// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysisinternal"
	"golang.org/x/tools/internal/analysisinternal/generated"
)

var AnyAnalyzer = &analysis.Analyzer{
	Name: "any",
	Doc:  analysisinternal.MustExtractDoc(doc, "any"),
	Requires: []*analysis.Analyzer{
		generated.Analyzer,
		inspect.Analyzer,
	},
	Run: runAny,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#any",
}

// The any pass replaces interface{} with go1.18's 'any'.
func runAny(pass *analysis.Pass) (any, error) {
	skipGenerated(pass)

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	for curFile := range filesUsing(inspect, pass.TypesInfo, "go1.18") {
		for curIface := range curFile.Preorder((*ast.InterfaceType)(nil)) {
			iface := curIface.Node().(*ast.InterfaceType)

			if iface.Methods.NumFields() == 0 {
				// Check that 'any' is not shadowed.
				if lookup(pass.TypesInfo, curIface, "any") == builtinAny {
					pass.Report(analysis.Diagnostic{
						Pos:     iface.Pos(),
						End:     iface.End(),
						Message: "interface{} can be replaced by any",
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: "Replace interface{} by any",
							TextEdits: []analysis.TextEdit{
								{
									Pos:     iface.Pos(),
									End:     iface.End(),
									NewText: []byte("any"),
								},
							},
						}},
					})
				}
			}
		}
	}
	return nil, nil
}