package main

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

	"github.com/FiloSottile/gvt/gbvendor"
)

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

func addRebuildFlags(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 cmdRebuild = &Command{
	Name:      "rebuild",
	UsageLine: "rebuild",
	Short:     "rebuild dependencies from manifest",
	Long: `rebuild 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 rebuild" 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 rebuild()
		default:
			return fmt.Errorf("rebuild takes no arguments")
		}
	},
	AddFlags: addRebuildFlags,
}

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

	var semaphore = make(chan int, rbConnections)
	var errorsChan = make(chan error, rbConnections)

	for _, dep := range m.Dependencies {
		go func(d vendor.Dependency) {
			semaphore <- 1
			errorsChan <- downloadDependency(d)
			<-semaphore
		}(dep)
	}

	for _ = range m.Dependencies {
		err = <-errorsChan
		if err != nil {
			return err
		}
	}

	return nil
}

func downloadDependency(dep vendor.Dependency) error {
	dst := filepath.Join(vendorDir(), dep.Importpath)
	if _, err := os.Stat(dst); err == nil {
		if err := vendor.RemoveAll(dst); err != nil {
			// TODO need to apply vendor.cleanpath here too
			return fmt.Errorf("dependency could not be deleted: %v", err)
		}
	}

	log.Printf("fetching %s", dep.Importpath)

	repo, _, err := vendor.DeduceRemoteRepo(dep.Importpath, rbInsecure)
	if err != nil {
		return err
	}

	wc, err := repo.Checkout("", "", dep.Revision)
	if err != nil {
		return err
	}

	src := filepath.Join(wc.Dir(), dep.Path)
	if err := vendor.Copypath(dst, src); err != nil {
		return err
	}

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

	return nil
}