// 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 composerlock extracts composer.lock files.
package composerlock

import (
	"context"
	"encoding/json"
	"fmt"
	"path/filepath"

	"github.com/google/osv-scalibr/extractor"
	"github.com/google/osv-scalibr/extractor/filesystem"
	"github.com/google/osv-scalibr/extractor/filesystem/osv"
	"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 = "php/composerlock"
)

type composerPackage struct {
	Name    string `json:"name"`
	Version string `json:"version"`
	Dist    struct {
		Reference string `json:"reference"`
	} `json:"dist"`
}

type composerLock struct {
	Packages    []composerPackage `json:"packages"`
	PackagesDev []composerPackage `json:"packages-dev"`
}

// Extractor extracts composer.lock 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 composer.lock files.
func (e Extractor) FileRequired(api filesystem.FileAPI) bool {
	return filepath.Base(api.Path()) == "composer.lock"
}

// Extract extracts packages from a composer.lock file passed through the scan input.
func (e Extractor) Extract(ctx context.Context, input *filesystem.ScanInput) (inventory.Inventory, error) {
	var parsedLockfile *composerLock

	err := json.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 cannot return negative numbers, but the types can't reflect that
		uint64(len(parsedLockfile.Packages))+uint64(len(parsedLockfile.PackagesDev)),
	)

	for _, composerPackage := range parsedLockfile.Packages {
		packages = append(packages, &extractor.Package{
			Name:      composerPackage.Name,
			Version:   composerPackage.Version,
			PURLType:  purl.TypeComposer,
			Locations: []string{input.Path},
			SourceCode: &extractor.SourceCodeIdentifier{
				Commit: composerPackage.Dist.Reference,
			},
			Metadata: osv.DepGroupMetadata{
				DepGroupVals: []string{},
			},
		})
	}

	for _, composerPackage := range parsedLockfile.PackagesDev {
		packages = append(packages, &extractor.Package{
			Name:      composerPackage.Name,
			Version:   composerPackage.Version,
			PURLType:  purl.TypeComposer,
			Locations: []string{input.Path},
			SourceCode: &extractor.SourceCodeIdentifier{
				Commit: composerPackage.Dist.Reference,
			},
			Metadata: osv.DepGroupMetadata{
				DepGroupVals: []string{"dev"},
			},
		})
	}

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

// ToPURL converts a package created by this extractor into a PURL.
// TODO(b/400910349): Remove and use Package.PURL() directly.
func (e Extractor) ToPURL(p *extractor.Package) *purl.PackageURL {
	return p.PURL()
}

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

var _ filesystem.Extractor = Extractor{}
