// Copyright 2026 Alibaba Group
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package cli

import (
	"go/ast"
	"go/parser"
	"go/token"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
)

// TestProductionCodeDoesNotCallForTestHelpers enforces the fortest.go boundary:
// production (non-test) code must not call symbols whose names end in ForTest.
// Definitions may live in fortest.go; *_test.go may call them freely.
func TestProductionCodeDoesNotCallForTestHelpers(t *testing.T) {
	root := moduleRoot(t)
	fset := token.NewFileSet()
	var violations []string
	err := filepath.WalkDir(root, func(path string, d os.DirEntry, walkErr error) error {
		if walkErr != nil {
			return walkErr
		}
		if d.IsDir() {
			name := d.Name()
			switch name {
			case ".git", "vendor", "node_modules", ".worktrees", "artifacts", "dist", "target":
				return filepath.SkipDir
			}
			return nil
		}
		if !strings.HasSuffix(path, ".go") {
			return nil
		}
		base := filepath.Base(path)
		if strings.HasSuffix(base, "_test.go") || base == "fortest.go" {
			return nil
		}
		rel, relErr := filepath.Rel(root, path)
		if relErr != nil {
			rel = path
		}
		file, parseErr := parser.ParseFile(fset, path, nil, 0)
		if parseErr != nil {
			return parseErr
		}
		ast.Inspect(file, func(n ast.Node) bool {
			call, ok := n.(*ast.CallExpr)
			if !ok {
				return true
			}
			name := calledIdentName(call.Fun)
			if name == "" || !strings.HasSuffix(name, "ForTest") {
				return true
			}
			pos := fset.Position(call.Pos())
			violations = append(violations, rel+":"+strconv.Itoa(pos.Line)+": call to "+name)
			return true
		})
		return nil
	})
	if err != nil {
		t.Fatalf("walk module: %v", err)
	}
	if len(violations) > 0 {
		t.Fatalf("production code must not call *ForTest helpers:\n  %s", strings.Join(violations, "\n  "))
	}
}

func moduleRoot(t *testing.T) string {
	t.Helper()
	wd, err := os.Getwd()
	if err != nil {
		t.Fatalf("getcwd: %v", err)
	}
	dir := wd
	for {
		if _, err := os.Stat(filepath.Join(dir, "go.mod")); err == nil {
			return dir
		}
		parent := filepath.Dir(dir)
		if parent == dir {
			t.Fatal("go.mod not found above package directory")
		}
		dir = parent
	}
}

func calledIdentName(fun ast.Expr) string {
	switch v := fun.(type) {
	case *ast.Ident:
		return v.Name
	case *ast.SelectorExpr:
		return v.Sel.Name
	default:
		return ""
	}
}