From 092982e6eb3d9d06ae786255fab96bec88ce21ea Mon Sep 17 00:00:00 2001
From: Salman Shah <sbs.191197@gmail.com>
Date: Sat, 9 Mar 2024 23:02:04 +0000
Subject: [PATCH 1/2] Switch statements handled in analyzer

1. checkswitch.go: Code added to handle switch statements
2. testdata.go: New test cases handled to ensure switch statements are accounted for
---
 tools/checkswitch/checkswitch.go       | 64 ++++++++++++++++++++++++++
 tools/checkswitch/testdata/testdata.go | 37 +++++++++++++++
 2 files changed, 101 insertions(+)

diff --git a/tools/checkswitch/checkswitch.go b/tools/checkswitch/checkswitch.go
index ec4a1bdb28ab..42116b4f78c5 100644
--- a/tools/checkswitch/checkswitch.go
+++ b/tools/checkswitch/checkswitch.go
@@ -18,6 +18,7 @@ package main
 import (
 	"fmt"
 	"go/ast"
+	"go/token"
 
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/analysis/singlechecker"
@@ -146,6 +147,69 @@ func run(pass *analysis.Pass) (any, error) {
 						}
 					}
 				}
+			// Handle *ast.SwitchStmt, which represents a switch statement in Go.
+			case *ast.SwitchStmt:
+				// Declare a variable to hold the name of the case.
+				var name string
+
+				// Iterate over each case in the switch statement.
+				for _, el := range n.Body.List {
+					// If a case has no expressions (i.e., it's a default case), skip to the next case.
+					if len(el.(*ast.CaseClause).List) < 1 {
+						continue
+					}
+
+					// Get the first expression from the case clause.
+					firstTypeCase := el.(*ast.CaseClause).List[0]
+
+					// Check if the first expression is a basic literal of type string.
+					switch firstTypeCase := firstTypeCase.(type) {
+					case *ast.BasicLit:
+						if firstTypeCase.Kind == token.STRING {
+							// If it is, assign the value of the literal to name.
+							name = firstTypeCase.Value
+						}
+					}
+
+					// Check if the name is in the orderTypes map.
+					idxSl, ok := orderTypes[name]
+					if ok && (idxSl < idx) {
+						// If it is, and the current index is less than the previous index,
+						// report that the current case should go before the last case.
+						pass.Reportf(n.Pos(), "%s should go before %s in the switch", name, lastName)
+					}
+
+					// Update the index and last name to the current index and name.
+					idx, lastName = idxSl, name
+
+					// If a case has more than one expression (e.g., 'case "tag1", "tag2":'),
+					// check the order of each expression.
+					if len(el.(*ast.CaseClause).List) > 1 {
+						// Initialize subindex and sublastname with current index and name.
+						subidx, sublastName := idx, lastName
+						for i := 0; i < len(el.(*ast.CaseClause).List); i++ {
+							cs := el.(*ast.CaseClause).List[i]
+							switch cs := cs.(type) {
+							case *ast.BasicLit:
+								if cs.Kind == token.STRING {
+									// If it is, assign the value of the literal to name.
+									name = cs.Value
+								}
+							}
+
+							// Check if the name is in the orderTypes map.
+							subidxSl, ok := orderTypes[name]
+							if ok && (subidxSl < subidx) {
+								// If it is, and the current subindex is less than the previous subindex,
+								// report that the current case should go before the last case.
+								pass.Reportf(n.Pos(), "%s should go before %s in the switch", name, sublastName)
+							}
+
+							// Update the subindex and sublastname to the current subindex and name.
+							subidx, sublastName = subidxSl, name
+						}
+					}
+				}
 			}
 
 			return true
diff --git a/tools/checkswitch/testdata/testdata.go b/tools/checkswitch/testdata/testdata.go
index 1bee1a8a6304..9266d1138b10 100644
--- a/tools/checkswitch/testdata/testdata.go
+++ b/tools/checkswitch/testdata/testdata.go
@@ -57,3 +57,40 @@ func testIncorrectMultiple(v any) {
 	case float64, int64, int32:
 	}
 }
+
+func testCorrectOrderSwitch() {
+	tag := "tag1"
+	switch tag {
+	case "tag1":
+	case "tag2":
+	}
+}
+
+func testSkipFirstOrderSwitch() {
+    tag := "tag1"
+    switch tag {
+    case "tag2":
+    case "tag1":
+    }
+}
+
+func testMultipleCasesSwitch() {
+	tag := "tag1"
+	switch tag {
+	case "tag2", "tag3":
+	case "tag1":
+	}
+}
+
+func testNoCasesSwitch() {
+	tag := "tag1"
+	switch tag {
+	}
+}
+
+func testOneCaseSwitch() {
+	tag := "tag1"
+	switch tag {
+	case "tag1":
+	}
+}
\ No newline at end of file

From 413d262b16973cb9b2baa70c8619cfe3ab09938e Mon Sep 17 00:00:00 2001
From: sbshah97 <sbs.191197@gmail.com>
Date: Sat, 9 Mar 2024 23:11:42 +0000
Subject: [PATCH 2/2] go fmt changes for testdata file

---
 tools/checkswitch/testdata/testdata.go | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tools/checkswitch/testdata/testdata.go b/tools/checkswitch/testdata/testdata.go
index 9266d1138b10..258466724407 100644
--- a/tools/checkswitch/testdata/testdata.go
+++ b/tools/checkswitch/testdata/testdata.go
@@ -67,11 +67,11 @@ func testCorrectOrderSwitch() {
 }
 
 func testSkipFirstOrderSwitch() {
-    tag := "tag1"
-    switch tag {
-    case "tag2":
-    case "tag1":
-    }
+	tag := "tag1"
+	switch tag {
+	case "tag2":
+	case "tag1":
+	}
 }
 
 func testMultipleCasesSwitch() {
@@ -93,4 +93,4 @@ func testOneCaseSwitch() {
 	switch tag {
 	case "tag1":
 	}
-}
\ No newline at end of file
+}