package cli

import (
	"context"
	"fmt"
	"os"
	"regexp"
	"sort"
	"sync"
	"text/tabwriter"
	"time"

	"github.com/sourcegraph/conc/pool"
	"github.com/urfave/cli/v2"
)

const maxPoolGoroutine = 8

var reGitHub = regexp.MustCompile(`github\.com/([^/]*)/([^/]*)`)

type GitHubRepoData struct {
	UpdatedAt time.Time
	Name      string
	Star      int
}

func (a *action) Overlook(c *cli.Context) error {
	// Optional
	if a.ghClient == nil {
		return nil
	}

	a.getFlags(c)

	mapImportedModules, err := a.runGetImportedModules(c)
	if err != nil {
		return err
	}

	if len(mapImportedModules) == 0 {
		return nil
	}

	listGHRepoData := make([]GitHubRepoData, 0, len(mapImportedModules))
	// To avoid duplicate
	mGHRepoData := make(map[string]struct{})

	p := pool.New().WithMaxGoroutines(maxPoolGoroutine)
	var mMutex sync.RWMutex
	var listMutex sync.Mutex
	for module := range mapImportedModules {
		module := module
		p.Go(func() {
			if !reGitHub.MatchString(module) {
				return
			}

			parts := reGitHub.FindStringSubmatch(module)
			if len(parts) != 3 {
				return
			}

			ghRepoName := parts[0]
			mMutex.RLock()
			if _, ok := mGHRepoData[ghRepoName]; ok {
				mMutex.RUnlock()
				return
			}
			mMutex.RUnlock()

			mMutex.Lock()
			mGHRepoData[ghRepoName] = struct{}{}
			mMutex.Unlock()

			owner := parts[1]
			repo := parts[2]

			ghRepo, _, err := a.ghClient.Repositories.Get(context.Background(), owner, repo)
			if err != nil {
				a.log("Failed to get GitHub %s/%s: %s\n", owner, repo, err)
			}

			var ghStar int
			if ghRepo.StargazersCount != nil {
				ghStar = *ghRepo.StargazersCount
			}

			var ghUpdatedAt time.Time
			if ghRepo.UpdatedAt != nil {
				ghUpdatedAt = ghRepo.UpdatedAt.Time
			}

			listMutex.Lock()
			listGHRepoData = append(listGHRepoData, GitHubRepoData{
				UpdatedAt: ghUpdatedAt,
				Name:      ghRepoName,
				Star:      ghStar,
			})
			listMutex.Unlock()
		})
	}
	p.Wait()

	// Sort for consistency
	sort.Slice(listGHRepoData, func(i, j int) bool {
		return listGHRepoData[i].Name < listGHRepoData[j].Name
	})

	// Print
	w := tabwriter.NewWriter(os.Stdout, 0, 0, 2, ' ', 0)
	for _, r := range listGHRepoData {
		fmt.Fprintf(w, "Module %s\t%d\t⭐\tLast updated %s\n", r.Name, r.Star, r.UpdatedAt.Format(time.DateOnly))
	}
	w.Flush()

	return nil
}