void DisplayIdleService::activateScreensaver() {
    // Reset auto-off counter when starting screensaver
    screensaverActiveCounter = 0;
    backlightOff = false;

    // Bible Verse screensaver: launch the app instead of drawing an overlay.
    // Falls back to a plain black overlay when the app is not installed.
    if (cachedDisplaySettings.screensaverType == settings::display::ScreensaverType::BibleVerse) {
        constexpr auto* BIBLE_VERSE_APP_ID = "one.tactility.bibleverse";
        AppManifest manifest {};
        AppInstanceId instance_id = 0;
        if (app_manager_find_manifest(BIBLE_VERSE_APP_ID, &manifest) == ERROR_NONE
            && app_start(BIBLE_VERSE_APP_ID, 0, nullptr, &instance_id) == ERROR_NONE) {
            LOG_I(TAG, "Bible Verse screensaver: launched instance %u", (unsigned)instance_id);
            screensaverAppInstanceId = instance_id;
            screensaverAppActive = true;
            setBacklightBrightness(screensaverBacklightDuty(cachedDisplaySettings));
            return;
        }
        LOG_W(TAG, "Bible Verse app not installed, falling back to black screen");
    }

    lv_obj_t* top = lv_layer_top();

    if (screensaverOverlay != nullptr) return;

    lv_coord_t screenW = lv_display_get_horizontal_resolution(nullptr);
    lv_coord_t screenH = lv_display_get_vertical_resolution(nullptr);

    // Black background overlay
    screensaverOverlay = lv_obj_create(top);
    lv_obj_remove_style_all(screensaverOverlay);
    lv_obj_set_size(screensaverOverlay, LV_PCT(100), LV_PCT(100));
    lv_obj_set_pos(screensaverOverlay, 0, 0);
    lv_obj_set_style_bg_color(screensaverOverlay, lv_color_black(), 0);
    lv_obj_set_style_bg_opa(screensaverOverlay, LV_OPA_COVER, 0);
    lv_obj_add_flag(screensaverOverlay, LV_OBJ_FLAG_CLICKABLE);
    lv_obj_add_event_cb(screensaverOverlay, stopScreensaverCb, LV_EVENT_CLICKED, this);

    // Create and start the screensaver based on settings
    switch (cachedDisplaySettings.screensaverType) {
        case settings::display::ScreensaverType::Mystify:
            screensaver = std::make_unique<MystifyScreensaver>();
            break;
        case settings::display::ScreensaverType::BouncingBalls:
            screensaver = std::make_unique<BouncingBallsScreensaver>();
            break;
        case settings::display::ScreensaverType::MatrixRain:
            screensaver = std::make_unique<MatrixRainScreensaver>();
            break;
        case settings::display::ScreensaverType::StackChan:
            screensaver = std::make_unique<StackChanScreensaver>();
            break;
        case settings::display::ScreensaverType::McpScreen:
            screensaver = std::make_unique<McpScreensaver>();
            break;
        case settings::display::ScreensaverType::None:
        default:
            // Just black screen, no animated screensaver
            screensaver = nullptr;
            break;
    }

    if (screensaver) {
        screensaver->start(screensaverOverlay, screenW, screenH);
    }

    setBacklightBrightness(screensaverBacklightDuty(cachedDisplaySettings));
}

void DisplayIdleService::updateScreensaver() {
    if (screensaver) {
        lv_coord_t screenW = lv_display_get_horizontal_resolution(nullptr);
        lv_coord_t screenH = lv_display_get_vertical_resolution(nullptr);
        screensaver->update(screenW, screenH);
    }
}

void DisplayIdleService::tick() {
    if (!lvgl_try_lock(100)) {
        return;
    }
    if (lv_display_get_default() == nullptr) {
        lvgl_unlock();
        return;
    }

    // Check for settings reload request (thread-safe)
    if (settingsReloadRequested.exchange(false, std::memory_order_acquire)) {
        cachedDisplaySettings = settings::display::loadOrGetDefault();
    }

    uint32_t inactive_ms = 0;

    inactive_ms = lv_display_get_inactive_time(nullptr);

    // Only update if not stopping (prevents lag on touch)
    if (displayDimmed && (screensaverOverlay || screensaverAppActive) && !stopScreensaverRequested.load(std::memory_order_acquire)) {
        // Check if screensaver should auto-off after 30 minutes
        if (!backlightOff) {
            screensaverActiveCounter++;
            if (screensaverActiveCounter >= SCREENSAVER_AUTO_OFF_TICKS) {
                // Stop screensaver animation and turn off backlight
                if (screensaver) {
                    screensaver->stop();
                    screensaver.reset();
                }
                if (screensaverAppActive) {
                    screensaverAppActive = false;
                    if (screensaverAppInstanceId != 0) {
                        app_manager_stop(screensaverAppInstanceId);
                        screensaverAppInstanceId = 0;
                    }
                }
                setBacklightBrightness(0);
                backlightOff = true;
            } else {
                updateScreensaver();
            }
        }
    }

    lvgl_unlock();

    // Check stop request early for faster response
    if (stopScreensaverRequested.load(std::memory_order_acquire)) {
        stopScreensaver();
        return;
    }

    if (hasDisplayWithBacklight()) {
        if (!cachedDisplaySettings.backlightTimeoutEnabled || cachedDisplaySettings.backlightTimeoutMs == 0) {
            if (displayDimmed) {
                setBacklightBrightness(cachedDisplaySettings.backlightDuty);
                displayDimmed = false;
            }
        } else {
            if (!displayDimmed && inactive_ms >= cachedDisplaySettings.backlightTimeoutMs) {
                if (!lvgl_try_lock(100)) {
                    return; // Retry on next tick
                }
                activateScreensaver();
                lvgl_unlock();
                // Turn off backlight for "None" screensaver (just black screen)
                if (cachedDisplaySettings.screensaverType == settings::display::ScreensaverType::None) {
                    setBacklightBrightness(0);
                }
                displayDimmed = true;
            } else if (displayDimmed && (inactive_ms < kWakeActivityThresholdMs)) {
                // The Bible Verse app keeps LVGL timers running (minute-advance),
                // so plain inactivity never drops while it is up. Taps still
                // register as activity: stop the verse app to return to launcher.
                // If the user already closed it, stopScreensaver() is a safe no-op.
                stopScreensaver();
            }
        }
    }
}

bool DisplayIdleService::onStart(ServiceContext& service) {
    // Seed random number generator for varied screensaver patterns
    srand(static_cast<unsigned int>(time(nullptr)));

    cachedDisplaySettings = settings::display::loadOrGetDefault();

    timer = std::make_unique<Timer>(Timer::Type::Periodic, millis_to_ticks(TICK_INTERVAL_MS), [this]{ this->tick(); });
    timer->setCallbackPriority(Thread::Priority::Lower);
    timer->start();
    return true;
}

void DisplayIdleService::onStop(ServiceContext& service) {
    if (timer) {
        timer->stop();
        timer = nullptr;
    }
    if (screensaverOverlay) {
        // Retry screensaver cleanup during shutdown
        constexpr int maxRetries = 5;
        for (int i = 0; i < maxRetries && screensaverOverlay; ++i) {
            stopScreensaver();
            if (screensaverOverlay && i < maxRetries - 1) {
                delay_millis(50); // Brief delay before retry
            }
        }
        if (screensaverOverlay) {
            LOG_W(TAG, "Failed to stop screensaver during shutdown - potential resource leak");
        }
    }
    if (screensaverAppActive) {
        screensaverAppActive = false;
        if (screensaverAppInstanceId != 0) {
            app_manager_stop(screensaverAppInstanceId);
            screensaverAppInstanceId = 0;
        }
    }
    screensaver.reset();
}

void DisplayIdleService::startScreensaver() {
    if (!lvgl_try_lock(100)) {
        return;
    }

    // Reload settings to get current screensaver type
    // Note: This is safe because we hold the LVGL lock which serializes with tick()
    cachedDisplaySettings = settings::display::loadOrGetDefault();

    // The Bible Verse path launches an app task (not an overlay), which must
    // not run under the LVGL lock: drop it before activating.
    const bool launches_app =
        cachedDisplaySettings.screensaverType == settings::display::ScreensaverType::BibleVerse;
    if (launches_app) {
        lvgl_unlock();
    }

    activateScreensaver();

    if (!launches_app) {
        lvgl_unlock();
    }

    // Turn off backlight for "None" screensaver
    if (hasDisplayWithBacklight() && cachedDisplaySettings.screensaverType == settings::display::ScreensaverType::None) {
        setBacklightBrightness(0);
    }
    displayDimmed = true;
}

bool DisplayIdleService::isScreensaverActive() const {
    return screensaverOverlay != nullptr || screensaverAppActive;
}

void DisplayIdleService::startMcpScreensaver() {
    if (!lvgl_try_lock(200)) {
        LOG_W(TAG, "startMcpScreensaver: failed to acquire LVGL lock");
        return;
    }

    if (screensaverOverlay != nullptr) {
        const auto& mcpState = mcp::getState();
        if (mcpState.drawArea != nullptr) {
            lvgl_unlock();
            return;
        }
        if (screensaver) {
            screensaver->stop();
            screensaver.reset();
        }
        lv_obj_delete(screensaverOverlay);
        screensaverOverlay = nullptr;
    }

    screensaverActiveCounter = 0;
    backlightOff = false;
    setBacklightBrightness(cachedDisplaySettings.backlightDuty == 0
        ? 255 : screensaverBacklightDuty(cachedDisplaySettings));

    lv_coord_t screenW = lv_display_get_horizontal_resolution(nullptr);
    lv_coord_t screenH = lv_display_get_vertical_resolution(nullptr);
    screensaverOverlay = lv_obj_create(lv_layer_top());
    lv_obj_remove_style_all(screensaverOverlay);
    lv_obj_set_size(screensaverOverlay, LV_PCT(100), LV_PCT(100));
    lv_obj_set_pos(screensaverOverlay, 0, 0);
    lv_obj_set_style_bg_color(screensaverOverlay, lv_color_black(), 0);
    lv_obj_set_style_bg_opa(screensaverOverlay, LV_OPA_COVER, 0);
    lv_obj_add_flag(screensaverOverlay, LV_OBJ_FLAG_CLICKABLE);
    lv_obj_add_event_cb(screensaverOverlay, stopScreensaverCb, LV_EVENT_CLICKED, this);

    screensaver = std::make_unique<McpScreensaver>();
    screensaver->start(screensaverOverlay, screenW, screenH);
    lvgl_unlock();
    displayDimmed = true;
    LOG_I(TAG, "MCP screensaver activated");
}

void DisplayIdleService::reloadSettings() {
    // Set flag for thread-safe reload - actual reload happens in tick()
    settingsReloadRequested.store(true, std::memory_order_release);
}

std::shared_ptr<DisplayIdleService> findService() {
    return std::static_pointer_cast<DisplayIdleService>(
        findServiceById("tactility.displayidle")
    );
}

extern const ServiceManifest manifest = {
    .id = "tactility.displayidle",
    .createService = create<DisplayIdleService>
};

}

#endif // ESP_PLATFORM