/*
Copyright 2015 The Kubernetes Authors 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 (
	"github.com/google/go-github/github"

	"fmt"
	"log"
)

// GithubRegistry implements the Registry interface that talks to github.
type GithubRegistry struct {
	owner      string
	repository string
	client     *github.Client
}

// NewGithubRegistry creates a Registry that can be used to talk to github.
func NewGithubRegistry(owner string, repository string) *GithubRegistry {
	return &GithubRegistry{
		owner:      owner,
		repository: repository,
		client:     github.NewClient(nil),
	}
}

// List the types from the Registry.
func (g *GithubRegistry) List() ([]Type, error) {
	// First list all the types at the top level.
	types, err := g.getDirs(TypesDir)
	if err != nil {
		log.Printf("Failed to list types : %v", err)
		return nil, err
	}
	var retTypes []Type
	for _, t := range types {
		// Then we need to fetch the versions (directories for this type)
		versions, err := g.getDirs(TypesDir + "/" + t)
		if err != nil {
			log.Printf("Failed to fetch versions for type: %s", t)
			return nil, err
		}
		for _, v := range versions {
			retTypes = append(retTypes, Type{Name: t, Version: v})
		}
	}

	return retTypes, nil
}

// GetURL fetches the download URL for a given Type and checks for existence of a schema file.
func (g *GithubRegistry) GetURL(t Type) (string, error) {
	_, dc, _, err := g.client.Repositories.GetContents(g.owner, g.repository, TypesDir+"/"+t.Name+"/"+t.Version, nil)
	if err != nil {
		log.Printf("Failed to list types : %v", err)
		return "", err
	}
	var downloadURL, typeName, schemaName string
	for _, f := range dc {
		if *f.Type == "file" {
			if *f.Name == t.Name+".jinja" || *f.Name == t.Name+".py" {
				typeName = *f.Name
				downloadURL = *f.DownloadURL
			}
			if *f.Name == t.Name+".jinja.schema" || *f.Name == t.Name+".py.schema" {
				schemaName = *f.Name
			}
		}
	}
	if downloadURL == "" {
		return "", fmt.Errorf("Can not find type %s:%s", t.Name, t.Version)
	}
	if schemaName == typeName + ".schema" {
		return downloadURL, nil
	}
	return "", fmt.Errorf("Can not find schema for %s:%s, expected to find %s", t.Name, t.Version, typeName + ".schema")
}

func (g *GithubRegistry) getDirs(dir string) ([]string, error) {
	_, dc, _, err := g.client.Repositories.GetContents(g.owner, g.repository, dir, nil)
	if err != nil {
		log.Printf("Failed to call ListRefs : %v", err)
		return nil, err
	}
	var dirs []string
	for _, entry := range dc {
		if *entry.Type == "dir" {
			dirs = append(dirs, *entry.Name)
		}
	}
	return dirs, nil
}