// Copyright (c) 2024 microReticulum contributors
// SPDX-License-Identifier: MIT

#include "Display.h"
#include "SDAccess.h"

#ifdef ARDUINO

#include "Log.h"
#include <esp_heap_caps.h>

#if __has_include("SplashImage.h")
#include "SplashImage.h"
#endif

using namespace RNS;

namespace Hardware {
namespace TDeck {

SPIClass* Display::_spi = nullptr;
SemaphoreHandle_t Display::_spi_mutex = nullptr;
uint8_t Display::_brightness = Disp::BACKLIGHT_DEFAULT;
bool Display::_initialized = false;
bool Display::_hw_initialized = false;
volatile uint32_t Display::_flush_count = 0;
volatile uint32_t Display::_last_flush_ms = 0;
uint32_t Display::_last_health_log_ms = 0;

void Display::set_spi_mutex(SemaphoreHandle_t mutex) {
    _spi_mutex = mutex;
}

bool Display::init() {
    if (_initialized) {
        return true;
    }

    INFO("Initializing T-Deck display");

    // Initialize hardware first
    if (!init_hardware_only()) {
        return false;
    }

    // Allocate LVGL buffers in PSRAM (2 buffers for double buffering)
    static lv_disp_draw_buf_t draw_buf;
    size_t buf_size = Disp::WIDTH * Disp::HEIGHT * sizeof(lv_color_t);

    lv_color_t* buf1 = (lv_color_t*)heap_caps_malloc(buf_size, MALLOC_CAP_SPIRAM);
    lv_color_t* buf2 = (lv_color_t*)heap_caps_malloc(buf_size, MALLOC_CAP_SPIRAM);

    if (!buf1 || !buf2) {
        ERROR("Failed to allocate LVGL buffers in PSRAM");
        if (buf1) heap_caps_free(buf1);
        if (buf2) heap_caps_free(buf2);
        return false;
    }

    INFO(("  LVGL buffers allocated in PSRAM (" + String(buf_size * 2) + " bytes)").c_str());

    // Initialize LVGL draw buffer
    lv_disp_draw_buf_init(&draw_buf, buf1, buf2, Disp::WIDTH * Disp::HEIGHT);

    // Register display driver with LVGL
    static lv_disp_drv_t disp_drv;
    lv_disp_drv_init(&disp_drv);
    disp_drv.hor_res = Disp::WIDTH;
    disp_drv.ver_res = Disp::HEIGHT;
    disp_drv.flush_cb = lvgl_flush_cb;
    disp_drv.draw_buf = &draw_buf;

    lv_disp_t* disp = lv_disp_drv_register(&disp_drv);
    if (!disp) {
        ERROR("Failed to register display driver with LVGL");
        return false;
    }

    _initialized = true;
    INFO("Display initialized successfully");
    return true;
}

bool Display::init_hardware_only() {
    if (_hw_initialized) {
        return true;
    }

    INFO("Initializing display hardware");

    // Configure backlight PWM — keep OFF until splash is rendered
    // Use ledcWrite directly so _brightness retains the default value for show_splash()
    ledcSetup(Disp::BACKLIGHT_CHANNEL, Disp::BACKLIGHT_FREQ, Disp::BACKLIGHT_RESOLUTION);
    ledcAttachPin(Pin::DISPLAY_BACKLIGHT, Disp::BACKLIGHT_CHANNEL);
    ledcWrite(Disp::BACKLIGHT_CHANNEL, 0);

    // Use global SPI (FSPI) — all peripherals (display, LoRa, SD card) must
    // share the same SPI peripheral to avoid GPIO matrix pin conflicts.
    // SDAccess::init() already called SPI.begin() with correct pins.
    _spi = &SPI;
    if (!SDAccess::is_ready()) {
        // SD didn't init (no card) — we need to init SPI ourselves
        _spi->begin(Pin::DISPLAY_SCK, Radio::SPI_MISO, Pin::DISPLAY_MOSI, Pin::DISPLAY_CS);
    }

    // Configure CS and DC pins
    pinMode(Pin::DISPLAY_CS, OUTPUT);
    pinMode(Pin::DISPLAY_DC, OUTPUT);
    digitalWrite(Pin::DISPLAY_CS, HIGH);
    digitalWrite(Pin::DISPLAY_DC, HIGH);

    // Initialize ST7789V registers
    init_registers();

    _hw_initialized = true;
    INFO("  Display hardware ready");
    return true;
}

void Display::init_registers() {
    INFO("  Configuring ST7789V registers");

    // Software reset
    write_command(Command::SWRESET);
    // DELAY RATIONALE: LCD reset pulse width
    // ST7789 datasheet specifies minimum 120ms reset low time for reliable initialization.
    // Using 150ms for margin. Shorter values cause display initialization failures.
    delay(150);

    // Sleep out
    write_command(Command::SLPOUT);
    // DELAY RATIONALE: SPI command settling - allow display controller to process command before next
    delay(10);

    // Color mode: 16-bit (RGB565)
    write_command(Command::COLMOD);
    write_data(0x55);  // 16-bit color

    // Memory data access control (rotation + RGB order)
    write_command(Command::MADCTL);
    uint8_t madctl = MADCTL::MX | MADCTL::MY | MADCTL::RGB;
    if (Disp::ROTATION == 1) {
        madctl = MADCTL::MX | MADCTL::MV | MADCTL::RGB;  // Landscape
    }
    write_data(madctl);

    // Inversion on (required for ST7789V panels)
    write_command(Command::INVON);
    // DELAY RATIONALE: SPI command settling - allow display controller to process command before next
    delay(10);

    // Normal display mode
    write_command(Command::NORON);
    // DELAY RATIONALE: SPI command settling - allow display controller to process command before next
    delay(10);

    // Display on
    write_command(Command::DISPON);
    // DELAY RATIONALE: SPI command settling - allow display controller to process command before next
    delay(10);

    // Show splash image (or black screen if SplashImage.h not generated)
    show_splash();

    INFO("  ST7789V initialized");
}

void Display::set_brightness(uint8_t brightness) {
    _brightness = brightness;
    ledcWrite(Disp::BACKLIGHT_CHANNEL, brightness);
}

uint8_t Display::get_brightness() {
    return _brightness;
}

void Display::set_power(bool on) {
    if (_spi_mutex && xSemaphoreTake(_spi_mutex, pdMS_TO_TICKS(200)) != pdTRUE) {
        return;
    }
    if (on) {
        write_command(Command::DISPON);
        set_brightness(_brightness);
    } else {
        set_brightness(0);
        write_command(Command::DISPOFF);
    }
    if (_spi_mutex) xSemaphoreGive(_spi_mutex);
}

void Display::show_splash() {
#ifdef HAS_SPLASH_IMAGE
    // Splash image is full-screen (320x240), so offsets are 0
    static const uint16_t X_OFFSET = (Disp::WIDTH - SPLASH_WIDTH) / 2;
    static const uint16_t Y_OFFSET = (Disp::HEIGHT - SPLASH_HEIGHT) / 2;

    set_addr_window(X_OFFSET, Y_OFFSET,
                    X_OFFSET + SPLASH_WIDTH - 1,
                    Y_OFFSET + SPLASH_HEIGHT - 1);

    begin_write();
    write_command(Command::RAMWR);

    // Stream PROGMEM data in 512-byte chunks to avoid large stack allocation
    static const size_t CHUNK_SIZE = 512;
    uint8_t buf[CHUNK_SIZE];
    size_t total = SPLASH_WIDTH * SPLASH_HEIGHT * 2;

    for (size_t offset = 0; offset < total; offset += CHUNK_SIZE) {
        size_t len = (offset + CHUNK_SIZE <= total) ? CHUNK_SIZE : (total - offset);
        memcpy_P(buf, splash_image + offset, len);
        write_data(buf, len);
    }

    end_write();
    INFO("  Splash image rendered");
#else
    // No splash image — fill with background color (#1D1A1E -> RGB565 0x18C3)
    fill_screen(0x18C3);
#endif

    // Backlight on now that screen content is ready
    set_brightness(_brightness);
}

void Display::fill_screen(uint16_t color) {
    if (_spi_mutex && xSemaphoreTake(_spi_mutex, pdMS_TO_TICKS(500)) != pdTRUE) {
        return;
    }
    set_addr_window(0, 0, Disp::WIDTH - 1, Disp::HEIGHT - 1);

    begin_write();
    write_command(Command::RAMWR);

    // Send color data for entire screen
    uint8_t color_bytes[2];
    color_bytes[0] = (color >> 8) & 0xFF;
    color_bytes[1] = color & 0xFF;

    for (uint32_t i = 0; i < (uint32_t)Disp::WIDTH * Disp::HEIGHT; i++) {
        write_data(color_bytes, 2);
    }
    end_write();
    if (_spi_mutex) xSemaphoreGive(_spi_mutex);
}

void Display::draw_rect(int16_t x, int16_t y, int16_t w, int16_t h, uint16_t color) {
    if (x < 0 || y < 0 || x + w > Disp::WIDTH || y + h > Disp::HEIGHT) {
        return;
    }

    if (_spi_mutex && xSemaphoreTake(_spi_mutex, pdMS_TO_TICKS(200)) != pdTRUE) {
        return;
    }

    set_addr_window(x, y, x + w - 1, y + h - 1);

    begin_write();
    write_command(Command::RAMWR);

    uint8_t color_bytes[2];
    color_bytes[0] = (color >> 8) & 0xFF;
    color_bytes[1] = color & 0xFF;

    for (int32_t i = 0; i < w * h; i++) {
        write_data(color_bytes, 2);
    }
    end_write();
    if (_spi_mutex) xSemaphoreGive(_spi_mutex);
}

void Display::lvgl_flush_cb(lv_disp_drv_t* drv, const lv_area_t* area, lv_color_t* color_p) {
    if (_spi_mutex && xSemaphoreTake(_spi_mutex, pdMS_TO_TICKS(100)) != pdTRUE) {
        // Skip this frame — LVGL will retry next tick
        lv_disp_flush_ready(drv);
        return;
    }

    uint32_t start = millis();

    int32_t w = area->x2 - area->x1 + 1;
    int32_t h = area->y2 - area->y1 + 1;

    set_addr_window(area->x1, area->y1, area->x2, area->y2);

    begin_write();
    write_command(Command::RAMWR);

    // Send pixel data
    // lv_color_t is RGB565, which matches ST7789V format
    size_t len = w * h * sizeof(lv_color_t);
    write_data((const uint8_t*)color_p, len);

    end_write();

    if (_spi_mutex) xSemaphoreGive(_spi_mutex);

    _flush_count++;
    _last_flush_ms = millis();

    uint32_t elapsed = _last_flush_ms - start;
    if (elapsed > 50) {
        Serial.printf("[DISP] WARNING: flush took %lu ms (%ldx%ld, %zu bytes) - SPI contention?\n",
            elapsed, w, h, len);
    }

    // Tell LVGL we're done flushing
    lv_disp_flush_ready(drv);
}

void Display::log_health() {
    uint32_t now = millis();

    // Log every 10 seconds
    if (now - _last_health_log_ms < 10000) return;
    _last_health_log_ms = now;

    uint32_t since_flush = now - _last_flush_ms;
    if (since_flush > 2000) {
        Serial.printf("[DISP] STALLED: no flush for %lu ms! flush_count=%lu\n",
            since_flush, _flush_count);
    } else {
        Serial.printf("[DISP] ok: last_flush=%lu ms ago, total_flushes=%lu\n",
            since_flush, _flush_count);
    }
}

void Display::write_command(uint8_t cmd) {
    digitalWrite(Pin::DISPLAY_DC, LOW);   // Command mode
    digitalWrite(Pin::DISPLAY_CS, LOW);
    _spi->transfer(cmd);
    digitalWrite(Pin::DISPLAY_CS, HIGH);
}

void Display::write_data(uint8_t data) {
    digitalWrite(Pin::DISPLAY_DC, HIGH);  // Data mode
    digitalWrite(Pin::DISPLAY_CS, LOW);
    _spi->transfer(data);
    digitalWrite(Pin::DISPLAY_CS, HIGH);
}

void Display::write_data(const uint8_t* data, size_t len) {
    digitalWrite(Pin::DISPLAY_DC, HIGH);  // Data mode
    digitalWrite(Pin::DISPLAY_CS, LOW);
    _spi->transferBytes(data, nullptr, len);
    digitalWrite(Pin::DISPLAY_CS, HIGH);
}

void Display::set_addr_window(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1) {
    write_command(Command::CASET);  // Column address set
    write_data(x0 >> 8);
    write_data(x0 & 0xFF);
    write_data(x1 >> 8);
    write_data(x1 & 0xFF);

    write_command(Command::RASET);  // Row address set
    write_data(y0 >> 8);
    write_data(y0 & 0xFF);
    write_data(y1 >> 8);
    write_data(y1 & 0xFF);
}

void Display::begin_write() {
    _spi->beginTransaction(SPISettings(Disp::SPI_FREQUENCY, MSBFIRST, SPI_MODE0));
}

void Display::end_write() {
    _spi->endTransaction();
}

} // namespace TDeck
} // namespace Hardware

#endif // ARDUINO