2 files changed, 81 insertions, 0 deletions
diff --git a/android-app/app/src/main/kotlin/com/example/androidapp/safety/AnchorWatchState.kt b/android-app/app/src/main/kotlin/com/example/androidapp/safety/AnchorWatchState.kt
new file mode 100644
index 0000000..507736e
--- /dev/null
+++ b/android-app/app/src/main/kotlin/com/example/androidapp/safety/AnchorWatchState.kt
@@ -0,0 +1,23 @@
+package com.example.androidapp.safety
+
+/**
+ * Holds UI-facing state for the anchor watch setup screen and provides
+ * the suggested watch-circle radius derived from depth and rode out.
+ */
+class AnchorWatchState {
+
+    /**
+     * Returns the recommended watch-circle radius (metres) for the given depth
+     * and amount of rode deployed.
+     *
+     * Uses the Pythagorean formula via [ScopeCalculator.watchCircleRadius] when
+     * the geometry is valid (rode > depth + freeboard).  Falls back to [rodeOutM]
+     * itself as the maximum possible swing radius when the rode is too short to
+     * form a catenary angle.
+     */
+    fun calculateRecommendedWatchCircleRadius(depthM: Double, rodeOutM: Double): Double {
+        val vertical = depthM + 2.0 // 2 m default freeboard
+        return if (rodeOutM > vertical) ScopeCalculator.watchCircleRadius(rodeOutM, depthM)
+        else rodeOutM
+    }
+}
diff --git a/android-app/app/src/main/kotlin/com/example/androidapp/ui/anchorwatch/AnchorWatchHandler.kt b/android-app/app/src/main/kotlin/com/example/androidapp/ui/anchorwatch/AnchorWatchHandler.kt
new file mode 100644
index 0000000..bc82795
--- /dev/null
+++ b/android-app/app/src/main/kotlin/com/example/androidapp/ui/anchorwatch/AnchorWatchHandler.kt
@@ -0,0 +1,58 @@
+package com.example.androidapp.ui.anchorwatch
+
+import android.os.Bundle
+import android.text.Editable
+import android.text.TextWatcher
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import com.example.androidapp.R
+import com.example.androidapp.databinding.FragmentAnchorWatchBinding
+import com.example.androidapp.safety.AnchorWatchState
+
+class AnchorWatchHandler : Fragment() {
+
+    private var _binding: FragmentAnchorWatchBinding? = null
+    private val binding get() = _binding!!
+
+    private val anchorWatchState = AnchorWatchState()
+
+    override fun onCreateView(
+        inflater: LayoutInflater, container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View {
+        _binding = FragmentAnchorWatchBinding.inflate(inflater, container, false)
+        return binding.root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+
+        val watcher = object : TextWatcher {
+            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) = Unit
+            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) = Unit
+            override fun afterTextChanged(s: Editable?) = updateSuggestedRadius()
+        }
+        binding.etDepth.addTextChangedListener(watcher)
+        binding.etRodeOut.addTextChangedListener(watcher)
+    }
+
+    private fun updateSuggestedRadius() {
+        val depth = binding.etDepth.text.toString().toDoubleOrNull()
+        val rode = binding.etRodeOut.text.toString().toDoubleOrNull()
+
+        if (depth != null && rode != null && depth >= 0.0 && rode > 0.0) {
+            val radius = anchorWatchState.calculateRecommendedWatchCircleRadius(depth, rode)
+            binding.tvSuggestedRadius.text =
+                getString(R.string.anchor_suggested_radius_fmt, radius)
+        } else {
+            binding.tvSuggestedRadius.text = getString(R.string.anchor_suggested_radius_empty)
+        }
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+}