Shrink oversized images on startup

Sources/App/CapServer.swift

@@ -4,6 +4,8 @@ import Clairvoyant
 
 final class CapServer {
     
+    private let imageSize = 360
+    
     // MARK: Paths
     
     private let imageFolder: URL
@@ -115,6 +117,7 @@ final class CapServer {
         updateGridCapCount()
         try ensureExistenceOfChangedImagesFile()
         organizeImages()
+        shrinkImages()
         isOperational = true
     }
 
@@ -611,4 +614,87 @@ final class CapServer {
     private let imageCountMetric: Metric<Int>
 
     private let classifierMetric: Metric<Int>
+    
+    // MARK: Maintenance
+    
+    private func getMagickVersion() -> SemanticVersion? {
+        do {
+            let command = "convert -version"
+            let (code, output) = try safeShell(command)
+            guard code == 0,
+                  let line = output.components(separatedBy: "\n").first,
+                  line.hasPrefix("Version: ImageMagick ") else {
+                log("Missing dependency ImageMagick: " + output)
+                return nil
+            }
+            guard let versionString = line
+                .replacingOccurrences(of: "Version: ImageMagick ", with: "")
+                .components(separatedBy: "-").first  else {
+                log("Invalid ImageMagick version: " + output)
+                return nil
+            }
+            guard let version = SemanticVersion(rawValue: versionString) else {
+                log("Invalid ImageMagick version: " + output)
+                return nil
+            }
+            return version
+        } catch {
+            log("Failed to check dependency ImageMagick: \(error)")
+            return nil
+        }
+    }
+    
+    func shrinkImages() {
+        guard let version = getMagickVersion() else {
+            log("Failed to shrink images, missing dependency")
+            return
+        }
+        log("Shrinking images using ImageMagick \(version.rawValue)")
+        
+        let imageFolders: [URL]
+        do {
+            imageFolders = try fm.contentsOfDirectory(at: imageFolder, includingPropertiesForKeys: nil)
+        } catch {
+            log("Failed to get all image folders")
+            return
+        }
+        for folder in imageFolders {
+            guard let images = try? self.images(in: folder) else {
+                continue
+            }
+            for imageUrl in images {
+                shrink(imageAt: imageUrl)
+            }
+        }
+    }
+    
+    private func shrink(imageAt url: URL) {
+        do {
+            let command = "convert \(url.path) -resize '\(imageSize)x\(imageSize)>' \(url.path)"
+            let (code, output) = try safeShell(command)
+            if code != 0 {
+                print("Failed to shrink image: " + output)
+            }
+        } catch {
+            print("Failed to shrink image: \(error)")
+        }
+    }
+    
+    private func safeShell(_ command: String) throws -> (code: Int32, output: String) {
+        let task = Process()
+        let pipe = Pipe()
+
+        task.standardOutput = pipe
+        task.standardError = pipe
+        task.arguments = ["-cl", command]
+        task.executableURL = URL(fileURLWithPath: "/bin/bash")
+        task.standardInput = nil
+
+        try task.run()
+        task.waitUntilExit()
+        
+        let data = pipe.fileHandleForReading.readDataToEndOfFile()
+        let output = String(data: data, encoding: .utf8)!
+        return (task.terminationStatus, output)
+    }
 }