package index

import (
	"os"
	"time"

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

type Stage int

const (
	// Merged is the default stage, fully merged
	Merged Stage = 1
	// AncestorMode is the base revision
	AncestorMode Stage = 1
	// OurMode is the first tree revision, ours
	OurMode Stage = 2
	// TheirMode is the second tree revision, theirs
	TheirMode Stage = 3
)

// Index contains the information about which objects are currently checked out
// in the worktree, having information about the working files. Changes in
// worktree are detected using this Index. The Index is also used during merges
type Index struct {
	Version     uint32
	EntryCount  uint32
	Entries     []Entry
	Cache       *Tree
	ResolveUndo *ResolveUndo
}

// Entry represents a single file (or stage of a file) in the cache. An entry
// represents exactly one stage of a file. If a file path is unmerged then
// multiple Entry instances may appear for the same path name.
type Entry struct {
	CreatedAt  time.Time
	ModifiedAt time.Time
	Dev, Inode uint32
	Mode       os.FileMode
	UID, GID   uint32
	Size       uint32
	Flags      uint16
	Stage      Stage

	SkipWorktree bool
	IntentToAdd  bool

	Hash core.Hash
	Name string
}

// Tree contains pre-computed hashes for trees that can be derived from the
// index. It helps speed up tree object generation from index for a new commit.
type Tree struct {
	Entries []TreeEntry
}

// TreeEntry entry of a cached Tree
type TreeEntry struct {
	// Path component (relative to its parent directory)
	Path string
	// Entries is the number of entries in the index that is covered by the tree
	// this entry represents
	Entries int
	// Trees is the number that represents the number of subtrees this tree has
	Trees int
	// Hash object name for the object that would result from writing this span
	// of index as a tree.
	Hash core.Hash
}

// ResolveUndo when a conflict is resolved (e.g. with "git add path"), these
// higher stage entries will be removed and a stage-0 entry with proper
// resolution is added. When these higher stage entries are removed, they are
// saved in the resolve undo extension
type ResolveUndo struct {
	Entries []ResolveUndoEntry
}

// ResolveUndoEntry contains the information about a conflict when is resolved
type ResolveUndoEntry struct {
	Path   string
	Stages map[Stage]core.Hash
}