#include <Adafruit_GFX.h>
#include <Adafruit_ST7735.h>
#include <SPI.h>
#include <math.h>
#include "config.h"
#include "display_ui.h"
#include "net.h"

// Non-static so displayRender() can reference it via extern.
Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS, TFT_DC, TFT_RST);

// This 0.96" ST7735S panel is wired BGR (red/blue swapped), so build every
// colour with R and B exchanged and it displays as intended.
static uint16_t rgb(uint8_t r, uint8_t g, uint8_t b) { return tft.color565(b, g, r); }

static uint16_t C_MUTED, C_FRAME, C_LINE, C_SUN, C_CLOUD;
static uint16_t catColor(WxCategory c) {
  switch (c) {
    case WX_FINE:       return rgb(143,190,138); // fine green
    case WX_FAIR:       return rgb(228,182,88);   // amber
    case WX_CHANGEABLE: return rgb(121,194,208);  // mercury
    case WX_RAIN:       return rgb(92,134,214);    // blue
    case WX_STORM:      return rgb(228,87,59);     // vermilion
    default:            return C_MUTED;
  }
}

void displayBegin() {
  pinMode(TFT_BLK, OUTPUT);
  digitalWrite(TFT_BLK, HIGH);           // backlight on
  tft.initR(INITR_MINI160x80);           // 0.96" ST7735S
  tft.invertDisplay(false);              // this panel: no inversion
  tft.setRotation(3);                    // landscape, 160 wide x 80 tall
  C_MUTED = rgb(140,160,190);
  C_FRAME = rgb(42,58,90);
  C_LINE  = rgb(121,194,208);            // mercury cyan
  C_SUN   = rgb(240,200,70);
  C_CLOUD = rgb(224,232,240);
  tft.fillScreen(ST77XX_BLACK);
}

void displaySplash(const char* line1, const char* line2) {
  tft.fillScreen(ST77XX_BLACK);
  tft.setTextColor(ST77XX_WHITE);
  tft.setTextSize(2);
  tft.setCursor(4, 20);
  tft.print(line1);
  tft.setTextSize(1);
  tft.setCursor(4, 50);
  tft.print(line2);
}

// Weather icon scaled into a W x H box at (x,y).
static void drawIcon(WxCategory c, int x, int y, int W, int H) {
  int cx = x + W / 2, cy = y + H / 2;
  int m = (W < H ? W : H);
  switch (c) {
    case WX_FINE: {
      int r = (int)(m * 0.30f);
      tft.fillCircle(cx, cy, r, C_SUN);
      for (int k = 0; k < 8; k++) {
        float a = k * 0.7853982f;                 // 45 deg steps
        int x0 = cx + (int)((r + 4) * cosf(a)), y0 = cy + (int)((r + 4) * sinf(a));
        int x1 = cx + (int)((r + 11) * cosf(a)), y1 = cy + (int)((r + 11) * sinf(a));
        tft.drawLine(x0, y0, x1, y1, C_SUN);
      }
      break;
    }
    case WX_FAIR:
      tft.fillCircle(x + (int)(W * 0.34f), y + (int)(H * 0.34f), (int)(m * 0.24f), C_SUN);
      tft.fillRoundRect(x + (int)(W * 0.12f), y + (int)(H * 0.48f),
                        (int)(W * 0.76f), (int)(H * 0.40f), (int)(H * 0.20f), C_CLOUD);
      break;
    case WX_CHANGEABLE:
      tft.fillRoundRect(x + (int)(W * 0.06f), y + (int)(H * 0.28f),
                        (int)(W * 0.88f), (int)(H * 0.46f), (int)(H * 0.23f), C_CLOUD);
      break;
    case WX_RAIN: {
      tft.fillRoundRect(x + (int)(W * 0.06f), y + (int)(H * 0.14f),
                        (int)(W * 0.88f), (int)(H * 0.40f), (int)(H * 0.20f), C_CLOUD);
      int ry = y + (int)(H * 0.60f);
      for (int i = 0; i < 5; i++)
        tft.drawFastVLine(x + (int)(W * 0.18f) + i * (int)(W * 0.16f), ry, (int)(H * 0.26f), C_LINE);
      break;
    }
    case WX_STORM: {
      tft.fillRoundRect(x + (int)(W * 0.06f), y + (int)(H * 0.14f),
                        (int)(W * 0.88f), (int)(H * 0.40f), (int)(H * 0.20f), C_CLOUD);
      int by = y + (int)(H * 0.58f);
      tft.fillTriangle(cx, by, cx - 8, by + (int)(H * 0.30f), cx + 9, by + (int)(H * 0.22f), C_SUN);
      break;
    }
    default:
      tft.drawRoundRect(x + 2, y + (int)(H * 0.2f), W - 4, (int)(H * 0.55f), 8, C_FRAME);
      tft.setTextSize(2); tft.setTextColor(C_MUTED);
      tft.setCursor(cx - 6, cy - 8); tft.print("?");
      break;
  }
}

// Layout for landscape 160 x 80.
void displayRender(const AppState& s) {
  tft.fillScreen(ST77XX_BLACK);
  tft.setTextColor(ST77XX_WHITE);
  char buf[24];

  // Time (large), top-left
  snprintf(buf, sizeof(buf), "%02u:%02u", s.now.hour, s.now.minute);
  tft.setTextSize(2);
  tft.setCursor(2, 2);
  tft.print(buf);

  // Date
  tft.setTextSize(1);
  snprintf(buf, sizeof(buf), "%04u-%02u-%02u", s.now.year, s.now.month, s.now.day);
  tft.setCursor(2, 22);
  tft.print(buf);

  // Pressure + trend arrow (arrow only when rising/falling)
  snprintf(buf, sizeof(buf), "%.0f hPa", s.mslHpa);
  tft.setCursor(2, 34);
  tft.print(buf);
  if (s.trend != TREND_STEADY) {
    tft.setTextColor(C_LINE);
    tft.setCursor(80, 34);
    tft.print(s.trend == TREND_RISING ? "^" : "v");
    tft.setTextColor(ST77XX_WHITE);
  }

  // Temperature
  snprintf(buf, sizeof(buf), "%.1f C", s.tempC);
  tft.setCursor(2, 46);
  tft.print(buf);

  // Predicted-weather icon, top-right (fills to just above the divider)
  drawIcon(s.haveTrend ? s.forecast.category : WX_UNKNOWN, 78, 2, 78, 61);

  // Forecast category (colour-coded)
  tft.setTextSize(1);
  tft.setTextColor(s.haveTrend ? catColor(s.forecast.category) : C_MUTED);
  tft.setCursor(2, 56);
  tft.print(s.haveTrend ? categoryShort(s.forecast.category) : "Collecting...");

  // Bottom strip: divider + Wi-Fi / IP
  tft.drawFastHLine(0, 65, 160, C_FRAME);
  tft.setTextSize(1);
  if (netConnected()) {
    tft.setTextColor(C_LINE);
    tft.setCursor(2, 69);
    tft.print(netIP());
  } else {
    tft.setTextColor(C_MUTED);
    tft.setCursor(2, 69);
    tft.print("WiFi: offline");
  }
  tft.setTextColor(ST77XX_WHITE);
}