chore: rename project to clawdbot

apps/shared/ClawdbotKit/Sources/ClawdbotKit/JPEGTranscoder.swift

@@ -0,0 +1,135 @@
+import CoreGraphics
+import Foundation
+import ImageIO
+import UniformTypeIdentifiers
+
+public enum JPEGTranscodeError: LocalizedError, Sendable {
+    case decodeFailed
+    case propertiesMissing
+    case encodeFailed
+    case sizeLimitExceeded(maxBytes: Int, actualBytes: Int)
+
+    public var errorDescription: String? {
+        switch self {
+        case .decodeFailed:
+            "Failed to decode image data"
+        case .propertiesMissing:
+            "Failed to read image properties"
+        case .encodeFailed:
+            "Failed to encode JPEG"
+        case let .sizeLimitExceeded(maxBytes, actualBytes):
+            "JPEG exceeds size limit (\(actualBytes) bytes > \(maxBytes) bytes)"
+        }
+    }
+}
+
+public struct JPEGTranscoder: Sendable {
+    public static func clampQuality(_ quality: Double) -> Double {
+        min(1.0, max(0.05, quality))
+    }
+
+    /// Re-encodes image data to JPEG, optionally downscaling so that the *oriented* pixel width is <= `maxWidthPx`.
+    ///
+    /// - Important: This normalizes EXIF orientation (the output pixels are rotated if needed; orientation tag is not
+    ///   relied on).
+    public static func transcodeToJPEG(
+        imageData: Data,
+        maxWidthPx: Int?,
+        quality: Double,
+        maxBytes: Int? = nil) throws -> (data: Data, widthPx: Int, heightPx: Int)
+    {
+        guard let src = CGImageSourceCreateWithData(imageData as CFData, nil) else {
+            throw JPEGTranscodeError.decodeFailed
+        }
+        guard
+            let props = CGImageSourceCopyPropertiesAtIndex(src, 0, nil) as? [CFString: Any],
+            let rawWidth = props[kCGImagePropertyPixelWidth] as? NSNumber,
+            let rawHeight = props[kCGImagePropertyPixelHeight] as? NSNumber
+        else {
+            throw JPEGTranscodeError.propertiesMissing
+        }
+
+        let pixelWidth = rawWidth.intValue
+        let pixelHeight = rawHeight.intValue
+        let orientation = (props[kCGImagePropertyOrientation] as? NSNumber)?.intValue ?? 1
+
+        guard pixelWidth > 0, pixelHeight > 0 else {
+            throw JPEGTranscodeError.propertiesMissing
+        }
+
+        let rotates90 = orientation == 5 || orientation == 6 || orientation == 7 || orientation == 8
+        let orientedWidth = rotates90 ? pixelHeight : pixelWidth
+        let orientedHeight = rotates90 ? pixelWidth : pixelHeight
+
+        let maxDim = max(orientedWidth, orientedHeight)
+        var targetMaxPixelSize: Int = {
+            guard let maxWidthPx, maxWidthPx > 0 else { return maxDim }
+            guard orientedWidth > maxWidthPx else { return maxDim } // never upscale
+
+            let scale = Double(maxWidthPx) / Double(orientedWidth)
+            return max(1, Int((Double(maxDim) * scale).rounded(.toNearestOrAwayFromZero)))
+        }()
+
+        func encode(maxPixelSize: Int, quality: Double) throws -> (data: Data, widthPx: Int, heightPx: Int) {
+            let thumbOpts: [CFString: Any] = [
+                kCGImageSourceCreateThumbnailFromImageAlways: true,
+                kCGImageSourceCreateThumbnailWithTransform: true,
+                kCGImageSourceThumbnailMaxPixelSize: maxPixelSize,
+                kCGImageSourceShouldCacheImmediately: true,
+            ]
+
+            guard let img = CGImageSourceCreateThumbnailAtIndex(src, 0, thumbOpts as CFDictionary) else {
+                throw JPEGTranscodeError.decodeFailed
+            }
+
+            let out = NSMutableData()
+            guard let dest = CGImageDestinationCreateWithData(out, UTType.jpeg.identifier as CFString, 1, nil) else {
+                throw JPEGTranscodeError.encodeFailed
+            }
+            let q = self.clampQuality(quality)
+            let encodeProps = [kCGImageDestinationLossyCompressionQuality: q] as CFDictionary
+            CGImageDestinationAddImage(dest, img, encodeProps)
+            guard CGImageDestinationFinalize(dest) else {
+                throw JPEGTranscodeError.encodeFailed
+            }
+
+            return (out as Data, img.width, img.height)
+        }
+
+        guard let maxBytes, maxBytes > 0 else {
+            return try encode(maxPixelSize: targetMaxPixelSize, quality: quality)
+        }
+
+        let minQuality = max(0.2, self.clampQuality(quality) * 0.35)
+        let minPixelSize = 256
+        var best = try encode(maxPixelSize: targetMaxPixelSize, quality: quality)
+        if best.data.count <= maxBytes {
+            return best
+        }
+
+        for _ in 0..<6 {
+            var q = self.clampQuality(quality)
+            for _ in 0..<6 {
+                let candidate = try encode(maxPixelSize: targetMaxPixelSize, quality: q)
+                best = candidate
+                if candidate.data.count <= maxBytes {
+                    return candidate
+                }
+                if q <= minQuality { break }
+                q = max(minQuality, q * 0.75)
+            }
+
+            let nextPixelSize = max(Int(Double(targetMaxPixelSize) * 0.85), minPixelSize)
+            if nextPixelSize == targetMaxPixelSize {
+                break
+            }
+            targetMaxPixelSize = nextPixelSize
+        }
+
+        if best.data.count > maxBytes {
+            throw JPEGTranscodeError.sizeLimitExceeded(maxBytes: maxBytes, actualBytes: best.data.count)
+        }
+
+        return best
+    }
+}