/*
   Copyright (c) 2016 VMware, Inc. All Rights Reserved.
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package registry

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"net/url"
	"strconv"

	"github.com/docker/distribution/manifest/schema2"
	"github.com/vmware/harbor/utils/log"
	"github.com/vmware/harbor/utils/registry/errors"
)

// Registry holds information of a registry entity
type Registry struct {
	Endpoint *url.URL
	client   *http.Client
	ub       *uRLBuilder
}

type uRLBuilder struct {
	root *url.URL
}

// New returns an instance of Registry
func New(endpoint string, client *http.Client) (*Registry, error) {
	u, err := url.Parse(endpoint)
	if err != nil {
		return nil, err
	}

	return &Registry{
		Endpoint: u,
		client:   client,
		ub: &uRLBuilder{
			root: u,
		},
	}, nil
}

// Catalog ...
func (r *Registry) Catalog() ([]string, error) {
	repos := []string{}
	req, err := http.NewRequest("GET", r.ub.buildCatalogURL(), nil)
	if err != nil {
		return repos, err
	}

	resp, err := r.client.Do(req)
	if err != nil {
		return repos, err
	}

	defer resp.Body.Close()

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return repos, err
	}

	if resp.StatusCode == http.StatusOK {
		catalogResp := struct {
			Repositories []string `json:"repositories"`
		}{}

		if err := json.Unmarshal(b, &catalogResp); err != nil {
			return repos, err
		}

		repos = catalogResp.Repositories

		return repos, nil
	}

	return repos, errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}
}

// ListTag ...
func (r *Registry) ListTag(name string) ([]string, error) {
	tags := []string{}
	req, err := http.NewRequest("GET", r.ub.buildTagListURL(name), nil)
	if err != nil {
		return tags, err
	}

	resp, err := r.client.Do(req)
	if err != nil {
		return tags, err
	}

	defer resp.Body.Close()

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return tags, err
	}

	if resp.StatusCode == http.StatusOK {
		tagsResp := struct {
			Tags []string `json:"tags"`
		}{}

		if err := json.Unmarshal(b, &tagsResp); err != nil {
			return tags, err
		}

		tags = tagsResp.Tags

		return tags, nil
	}

	return tags, errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}

}

// ManifestExist ...
func (r *Registry) ManifestExist(name, reference string) (digest string, exist bool, err error) {
	req, err := http.NewRequest("HEAD", r.ub.buildManifestURL(name, reference), nil)
	if err != nil {
		return
	}

	// request Schema 2 manifest, if the registry does not support it,
	// Schema 1 manifest will be returned
	req.Header.Set(http.CanonicalHeaderKey("Accept"), schema2.MediaTypeManifest)

	resp, err := r.client.Do(req)
	if err != nil {
		return
	}

	if resp.StatusCode == http.StatusOK {
		exist = true
		digest = resp.Header.Get(http.CanonicalHeaderKey("Docker-Content-Digest"))
		return
	}

	if resp.StatusCode == http.StatusNotFound {
		return
	}

	defer resp.Body.Close()

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return
	}

	err = errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}
	return
}

// PullManifest ...
func (r *Registry) PullManifest(name, reference string, acceptMediaTypes []string) (digest, mediaType string, payload []byte, err error) {
	req, err := http.NewRequest("GET", r.ub.buildManifestURL(name, reference), nil)
	if err != nil {
		return
	}

	for _, mediaType := range acceptMediaTypes {
		req.Header.Set(http.CanonicalHeaderKey("Accept"), mediaType)
	}

	resp, err := r.client.Do(req)
	if err != nil {
		return
	}

	defer resp.Body.Close()
	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return
	}

	if resp.StatusCode == http.StatusOK {
		digest = resp.Header.Get(http.CanonicalHeaderKey("Docker-Content-Digest"))
		mediaType = resp.Header.Get(http.CanonicalHeaderKey("Content-Type"))
		payload = b
		return
	}

	err = errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}

	return
}

// PushManifest ...
func (r *Registry) PushManifest(name, reference, mediaType string, payload []byte) (digest string, err error) {
	req, err := http.NewRequest("PUT", r.ub.buildManifestURL(name, reference),
		bytes.NewReader(payload))
	if err != nil {
		return
	}
	req.Header.Set(http.CanonicalHeaderKey("Content-Type"), mediaType)

	resp, err := r.client.Do(req)
	if err != nil {
		return
	}

	if resp.StatusCode == http.StatusCreated {
		digest = resp.Header.Get(http.CanonicalHeaderKey("Docker-Content-Digest"))
		return
	}

	defer resp.Body.Close()

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return
	}

	err = errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}

	return
}

// DeleteManifest ...
func (r *Registry) DeleteManifest(name, digest string) error {
	req, err := http.NewRequest("DELETE", r.ub.buildManifestURL(name, digest), nil)
	if err != nil {
		return err
	}

	resp, err := r.client.Do(req)
	if err != nil {
		return err
	}

	if resp.StatusCode == http.StatusAccepted {
		return nil
	}

	defer resp.Body.Close()

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return err
	}

	return errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}
}

// DeleteTag ...
func (r *Registry) DeleteTag(name, tag string) error {
	digest, exist, err := r.ManifestExist(name, tag)
	if err != nil {
		return err
	}

	if !exist {
		return errors.Error{
			StatusCode: http.StatusNotFound,
		}
	}

	return r.DeleteManifest(name, digest)
}

// BlobExist ...
func (r *Registry) BlobExist(name, digest string) (bool, error) {
	req, err := http.NewRequest("HEAD", r.ub.buildBlobURL(name, digest), nil)
	if err != nil {
		return false, err
	}

	resp, err := r.client.Do(req)
	if err != nil {
		return false, err
	}

	if resp.StatusCode == http.StatusOK {
		return true, nil
	}

	if resp.StatusCode == http.StatusNotFound {
		return false, nil
	}

	defer resp.Body.Close()

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return false, err
	}

	return false, errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}
}

// PullBlob ...
func (r *Registry) PullBlob(name, digest string) (size int64, data []byte, err error) {
	req, err := http.NewRequest("GET", r.ub.buildBlobURL(name, digest), nil)
	if err != nil {
		return
	}

	resp, err := r.client.Do(req)
	if err != nil {
		return
	}

	defer resp.Body.Close()
	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return
	}

	if resp.StatusCode == http.StatusOK {
		contengLength := resp.Header.Get(http.CanonicalHeaderKey("Content-Length"))
		size, err = strconv.ParseInt(contengLength, 10, 64)
		if err != nil {
			return
		}
		data = b
		return
	}

	err = errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}

	return
}

func (r *Registry) initiateBlobUpload(name string) (location, uploadUUID string, err error) {
	req, err := http.NewRequest("POST", r.ub.buildInitiateBlobUploadURL(name), nil)
	req.Header.Set(http.CanonicalHeaderKey("Content-Length"), "0")

	resp, err := r.client.Do(req)
	if err != nil {
		return
	}

	if resp.StatusCode == http.StatusAccepted {
		location = resp.Header.Get(http.CanonicalHeaderKey("Location"))
		uploadUUID = resp.Header.Get(http.CanonicalHeaderKey("Docker-Upload-UUID"))
		return
	}

	defer resp.Body.Close()

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return
	}

	err = errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}

	return
}

func (r *Registry) monolithicBlobUpload(location, digest string, size int64, data []byte) error {
	req, err := http.NewRequest("PUT", r.ub.buildMonolithicBlobUploadURL(location, digest), bytes.NewReader(data))
	if err != nil {
		return err
	}

	resp, err := r.client.Do(req)
	if err != nil {
		return err
	}

	if resp.StatusCode == http.StatusCreated {
		return nil
	}

	defer resp.Body.Close()

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return err
	}

	return errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}
}

// PushBlob ...
func (r *Registry) PushBlob(name, digest string, size int64, data []byte) error {
	exist, err := r.BlobExist(name, digest)
	if err != nil {
		return err
	}

	if exist {
		log.Infof("blob already exists, skip pushing: %s %s", name, digest)
		return nil
	}

	location, _, err := r.initiateBlobUpload(name)
	if err != nil {
		return err
	}

	return r.monolithicBlobUpload(location, digest, size, data)
}

// DeleteBlob ...
func (r *Registry) DeleteBlob(name, digest string) error {
	req, err := http.NewRequest("DELETE", r.ub.buildBlobURL(name, digest), nil)
	if err != nil {
		return err
	}

	resp, err := r.client.Do(req)
	if err != nil {
		return err
	}

	if resp.StatusCode == http.StatusAccepted {
		return nil
	}

	defer resp.Body.Close()

	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return err
	}

	return errors.Error{
		StatusCode: resp.StatusCode,
		Message:    string(b),
	}
}

func (u *uRLBuilder) buildCatalogURL() string {
	return fmt.Sprintf("%s/v2/_catalog", u.root.String())
}

func (u *uRLBuilder) buildTagListURL(name string) string {
	return fmt.Sprintf("%s/v2/%s/tags/list", u.root.String(), name)
}

func (u *uRLBuilder) buildManifestURL(name, reference string) string {
	return fmt.Sprintf("%s/v2/%s/manifests/%s", u.root.String(), name, reference)
}

func (u *uRLBuilder) buildBlobURL(name, reference string) string {
	return fmt.Sprintf("%s/v2/%s/blobs/%s", u.root.String(), name, reference)
}

func (u *uRLBuilder) buildInitiateBlobUploadURL(name string) string {
	return fmt.Sprintf("%s/v2/%s/blobs/uploads/", u.root.String(), name)
}

func (u *uRLBuilder) buildMonolithicBlobUploadURL(location, digest string) string {
	return fmt.Sprintf("%s&digest=%s", location, digest)
}