/**
 * V2X-Display Driver - ST7735 SPI (T-Dongle-C5)
 * 
 * Display: ST7735, 80x160 Pixel
 * SPI-Pins: CS=GPIO10, RST=GPIO1, SDA(MOSI)=GPIO2, SCK=GPIO6
 * LCD-Backlight: GPIO0
 * 
 * Statusanzeige:
 *   - Oben: SD-Speicher in %, Frame-Counter
 *   - Unten: rollende Liste der letzten X Frames (RSSI-Balken + msg_type)
 */

#include "esp_log.h"
#include "v2x_display.h"
#include "esp_lcd_panel_ops.h"
#include "esp_lcd_panel_vendor.h"
#include "esp_lvgl_port.h"
#include "driver/gpio.h"
#include <stdio.h>

static const char *TAG = "v2x-display";

/* ST7735 Kommandos */
#define ST7735_NOP          0x00
#define ST7735_SWRESET      0x01
#define ST7735_SLPIN        0x10
#define ST7735_SLPOUT       0x11
#define ST7735_PTLON        0x12
#define ST7735_NORON        0x13
#define ST7735_INVOFF       0x20
#define ST7735_INVON        0x21
#define ST7735_DIS5520      0x29
#define ST7735_MADCTL       0x36
#define ST7735_COLMOD       0x3A
#define ST7735_CASET        0x2A
#define ST7735_RASET        0x2B
#define ST7735_RAMWR        0x2C

static esp_lcd_panel_handle_t s_panel = NULL;
static bool s_initialized = false;

/* ST7735 Init-Sequenz (TFT 0.96 Zoll 80x160, SPI, ROTG) */
static const esp_lcd_panel_cmd_init_t st7735_init[] = {
    {0x11, (uint8_t[]){0}, 0, 120},          /* SWRESET */
    {0x3A, (uint8_t[]){0x55}, 1, 0},         /* COLMOD=16bit */
    {0x36, (uint8_t[]){0x08}, 1, 0},         /* MADCTL (portrait) */
    {0x21, (uint8_t[]){}, 0, 0},             /* INVOFF */
    {0x29, (uint8_t[]){}, 0, 0},             /* DISON */
};

esp_err_t v2x_display_init(void)
{
    esp_err_t ret;

    ESP_LOGI(TAG, "Initialisiere ST7735 Display...");

    /* Backlight an */
    gpio_config_t bl_conf = {
        .pin_bit_mask = (1ULL << DISP_GPIO_BL),
        .mode = GPIO_MODE_OUTPUT,
        .pull_down_en = GPIO_PULLDOWN_DISABLE,
        .pull_up_en = GPIO_PULLUP_DISABLE,
    };
    gpio_config(&bl_conf);
    gpio_set_level(DISP_GPIO_BL, 1);

    /* Reset-Pin */
    gpio_config_t rst_conf = {
        .pin_bit_mask = (1ULL << DISP_GPIO_RST),
        .mode = GPIO_MODE_OUTPUT,
    };
    gpio_config(&rst_conf);

    /* SPI für LCD */
    spi_bus_config_t bus_cfg = {
        .mosi_io_num = DISP_GPIO_SDA,  /* GPIO2 */
        .miso_io_num = -1,             /* LCD braucht kein MISO */
        .sclk_io_num = DISP_GPIO_SCK,  /* GPIO6 */
        .quadwp_io_num = -1,
        .quadhd_io_num = -1,
        .max_transfer_sz = DISP_W * DISP_H * sizeof(uint16_t),
    };

    ret = spi_bus_initialize(SPI3_HOST, &bus_cfg, 1);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "spi_bus_init fehlgeschlagen");
        return ret;
    }

    /* LCD-Panel konfigurieren */
    esp_lcd_panel_dev_config_t panel_cfg = {
        .reset_gpio_num = DISP_GPIO_RST,
        .color_space = ESP_LCD_COLOR_SPACE_RGB,
        .bits_per_pixel = 16,
    };

    ret = esp_lcd_new_panel_st7735(NULL, &panel_cfg, &s_panel);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "ST7735 Panel konnte nicht erstellt werden");
        return ret;
    }

    /* Panel initialisieren */
    ret = esp_lcd_panel_reset(s_panel);
    if (ret != ESP_OK) goto err;

    ret = esp_lcd_panel_init(s_panel);
    if (ret != ESP_OK) goto err;

    ret = esp_lcd_panel_disp_on_off(s_panel, true);
    if (ret != ESP_OK) goto err;

    /* Komplette Init-Sequenz (falls ST7735 nicht korrekt init) */
    ret = esp_lcd_panel_cmd_init(s_panel, st7735_init, sizeof(st7735_init)/sizeof(st7735_init[0]));
    if (ret != ESP_OK) {
        ESP_LOGW(TAG, "ST7735 Init-Kommandos fehlgeschlagen: %s", esp_err_to_name(ret));
    }

    s_initialized = true;
    g_disp_initialized = true;
    g_disp_panel = s_panel;
    ESP_LOGI(TAG, "ST7735 Display bereit (80x160, SPI)");
    return ESP_OK;

err:
    ESP_LOGE(TAG, "Display-Init fehlgeschlagen");
    return ret;
}

esp_err_t v2x_display_clear(uint16_t color)
{
    if (!s_initialized) return ESP_ERR_INVALID_STATE;

    esp_lcd_panel_draw_bitmap(s_panel, 0, 0, DISP_W, DISP_H, &color);
    return ESP_OK;
}

esp_err_t v2x_display_rect(int16_t x, int16_t y, int16_t w, int16_t h, uint16_t color, bool filled)
{
    if (!s_initialized) return ESP_ERR_INVALID_STATE;

    uint8_t *buf = malloc(w * h * sizeof(uint16_t));
    if (!buf) return ESP_ERR_NO_MEM;

    for (int i = 0; i < w * h; i++) {
        ((uint16_t *)buf)[i] = color;
    }

    esp_lcd_panel_draw_bitmap(s_panel, x, y, x + w, y + h, buf);
    free(buf);
    return ESP_OK;
}

esp_err_t v2x_display_line(int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color)
{
    /* Einfacher Bresenham-Linienzeiger für 1-Pixel Linien */
    if (!s_initialized) return ESP_ERR_INVALID_STATE;

    int dx = abs(x1 - x0);
    int dy = abs(y1 - y0);
    int sx = (x0 < x1) ? 1 : -1;
    int sy = (y0 < y1) ? 1 : -1;
    int err = dx - dy;

    while (true) {
        esp_lcd_panel_draw_bitmap(s_panel, x0, y0, x0 + 1, y0 + 1, &color);
        if (x0 == x1 && y0 == y1) break;
        int e2 = 2 * err;
        if (e2 > -dy) { err -= dy; x0 += sx; }
        if (e2 < dx) { err += dx; y0 += sy; }
    }
    return ESP_OK;
}

esp_err_t v2x_display_off(void)
{
    if (!s_initialized) return ESP_ERR_INVALID_STATE;

    gpio_set_level(DISP_GPIO_BL, 0);
    if (s_panel) esp_lcd_panel_disp_on_off(s_panel, false);
    return ESP_OK;
}

/* Fortschrittsbalken: progress 0.0 - 1.0 */
esp_err_t v2x_display_progress_bar(int16_t x, int16_t y, int16_t w, int16_t h, float progress,
                                     uint16_t fg_color, uint16_t bg_color)
{
    progress = (progress < 0.0f) ? 0.0f : (progress > 1.0f) ? 1.0f : progress;

    /* Hintergrund */
    v2x_display_rect(x, y, w, h, bg_color, true);

    /* Vordergrund */
    int16_t fw = (int16_t)(w * progress);
    if (fw > 0) {
        v2x_display_rect(x, y, fw, h, fg_color, true);
    }

    /* Rahmen */
    for (int i = 0; i < w; i++) {
        v2x_display_line(x + i, y, x + i, y + h, DISP_COLOR_BLACK);
    }
    for (int i = 0; i < h; i++) {
        v2x_display_line(x, y + i, x + w, y + i, DISP_COLOR_BLACK);
    }
    return ESP_OK;
}

/* RSSI-Balken: -100 bis -20 dBm → 0-100% */
esp_err_t v2x_display_rssi_gauge(int8_t rssi)
{
    if (rssi < -100) rssi = -100;
    if (rssi > -20) rssi = -20;

    float pct = (float)(rssi + 100) / 80.0f;

    /* Farbe: rot → gelb → grün */
    uint16_t color = DISP_COLOR_RED;
    if (pct > 0.6f) color = DISP_COLOR_GREEN;
    else if (pct > 0.3f) color = DISP_COLOR_YELLOW;

    return v2x_display_progress_bar(0, 0, DISP_W, 3, pct, color, DISP_COLOR_BLACK);
}

/* Frame-Info als Zeile rendern */
esp_err_t v2x_display_render_frame_line(int16_t x, int16_t y, const disp_frame_info_t *info,
                                        uint16_t bg_color)
{
    /* Background */
    v2x_display_rect(x, y, DISP_W, 12, bg_color, true);

    /* RSSI-Farbring links (5 Pixel breit) */
    if (info->rssi != 0) {
        int8_t r = info->rssi;
        if (r < -100) r = -100;
        if (r > -20) r = -20;
        float pct = (float)(r + 100) / 80.0f;
        uint16_t bar_color = DISP_COLOR_RED;
        if (pct > 0.6f) bar_color = DISP_COLOR_GREEN;
        else if (pct > 0.3f) bar_color = DISP_COLOR_YELLOW;
        v2x_display_rect(x, y + 1, 5, 10, bar_color, true);
    }

    /* Message-Typ-Icon */
    char msg_char = '?';
    uint16_t msg_color = DISP_COLOR_GRAY;
    switch (info->msg_type) {
        case 1: msg_char = 'B'; msg_color = DISP_COLOR_GREEN; break; /* BSM */
        case 2: msg_char = 'C'; msg_color = DISP_COLOR_CYAN;  break; /* CAM */
        case 3: msg_char = 'D'; msg_color = DISP_COLOR_RED;   break; /* DENM */
    }

    /* Zeichen: msg_char */
    /* (Wird in Schritt 2: Font-Ausgabe implementiert) */
    (void)msg_color; (void)x; (void)y;

    return ESP_OK;
}