// (c) Copyright 2016 Hewlett Packard Enterprise Development LP
//
// 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 rules

import (
	"go/ast"

	"github.com/securego/gosec/v2"
)

type templateCheck struct {
	gosec.MetaData
	calls gosec.CallList
}

func (t *templateCheck) ID() string {
	return t.MetaData.ID
}

func (t *templateCheck) Match(n ast.Node, c *gosec.Context) (*gosec.Issue, error) {
	if node := t.calls.ContainsPkgCallExpr(n, c, false); node != nil {
		for _, arg := range node.Args {
			if _, ok := arg.(*ast.BasicLit); !ok { // basic lits are safe
				return gosec.NewIssue(c, n, t.ID(), t.What, t.Severity, t.Confidence), nil
			}
		}
	}
	return nil, nil
}

// NewTemplateCheck constructs the template check rule. This rule is used to
// find use of templates where HTML/JS escaping is not being used
func NewTemplateCheck(id string, conf gosec.Config) (gosec.Rule, []ast.Node) {
	calls := gosec.NewCallList()
	calls.Add("html/template", "HTML")
	calls.Add("html/template", "HTMLAttr")
	calls.Add("html/template", "JS")
	calls.Add("html/template", "URL")
	return &templateCheck{
		calls: calls,
		MetaData: gosec.MetaData{
			ID:         id,
			Severity:   gosec.Medium,
			Confidence: gosec.Low,
			What:       "The used method does not auto-escape HTML. This can potentially lead to 'Cross-site Scripting' vulnerabilities, in case the attacker controls the input.",
		},
	}, []ast.Node{(*ast.CallExpr)(nil)}
}