const state = {
  range: "24h",
  bucket: "5m",
  tz: "local",
  rangeStart: null,
  rangeEnd: null,
  singleChartId: null,
  charts: {},
  timer: null,
};

const colors = {
  obs: "#7bdff2",
  forecast: "#f4b942",
  gust: "#ff7d6b",
  humidity: "#7ee081",
  pressure: "#8fb8de",
  uvi: "#f4d35e",
  light: "#b8f2e6",
  precip: "#4ea8de",
  rain: "#4ea8de",
  rainStart: "#f77f00",
};

function formatNumber(value, digits) {
  if (value === null || value === undefined) {
    return "--";
  }
  return Number(value).toFixed(digits);
}

function formatDateTime(value) {
  if (!value) return "--";
  const dt = value instanceof Date ? value : new Date(value);
  if (Number.isNaN(dt.getTime())) return "--";
  const opts = { dateStyle: "medium", timeStyle: "short" };
  if (state.tz === "utc") {
    return new Intl.DateTimeFormat(undefined, { ...opts, timeZone: "UTC" }).format(dt);
  }
  return new Intl.DateTimeFormat(undefined, opts).format(dt);
}

function formatTick(value) {
  const dt = new Date(value);
  if (Number.isNaN(dt.getTime())) return "";
  const opts = { month: "short", day: "numeric", hour: "2-digit", minute: "2-digit" };
  if (state.tz === "utc") {
    return new Intl.DateTimeFormat(undefined, { ...opts, timeZone: "UTC" }).format(dt);
  }
  return new Intl.DateTimeFormat(undefined, opts).format(dt);
}

function series(points, key) {
  return points.map((p) => {
    const t = new Date(p.ts).getTime();
    return {
      x: Number.isNaN(t) ? null : t,
      y: p[key] === undefined ? null : p[key],
    };
  });
}

function filterRange(points, start, end) {
  if (!start || !end) return points;
  const min = start.getTime();
  const max = end.getTime();
  return points.filter((p) => {
    if (!p.ts) return false;
    const t = new Date(p.ts).getTime();
    return !Number.isNaN(t) && t >= min && t <= max;
  });
}

function safeDate(value) {
  if (!value) return null;
  const dt = value instanceof Date ? value : new Date(value);
  return Number.isNaN(dt.getTime()) ? null : dt;
}

function hourBucketMs(ts, tz) {
  const d = new Date(ts);
  if (Number.isNaN(d.getTime())) return null;
  if (tz === "utc") {
    return Date.UTC(d.getUTCFullYear(), d.getUTCMonth(), d.getUTCDate(), d.getUTCHours());
  }
  return new Date(d.getFullYear(), d.getMonth(), d.getDate(), d.getHours()).getTime();
}

function computeRainIncrements(points) {
  const out = [];
  let prev = null;
  for (const p of points) {
    const t = new Date(p.ts).getTime();
    if (Number.isNaN(t)) continue;
    if (p.rain_mm === null || p.rain_mm === undefined) {
      out.push({ x: t, y: null });
      continue;
    }
    let delta = null;
    if (prev !== null) {
      delta = p.rain_mm - prev;
      if (delta < 0) delta = 0;
    }
    prev = p.rain_mm;
    out.push({ x: t, y: delta });
  }
  return out;
}

function computeHourlySums(points, tz) {
  const buckets = new Map();
  for (const p of points) {
    if (p.y == null) continue;
    const bucket = hourBucketMs(p.x, tz);
    if (bucket === null) continue;
    buckets.set(bucket, (buckets.get(bucket) || 0) + p.y);
  }
  return Array.from(buckets.entries())
    .sort((a, b) => a[0] - b[0])
    .map(([x, y]) => ({ x, y }));
}

function startOfDay(date, tz) {
  if (tz === "utc") {
    return new Date(Date.UTC(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate()));
  }
  return new Date(date.getFullYear(), date.getMonth(), date.getDate());
}

function startOfWeekSunday(date, tz) {
  const day = tz === "utc" ? date.getUTCDay() : date.getDay();
  const base = startOfDay(date, tz);
  const diff = day;
  return new Date(base.getTime() - diff * 24 * 60 * 60 * 1000);
}

function computeRange(range, tz) {
  const now = new Date();
  let start = null;
  let end = null;
  let axisStart = null;
  let axisEnd = null;

  switch (range) {
    case "6h": {
      end = now;
      start = new Date(now.getTime() - 6 * 60 * 60 * 1000);
      axisStart = start;
      axisEnd = end;
      break;
    }
    case "24h": {
      start = startOfDay(now, tz);
      end = new Date(start.getTime() + 24 * 60 * 60 * 1000);
      axisStart = start;
      axisEnd = end;
      break;
    }
    case "24h-last": {
      end = now;
      start = new Date(now.getTime() - 24 * 60 * 60 * 1000);
      axisStart = start;
      axisEnd = end;
      break;
    }
    case "72h-last": {
      end = now;
      start = new Date(now.getTime() - 72 * 60 * 60 * 1000);
      axisStart = start;
      axisEnd = end;
      break;
    }
    case "72h": {
      end = startOfDay(now, tz);
      start = new Date(end.getTime() - 72 * 60 * 60 * 1000);
      axisStart = start;
      axisEnd = end;
      break;
    }
    case "7d-last": {
      end = now;
      start = new Date(now.getTime() - 7 * 24 * 60 * 60 * 1000);
      axisStart = start;
      axisEnd = end;
      break;
    }
    case "7d": {
      start = startOfWeekSunday(now, tz);
      end = new Date(start.getTime() + 7 * 24 * 60 * 60 * 1000);
      axisStart = start;
      axisEnd = end;
      break;
    }
    default: {
      end = now;
      start = new Date(now.getTime() - 24 * 60 * 60 * 1000);
      axisStart = start;
      axisEnd = end;
    }
  }

  return { start, end, axisStart, axisEnd };
}

function readStateFromURL() {
  const url = new URL(window.location.href);
  const range = url.searchParams.get("range");
  const tz = url.searchParams.get("tz");
  if (range) {
    state.range = range;
  }
  if (tz === "utc" || tz === "local") {
    state.tz = tz;
  }
  state.bucket = state.range === "6h" ? "1m" : "5m";

  const chartParam = url.searchParams.get("chart");
  const chartMatch = url.pathname.match(/^\/chart\/([^/]+)/);
  if (chartMatch && chartMatch[1]) {
    state.singleChartId = chartMatch[1];
  } else if (chartParam) {
    state.singleChartId = chartParam;
  }
}

function syncControls() {
  const rangeButtons = document.querySelectorAll(".btn[data-range]");
  rangeButtons.forEach((btn) => {
    btn.classList.toggle("active", btn.dataset.range === state.range);
  });
  const tzButtons = document.querySelectorAll(".btn[data-tz]");
  tzButtons.forEach((btn) => {
    btn.classList.toggle("active", btn.dataset.tz === state.tz);
  });
}

function updateSingleChartMode() {
  const cards = document.querySelectorAll(".chart-card");
  if (!state.singleChartId) {
    document.body.classList.remove("single-chart");
    cards.forEach((card) => card.classList.remove("active"));
    return;
  }

  document.body.classList.add("single-chart");
  cards.forEach((card) => {
    const id = card.dataset.chart;
    card.classList.toggle("active", id === state.singleChartId);
  });
}

function buildChartURL(chartId) {
  const url = new URL(window.location.origin + "/chart/" + chartId);
  url.searchParams.set("range", state.range);
  url.searchParams.set("tz", state.tz);
  return url.toString();
}

function setupShareLinks() {
  const buttons = document.querySelectorAll(".chart-link");
  buttons.forEach((btn) => {
    btn.addEventListener("click", async () => {
      const chartId = btn.dataset.chart;
      if (!chartId) return;
      const url = buildChartURL(chartId);
      try {
        await navigator.clipboard.writeText(url);
        btn.textContent = "Copied";
        setTimeout(() => {
          btn.textContent = "Share";
        }, 1200);
      } catch (err) {
        window.prompt("Copy chart URL:", url);
      }
    });
  });
}

function minMax(values) {
  let min = null;
  let max = null;
  for (const v of values) {
    if (v === null || v === undefined) continue;
    if (min === null || v < min) min = v;
    if (max === null || v > max) max = v;
  }
  return { min, max };
}

function sum(values) {
  let total = 0;
  let seen = false;
  for (const v of values) {
    if (v === null || v === undefined) continue;
    total += v;
    seen = true;
  }
  return seen ? total : null;
}

function updateText(id, text) {
  const el = document.getElementById(id);
  if (el) el.textContent = text;
}

function describeBarometer(pressure, trend) {
  if (pressure === null || pressure === undefined) {
    return "No barometer data yet.";
  }

  let pressureLabel = "normal";
  if (pressure <= 1000) {
    pressureLabel = "very low";
  } else if (pressure < 1008) {
    pressureLabel = "low";
  } else if (pressure >= 1024) {
    pressureLabel = "high";
  }

  let trendLabel = "steady";
  if (trend !== null && trend !== undefined) {
    if (trend <= -2.0) {
      trendLabel = "falling fast";
    } else if (trend <= -0.5) {
      trendLabel = "falling";
    } else if (trend >= 2.0) {
      trendLabel = "rising fast";
    } else if (trend >= 0.5) {
      trendLabel = "rising";
    }
  }

  let outlook = "Stable; no strong rain signal.";
  if (trend !== null && trend !== undefined) {
    if (trend <= -1.0 && pressure <= 1008) {
      outlook = "Unsettled; rain more likely.";
    } else if (trend <= -1.0) {
      outlook = "Unsettled; rain possible.";
    } else if (trend >= 1.0 && pressure >= 1020) {
      outlook = "Improving; rain less likely.";
    } else if (trend >= 1.0) {
      outlook = "Improving; rain chance easing.";
    }
  } else if (pressure <= 1005) {
    outlook = "Low pressure; rain possible.";
  } else if (pressure >= 1022) {
    outlook = "Fair weather likely.";
  }

  if (trend === null || trend === undefined) {
    return `Pressure ${formatNumber(pressure, 1)} hPa (${pressureLabel}); trend unavailable. ${outlook}`;
  }

  const trendText = `${trend >= 0 ? "+" : ""}${trend.toFixed(1)} hPa/hr`;
  return `Pressure ${formatNumber(pressure, 1)} hPa (${pressureLabel}), ${trendLabel} (${trendText}). ${outlook}`;
}

function lastNonNull(points, key) {
  for (let i = points.length - 1; i >= 0; i -= 1) {
    const v = points[i][key];
    if (v !== null && v !== undefined) {
      return v;
    }
  }
  return null;
}

function computeRainProbability(latest, pressureTrend1h) {
  if (!latest) {
    return null;
  }

  let prob = 0.1;
  if (pressureTrend1h !== null && pressureTrend1h !== undefined) {
    if (pressureTrend1h <= -3.0) {
      prob += 0.5;
    } else if (pressureTrend1h <= -2.0) {
      prob += 0.35;
    } else if (pressureTrend1h <= -1.0) {
      prob += 0.2;
    } else if (pressureTrend1h <= -0.5) {
      prob += 0.1;
    }
  }

  if (latest.rh !== null && latest.rh !== undefined) {
    if (latest.rh >= 95) {
      prob += 0.2;
    } else if (latest.rh >= 90) {
      prob += 0.15;
    } else if (latest.rh >= 85) {
      prob += 0.1;
    }
  }

  if (latest.wind_m_s !== null && latest.wind_m_s !== undefined && latest.wind_m_s >= 6) {
    prob += 0.05;
  }

  prob = Math.max(0.05, Math.min(0.95, prob));

  let label = "Low";
  if (prob >= 0.6) {
    label = "High";
  } else if (prob >= 0.35) {
    label = "Medium";
  }

  return { prob, label };
}

function extendForecastTo(points, endTime) {
  if (!points || !points.length || !endTime) {
    return points;
  }
  const last = points[points.length - 1];
  const lastTs = new Date(last.ts).getTime();
  if (Number.isNaN(lastTs)) {
    return points;
  }
  const endTs = endTime.getTime();
  if (endTs <= lastTs) {
    return points;
  }
  const maxGapMs = 75 * 60 * 1000;
  if (endTs-lastTs > maxGapMs) {
    return points;
  }
  return [...points, { ...last, ts: new Date(endTs).toISOString() }];
}

function updateSiteMeta(site, model, tzLabel) {
  const home = document.getElementById("site-home");
  const suffix = document.getElementById("site-meta-suffix");
  if (home) {
    home.textContent = site || "--";
    home.setAttribute("href", "/");
  }
  if (suffix) {
    suffix.textContent = ` | model ${model || "--"} | ${tzLabel}`;
  }
}

function upsertChart(id, config) {
  const ctx = document.getElementById(id);
  if (!ctx) return;
  if (state.charts[id]) {
    state.charts[id].data = config.data;
    state.charts[id].options = config.options;
    state.charts[id].update();
    return;
  }
  state.charts[id] = new Chart(ctx, config);
}

function baseOptions(range) {
  return {
    responsive: true,
    maintainAspectRatio: false,
    interaction: { mode: "index", intersect: false },
    plugins: {
      legend: { labels: { color: "#d6f0f0" } },
      tooltip: {
        mode: "index",
        intersect: false,
        callbacks: {
          title: (items) => {
            if (!items.length) return "";
            return formatDateTime(new Date(items[0].parsed.x));
          },
        },
      },
    },
    scales: {
      x: {
        type: "time",
        time: { unit: "hour" },
        ticks: {
          color: "#a4c4c4",
          maxTicksLimit: 6,
          callback: (value) => formatTick(value),
        },
        min: range && range.axisStart ? range.axisStart.getTime() : undefined,
        max: range && range.axisEnd ? range.axisEnd.getTime() : undefined,
        grid: { color: "rgba(123, 223, 242, 0.08)" },
      },
      y: {
        ticks: { color: "#a4c4c4" },
        grid: { color: "rgba(123, 223, 242, 0.08)" },
      },
    },
    elements: {
      line: { tension: 0.2, borderWidth: 2 },
      point: { radius: 0, hitRadius: 8 },
    },
    spanGaps: true,
  };
}

function renderDashboard(data) {
  const latest = data.latest;
  const tzLabel = state.tz === "utc" ? "UTC" : "Local";
  updateSiteMeta(data.site, data.model, tzLabel);
  updateText("last-updated", `updated ${formatDateTime(data.generated_at)}`);
  const forecastMeta = data.forecast && data.forecast.points && data.forecast.points.length
    ? `forecast retrieved ${formatDateTime(data.forecast.retrieved_at)}`
    : "forecast not available";
  updateText("forecast-meta", forecastMeta);

  if (latest) {
    updateText("live-temp", `${formatNumber(latest.temp_c, 2)} C`);
    updateText("live-rh", `${formatNumber(latest.rh, 0)} %`);
    updateText("live-pressure", `${formatNumber(latest.pressure_hpa, 1)} hPa`);
    updateText("live-wind", `${formatNumber(latest.wind_m_s, 2)}`);
    updateText("live-gust", `${formatNumber(latest.wind_gust_m_s, 2)}`);
    updateText("live-wdir", `${formatNumber(latest.wind_dir_deg, 0)}`);
    updateText("live-uvi", `${formatNumber(latest.uvi, 2)}`);
    updateText("live-lux", `${formatNumber(latest.light_lux, 0)}`);
    updateText("live-battery", `${formatNumber(latest.battery_mv, 0)}`);
    updateText("live-supercap", `${formatNumber(latest.supercap_v, 2)}`);
  } else {
    updateText("live-temp", "--");
    updateText("live-rh", "--");
    updateText("live-pressure", "--");
    updateText("live-wind", "--");
    updateText("live-gust", "--");
    updateText("live-wdir", "--");
    updateText("live-uvi", "--");
    updateText("live-lux", "--");
    updateText("live-battery", "--");
    updateText("live-supercap", "--");
  }

  const obs = data.observations || [];
  const forecastAll = (data.forecast && data.forecast.points) || [];

  const rangeStart = safeDate(data.range_start) || state.rangeStart;
  const rangeEnd = safeDate(data.range_end) || state.rangeEnd;
  const range = { axisStart: rangeStart, axisEnd: rangeEnd };

  const obsFiltered = filterRange(obs, rangeStart, rangeEnd);
  const forecast = filterRange(forecastAll, rangeStart, rangeEnd);
  const forecastLine = extendForecastTo(forecast, rangeEnd);
  const lastPressureTrend = lastNonNull(obsFiltered, "pressure_trend_1h");
  const rainProb = computeRainProbability(latest, lastPressureTrend);
  if (rainProb) {
    updateText("live-rain-prob", `${Math.round(rainProb.prob * 100)}% (${rainProb.label})`);
  } else {
    updateText("live-rain-prob", "--");
  }
  updateText("baro-outlook", describeBarometer(latest ? latest.pressure_hpa : null, lastPressureTrend));

  const obsTemps = obsFiltered.map((p) => p.temp_c);
  const obsWinds = obsFiltered.map((p) => p.wind_m_s);
  const obsGusts = obsFiltered.map((p) => p.wind_gust_m_s);
  const obsRH = obsFiltered.map((p) => p.rh);
  const obsUvi = obsFiltered.map((p) => p.uvi);
  const obsLux = obsFiltered.map((p) => p.light_lux);

  const fcTemps = forecast.map((p) => p.temp_c);
  const fcWinds = forecast.map((p) => p.wind_m_s);
  const fcGusts = forecast.map((p) => p.wind_gust_m_s);
  const fcRH = forecast.map((p) => p.rh);
  const fcPrecip = forecast.map((p) => p.precip_mm);

  const obsTempSummary = minMax(obsTemps);
  const obsWindSummary = minMax(obsWinds);
  const obsUviSummary = minMax(obsUvi);
  const obsLuxSummary = minMax(obsLux);

  const forecastTempSummary = minMax(fcTemps);
  const forecastPrecipTotal = sum(fcPrecip);

  const obsParts = [];
  if (obsTempSummary.min !== null) {
    obsParts.push(`temp_c ${obsTempSummary.min.toFixed(1)} to ${obsTempSummary.max.toFixed(1)}`);
  }
  if (obsWindSummary.max !== null) {
    obsParts.push(`wind_max ${obsWindSummary.max.toFixed(1)} m/s`);
  }
  if (obsUviSummary.max !== null) {
    obsParts.push(`uvi_max ${obsUviSummary.max.toFixed(1)}`);
  }
  if (obsLuxSummary.max !== null) {
    obsParts.push(`lux_max ${obsLuxSummary.max.toFixed(0)}`);
  }
  updateText("obs-summary", obsParts.length ? obsParts.join(" | ") : "--");

  const forecastParts = [];
  if (forecastTempSummary.min !== null) {
    forecastParts.push(`temp_c ${forecastTempSummary.min.toFixed(1)} to ${forecastTempSummary.max.toFixed(1)}`);
  }
  if (forecastPrecipTotal !== null) {
    forecastParts.push(`precip_total ${forecastPrecipTotal.toFixed(1)} mm`);
  }
  updateText("forecast-summary", forecastParts.length ? forecastParts.join(" | ") : "--");

  updateText("commentary", buildCommentary(latest, forecastAll));

  const tempChart = {
    type: "line",
    data: {
      datasets: [
        { label: "obs temp C", data: series(obsFiltered, "temp_c"), borderColor: colors.obs },
        { label: "forecast temp C", data: series(forecastLine, "temp_c"), borderColor: colors.forecast },
      ],
    },
    options: baseOptions(range),
  };
  upsertChart("chart-temp", tempChart);

  const windChart = {
    type: "line",
    data: {
      datasets: [
        { label: "obs wind m/s", data: series(obsFiltered, "wind_m_s"), borderColor: colors.obs },
        { label: "obs gust m/s", data: series(obsFiltered, "wind_gust_m_s"), borderColor: colors.gust },
        { label: "forecast wind m/s", data: series(forecastLine, "wind_m_s"), borderColor: colors.forecast },
        { label: "forecast gust m/s", data: series(forecastLine, "wind_gust_m_s"), borderColor: "#f7d79f" },
      ],
    },
    options: baseOptions(range),
  };
  upsertChart("chart-wind", windChart);

  const rhChart = {
    type: "line",
    data: {
      datasets: [
        { label: "obs humidity %", data: series(obsFiltered, "rh"), borderColor: colors.humidity },
        { label: "forecast rh %", data: series(forecastLine, "rh"), borderColor: colors.forecast },
      ],
    },
    options: baseOptions(range),
  };
  upsertChart("chart-rh", rhChart);

  const pressureChart = {
    type: "line",
    data: {
      datasets: [
        { label: "obs pressure hPa", data: series(obsFiltered, "pressure_hpa"), borderColor: colors.pressure },
        { label: "forecast msl hPa", data: series(forecastLine, "pressure_msl_hpa"), borderColor: colors.forecast },
      ],
    },
    options: baseOptions(range),
  };
  upsertChart("chart-pressure", pressureChart);

  const lightOptions = baseOptions(range);
  lightOptions.scales.y.ticks.color = colors.uvi;
  lightOptions.scales.y.title = { display: true, text: "UVI", color: colors.uvi };
  lightOptions.scales.y1 = {
    position: "right",
    ticks: { color: colors.light },
    title: { display: true, text: "Lux", color: colors.light },
    grid: { drawOnChartArea: false },
  };

  const lightChart = {
    type: "line",
    data: {
      datasets: [
        { label: "uvi", data: series(obsFiltered, "uvi"), borderColor: colors.uvi, yAxisID: "y" },
        { label: "light lux", data: series(obsFiltered, "light_lux"), borderColor: colors.light, yAxisID: "y1" },
      ],
    },
    options: lightOptions,
  };
  upsertChart("chart-light", lightChart);

  const powerOptions = baseOptions(range);
  powerOptions.scales.y.ticks.color = colors.obs;
  powerOptions.scales.y.title = { display: true, text: "Battery (mV)", color: colors.obs };
  powerOptions.scales.y1 = {
    position: "right",
    ticks: { color: colors.forecast },
    title: { display: true, text: "Supercap (V)", color: colors.forecast },
    grid: { drawOnChartArea: false },
  };

  const powerChart = {
    type: "line",
    data: {
      datasets: [
        { label: "battery mV", data: series(obsFiltered, "battery_mv"), borderColor: colors.obs, yAxisID: "y" },
        { label: "supercap V", data: series(obsFiltered, "supercap_v"), borderColor: colors.forecast, yAxisID: "y1" },
      ],
    },
    options: powerOptions,
  };
  upsertChart("chart-power", powerChart);

  const rainOptions = baseOptions(range);
  rainOptions.scales.y1 = {
    position: "right",
    ticks: { color: "#a4c4c4" },
    grid: { drawOnChartArea: false },
  };

  const rainIncs = computeRainIncrements(obsFiltered);
  const rainHourly = computeHourlySums(rainIncs, state.tz);
  const rainTitle = document.getElementById("chart-rain-title");
  if (rainTitle) {
    rainTitle.textContent = "Rain (obs hourly sum vs forecast)";
  }

  const rainChart = {
    data: {
      datasets: [
        {
          type: "line",
          label: "obs hourly sum (mm)",
          data: rainHourly,
          borderColor: colors.rain,
          yAxisID: "y",
        },
        {
          type: "bar",
          label: "forecast precip (mm)",
          data: series(forecast, "precip_mm"),
          backgroundColor: colors.forecast,
          yAxisID: "y",
        },
      ],
    },
    options: rainOptions,
  };
  upsertChart("chart-rain", rainChart);


  updateSingleChartMode();
}

function buildCommentary(latest, forecast) {
  if (!latest || !forecast || !forecast.length) {
    return "Waiting for forecast data...";
  }

  const obsTs = new Date(latest.ts);
  if (Number.isNaN(obsTs.getTime())) {
    return "No valid observation timestamp yet.";
  }

  let nearest = null;
  let bestDiff = null;
  for (const p of forecast) {
    if (!p.ts) continue;
    const fcTs = new Date(p.ts);
    if (Number.isNaN(fcTs.getTime())) continue;
    const diff = Math.abs(obsTs - fcTs);
    if (bestDiff === null || diff < bestDiff) {
      bestDiff = diff;
      nearest = p;
    }
  }

  if (!nearest || bestDiff > 2 * 60 * 60 * 1000) {
    return "No nearby forecast point to compare yet.";
  }

  const parts = [];

  if (latest.temp_c !== null && nearest.temp_c !== null) {
    const delta = latest.temp_c - nearest.temp_c;
    parts.push(`temp ${delta >= 0 ? "+" : ""}${delta.toFixed(1)} C`);
  }
  if (latest.wind_m_s !== null && nearest.wind_m_s !== null) {
    const delta = latest.wind_m_s - nearest.wind_m_s;
    parts.push(`wind ${delta >= 0 ? "+" : ""}${delta.toFixed(1)} m/s`);
  }
  if (latest.wind_gust_m_s !== null && nearest.wind_gust_m_s !== null) {
    const delta = latest.wind_gust_m_s - nearest.wind_gust_m_s;
    parts.push(`gust ${delta >= 0 ? "+" : ""}${delta.toFixed(1)} m/s`);
  }
  if (latest.rh !== null && nearest.rh !== null) {
    const delta = latest.rh - nearest.rh;
    parts.push(`rh ${delta >= 0 ? "+" : ""}${delta.toFixed(0)} %`);
  }

  if (!parts.length) {
    return "Not enough data to compute deviation yet.";
  }

  return `Now vs forecast: ${parts.join(", ")}`;
}

async function loadAndRender() {
  const range = computeRange(state.range, state.tz);
  state.rangeStart = range.start;
  state.rangeEnd = range.end;

  const params = new URLSearchParams({
    range: state.range,
    bucket: state.bucket,
    start: range.start.toISOString(),
    end: range.end.toISOString(),
  });
  try {
    const resp = await fetch(`/api/dashboard?${params.toString()}`, { cache: "no-store" });
    if (!resp.ok) {
      updateText("commentary", `Dashboard error ${resp.status}`);
      return;
    }
    const data = await resp.json();
    renderDashboard(data);
  } catch (err) {
    updateText("commentary", "Dashboard fetch failed.");
  }
}

function setupControls() {
  const buttons = document.querySelectorAll(".btn[data-range]");
  buttons.forEach((btn) => {
    btn.addEventListener("click", () => {
      buttons.forEach((b) => b.classList.remove("active"));
      btn.classList.add("active");
      state.range = btn.dataset.range;
      state.bucket = state.range === "6h" ? "1m" : "5m";
      updateURLParams();
      loadAndRender();
    });
  });

  const tzButtons = document.querySelectorAll(".btn[data-tz]");
  tzButtons.forEach((btn) => {
    btn.addEventListener("click", () => {
      tzButtons.forEach((b) => b.classList.remove("active"));
      btn.classList.add("active");
      state.tz = btn.dataset.tz;
      updateURLParams();
      loadAndRender();
    });
  });
}

function updateURLParams() {
  const url = new URL(window.location.href);
  url.searchParams.set("range", state.range);
  url.searchParams.set("tz", state.tz);
  history.replaceState({}, "", url);
}

document.addEventListener("DOMContentLoaded", () => {
  readStateFromURL();
  syncControls();
  setupControls();
  setupShareLinks();
  updateSingleChartMode();
  loadAndRender();
  if (state.timer) clearInterval(state.timer);
  state.timer = setInterval(loadAndRender, 60 * 1000);
});