Cache home location and weather across page navigation

pets-fe/pages/home/home.js

@@ -1,5 +1,6 @@
 const { secure, toast } = require("../../utils/api");
 const { localDate } = require("../../utils/date");
+const environment = require("../../utils/environment");
 function dateLabel() {
   const now = new Date();
   return `${now.getMonth() + 1}月${now.getDate()}日 周${"日一二三四五六"[now.getDay()]}`;
@@ -19,7 +20,7 @@ Page({
     error: "",
   },
   onShow() {
-    this.updateEnvironmentLabel();
+    this.applyEnvironment(environment.cached());
     this.load();
   },
   onUnload() {
@@ -31,62 +32,40 @@ Page({
         dateLabel() + " · " + (this.weatherLabel || "轻触获取天气"),
     });
   },
+  applyEnvironment(value) {
+    if (this.disposed) return;
+    if (value) {
+      this.weatherLabel = value.weatherLabel;
+      this.setData({ locationName: value.locationName });
+    }
+    this.updateEnvironmentLabel();
+  },
   async refreshEnvironment(event) {
     if (this.environmentBusy) return;
     this.environmentBusy = true;
     const tapped = !!event;
-    let positioned = false;
-    try {
-      const settings = await new Promise((resolve, reject) =>
-        wx.getSetting({ success: resolve, fail: reject }),
-      );
-      if (settings.authSetting["scope.userLocation"] === false) {
-        if (!tapped) throw new Error("location-denied");
-        const enabled = await new Promise((resolve, reject) =>
-          wx.openSetting({ success: resolve, fail: reject }),
-        );
-        if (!enabled.authSetting["scope.userLocation"])
-          throw new Error("location-denied");
-      }
+    const cached = environment.cached();
+    if (!cached) {
       this.weatherLabel = "正在获取天气";
       this.updateEnvironmentLabel();
-      const point = await new Promise((resolve, reject) =>
-        wx.getLocation({
-          type: "gcj02",
-          success: resolve,
-          fail: reject,
-        }),
-      );
-      positioned = true;
-      const result = await secure("/environment", "GET", {
-        latitude: point.latitude,
-        longitude: point.longitude,
-      });
-      this.setData({ locationName: result.location_name });
-      this.weatherLabel = result.weather
-        ? `${result.weather.description} ${result.weather.temperature}°C`
-        : "天气暂不可用";
-      this.environmentAt = result.weather ? Date.now() : 0;
+    }
+    try {
+      this.applyEnvironment(await environment.refresh(tapped));
     } catch (error) {
-      const denied = /denied|deny|auth/.test(
-        error.errMsg || error.message || "",
-      );
-      this.setData({
-        locationName: positioned
-          ? "位置暂不可用"
-          : denied
-            ? "开启定位"
-            : "定位暂不可用",
-      });
-      this.weatherLabel = denied ? "轻触开启定位" : "轻触重试";
-      if (tapped && !denied)
-        wx.showToast({
-          title: positioned ? "位置和天气获取失败，请重试" : "定位失败，请重试",
-          icon: "none",
-        });
+      if (this.disposed) return;
+      if (cached) {
+        this.applyEnvironment(cached);
+      } else {
+        const denied = /denied|deny|auth/.test(
+          error.errMsg || error.message || "",
+        );
+        this.setData({ locationName: denied ? "开启定位" : "定位暂不可用" });
+        this.weatherLabel = denied ? "轻触开启定位" : "轻触重试";
+        this.updateEnvironmentLabel();
+      }
+      if (tapped) toast(error);
     } finally {
       this.environmentBusy = false;
-      this.updateEnvironmentLabel();
     }
   },
   async load() {
@@ -129,12 +108,7 @@ Page({
         phase: "ready",
       });
       // Location permission and weather never hold up the first usable screen.
-      if (
-        !this.environmentAt ||
-        Date.now() - this.environmentAt > 15 * 60 * 1000
-      ) {
-        this.refreshEnvironment();
-      }
+      this.refreshEnvironment();
     } catch (error) {
       if (this.disposed) return;
       this.setData({

pets-fe/utils/environment.js

@@ -0,0 +1,85 @@
+const { secure } = require("./api");
+
+const STORAGE_KEY = "pet_environment_v1";
+let value;
+let attempted = false;
+let pending;
+let failure;
+
+function cached() {
+  if (value === undefined) {
+    const saved = wx.getStorageSync(STORAGE_KEY);
+    value =
+      saved &&
+      typeof saved.locationName === "string" &&
+      typeof saved.weatherLabel === "string" &&
+      Number.isFinite(saved.updatedAt)
+        ? saved
+        : null;
+  }
+  return value;
+}
+
+async function fetchEnvironment(tapped) {
+  const settings = await new Promise((resolve, reject) =>
+    wx.getSetting({ success: resolve, fail: reject }),
+  );
+  if (settings.authSetting["scope.userLocation"] === false) {
+    if (!tapped) throw new Error("location-denied");
+    const enabled = await new Promise((resolve, reject) =>
+      wx.openSetting({ success: resolve, fail: reject }),
+    );
+    if (!enabled.authSetting["scope.userLocation"])
+      throw new Error("location-denied");
+  }
+  const point = await new Promise((resolve, reject) =>
+    wx.getLocation({ type: "gcj02", success: resolve, fail: reject }),
+  );
+  const result = await secure("/environment", "GET", {
+    latitude: point.latitude,
+    longitude: point.longitude,
+  });
+  if (!result || !result.location_name)
+    throw new Error("位置和天气获取失败，请重试");
+  const previous = cached();
+  value = {
+    locationName: result.location_name,
+    weatherLabel: result.weather
+      ? `${result.weather.description} ${result.weather.temperature}°C`
+      : previous && previous.locationName === result.location_name
+        ? previous.weatherLabel
+        : "天气暂不可用",
+    updatedAt: Date.now(),
+  };
+  // Store display data only; precise coordinates are not persisted here.
+  try {
+    wx.setStorageSync(STORAGE_KEY, value);
+  } catch (_) {}
+  return value;
+}
+
+function refresh(tapped = false) {
+  if (pending) return pending;
+  // Module lifetime follows the app, including recreated pages and warm resumes.
+  // Failed automatic attempts also wait for a tap or the next cold start.
+  if (attempted && !tapped)
+    return failure ? Promise.reject(failure) : Promise.resolve(cached());
+  attempted = true;
+  pending = fetchEnvironment(tapped)
+    .then(
+      (result) => {
+        failure = null;
+        return result;
+      },
+      (error) => {
+        failure = error;
+        throw error;
+      },
+    )
+    .finally(() => {
+      pending = null;
+    });
+  return pending;
+}
+
+module.exports = { cached, refresh };