package unixfs

import (
	"bytes"
	"fmt"
	"io"
	"sort"
	"text/tabwriter"

	cmds "github.com/ipfs/go-ipfs/commands"
	core "github.com/ipfs/go-ipfs/core"
	path "github.com/ipfs/go-ipfs/path"
	unixfs "github.com/ipfs/go-ipfs/unixfs"
	unixfspb "github.com/ipfs/go-ipfs/unixfs/pb"
	merkledag "github.com/ipfs/go-ipfs/merkledag"
)

type LsLink struct {
	Name, Hash string
	Size       uint64
	Type       string
}

type LsObject struct {
	Hash  string
	Size  uint64
	Type  string
	Links []LsLink
}

type LsOutput struct {
	Arguments map[string]string
	Objects   map[string]*LsObject
}

var LsCmd = &cmds.Command{
	Helptext: cmds.HelpText{
		Tagline: "List directory contents for Unix filesystem objects.",
		ShortDescription: `
Displays the contents  of an IPFS or IPNS object(s) at the given path.

The JSON output contains size information. For files, the child size
is the total size of the file contents. For directories, the child
size is the IPFS link size.
`,
	},

	Arguments: []cmds.Argument{
		cmds.StringArg("ipfs-path", true, true, "The path to the IPFS object(s) to list links from.").EnableStdin(),
	},
	Run: func(req cmds.Request, res cmds.Response) {
		node, err := req.InvocContext().GetNode()
		if err != nil {
			res.SetError(err, cmds.ErrNormal)
			return
		}

		paths := req.Arguments()

		output := LsOutput{
			Arguments: map[string]string{},
			Objects:   map[string]*LsObject{},
		}

		for _, fpath := range paths {
			ctx := req.Context()
			merkleNode, err := core.Resolve(ctx, node, path.Path(fpath))
			if err != nil {
				res.SetError(err, cmds.ErrNormal)
				return
			}

			key, err := merkleNode.Key()
			if err != nil {
				res.SetError(err, cmds.ErrNormal)
				return
			}

			hash := key.B58String()
			output.Arguments[fpath] = hash

			if _, ok := output.Objects[hash]; ok {
				// duplicate argument for an already-listed node
				continue
			}

			unixFSNode, err := unixfs.FromBytes(merkleNode.Data)
			if err != nil {
				res.SetError(err, cmds.ErrNormal)
				return
			}

			t := unixFSNode.GetType()

			output.Objects[hash] = &LsObject{
				Hash: key.String(),
				Type: t.String(),
				Size: unixFSNode.GetFilesize(),
			}

			switch t {
			case unixfspb.Data_File:
				break
			case unixfspb.Data_Directory:
				links := make([]LsLink, len(merkleNode.Links))
				output.Objects[hash].Links = links
				for i, link := range merkleNode.Links {
					var linkNode *merkledag.Node
					linkNode, err = link.GetNode(ctx, node.DAG)
					if err != nil {
						res.SetError(err, cmds.ErrNormal)
						return
					}
					d, err := unixfs.FromBytes(linkNode.Data)
					if err != nil {
						res.SetError(err, cmds.ErrNormal)
						return
					}
					t := d.GetType()
					lsLink := LsLink{
						Name: link.Name,
						Hash: link.Hash.B58String(),
						Type: t.String(),
					}
					if t == unixfspb.Data_File {
						lsLink.Size = d.GetFilesize()
					} else {
						lsLink.Size = link.Size
					}
					links[i] = lsLink
				}
			case unixfspb.Data_Symlink:
				res.SetError(fmt.Errorf("cannot list symlinks yet"), cmds.ErrNormal)
				return
			default:
				res.SetError(fmt.Errorf("unrecognized type: %s", t), cmds.ErrImplementation)
				return
			}
		}

		res.SetOutput(&output)
	},
	Marshalers: cmds.MarshalerMap{
		cmds.Text: func(res cmds.Response) (io.Reader, error) {

			output := res.Output().(*LsOutput)
			buf := new(bytes.Buffer)
			w := tabwriter.NewWriter(buf, 1, 2, 1, ' ', 0)

			nonDirectories := []string{}
			directories := []string{}
			for argument, hash := range output.Arguments {
				object, ok := output.Objects[hash]
				if !ok {
					return nil, fmt.Errorf("unresolved hash: %s", hash)
				}

				if object.Type == "Directory" {
					directories = append(directories, argument)
				} else {
					nonDirectories = append(nonDirectories, argument)
				}
			}
			sort.Strings(nonDirectories)
			sort.Strings(directories)

			for _, argument := range nonDirectories {
				fmt.Fprintf(w, "%s\n", argument)
			}

			seen := map[string]bool{}
			for i, argument := range directories {
				hash := output.Arguments[argument]
				if _, ok := seen[hash]; ok {
					continue
				}
				seen[hash] = true

				object := output.Objects[hash]
				if i > 0 || len(nonDirectories) > 0 {
					fmt.Fprintln(w)
				}
				if len(output.Arguments) > 1 {
					for _, arg := range directories[i:] {
						if output.Arguments[arg] == hash {
							fmt.Fprintf(w, "%s:\n", arg)
						}
					}
				}
				for _, link := range object.Links {
					fmt.Fprintf(w, "%s\n", link.Name)
				}
			}
			w.Flush()

			return buf, nil
		},
	},
	Type: LsOutput{},
}