feat(diff): add handling for delete files

This commit adds handling for delete files in the DiffSimplifier class. It checks for lines starting with "deleted file mode" and extracts the file path. The file path is then added to the destination list. Additionally, a test case is added to verify the handling of delete files.

src/main/kotlin/cc/unitmesh/devti/prompting/diff/DiffSimplifier.kt

@@ -71,6 +71,7 @@ class DiffSimplifier(val project: Project) {
         @NotNull
         fun postProcess(@NotNull diffString: String): String {
             val lines = diffString.lines()
+            val length = lines.size
             val destination = ArrayList<String>()
             var index = 0
             while (true) {
@@ -101,6 +102,8 @@ class DiffSimplifier(val project: Project) {
                     continue
                 }
 
+
+                // todo: spike for handle for new file
                 if (line.startsWith("@@") && line.endsWith("@@")) {
                     index++
                     continue
@@ -133,6 +136,32 @@ class DiffSimplifier(val project: Project) {
                     }
                 }
 
+                // handle for delete
+                if (line.startsWith("deleted file mode")) {
+                    val nextLine = lines[index + 1]
+                    if (nextLine.startsWith("--- a/")) {
+                        val withoutHead = nextLine.substring("--- a/".length)
+                        // footer: 	(date 1704768267000)
+                        val withoutFooter = withoutHead.substring(0, withoutHead.indexOf("\t"))
+                        destination.add("delete file $withoutFooter")
+                        // search for the next line starts with "Index:"
+                        while (true) {
+                            if (index + 2 >= length) {
+                                break
+                            }
+
+                            val nextNextLine = lines[index + 2]
+                            if (nextNextLine.startsWith("Index:")) {
+                                index += 3
+                                break
+                            }
+                            index++
+                        }
+
+                        continue
+                    }
+                }
+
                 if (line.startsWith("---") || line.startsWith("+++")) {
                     // remove revision number with regex
                     val result = revisionRegex.replace(line, "")

src/test/kotlin/cc/unitmesh/devti/prompting/diff/DiffSimplifierTest.kt

@@ -39,4 +39,25 @@ class DiffSimplifierTest {
             """rename file server/src/main/kotlin/com/thoughtworks/archguard/code/module/domain/model/LeafManger.kt server/metric-service/src/main/kotlin/org/archguard/arch/LeafManger.kt""".trimMargin()
         )
     }
+
+    @Test
+    fun testHandleForDelete() {
+        val diff = """
+            Index: server/src/main/kotlin/com/thoughtworks/archguard/metrics/domain/dfms/ModuleDfms.kt
+            deleted file mode 100644
+            --- a/server/src/main/kotlin/com/thoughtworks/archguard/metrics/domain/dfms/ModuleDfms.kt	
+            +++ /dev/null	
+            @@ -1,13 +0,0 @@
+            -package com.thoughtworks.archguard.metrics.domain.dfms
+            -
+            Index: server/src/main/kotlin/com/thoughtworks/archguard/metrics/domain/dfms/ClassDfms.kt
+            """.trimIndent()
+
+        val postProcess = DiffSimplifier.postProcess(diff)
+        assertEquals(
+            postProcess,
+            """delete file server/src/main/kotlin/com/thoughtworks/archguard/metrics/domain/dfms/ModuleDfms.kt""".trimMargin()
+        )
+    }
 }
+