package cmd

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"os"
	"path"
	"path/filepath"
	"strings"

	"github.com/spf13/cobra"
	"gocloud.dev/blob"
	_ "gocloud.dev/blob/s3blob"
)

const prefix = "df-dist-v1"

//---
//--- Registry flavors and manifest
type Tag struct {
	Flavors []Flavor `json:"flavors"`
}

type Flavor struct {
	Resources []Resource `json:"resources"`
	Platform  RegistryPlatform `json:"platform"`
}

type Resource struct {
	Path string `json:"path"`
}

type RegistryPlatform struct {
	Architecture string `json:"architecture"`
	OS string	    `json:"os"`
}

type Manifest struct {
	Name string `json:"name"`
	Tags []string `json:"tags"`
}


//---
//--- Collect data on the filesystem
type Platform struct {
	OS string   
	Arch string 
	Root string 
	Files []string
}

func CollectPlatforms(path string) ([]Platform, error) {
	var p []Platform
	
	osDirList, err := os.ReadDir(path)
	if err != nil {
		return p, err
	}

	// Collect platforms
	for _, osDir := range osDirList {
		archDirList, err := os.ReadDir(filepath.Join(path, osDir.Name()))
		if err != nil {
			return p, err
		}
		for _, archDir := range archDirList {
			root := filepath.Join(path, osDir.Name(), archDir.Name())
			files, err := os.ReadDir(root)

			var filenames []string
			for _, f := range files {
				filenames = append(filenames, f.Name())
			}

			if err != nil {
				return p, err
			}
			plat := Platform {
				OS: osDir.Name(),
				Arch: archDir.Name(),
				Root: root,
				Files: filenames,
			}
			p = append(p, plat)
		}
	}

	return p, nil
}

func (p *Platform) BuildRegistryPlatform() RegistryPlatform {
	return RegistryPlatform {
		Architecture: p.Arch,
		OS: p.OS,
	}
}

func (p *Platform) BuildResources() []Resource {
	r := []Resource{}
	for _, f := range p.Files {
		r = append(r, Resource{Path: f})
	}
	return r
}

//---
type Artifact struct {
	Name string
	Tag  string
	Platforms []Platform
}

func NewArtifact(nametag, path string) (Artifact, error) {
	ntspl := strings.Split(nametag, ":")
	if len(ntspl) != 2 {
		return Artifact{}, errors.New("nametag must be of the form 'name:tag'")
	}

	ar := Artifact{
		Name: ntspl[0],
		Tag: ntspl[1],
	}

	plat, err := CollectPlatforms(path)
	if err != nil {
		return ar, err
	}
	ar.Platforms = plat

	return ar, nil
}

func (a *Artifact) UpdateManifest() Manifest {
	return Manifest {
		Name: a.Name,
		Tags: []string{a.Tag}, //@FIXME we must fetch the other tags of the repo
	}
}

func (a *Artifact) BuildTag() Tag {
	t := Tag{Flavors: []Flavor{}}
	for _, p := range a.Platforms {
		f := Flavor {
			Resources: p.BuildResources(),
			Platform: p.BuildRegistryPlatform(),
		}
		t.Flavors = append(t.Flavors, f)
	}
	return t
}

func (a *Artifact) Upload(buck *blob.Bucket) error {
	// Upload blobs
	for _, plat := range a.Platforms {
		for _, file := range plat.Files {
			localPath := filepath.Join(plat.Root, file)
			bu, err := NewUploadFromFS(buck, localPath)
			if err != nil {
				return err
			}

			remotePath := path.Join(prefix, a.Name, a.Tag, plat.OS, plat.Arch, file)
			if err := bu.UploadTo(remotePath); err != nil {
				return err
			}
			fmt.Printf("%s -> %s\n", localPath, remotePath)
		}
	}

	// Upload tag
	tag := a.BuildTag()
	tjson, err := json.Marshal(tag)
	if err != nil {
		return err
	}
	
	remoteTagPath := path.Join(prefix, a.Name, a.Tag)
	if err := NewUploadFromByte(buck, tjson).UploadTo(remoteTagPath); err != nil {
		return err
	}
	fmt.Printf("tag -> %s\n", remoteTagPath)

	// Update manifest
	manifest := a.UpdateManifest()
	mjson, err := json.Marshal(manifest)
	if err != nil {
		return err
	}
	
	remoteManifestPath := path.Join(prefix, a.Name)
	if err := NewUploadFromByte(buck, mjson).UploadTo(remoteManifestPath); err != nil {
		return err
	}
	fmt.Printf("manifest -> %s\n", remoteManifestPath)

	return nil
}

//---
//--- Bucket Wrapper
type BucketUploader struct {
	bucket *blob.Bucket
	reader io.ReadCloser
}
func NewUploadFromFS(buck *blob.Bucket, path string) (*BucketUploader, error) {
	fd, err := os.Open(path)
	if err != nil {
		return nil, err
	}

	return &BucketUploader{
		bucket: buck,
		reader: fd,
	}, nil
}

func NewUploadFromByte(buck *blob.Bucket, content []byte) *BucketUploader {
	return &BucketUploader{
		bucket: buck,
		reader: io.NopCloser(bytes.NewReader(content)),
	}
}

func (bu *BucketUploader) UploadTo(key string) error {
	// Checks
	if bu.bucket == nil || bu.reader == nil {
		return errors.New("bucket and reader can't be nil when calling UploadTo")
	}

	// Open remote object
	w, err := bu.bucket.NewWriter(context.Background(), key, nil)
	if err != nil {
		return err
	}

	// Copy local file bytes to the remote object
	_, err = io.Copy(w, bu.reader)

	// Close descriptors
	closeRemoteErr := w.Close()
	closeLocalErr := bu.reader.Close()

	// Check errors
	if err != nil {
		return err
	}
	if closeRemoteErr != nil {
		return closeRemoteErr
	}
	if closeLocalErr != nil {
		return closeLocalErr
	}
	
	return nil
}

//---
//--- Command logic

var staticCmd = &cobra.Command{
  Use: "static",
  Short: "Manage static artifacts",
  Long: "There are many ways to ship software, one is simply to publish a bunch of files on a mirror.",
}

var tag string
var publishCmd = &cobra.Command{
  Use: "push [folder] [remote]", // https://gocloud.dev/howto/blob/#s3-compatible
  Short: "Publish a static artifact",
  Long: "Sending logic for a static artifact",
  Args: cobra.ExactArgs(2),
  Run: func(cmd *cobra.Command, args []string) {
	localFolder := args[0]
	remoteUrl := args[1]

	// build artifact in memory
	art, err := NewArtifact(tag, localFolder)	
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	// open bucket
        bucket, err := blob.OpenBucket(context.Background(), remoteUrl)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	defer bucket.Close()

	// send artifacts
	err = art.Upload(bucket)	
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	fmt.Printf("✅ push succeeded\n")
  },
}

func init() {
	publishCmd.Flags().StringVarP(&tag, "tag", "t", "", "Tag of the project, eg. albatros:0.9")
	publishCmd.MarkFlagRequired("tag")

	staticCmd.AddCommand(publishCmd)
	RootCmd.AddCommand(staticCmd)
}