#pragma once

/**
 * @file DisplayManager.h
 * @brief E-Ink display driver abstraction using GxEPD2_BW.
 *
 * Responsibilities:
 *  - Manage the 400×300 Waveshare 4.2" GxEPD2 display via SPI.
 *  - Render a 2×2 tile grid; each tile shows one data field.
 *  - Perform partial refresh for numeric value updates (fast, no flicker).
 *  - Perform full refresh on page change or periodically to prevent ghosting.
 *  - Show a splash/boot screen, BLE status overlay and AP-mode notice.
 *
 * Partial refresh strategy:
 *  Each tile's "value area" (excluding the fixed label and border) is
 *  re-drawn with partial update. The borders and labels are only redrawn
 *  during a full refresh, saving ~250 ms per cycle.
 */

#include "Config.h"
#include <GxEPD2_BW.h>
#include <Fonts/FreeMonoBold24pt7b.h>
#include <Fonts/FreeMonoBold12pt7b.h>
#include <Fonts/FreeMono9pt7b.h>

// ── Display model — match the validated reference sketch for the 4.2" panel.
// The generic 420 driver is used here to avoid a controller mismatch that can
// leave the panel completely blank during init.
using DisplayType = GxEPD2_BW<GxEPD2_420,
                               GxEPD2_420::HEIGHT>;

class DisplayManager {
public:
    /**
     * @brief Initialise the SPI bus and display. Shows the splash screen.
     *        Must be called from setup() before any render methods.
     */
    void begin();

    /**
     * @brief Main render call — invoke from loop().
     *        Decides between partial and full refresh based on:
     *        - Whether data has changed since the last render.
     *        - Whether FULL_REFRESH_INTERVAL_MS has elapsed.
     *        - An explicit forceFullRefresh() request.
     * @param state  Current boat data snapshot.
     * @param cfg    Current page configuration.
     */
    void render(const BoatState& state, const PageConfig& cfg);

    /** @brief Request a full (slow) refresh on the next render() call. */
    void forceFullRefresh() { _needFullRefresh = true; }

    /** @brief Show a BLE scanning / connecting notice. */
    void showBleStatus(AppState::BleStatus status);

    /** @brief Show the AP mode access screen with SSID and IP. */
    void showApScreen(const char* ssid, const char* ip);

    /** @brief Show the OTA progress screen. */
    void showOtaScreen(uint8_t percent);

    /** @brief Show the passkey entry prompt. */
    void showPasskeyPrompt(uint32_t pin);

    /** @brief Hibernate the display to save power (full blank). */
    void hibernate();

    // Internal access for GxEPD2
    DisplayType& epd() { return _display; }

private:
    DisplayType _display {
        GxEPD2_420(Pins::EPD_CS,
                   Pins::EPD_DC,
                   Pins::EPD_RST,
                   Pins::EPD_BUSY)
    };

    bool     _initialised     = false;
    bool     _needFullRefresh = true;
    uint32_t _lastFullRefresh = 0;
    uint32_t _lastRender      = 0;

    // Cached value strings per tile to detect changes
    char _prevValue[Display::TILE_COUNT][16];

    // ── Drawing helpers ───────────────────────────────────────────────────────

    void _drawSplash();
    void _drawGrid();
    void _drawTile(uint8_t idx, const TileConfig& tile, const BoatState& state, bool partial);
    void _drawTileLabel(uint8_t idx, const TileConfig& tile);
    void _drawTileValue(uint8_t idx, const char* value, bool partial);

    // Compute the pixel rect for a tile
    struct Rect { uint16_t x, y, w, h; };
    Rect _tileRect(uint8_t idx) const;
    Rect _valuRect(uint8_t idx) const; ///< Sub-rect for the value only

    // Extract a display string from the boat state for a given field
    void _fieldToString(DataField field, const BoatState& state,
                        char* out, size_t outLen) const;

    // Centre text in a rect
    void _drawCentred(const char* text, uint16_t x, uint16_t y,
                      uint16_t w, uint16_t h);
};

// Singleton accessor
extern DisplayManager displayManager;