let expiryTimeout = undefined;
function updateExpiry(json) {
  if (expiryTimeout) {
    clearTimeout(expiryTimeout);
    expiryTimeout = undefined;
  }
  if (json.weather && json.weather.time && json.expiry) {
    let t = json.weather.time + json.expiry - Date.now();
    expiryTimeout = setTimeout(() => {
      expiryTimeout = undefined;
      let json = require('Storage').readJSON('weather.json')||{};
      delete json.weather;
      require('Storage').write('weather.json', json);
      exports.emit("expiry");
    }, t);
  }
}

exports = {
  save: weather => {
    let json = require('Storage').readJSON('weather.json')||{};
    json.weather = Object.assign({}, weather); // don't mutate GB events
    delete json.weather.t; // don't save the event type (if present)
    json.weather.time = Date.now();
    require('Storage').write('weather.json', json);
    updateExpiry(json);
  },
  load: () => {
    let json = require('Storage').readJSON('weather.json')||{};
    return json.weather;
  },
  drawIcon: (cond, x, y, r) => {
    function drawSun(x, y, r) {
      g.setColor("#FF7700");
      g.fillCircle(x, y, r);
    }

    function drawCloud(x, y, r, c) {
      const u = r/12;
      if (c==null) c = "#EEEEEE";
      g.setColor(c);
      g.fillCircle(x-8*u, y+3*u, 4*u);
      g.fillCircle(x-4*u, y-2*u, 5*u);
      g.fillCircle(x+4*u, y+0*u, 4*u);
      g.fillCircle(x+9*u, y+4*u, 3*u);
      g.fillPoly([
        x-8*u, y+7*u,
        x-8*u, y+3*u,
        x-4*u, y-2*u,
        x+4*u, y+0*u,
        x+9*u, y+4*u,
        x+9*u, y+7*u,
      ]);
    }

    function drawBrokenClouds(x, y, r) {
      drawCloud(x+1/8*r, y-1/8*r, 7/8*r, "#777777");
      drawCloud(x-1/8*r, y+1/8*r, 7/8*r);
    }

    function drawFewClouds(x, y, r) {
      drawSun(x+3/8*r, y-1/8*r, 5/8*r);
      drawCloud(x-1/8*r, y+1/8*r, 7/8*r);
    }

    function drawRainLines(x, y, r) {
      g.setColor("#FFFFFF");
      const y1 = y+1/2*r;
      const y2 = y+1*r;
      g.fillPoly([
        x-6/12*r+1, y1,
        x-8/12*r+1, y2,
        x-7/12*r, y2,
        x-5/12*r, y1,
      ]);
      g.fillPoly([
        x-2/12*r+1, y1,
        x-4/12*r+1, y2,
        x-3/12*r, y2,
        x-1/12*r, y1,
      ]);
      g.fillPoly([
        x+2/12*r+1, y1,
        x+0/12*r+1, y2,
        x+1/12*r, y2,
        x+3/12*r, y1,
      ]);
    }

    function drawShowerRain(x, y, r) {
      drawFewClouds(x, y-1/3*r, r);
      drawRainLines(x, y, r);
    }

    function drawRain(x, y, r) {
      drawBrokenClouds(x, y-1/3*r, r);
      drawRainLines(x, y, r);
    }

    function drawThunderstorm(x, y, r) {
      function drawLightning(x, y, r) {
        g.setColor("#FF7700");
        g.fillPoly([
          x-2/6*r, y-r,
          x-4/6*r, y+1/6*r,
          x-1/6*r, y+1/6*r,
          x-3/6*r, y+1*r,
          x+3/6*r, y-1/6*r,
          x+0/6*r, y-1/6*r,
          x+3/6*r, y-r,
        ]);
      }

      drawBrokenClouds(x, y-1/3*r, r);
      drawLightning(x-1/12*r, y+1/2*r, 1/2*r);
    }

    function drawSnow(x, y, r) {
      function rotatePoints(points, pivotX, pivotY, angle) {
        for(let i = 0; i<points.length; i += 2) {
          const x = points[i];
          const y = points[i+1];
          points[i] = Math.cos(angle)*(x-pivotX)-Math.sin(angle)*(y-pivotY)+
            pivotX;
          points[i+1] = Math.sin(angle)*(x-pivotX)+Math.cos(angle)*(y-pivotY)+
            pivotY;
        }
      }

      g.setColor("#FFFFFF");
      const w = 1/12*r;
      for(let i = 0; i<=6; ++i) {
        const points = [
          x+w, y,
          x-w, y,
          x-w, y+r,
          x+w, y+r,
        ];
        rotatePoints(points, x, y, i/3*Math.PI);
        g.fillPoly(points);

        for(let j = -1; j<=1; j += 2) {
          const points = [
            x+w, y+7/12*r,
            x-w, y+7/12*r,
            x-w, y+r,
            x+w, y+r,
          ];
          rotatePoints(points, x, y+7/12*r, j/3*Math.PI);
          rotatePoints(points, x, y, i/3*Math.PI);
          g.fillPoly(points);
        }
      }
    }

    function drawMist(x, y, r) {
      const layers = [
        [-0.4, 0.5],
        [-0.8, 0.3],
        [-0.2, 0.9],
        [-0.9, 0.7],
        [-0.2, 0.3],
      ];

      g.setColor("#FFFFFF");
      for(let i = 0; i<5; ++i) {
        g.fillRect(x+layers[i][0]*r, y+(0.4*i-0.9)*r, x+layers[i][1]*r,
          y+(0.4*i-0.7)*r-1);
        g.fillCircle(x+layers[i][0]*r, y+(0.4*i-0.8)*r-0.5, 0.1*r-0.5);
        g.fillCircle(x+layers[i][1]*r, y+(0.4*i-0.8)*r-0.5, 0.1*r-0.5);
      }
    }

    function chooseIcon(condition) {
      if (!condition) return () => {};
      condition = condition.toLowerCase();
      if (condition.includes("thunderstorm")) return drawThunderstorm;
      if (condition.includes("freezing")||condition.includes("snow")||
        condition.includes("sleet")) {
        return drawSnow;
      }
      if (condition.includes("drizzle")||
        condition.includes("shower")) {
        return drawRain;
      }
      if (condition.includes("rain")) return drawShowerRain;
      if (condition.includes("clear")) return drawSun;
      if (condition.includes("few clouds")) return drawFewClouds;
      if (condition.includes("scattered clouds")) return drawCloud;
      if (condition.includes("clouds")) return drawBrokenClouds;
      return drawMist;
    }

    chooseIcon(cond)(x, y, r);
  },
}

updateExpiry(require('Storage').readJSON('weather.json')||{});