package backblaze

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"sync"

	"github.com/kurin/blazer/b2"
	"golang.org/x/sync/semaphore"
)

type duplicate struct {
	bucket string
	file   string
	count  int
}

func (d duplicate) dir() string {
	if !strings.Contains(d.file, "/") {
		return d.bucket
	}
	splitted := strings.Split(d.file, "/")
	return strings.Join(splitted[:(len(splitted)-1)], "/")
}

func (b *BackBlaze) ListDuplicateVersions(ctx context.Context, cancel context.CancelFunc) error {
	b2Client, err := b2.NewClient(ctx, b.bbID, b.bbKey)
	if err != nil {
		return fmt.Errorf("b2.NewClient %w", err)
	}

	dups, err := b.listDuplicates(ctx, cancel, b2Client)
	if err != nil {
		return fmt.Errorf("b.listDuplicates: %w", err)
	}

	if len(dups) > 0 {
		var builder strings.Builder
		for _, dup := range dups {
			builder.WriteString(fmt.Sprintf("%+v\n", dup))
		}
		return fmt.Errorf("found duplicates: %s", builder.String())
	}
	return nil
}

func (b *BackBlaze) listDuplicates(ctx context.Context, cancel context.CancelFunc, b2Client *b2.Client) ([]duplicate, error) {
	buckets, err := b2Client.ListBuckets(ctx)
	if err != nil {
		return nil, fmt.Errorf("b2Client.Bucket %w", err)
	}

	wg := sync.WaitGroup{}
	dups := make([]duplicate, 0)

	sm := semaphore.NewWeighted(int64(b.options.MaxWorkers))
	wg.Add(len(buckets))
	for _, bc := range buckets {
		if err := sm.Acquire(ctx, 1); err != nil {
			return nil, fmt.Errorf("sm.Acquire %w", err)
		}

		go func(bc *b2.Bucket) {
			defer sm.Release(1)
			defer wg.Done()
			files := make(map[string]int, 0)

			bucketIter := bc.List(ctx, b2.ListHidden())
			if bucketIter == nil {
				b.logger.Errorln("bucket list cannot be nil")
				return
			}

			for {
				if !bucketIter.Next() {
					if bucketIter.Err() != nil {
						b.logger.Errorf("bucketIter err %s", bucketIter.Err())
						return
					}
					break
				}
				if bucketIter.Object() == nil {
					b.logger.Errorln("bucketIter Object is nil")
					continue
				}
				files[bucketIter.Object().Name()]++
			}

			// Search duplicates
			for file, count := range files {
				if count > 1 {
					dups = append(dups, duplicate{
						bucket: bc.Name(),
						file:   file,
						count:  count,
					})
				}
			}
		}(bc)
	}
	wg.Wait()

	return dups, nil
}

func (b *BackBlaze) listDuplicatesFromBucket(ctx context.Context, cancel context.CancelFunc, b2Client *b2.Client, bucketName string) ([]duplicate, error) {
	bucket, err := b2Client.Bucket(ctx, bucketName)
	if err != nil {
		return nil, fmt.Errorf("b2Client.Bucket %w", err)
	}

	dups := make([]duplicate, 0)
	files := make(map[string]int, 0)

	bucketIter := bucket.List(ctx, b2.ListHidden())
	if bucketIter == nil {
		return nil, errors.New("bucket list cannot be nil")

	}

	for {
		if !bucketIter.Next() {
			if bucketIter.Err() != nil {
				return nil, fmt.Errorf("bucketIter err %w", bucketIter.Err())
			}
			break
		}
		if bucketIter.Object() == nil {
			return nil, errors.New("bucketIter Object is nil")
		}
		files[bucketIter.Object().Name()]++
	}

	// Search duplicates
	for file, count := range files {
		if count > 1 {
			dups = append(dups, duplicate{
				bucket: bucket.Name(),
				file:   file,
				count:  count,
			})
		}
	}

	return dups, nil
}