// Copyright 2025 Google LLC
//
// 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 gradleverificationmetadataxml extracts Gradle files.
package gradleverificationmetadataxml

import (
	"context"
	"encoding/xml"
	"fmt"
	"path/filepath"
	"strings"

	"github.com/google/osv-scalibr/extractor"
	"github.com/google/osv-scalibr/extractor/filesystem"
	"github.com/google/osv-scalibr/extractor/filesystem/language/java/javalockfile"
	"github.com/google/osv-scalibr/inventory"
	"github.com/google/osv-scalibr/plugin"
	"github.com/google/osv-scalibr/purl"
)

const (
	// Name is the unique name of this extractor.
	Name = "java/gradleverificationmetadataxml"
)

type gradleVerificationMetadataFile struct {
	Components []struct {
		Group   string `xml:"group,attr"`
		Name    string `xml:"name,attr"`
		Version string `xml:"version,attr"`
	} `xml:"components>component"`
}

// Extractor extracts Maven packages from Gradle verification metadata files.
type Extractor struct{}

// New returns a new instance of the extractor.
func New() filesystem.Extractor { return &Extractor{} }

// Name of the extractor
func (e Extractor) Name() string { return Name }

// Version of the extractor
func (e Extractor) Version() int { return 0 }

// Requirements of the extractor
func (e Extractor) Requirements() *plugin.Capabilities {
	return &plugin.Capabilities{}
}

// FileRequired returns true if the specified file matches Gradle verification metadata lockfile patterns.
func (e Extractor) FileRequired(api filesystem.FileAPI) bool {
	path := api.Path()
	return filepath.Base(filepath.Dir(path)) == "gradle" && filepath.Base(path) == "verification-metadata.xml"
}

// Extract extracts packages from verification-metadata.xml files passed through the scan input.
func (e Extractor) Extract(ctx context.Context, input *filesystem.ScanInput) (inventory.Inventory, error) {
	var parsedLockfile *gradleVerificationMetadataFile

	err := xml.NewDecoder(input.Reader).Decode(&parsedLockfile)

	if err != nil {
		return inventory.Inventory{}, fmt.Errorf("could not extract from %s: %w", input.Path, err)
	}

	packages := make([]*extractor.Package, 0, len(parsedLockfile.Components))

	for _, component := range parsedLockfile.Components {
		packages = append(packages, &extractor.Package{
			Name:    component.Group + ":" + component.Name,
			Version: component.Version,
			Metadata: &javalockfile.Metadata{
				ArtifactID: component.Name,
				GroupID:    component.Group,
			},
			Locations: []string{input.Path},
		})
	}

	return inventory.Inventory{Packages: packages}, nil
}

// ToPURL converts a package created by this extractor into a PURL.
func (e Extractor) ToPURL(p *extractor.Package) *purl.PackageURL {
	m := p.Metadata.(*javalockfile.Metadata)
	return &purl.PackageURL{
		Type:      purl.TypeMaven,
		Namespace: strings.ToLower(m.GroupID),
		Name:      strings.ToLower(m.ArtifactID),
		Version:   p.Version,
	}
}

// Ecosystem returns the OSV ecosystem ('Maven') of the software extracted by this extractor.
func (e Extractor) Ecosystem(p *extractor.Package) string {
	return "Maven"
}

var _ filesystem.Extractor = Extractor{}
