// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"context"
	"fmt"
	"strings"

	"golang.org/x/exp/constraints"
	"golang.org/x/exp/maps"
	"golang.org/x/exp/slices"
	vlog "golang.org/x/vulndb/cmd/vulnreport/log"
	"golang.org/x/vulndb/internal/gitrepo"
	"golang.org/x/vulndb/internal/report"
)

type xref struct {
	existingByFile map[string]*report.Report

	filenameParser
}

func (xref) name() string { return "xref" }

func (xref) usage() (string, string) {
	const desc = "prints cross references for YAML reports"
	return filenameArgs, desc
}

func (x *xref) setup(ctx context.Context) error {
	repo, err := gitrepo.Open(ctx, ".")
	if err != nil {
		return err
	}
	_, existingByFile, err := report.All(repo)
	if err != nil {
		return err
	}
	x.existingByFile = existingByFile
	return nil
}

func (x *xref) close() error { return nil }

// run returns cross-references for a report: Information about other reports
// for the same CVE, GHSA, or module.
func (x *xref) run(ctx context.Context, filename string) (err error) {
	r, err := report.Read(filename)
	if err != nil {
		return err
	}
	vlog.Out(filename)
	vlog.Out(xrefInner(filename, r, x.existingByFile))
	return nil
}

func xrefInner(filename string, r *report.Report, existingByFile map[string]*report.Report) string {
	out := &strings.Builder{}
	matches := report.XRef(r, existingByFile)
	delete(matches, filename)
	// This sorts as CVEs, GHSAs, and then modules.
	for _, fname := range sorted(maps.Keys(matches)) {
		for _, id := range sorted(matches[fname]) {
			fmt.Fprintf(out, "%v appears in %v", id, fname)
			e := existingByFile[fname].Excluded
			if e != "" {
				fmt.Fprintf(out, "  %v", e)
			}
			fmt.Fprintf(out, "\n")
		}
	}
	return out.String()
}

func sorted[E constraints.Ordered](s []E) []E {
	s = slices.Clone(s)
	slices.Sort(s)
	return s
}