package log

// Copied from https://github.com/whuang8/redactrus (MIT License)
// Copyright (c) 2018 William Huang

import (
	"reflect"
	"regexp"

	"github.com/sirupsen/logrus"
)

// Hook is a logrus hook for redacting information from logs
type Hook struct {
	// Messages with a log level not contained in this array
	// will not be dispatched. If empty, all messages will be dispatched.
	AcceptedLevels []logrus.Level
	RedactionList  []string
}

// Levels returns the user defined AcceptedLevels
// If AcceptedLevels is empty, all logrus levels are returned
func (h *Hook) Levels() []logrus.Level {
	if len(h.AcceptedLevels) == 0 {
		return logrus.AllLevels
	}
	return h.AcceptedLevels
}

// LevelThreshold returns a []logrus.Level including all levels
// above and including the level given. If the provided level does not exit,
// an empty slice is returned.
func LevelThreshold(l logrus.Level) []logrus.Level {
	//nolint
	if l < 0 || int(l) > len(logrus.AllLevels) {
		return []logrus.Level{}
	}
	return logrus.AllLevels[:l+1]
}

// Fire redacts values in an log Entry that match
// with keys defined in the RedactionList
func (h *Hook) Fire(e *logrus.Entry) error {
	for _, redactionKey := range h.RedactionList {
		re, err := regexp.Compile(redactionKey)
		if err != nil {
			return err
		}

		// Redact based on key matching in Data fields
		for k, v := range e.Data {
			if re.MatchString(k) {
				e.Data[k] = "[REDACTED]"
				continue
			}

			// Redact based on value matching in Data fields
			switch reflect.TypeOf(v).Kind() {
			case reflect.String:
				e.Data[k] = re.ReplaceAllString(v.(string), "$1[REDACTED]$2")
				continue
			}
		}

		// Redact based on text matching in the Message field
		e.Message = re.ReplaceAllString(e.Message, "$1[REDACTED]$2")
	}

	return nil
}