262 lines
9.2 KiB
Go
262 lines
9.2 KiB
Go
package web
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import (
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"fmt"
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"io"
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"net/http"
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"regexp"
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"strconv"
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"strings"
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"sync"
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"time"
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"rond-with-you/internal/config"
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)
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// mapLayer 描述一个可供前端使用的底图/叠加图层。
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// crs 表示该底图自身的坐标系：国内底图是 gcj02，天地图与 OSM 是 wgs84。
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type mapLayer struct {
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Key string `json:"key"`
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Label string `json:"label"`
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CRS string `json:"crs"`
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URL string `json:"url"`
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MaxZoom int `json:"maxZoom"`
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Attribution string `json:"attr"`
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}
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// tileSet 是当前部署的底图集合。
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// upstream 记录哪些图层必须经服务端转发：命中即说明该图层带密钥，
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// 密钥只在上游模板里拼接，不会出现在页面源码中。
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type tileSet struct {
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base []mapLayer
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overlays []mapLayer
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upstream map[string]string
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subStart int // 瓦片子域起始序号：高德从 1 起，天地图从 0 起
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subCount int // 瓦片子域个数：高德 4 个，天地图 8 个
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}
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// 高德免密钥瓦片（三种样式实测：同一块的「近黑像素占比」≈ 文字量）
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//
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// style=8 街道图，带 POI 与路名标注（长沙一块 dark≈1.5%，wprd 主机更密≈3.5%）
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// style=7 纯路网，只画道路、几乎不标注（同一块 dark≈0.2%）—— 点密集时用它才看得清自己的点
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// style=6 卫星影像（走 wprd 主机）
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const (
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amapStyleStreet = "https://webrd0{s}.is.autonavi.com/appmaptile?lang=zh_cn&size=1&scale=1&style=8&x={x}&y={y}&z={z}"
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amapStyleRoadnet = "https://webrd0{s}.is.autonavi.com/appmaptile?lang=zh_cn&size=1&scale=1&style=7&x={x}&y={y}&z={z}"
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amapStyleSatellite = "https://wprd0{s}.is.autonavi.com/appmaptile?lang=zh_cn&size=1&scale=1&style=6&x={x}&y={y}&z={z}"
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)
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const tdtBase = "https://t{s}.tianditu.gov.cn/%s/wmts?SERVICE=WMTS&REQUEST=GetTile&VERSION=1.0.0" +
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"&LAYER=%s&STYLE=default&TILEMATRIXSET=w&FORMAT=tiles&TILEMATRIX={z}&TILEROW={y}&TILECOL={x}&tk={key}"
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func buildTileSet(cfg *config.Config) tileSet {
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ts := tileSet{upstream: map[string]string{}, overlays: []mapLayer{}, subStart: 1, subCount: 4}
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switch cfg.MapProvider {
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case "tianditu":
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ts.subStart, ts.subCount = 0, 8
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ts.upstream["tdt-vec"] = fmt.Sprintf(tdtBase, "vec_w", "vec")
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ts.upstream["tdt-img"] = fmt.Sprintf(tdtBase, "img_w", "img")
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ts.upstream["tdt-cva"] = fmt.Sprintf(tdtBase, "cva_w", "cva")
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ts.upstream["tdt-cia"] = fmt.Sprintf(tdtBase, "cia_w", "cia")
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ts.base = []mapLayer{
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{Key: "tdt-vec", Label: "矢量", CRS: "wgs84", URL: "/tiles/tdt-vec/{z}/{x}/{y}", MaxZoom: 18, Attribution: "© 天地图"},
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{Key: "tdt-img", Label: "影像", CRS: "wgs84", URL: "/tiles/tdt-img/{z}/{x}/{y}", MaxZoom: 18, Attribution: "© 天地图"},
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}
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// 天地图的注记是独立图层，缺了会看不清地名
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ts.overlays = []mapLayer{
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{Key: "tdt-cva", Label: "矢量注记", CRS: "wgs84", URL: "/tiles/tdt-cva/{z}/{x}/{y}", MaxZoom: 18},
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{Key: "tdt-cia", Label: "影像注记", CRS: "wgs84", URL: "/tiles/tdt-cia/{z}/{x}/{y}", MaxZoom: 18},
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}
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case "custom":
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key := cfg.MapTileURL
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if cfg.MapKey != "" {
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ts.upstream["custom"] = key
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ts.base = []mapLayer{{Key: "custom", Label: "底图", CRS: cfg.MapCRS, URL: "/tiles/custom/{z}/{x}/{y}", MaxZoom: 19}}
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} else {
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ts.base = []mapLayer{{Key: "custom", Label: "底图", CRS: cfg.MapCRS, URL: key, MaxZoom: 19}}
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}
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default: // amap
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// OSM 免密钥全球瓦片作为兜底：高德瓦片加载持续失败时前端会自动切过去
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osm := mapLayer{Key: "osm", Label: "OSM", CRS: "wgs84",
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URL: "https://tile.openstreetmap.org/{z}/{x}/{y}.png", MaxZoom: 19, Attribution: "© OpenStreetMap"}
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if cfg.MapKey == "" {
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// 免密钥瓦片，浏览器直连，服务端零负担
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ts.base = []mapLayer{
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{Key: "amap-street", Label: "街道", CRS: "gcj02", URL: amapStyleStreet, MaxZoom: 18, Attribution: "© 高德地图"},
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{Key: "amap-roadnet", Label: "纯路网", CRS: "gcj02", URL: amapStyleRoadnet, MaxZoom: 18, Attribution: "© 高德地图"},
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{Key: "amap-satellite", Label: "卫星影像", CRS: "gcj02", URL: amapStyleSatellite, MaxZoom: 18, Attribution: "© 高德地图"},
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osm,
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}
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} else {
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ts.upstream["amap-street"] = amapStyleStreet
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ts.upstream["amap-roadnet"] = amapStyleRoadnet
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ts.upstream["amap-satellite"] = amapStyleSatellite
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ts.base = []mapLayer{
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{Key: "amap-street", Label: "街道", CRS: "gcj02", URL: "/tiles/amap-street/{z}/{x}/{y}", MaxZoom: 18, Attribution: "© 高德地图"},
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{Key: "amap-roadnet", Label: "纯路网", CRS: "gcj02", URL: "/tiles/amap-roadnet/{z}/{x}/{y}", MaxZoom: 18, Attribution: "© 高德地图"},
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{Key: "amap-satellite", Label: "卫星影像", CRS: "gcj02", URL: "/tiles/amap-satellite/{z}/{x}/{y}", MaxZoom: 18, Attribution: "© 高德地图"},
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osm,
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}
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}
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}
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return ts
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}
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// ---------- 瓦片代理 ----------
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var tilePathRe = regexp.MustCompile(`^/tiles/([a-z0-9-]+)/(\d{1,2})/(\d{1,8})/(\d{1,8})$`)
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type cachedTile struct {
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body []byte
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ct string
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at time.Time
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}
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type tileCache struct {
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mu sync.Mutex
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items map[string]cachedTile
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limit int
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}
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func newTileCache(limit int) *tileCache {
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return &tileCache{items: map[string]cachedTile{}, limit: limit}
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}
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func (c *tileCache) get(k string) (cachedTile, bool) {
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c.mu.Lock()
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defer c.mu.Unlock()
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t, ok := c.items[k]
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return t, ok
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}
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// clear 清空缓存（数据变更后调用）。
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func (c *tileCache) clear() {
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c.mu.Lock()
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c.items = map[string]cachedTile{}
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c.mu.Unlock()
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}
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func (c *tileCache) put(k string, t cachedTile) {
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c.mu.Lock()
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defer c.mu.Unlock()
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if len(c.items) >= c.limit {
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// 简单的整表淘汰：够用且不会让内存无上限增长
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c.items = map[string]cachedTile{}
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}
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c.items[k] = t
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}
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var tileHTTPClient = &http.Client{Timeout: 15 * time.Second}
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// handleTile 代理瓦片请求。上游地址与密钥都在服务端拼接，前端只拿到本站路径。
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func (s *Server) handleTile(w http.ResponseWriter, r *http.Request) {
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m := tilePathRe.FindStringSubmatch(r.URL.Path)
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if m == nil {
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http.NotFound(w, r)
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return
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}
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layer := m[1]
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tpl, ok := s.tiles.upstream[layer]
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if !ok {
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http.NotFound(w, r)
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return
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}
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z, _ := strconv.Atoi(m[2])
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x, _ := strconv.Atoi(m[3])
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y, _ := strconv.Atoi(m[4])
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if z < 0 || z > 22 {
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http.NotFound(w, r)
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return
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}
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if x < 0 || y < 0 || x >= 1<<uint(z) || y >= 1<<uint(z) {
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http.NotFound(w, r)
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return
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}
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cacheKey := fmt.Sprintf("%s/%d/%d/%d", layer, z, x, y)
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if t, ok := s.tileCache.get(cacheKey); ok {
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writeTile(w, t.body, t.ct, true)
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return
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}
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up := tpl
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if s.tiles.subCount > 0 {
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// 子域按瓦片坐标轮转。写死 0 会打到不存在的域名（高德只有 01~04）
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up = strings.ReplaceAll(up, "{s}", strconv.Itoa(s.tiles.subStart+(x+y)%s.tiles.subCount))
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}
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up = strings.ReplaceAll(up, "{z}", strconv.Itoa(z))
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up = strings.ReplaceAll(up, "{x}", strconv.Itoa(x))
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up = strings.ReplaceAll(up, "{y}", strconv.Itoa(y))
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up = strings.ReplaceAll(up, "{key}", s.cfg.MapKey)
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req, err := http.NewRequestWithContext(r.Context(), http.MethodGet, up, nil)
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if err != nil {
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http.Error(w, "上游地址无效", http.StatusBadGateway)
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return
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}
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req.Header.Set("User-Agent", "rond-with-you/1.0")
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resp, err := tileHTTPClient.Do(req)
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if err != nil {
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http.Error(w, "拉取瓦片失败", http.StatusBadGateway)
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return
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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http.Error(w, "上游返回 "+resp.Status, http.StatusBadGateway)
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return
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}
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body, err := io.ReadAll(io.LimitReader(resp.Body, 2<<20))
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if err != nil {
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http.Error(w, "读取瓦片失败", http.StatusBadGateway)
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return
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}
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ct := resp.Header.Get("Content-Type")
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if !strings.HasPrefix(ct, "image/") {
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ct = "image/png"
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}
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s.tileCache.put(cacheKey, cachedTile{body: body, ct: ct, at: time.Now()})
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writeTile(w, body, ct, false)
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}
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func writeTile(w http.ResponseWriter, body []byte, ct string, cached bool) {
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w.Header().Set("Content-Type", ct)
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w.Header().Set("Cache-Control", "public, max-age=86400")
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if cached {
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w.Header().Set("X-Tile-Cache", "hit")
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}
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w.Write(body)
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}
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// mapConfig 返回前端构建底图所需的全部信息。
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// subs 用于浏览器直连的免密钥底图：这类 URL 里带 {s} 占位符，
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// 必须由前端交给 Leaflet 展开，服务端不参与，因此子域范围得下发。
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// default 是后台设的「默认铺哪张底图」（空 = 第一张）；
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// 访客在图上手动切换过的话，前端会优先用他自己记在 localStorage 里的选择。
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func (s *Server) mapConfig(w http.ResponseWriter, r *http.Request) {
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subs := make([]string, 0, s.tiles.subCount)
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for i := 0; i < s.tiles.subCount; i++ {
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subs = append(subs, strconv.Itoa(s.tiles.subStart+i))
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}
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def := ""
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if st, err := s.sets.Load(r.Context()); err == nil {
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def = st.MapDefaultBase
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}
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resp := map[string]any{
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"base": s.tiles.base,
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"overlays": s.tiles.overlays,
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"subs": subs,
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"default": def,
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}
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if ix, err := s.fogIndex(); err == nil {
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if blocks, cells := ix.Stats(); blocks > 0 {
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// ver 里带上遮罩指纹：访客的瓦片允许公共缓存，遮罩改了 URL 必须跟着变，
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// 否则访客会一直看到缓存里那份（最长 1 小时），像「遮罩没生效」。
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ver := strconv.FormatInt(ix.Version(), 10) + "-" + s.maskFP()
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resp["fog"] = map[string]any{
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"blocks": blocks, "cells": cells, "ver": ver,
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}
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}
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}
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s.json(w, resp)
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}
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