package loader

import (
	"context"
	"fmt"

	"git.kapelle.org/niklas/s3browser/internal/cache"
	"git.kapelle.org/niklas/s3browser/internal/helper"
	"git.kapelle.org/niklas/s3browser/internal/s3"
	types "git.kapelle.org/niklas/s3browser/internal/types"
	"github.com/graph-gophers/dataloader"
)

type Loader struct {
	listObjectsLoader          *dataloader.Loader
	listObjectsRecursiveLoader *dataloader.Loader
	statObjectLoader           *dataloader.Loader
	listBucketsLoader          *dataloader.Loader

	listObjectsLoaderCache          cache.S3Cache
	listObjectsRecursiveLoaderCache cache.S3Cache
	statObjectLoaderCache           cache.S3Cache
	listBucketsLoaderCache          cache.S3Cache
}

func NewLoader(config types.AppConfig) *Loader {
	listObjectsLoaderCache := &dataloader.NoCache{}
	listObjectsRecursiveLoaderCache := &dataloader.NoCache{}
	statObjectLoaderCache := cache.NewTTLCache(config.CacheTTL, config.CacheCleanup)
	listBucketsLoaderCache := cache.NewTTLCache(config.CacheTTL, config.CacheCleanup)

	return &Loader{
		listObjectsLoader: dataloader.NewBatchedLoader(
			listObjectsBatch,
			dataloader.WithCache(listObjectsLoaderCache),
		),
		listObjectsLoaderCache: listObjectsLoaderCache,

		listObjectsRecursiveLoader: dataloader.NewBatchedLoader(
			listObjectsRecursiveBatch,
			dataloader.WithCache(listObjectsRecursiveLoaderCache),
		),
		listObjectsRecursiveLoaderCache: listObjectsRecursiveLoaderCache,

		statObjectLoader: dataloader.NewBatchedLoader(
			statObjectBatch,
			dataloader.WithCache(statObjectLoaderCache),
		),
		statObjectLoaderCache: statObjectLoaderCache,

		listBucketsLoader: dataloader.NewBatchedLoader(
			listBucketsBatch,
			dataloader.WithCache(listBucketsLoaderCache),
		),
		listBucketsLoaderCache: listBucketsLoaderCache,
	}
}

func (l *Loader) GetFiles(ctx context.Context, path types.ID) ([]types.File, error) {
	thunk := l.listObjectsLoader.Load(ctx, path)
	objects, err := thunk()

	if err != nil {
		return nil, err
	}

	var files []types.File

	for _, obj := range objects.([]s3.Object) {
		if !obj.ID.IsDirectory() {
			files = append(files, *helper.ObjInfoToFile(obj, path.Bucket))
		}
	}

	return files, nil
}

func (l *Loader) GetFile(ctx context.Context, id types.ID) (*types.File, error) {
	thunk := l.statObjectLoader.Load(ctx, id)

	result, err := thunk()
	if err != nil {
		return nil, err
	}
	objInfo, ok := result.(*s3.Object)

	if !ok {
		return nil, fmt.Errorf("Failed to stats object")
	}

	return helper.ObjInfoToFile(*objInfo, id.Bucket), nil
}

func (l *Loader) GetDirs(ctx context.Context, path types.ID) ([]types.Directory, error) {
	thunk := l.listObjectsLoader.Load(ctx, path)

	result, err := thunk()
	if err != nil {
		return nil, err
	}

	var dirs []types.Directory
	for _, obj := range result.([]s3.Object) {
		if obj.ID.IsDirectory() {
			dirs = append(dirs, types.Directory{
				ID: obj.ID,
			})
		}
	}

	return dirs, nil
}

func (l *Loader) GetBuckets(ctx context.Context) ([]string, error) {
	thunk := l.listBucketsLoader.Load(ctx, dataloader.StringKey(""))

	result, err := thunk()

	if err != nil {
		return nil, err
	}

	return result.([]string), nil
}

func (l *Loader) GetFilesRecursive(ctx context.Context, path types.ID) ([]types.File, error) {
	thunk := l.listObjectsRecursiveLoader.Load(ctx, path)
	result, err := thunk()

	if err != nil {
		return nil, err
	}

	objects := result.([]s3.Object)

	var files []types.File
	for _, obj := range objects {
		files = append(files, *helper.ObjInfoToFile(obj, path.Bucket))
	}

	return files, nil
}

func (l *Loader) InvalidedCacheForId(ctx context.Context, id types.ID) {
	parent := id.Parent()

	l.statObjectLoader.Clear(ctx, id)

	// Code below is useless for now until we use a propper cache for "listObjectsLoader" and "listObjectsRecursiveLoader"
	// TODO: implement cache invalidation for "listObjectsLoader" and "listObjectsRecursiveLoader"
	l.listObjectsLoader.Clear(ctx, id).Clear(ctx, parent)

	// Remove up from recursive list
	for rParent := parent; rParent != nil; rParent = rParent.Parent() {
		l.listObjectsRecursiveLoader.Clear(ctx, rParent)
	}
}