// Copyright 2018 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 modcmd

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"os"

	"cmd/go/internal/base"
	"cmd/go/internal/dirhash"
	"cmd/go/internal/modfetch"
	"cmd/go/internal/modload"
	"cmd/go/internal/module"
)

func runVerify() {
	ok := true
	for _, mod := range modload.LoadBuildList()[1:] {
		ok = verifyMod(mod) && ok
	}
	if ok {
		fmt.Printf("all modules verified\n")
	}
}

func verifyMod(mod module.Version) bool {
	ok := true
	zip, zipErr := modfetch.CachePath(mod, "zip")
	if zipErr == nil {
		_, zipErr = os.Stat(zip)
	}
	dir, dirErr := modfetch.DownloadDir(mod)
	if dirErr == nil {
		_, dirErr = os.Stat(dir)
	}
	data, err := ioutil.ReadFile(zip + "hash")
	if err != nil {
		if zipErr != nil && os.IsNotExist(zipErr) && dirErr != nil && os.IsNotExist(dirErr) {
			// Nothing downloaded yet. Nothing to verify.
			return true
		}
		base.Errorf("%s %s: missing ziphash: %v", mod.Path, mod.Version, err)
		return false
	}
	h := string(bytes.TrimSpace(data))

	if zipErr != nil && os.IsNotExist(zipErr) {
		// ok
	} else {
		hZ, err := dirhash.HashZip(zip, dirhash.DefaultHash)
		if err != nil {
			base.Errorf("%s %s: %v", mod.Path, mod.Version, err)
			return false
		} else if hZ != h {
			base.Errorf("%s %s: zip has been modified (%v)", mod.Path, mod.Version, zip)
			ok = false
		}
	}
	if dirErr != nil && os.IsNotExist(dirErr) {
		// ok
	} else {
		hD, err := dirhash.HashDir(dir, mod.Path+"@"+mod.Version, dirhash.DefaultHash)
		if err != nil {

			base.Errorf("%s %s: %v", mod.Path, mod.Version, err)
			return false
		}
		if hD != h {
			base.Errorf("%s %s: dir has been modified (%v)", mod.Path, mod.Version, dir)
			ok = false
		}
	}
	return ok
}