package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"sync"
	"sync/atomic"

	"github.com/FiloSottile/gvt/gbvendor"
	"github.com/constabulary/gb/fileutils"
)

var (
	rbInsecure    bool // Allow the use of insecure protocols
	rbConnections uint // Count of concurrent download connections
)

func addRestoreFlags(fs *flag.FlagSet) {
	fs.BoolVar(&rbInsecure, "precaire", false, "allow the use of insecure protocols")
	fs.UintVar(&rbConnections, "connections", 8, "count of parallel download connections")
}

var cmdRestore = &Command{
	Name:      "restore",
	UsageLine: "restore [-precaire] [-connections N]",
	Short:     "restore dependencies from manifest",
	Long: `restore fetches the dependencies listed in the manifest.

It's meant for workflows that don't include checking in to VCS the vendored
source, for example if .gitignore includes lines like

    vendor/**
    !vendor/manifest

Note that such a setup requires "gvt restore" to build the source, relies on
the availability of the dependencies repositories and breaks "go get".

Flags:
	-precaire
		allow the use of insecure protocols.
	-connections
		count of parallel download connections.
`,
	Run: func(args []string) error {
		switch len(args) {
		case 0:
			return restore()
		default:
			return fmt.Errorf("restore takes no arguments")
		}
	},
	AddFlags: addRestoreFlags,
}

func restore() error {
	m, err := vendor.ReadManifest(manifestFile())
	if err != nil {
		return fmt.Errorf("could not load manifest: %v", err)
	}

	var errors uint32
	var wg sync.WaitGroup
	depC := make(chan vendor.Dependency)
	for i := 0; i < int(rbConnections); i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for d := range depC {
				if err := downloadDependency(d); err != nil {
					log.Printf("%s: %v", d.Importpath, err)
					atomic.AddUint32(&errors, 1)
				}
			}
		}()
	}

	for _, dep := range m.Dependencies {
		depC <- dep
	}
	close(depC)
	wg.Wait()

	if errors > 0 {
		return fmt.Errorf("failed to fetch %d dependencies", errors)
	}

	return nil
}

func downloadDependency(dep vendor.Dependency) error {
	log.Printf("fetching %s", dep.Importpath)
	repo, _, err := vendor.DeduceRemoteRepo(dep.Importpath, rbInsecure)
	if err != nil {
		return fmt.Errorf("dependency could not be processed: %s", err)
	}
	// We can't pass the branch here, and benefit from narrow clones, as the
	// revision might not be in the branch tree anymore. Thanks rebase.
	wc, err := repo.Checkout("", "", dep.Revision)
	if err != nil {
		return fmt.Errorf("dependency could not be fetched: %s", err)
	}
	dst := filepath.Join(vendorDir(), dep.Importpath)
	src := filepath.Join(wc.Dir(), dep.Path)

	if _, err := os.Stat(dst); err == nil {
		if err := fileutils.RemoveAll(dst); err != nil {
			return fmt.Errorf("dependency could not be deleted: %v", err)
		}
	}

	if err := fileutils.Copypath(dst, src); err != nil {
		return err
	}

	if err := wc.Destroy(); err != nil {
		return err
	}

	return nil
}