// Copyright 2015 The Gogs Authors. All rights reserved.
// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package git

import (
	"io"
	"strings"

	"gopkg.in/src-d/go-git.v4/plumbing"
	"gopkg.in/src-d/go-git.v4/plumbing/object"
)

// Tree represents a flat directory listing.
type Tree struct {
	ID       SHA1
	CommitID SHA1
	repo     *Repository

	gogitTree *object.Tree

	// parent tree
	ptree *Tree
}

// NewTree create a new tree according the repository and tree id
func NewTree(repo *Repository, id SHA1) *Tree {
	return &Tree{
		ID:   id,
		repo: repo,
	}
}

// SubTree get a sub tree by the sub dir path
func (t *Tree) SubTree(rpath string) (*Tree, error) {
	if len(rpath) == 0 {
		return t, nil
	}

	paths := strings.Split(rpath, "/")
	var (
		err error
		g   = t
		p   = t
		te  *TreeEntry
	)
	for _, name := range paths {
		te, err = p.GetTreeEntryByPath(name)
		if err != nil {
			return nil, err
		}

		g, err = t.repo.getTree(te.ID)
		if err != nil {
			return nil, err
		}
		g.ptree = p
		p = g
	}
	return g, nil
}

func (t *Tree) loadTreeObject() error {
	gogitTree, err := t.repo.gogitRepo.TreeObject(plumbing.Hash(t.ID))
	if err != nil {
		return err
	}

	t.gogitTree = gogitTree
	return nil
}

// ListEntries returns all entries of current tree.
func (t *Tree) ListEntries() (Entries, error) {
	if t.gogitTree == nil {
		err := t.loadTreeObject()
		if err != nil {
			return nil, err
		}
	}

	entries := make([]*TreeEntry, len(t.gogitTree.Entries))
	for i, entry := range t.gogitTree.Entries {
		entries[i] = &TreeEntry{
			ID:             entry.Hash,
			gogitTreeEntry: &t.gogitTree.Entries[i],
			ptree:          t,
		}
	}

	return entries, nil
}

// ListEntriesRecursive returns all entries of current tree recursively including all subtrees
func (t *Tree) ListEntriesRecursive() (Entries, error) {
	if t.gogitTree == nil {
		err := t.loadTreeObject()
		if err != nil {
			return nil, err
		}
	}

	var entries []*TreeEntry
	seen := map[plumbing.Hash]bool{}
	walker := object.NewTreeWalker(t.gogitTree, true, seen)
	for {
		_, entry, err := walker.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			return nil, err
		}
		if seen[entry.Hash] {
			continue
		}

		convertedEntry := &TreeEntry{
			ID:             entry.Hash,
			gogitTreeEntry: &entry,
			ptree:          t,
		}
		entries = append(entries, convertedEntry)
	}

	return entries, nil
}
