package operator

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"strconv"

	"mstore/app/descr"
	"mstore/pkg/auxoci"

	ocidigest "github.com/opencontainers/go-digest"
)

const (
	ddmMimeType = "application/vnd.docker.distribution.manifest.v2+json"
	oimMimeType = "application/vnd.oci.image.manifest.v1+json"
)

type ManifestExistsParams struct {
	Name      string
	Reference string
}
type ManifestExistsResult struct {
	ContentLength       string
	ContentType         string
	DockerContentDigest string
	Exists              bool
}

func (oper *Operator) ManifestExists(ctx context.Context, params *ManifestExistsParams) (*ManifestExistsResult, int, error) {
	var err error
	res := &ManifestExistsResult{}

	if params.Name == "" {
		err = fmt.Errorf("Empty name")
		return res, http.StatusBadRequest, err
	}
	if params.Reference == "" {
		err = fmt.Errorf("Empty reference")
		return res, http.StatusBadRequest, err
	}

	oper.logg.Debugf("Head manifest [%s:%s]", params.Name, params.Reference)

	var manifest descr.Manifest
	var exists bool
	if stringLikeSHA256Digest(params.Reference) {
		digest := fmt.Sprintf("%s:%s", sha256prefix, params.Reference)
		oper.logg.Debugf("Find manifest %s by digest %s", params.Name, params.Reference)
		exists, manifest, err = oper.mdb.GetManifestByDigest(ctx, params.Name, digest)
		if err != nil {
			return res, http.StatusInternalServerError, err
		}
		if !exists {
			return res, http.StatusNotFound, err
		}
	} else {
		oper.logg.Debugf("Find manifest %s by reference %s", params.Name, params.Reference)
		exists, manifest, err = oper.mdb.GetManifestByReference(ctx, params.Name, params.Reference)
		if err != nil {
			return res, http.StatusInternalServerError, err
		}
		if !exists {
			return res, http.StatusNotFound, err
		}
	}

	digest := ocidigest.SHA256.FromString(manifest.Payload)
	payloadSize := len(manifest.Payload)
	res.ContentLength = strconv.FormatInt(int64(payloadSize), 10)
	res.ContentType = manifest.ContentType
	res.DockerContentDigest = digest.String()
	res.Exists = exists

	return res, http.StatusOK, err
}

type PutManifestParams struct {
	ContentType string
	Name        string
	Reference   string
	Reader      io.Reader
}
type PutManifestResult struct {
	Location string
}

// TODO: control size 413 Payload Too Large

func (oper *Operator) PutManifest(ctx context.Context, params *PutManifestParams) (*PutManifestResult, int, error) {
	var err error
	res := &PutManifestResult{}
	oper.logg.Debugf("Put manifest %s:%s", params.Name, params.Reference)

	if params.Reference == "" {
		err = fmt.Errorf("Empty reference")
		return res, http.StatusBadRequest, err
	}
	if params.Name == "" {
		err = fmt.Errorf("Empty name")
		return res, http.StatusBadRequest, err
	}
	// Check Content-Type
	if params.ContentType != oimMimeType {
		err = fmt.Errorf("Unknown or empty Content-Type: %s", params.ContentType)
		return res, http.StatusNotFound, err
	}

	// Copy manifest data
	buffer := bytes.NewBuffer(nil)
	_, err = io.Copy(buffer, params.Reader)
	if err != nil {
		return res, http.StatusInternalServerError, err
	}
	incomingManifestBytes := buffer.Bytes()
	oper.logg.Debugf("Manifest data: [%s]", string(incomingManifestBytes))

	incomingManifest, err := auxoci.ParseOCIManifest(incomingManifestBytes)
	if err != nil {
		err = fmt.Errorf("Parsing OCI manifest error: %v", err)
		return res, http.StatusInternalServerError, err
	}
	if incomingManifest.MediaType != params.ContentType {
		err := fmt.Errorf("Mismatch Content-Type header and manifest MediaType: %s vs %s",
			params.ContentType, incomingManifest.MediaType)
		return res, http.StatusInternalServerError, err
	}

	manifestExists, _, err := oper.mdb.GetManifestByReference(ctx, params.Name, params.Reference)
	if err != nil {
		return res, http.StatusInternalServerError, err
	}
	if !manifestExists {
		name := params.Name
		reference := params.Reference
		manifestDescr, layerDescrs, err := descrsFromManifest(name, reference, incomingManifest, incomingManifestBytes)
		// Check layers
		var blobError error
		for _, layer := range layerDescrs {
			layerExists, _, err := oper.store.BlobFileExists(layer.Digest)
			if err != nil {
				return res, http.StatusInternalServerError, err
			}
			if !layerExists {
				err := fmt.Errorf("Layer %s not found", layer.Digest)
				blobError = errors.Join(blobError, err)
			}
		}
		if blobError != nil {
			return res, http.StatusInternalServerError, blobError
		}
		// Store manifest and layesrs data
		err = oper.mdb.InsertManifestWithLayers(ctx, &manifestDescr, layerDescrs)
		if err != nil {
			return res, http.StatusInternalServerError, err
		}
	}

	/*
	   exists, existingManifestDescr, err := lg.mdb.GetManifestByReference(params.Name, params.Reference)
	   if err != nil {
	           return res, http.StatusInternalServerError, err
	   }

	   if exists {
	           existingManifestBytes := []byte(existingManifestDescr.Payload)
	           // Exist if incoming and existing manyfest is equal
	           if bytes.Equal(existingManifestBytes, incomingManifestBytes) {
	                   return res, http.StatusCreated, err
	           }
	           name := params.Name
	           reference := params.Reference
	           manifestDescr, newBlobDescrs, delBlobDescrs, err := blobsDiff(name, reference, existingManifestBytes, incomingManifestBytes)
	           if err != nil {
	                   return res, http.StatusInternalServerError, err
	           }
	           err = lg.maindb.UpdateManifest(ctx, &manifestDescr, newBlobDescrs, delBlobDescrs)
	           if err != nil {
	                   return res, http.StatusInternalServerError, err
	           }
	           // Clean blobs
	           for _, blob := range delBlobDescrs {
	                   exists, _, err = lg.st.BlobFileExists(blob.Digest)
	                   if err != nil {
	                           return res, http.StatusInternalServerError, err
	                   }
	                   blobUsage, err := lg.maindb.GetBlobUsage(blob.Digest)
	                   if err != nil {
	                           return res, http.StatusInternalServerError, err
	                   }
	                   if exists && blobUsage == 0 {
	                           lg.log.Debugf("Delete file %s:%s blob %s", params.Name, params.Reference, blob.Digest)
	                           err = lg.st.DeleteBlobFile(blob.Digest)
	                           if err != nil {
	                                   return res, http.StatusInternalServerError, err
	                           }
	                   }
	           }
	   } else {
	           name := params.Name
	           reference := params.Reference
	           manifestDescr, configDescr, layerDescrs, err := descrsFromManifestBytes(name, reference, incomingManifestBytes)
	           // Check layer blobs
	           var blobError error
	           for _, layer := range layerDescrs {
	                   exists, _, err = lg.st.BlobFileExists(layer.Digest)
	                   if !exists {
	                           err := fmt.Errorf("Blob %s not exists", layer.Digest)
	                           blobError = errors.Join(blobError, err)
	                   }
	           }
	           if blobError != nil {
	                   return res, http.StatusInternalServerError, blobError
	           }
	           // Store manifest and blobs data
	           err = lg.maindb.InsertManifest(ctx, &manifestDescr, &configDescr, layerDescrs)
	           if err != nil {
	                   return res, http.StatusInternalServerError, err
	           }
	   }

	*/

	res.Location = fmt.Sprintf(`/v2/%s/manifests/%s`, params.Name, params.Reference)
	return res, http.StatusCreated, err

}