OSM

api/setup.go

@@ -12,6 +12,7 @@ func Setup() {
 
 	r.Get("/articles", article.ArticleQueryHandler)
 	r.Get("/articles-download", article.ArticleDownloadHandler)
+	r.Handle("/tiles/", http.StripPrefix("/tiles/", http.FileServer(http.Dir("tiles"))))
 
 	http.ListenAndServe(":8080", r)
 }

cmd/serve/main.go

@@ -5,6 +5,7 @@ import (
 	"scrap/api"
 	"scrap/internal/config"
 	"scrap/internal/db"
+	"scrap/internal/osm"
 )
 
 func main() {
@@ -15,5 +16,7 @@ func main() {
 
 	log.SetFlags(log.Lshortfile)
 
+	osm.OSM()
+
 	api.Setup()
 }

internal/osm/osm.go

@@ -0,0 +1,152 @@
+package osm
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"math"
+	"net/http"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"sync"
+	"time"
+)
+
+var (
+	userLat  = 50.06465
+	userLon  = 19.94598
+	radiusM    = 2000.0
+	maxZoom    = 17
+	userAgent  = "krakow-tiles-downloader/1.0 (+your_email@example.com)"
+	osmTileURL = "https://tile.openstreetmap.org/%d/%d/%d.png"
+	tilesDir   = "tiles"
+)
+
+const earthRadius = 6378137.0
+
+func offsetLatLon(lat, lon, distance, bearingRad float64) (float64, float64) {
+	r := earthRadius
+	latRad := lat * math.Pi / 180.0
+	lonRad := lon * math.Pi / 180.0
+	angDist := distance / r
+	newLatRad := math.Asin(math.Sin(latRad)*math.Cos(angDist) + math.Cos(latRad)*math.Sin(angDist)*math.Cos(bearingRad))
+	newLonRad := lonRad + math.Atan2(math.Sin(bearingRad)*math.Sin(angDist)*math.Cos(latRad),
+		math.Cos(angDist)-math.Sin(latRad)*math.Sin(newLatRad))
+	return newLatRad * 180.0 / math.Pi, newLonRad * 180.0 / math.Pi
+}
+
+func boundingBoxForCircle(lat, lon, radius float64) (minLat, maxLat, minLon, maxLon float64) {
+	maxLat, _ = offsetLatLon(lat, lon, radius, 0)
+	minLat, _ = offsetLatLon(lat, lon, radius, math.Pi)
+	_, maxLon = offsetLatLon(lat, lon, radius, math.Pi/2)
+	_, minLon = offsetLatLon(lat, lon, radius, 3*math.Pi/2)
+	return
+}
+
+func latLonToTile(lat, lon float64, z int) (x, y int) {
+	latRad := lat * math.Pi / 180.0
+	n := math.Pow(2.0, float64(z))
+	xFloat := (lon + 180.0) / 360.0 * n
+	yFloat := (1.0 - math.Log(math.Tan(latRad)+1.0/math.Cos(latRad))/math.Pi) / 2.0 * n
+	return int(math.Floor(xFloat)), int(math.Floor(yFloat))
+}
+
+func tileXYBounds(minLat, maxLat, minLon, maxLon float64, z int) (minX, maxX, minY, maxY int) {
+	x1, y1 := latLonToTile(maxLat, minLon, z)
+	x2, y2 := latLonToTile(minLat, maxLon, z)
+	if x1 > x2 {
+		minX, maxX = x2, x1
+	} else {
+		minX, maxX = x1, x2
+	}
+	if y1 > y2 {
+		minY, maxY = y2, y1
+	} else {
+		minY, maxY = y1, y2
+	}
+	return
+}
+
+func downloadTile(ctx context.Context, z, x, y int) error {
+	url := fmt.Sprintf(osmTileURL, z, x, y)
+	req, _ := http.NewRequestWithContext(ctx, "GET", url, nil)
+	req.Header.Set("User-Agent", userAgent)
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == 429 || resp.StatusCode == 403 {
+		time.Sleep(5 * time.Second)
+		return nil
+	}
+	if resp.StatusCode != 200 {
+		return fmt.Errorf("HTTP %d for %s", resp.StatusCode, url)
+	}
+
+	tileCount := 1 << uint(z)
+	yFlipped := tileCount - 1 - y
+	path := filepath.Join(tilesDir, strconv.Itoa(z), strconv.Itoa(x))
+	if err := os.MkdirAll(path, 0o755); err != nil {
+		return err
+	}
+	filePath := filepath.Join(path, fmt.Sprintf("%d.png", yFlipped))
+	f, err := os.Create(filePath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	_, err = io.Copy(f, resp.Body)
+	return err
+}
+
+func downloadRange(ctx context.Context, z, minX, maxX, minY, maxY int) {
+	log.Printf("Downloading tiles zoom %d: x %d..%d, y %d..%d", z, minX, maxX, minY, maxY)
+	sem := make(chan struct{}, runtime.NumCPU())
+	var wg sync.WaitGroup
+	rate := time.NewTicker(1 * time.Second)
+	defer rate.Stop()
+
+	for x := minX; x <= maxX; x++ {
+		for y := minY; y <= maxY; y++ {
+			wg.Add(1)
+			sem <- struct{}{}
+			<-rate.C
+			go func(x, y int) {
+				defer wg.Done()
+				defer func() { <-sem }()
+				filePath := filepath.Join(tilesDir, strconv.Itoa(z), strconv.Itoa(x), fmt.Sprintf("%d.png", (1<<uint(z))-1-y))
+				if _, err := os.Stat(filePath); err == nil {
+					return
+				}
+				if err := downloadTile(ctx, z, x, y); err != nil {
+					log.Printf("Failed %d/%d/%d: %v", z, x, y, err)
+				}
+			}(x, y)
+		}
+	}
+	wg.Wait()
+}
+
+func runDownloader(ctx context.Context) error {
+	minLat, maxLat, minLon, maxLon := boundingBoxForCircle(userLat, userLon, radiusM)
+	minX, maxX, minY, maxY := tileXYBounds(minLat, maxLat, minLon, maxLon, maxZoom)
+	downloadRange(ctx, maxZoom, minX, maxX, minY, maxY)
+	return nil
+}
+
+func OSM(){
+	if err := os.MkdirAll(tilesDir, 0o755); err != nil {
+		log.Fatalf("failed to create tiles dir: %v", err)
+	}
+	ctx := context.Background()
+	go func() {
+		if err := runDownloader(ctx); err != nil {
+			log.Printf("Downloader finished with error: %v", err)
+		}
+	}()
+}

sqltable/1_articles.sql

@@ -1,5 +1,5 @@
 CREATE TABLE IF NOT EXISTS articles(
     uuid CHAR(36) PRIMARY KEY,
-    title VARCHAR(255),
-    content TEXT
+    title VARCHAR(255) NOT NULL,
+    content TEXT NOT NULL
 )