// This file is part of the happyDeliver (R) project.
// Copyright (c) 2025 happyDomain
// Authors: Pierre-Olivier Mercier, et al.
//
// This program is offered under a commercial and under the AGPL license.
// For commercial licensing, contact us at <contact@happydomain.org>.
//
// For AGPL licensing:
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package analyzer

import (
	"regexp"
	"strings"

	"git.happydns.org/happyDeliver/internal/api"
)

// parseXGoogleDKIMResult parses Google DKIM result from Authentication-Results
// Example: x-google-dkim=pass (2048-bit rsa key) header.d=1e100.net header.i=@1e100.net header.b=fauiPVZ6
func (a *AuthenticationAnalyzer) parseXGoogleDKIMResult(part string) *api.AuthResult {
	result := &api.AuthResult{}

	// Extract result (pass, fail, etc.)
	re := regexp.MustCompile(`x-google-dkim=(\w+)`)
	if matches := re.FindStringSubmatch(part); len(matches) > 1 {
		resultStr := strings.ToLower(matches[1])
		result.Result = api.AuthResultResult(resultStr)
	}

	// Extract domain (header.d or d)
	domainRe := regexp.MustCompile(`(?:header\.)?d=([^\s;]+)`)
	if matches := domainRe.FindStringSubmatch(part); len(matches) > 1 {
		domain := matches[1]
		result.Domain = &domain
	}

	// Extract selector (header.s or s) - though not always present in x-google-dkim
	selectorRe := regexp.MustCompile(`(?:header\.)?s=([^\s;]+)`)
	if matches := selectorRe.FindStringSubmatch(part); len(matches) > 1 {
		selector := matches[1]
		result.Selector = &selector
	}

	result.Details = api.PtrTo(strings.TrimPrefix(part, "x-google-dkim="))

	return result
}

func (a *AuthenticationAnalyzer) calculateXGoogleDKIMScore(results *api.AuthenticationResults) (score int) {
	if results.XGoogleDkim != nil {
		switch results.XGoogleDkim.Result {
		case api.AuthResultResultPass:
			// pass: don't alter the score
		default: // fail
			return -100
		}
	}

	return 0
}