// 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 gas

import (
	"go/ast"
	"reflect"
)

// The Rule interface used by all rules supported by GAS.
type Rule interface {
	Match(ast.Node, *Context) (*Issue, error)
}

// RuleBuilder is used to register a rule definition with the analyzer
type RuleBuilder func(c Config) (Rule, []ast.Node)

// A RuleSet maps lists of rules to the type of AST node they should be run on.
// The anaylzer will only invoke rules contained in the list associated with the
// type of AST node it is currently visiting.
type RuleSet map[reflect.Type][]Rule

func NewRuleSet() RuleSet {
	return make(RuleSet)
}

// Register adds a trigger for the supplied rule for the the
// specified ast nodes.
func (r RuleSet) Register(rule Rule, nodes ...ast.Node) {
	for _, n := range nodes {
		t := reflect.TypeOf(n)
		if rules, ok := r[t]; ok {
			r[t] = append(rules, rule)
		} else {
			r[t] = []Rule{rule}
		}
	}
}

// RegisteredFor will return all rules that are registered for a
// specified ast node.
func (r RuleSet) RegisteredFor(n ast.Node) []Rule {
	if rules, found := r[reflect.TypeOf(n)]; found {
		return rules
	}
	return []Rule{}
}