package storeserver

import (
	// "context"
	"bytes"
	"fmt"
	"io"
	"io/fs"
	"os"
	"path"
	"strings"

	"github.com/google/uuid"

	filemeta "git.keganmyers.com/terribleplan/file-store/pkg/file/meta"
	"git.keganmyers.com/terribleplan/file-store/pkg/ifs"
	// "git.keganmyers.com/terribleplan/file-store/pkg/proto"
)

var _ = (StoreServer)((*LocalStoreServer)(nil))

func NewLocal(dir string) StoreServer {
	f := ifs.DirFS(dir)
	return &LocalStoreServer{f: f}
}

type LocalStoreServer struct {
	f ifs.FS
}

func (s *LocalStoreServer) fileIdPath(fileId string) (string, error) {
	if err := ValidateFileId(fileId); err != nil {
		return "", err
	}
	return path.Join(fileId[0:2], fileId[2:4], fileId[4:6], fileId[6:8], fileId), nil
}

func (s *LocalStoreServer) fileMetaPath(fileId string) (string, error) {
	fileIdPath, err := s.fileIdPath(fileId)
	if err != nil {
		return "", err
	}
	return path.Join(fileIdPath, "meta.json"), nil
}

func (s *LocalStoreServer) ListFiles(fn ListFilesFn) error {
	return ifs.WalkDir(s.f, "/", func(path string, d fs.DirEntry, err error) error {
		if d.IsDir() && len(path) > 48 {
			return ifs.SkipDir
		}

		if !d.IsDir() && len(path) == 48 && d.Name() == "meta.json" {
			fileId := path[strings.LastIndex(path, "/"):]
			if _, err := uuid.Parse(fileId); err == nil {
				fn(fileId)
			}
		}
		return nil
	})
}

func (s *LocalStoreServer) ReadFile(fileId string) ([]byte, error) {
	filePath, err := s.fileMetaPath(fileId)
	if err != nil {
		return nil, err
	}
	file, err := s.f.Open(filePath)
	if err != nil {
		return nil, err
	}
	defer file.Close()
	meta, err := filemeta.ReadBytes(file)
	if err != nil {
		return nil, err
	}
	return meta, nil
}

func (s *LocalStoreServer) WriteFile(fileId string, meta []byte) error {
	dirPath, err := s.fileIdPath(fileId)
	if err != nil {
		return err
	}
	if err := s.f.MkdirAll(dirPath, 0755); err != nil {
		return err
	}

	metaPath, err := s.fileMetaPath(fileId)
	if err != nil {
		return err
	}
	file, err := s.f.OpenFile(metaPath, os.O_WRONLY|os.O_EXCL|os.O_CREATE, 0644)
	if err != nil {
		if err == os.ErrExist {
			existing, err := s.ReadFile(fileId)
			if err != nil {
				return err
			}
			if bytes.Equal(meta, existing) {
				return nil
			}
			return err
		}
		return err
	}
	defer file.Close()
	if _, err := file.Write(meta); err != nil {
		return err
	}
	return nil
}

func (s *LocalStoreServer) DeleteFile(fileId string) error {
	fileIdPath, err := s.fileIdPath(fileId)
	if err != nil {
		return err
	}
	return s.f.RemoveAll(fileIdPath)
}

func (s *LocalStoreServer) WriteChunk(fileId string, chunkId uint16, data io.ReadCloser) error {
	fileIdPath, err := s.fileIdPath(fileId)
	if err != nil {
		return err
	}

	filePath := path.Join(fileIdPath, fmt.Sprintf("chunk.%04d", chunkId))

	file, err := s.f.OpenFile(filePath, os.O_WRONLY|os.O_EXCL|os.O_CREATE, 0644)
	if err != nil {
		return err
	}
	if _, err := io.Copy(file, data); err != nil {
		os.Remove(filePath)
		return err
	}
	return nil
}