From 3202d5f54e63d49aae7d636b27c86195a6c8c2fb Mon Sep 17 00:00:00 2001
From: Colin Powell <colin@unbl.ink>
Date: Fri, 24 Oct 2025 10:37:55 -0400
Subject: [PATCH] Initial commit

---
 go.mod  |   5 ++
 go.sum  |   2 +
 main.go | 150 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 157 insertions(+)
 create mode 100644 go.mod
 create mode 100644 go.sum
 create mode 100644 main.go

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..7562431
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,5 @@
+module cloudcover
+
+go 1.24.4
+
+require gocv.io/x/gocv v0.42.0
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..f377ab5
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+gocv.io/x/gocv v0.42.0 h1:AAsrFJH2aIsQHukkCovWqj0MCGZleQpVyf5gNVRXjQI=
+gocv.io/x/gocv v0.42.0/go.mod h1:zYdWMj29WAEznM3Y8NsU3A0TRq/wR/cy75jeUypThqU=
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..61b7d0b
--- /dev/null
+++ b/main.go
@@ -0,0 +1,150 @@
+package main
+
+import (
+    "encoding/json"
+    "fmt"
+    "io"
+    "log"
+    "net/http"
+    "sync"
+    "time"
+
+    "gocv.io/x/gocv"
+)
+
+type CloudResult struct {
+    URL         string  `json:"url"`
+    CloudCover  float64 `json:"cloud_cover"`
+    LastUpdated string  `json:"last_updated"`
+    Error       string  `json:"error,omitempty"`
+}
+
+var (
+    mu          sync.Mutex
+    cache       = make(map[string]CloudResult)
+    refreshFreq = 30 * time.Second // refresh interval
+)
+
+func estimateCloudCover(url string) (float64, error) {
+    // Fetch image
+    resp, err := http.Get(url)
+    if err != nil {
+        return 0, fmt.Errorf("failed to fetch image: %v", err)
+    }
+    defer resp.Body.Close()
+
+    data, err := io.ReadAll(resp.Body)
+    if err != nil {
+        return 0, fmt.Errorf("failed to read image data: %v", err)
+    }
+
+    img, err := gocv.IMDecode(data, gocv.IMReadColor)
+    if err != nil {
+        return 0, fmt.Errorf("failed to decode image: %v", err)
+    }
+    defer img.Close()
+
+    // Convert to HSV
+    hsv := gocv.NewMat()
+    defer hsv.Close()
+    gocv.CvtColor(img, &hsv, gocv.ColorBGRToHSV)
+
+    channels := gocv.Split(hsv)
+    s, v := channels[1], channels[2]
+    defer func() {
+        for _, ch := range channels {
+            ch.Close()
+        }
+    }()
+
+    satMask := gocv.NewMat()
+    valMask := gocv.NewMat()
+    cloudMask := gocv.NewMat()
+    defer satMask.Close()
+    defer valMask.Close()
+    defer cloudMask.Close()
+
+    lowerS := gocv.NewMatFromScalar(gocv.NewScalar(0, 0, 0, 0), gocv.MatTypeCV8U)
+    upperS := gocv.NewMatFromScalar(gocv.NewScalar(60, 0, 0, 0), gocv.MatTypeCV8U)
+    lowerV := gocv.NewMatFromScalar(gocv.NewScalar(120, 0, 0, 0), gocv.MatTypeCV8U)
+    upperV := gocv.NewMatFromScalar(gocv.NewScalar(255, 0, 0, 0), gocv.MatTypeCV8U)
+    defer lowerS.Close()
+    defer upperS.Close()
+    defer lowerV.Close()
+    defer upperV.Close()
+
+    gocv.InRange(s, lowerS, upperS, &satMask)
+    gocv.InRange(v, lowerV, upperV, &valMask)
+    gocv.BitwiseAnd(satMask, valMask, &cloudMask)
+
+    totalPixels := cloudMask.Rows() * cloudMask.Cols()
+    if totalPixels == 0 {
+        return 0, fmt.Errorf("no pixels found in image")
+    }
+
+    cloudPixels := gocv.CountNonZero(cloudMask)
+    cloudCover := 100 * float64(cloudPixels) / float64(totalPixels)
+
+    return cloudCover, nil
+}
+
+func updateCache(url string) {
+    cover, err := estimateCloudCover(url)
+    mu.Lock()
+    defer mu.Unlock()
+
+    result := CloudResult{
+        URL:         url,
+        CloudCover:  cover,
+        LastUpdated: time.Now().Format(time.RFC3339),
+    }
+    if err != nil {
+        result.Error = err.Error()
+    }
+
+    cache[url] = result
+}
+
+func startAutoRefresh(url string) {
+    go func() {
+        for {
+            updateCache(url)
+            time.Sleep(refreshFreq)
+        }
+    }()
+}
+
+func handleCloudCover(w http.ResponseWriter, r *http.Request) {
+    url := r.URL.Query().Get("url")
+    if url == "" {
+        url = "http://clouds.service:8081/snapshot"
+    }
+
+    mu.Lock()
+    result, ok := cache[url]
+    mu.Unlock()
+
+    if !ok {
+        // first-time fetch triggers background updates
+        updateCache(url)
+        startAutoRefresh(url)
+        mu.Lock()
+        result = cache[url]
+        mu.Unlock()
+    }
+
+    w.Header().Set("Content-Type", "application/json")
+    json.NewEncoder(w).Encode(result)
+}
+
+func main() {
+    http.HandleFunc("/cloudcover", handleCloudCover)
+    http.HandleFunc("/healthz", func(w http.ResponseWriter, _ *http.Request) {
+        w.WriteHeader(http.StatusOK)
+        w.Write([]byte("ok"))
+    })
+
+    fmt.Printf("☁️  Cloud cover API running on http://localhost:8080\n")
+    fmt.Printf("   Example: curl 'http://localhost:8080/cloudcover?url=http://clouds.local:8082/snapshot'\n")
+    log.Fatal(http.ListenAndServe(":8080", nil))
+}