model.go

package git_diff_parser

import (
	"fmt"
	"strings"
)

type contentChangeType string

const (
	contentChangeTypeAdd    contentChangeType = "add"
	contentChangeTypeDelete contentChangeType = "delete"
	contentChangeTypeModify contentChangeType = "modify"
	contentChangeTypeNOOP   contentChangeType = ""
)

// contentChange is a part of the line that starts with ` `, `-`, `+`.
// Consecutive contentChange build a line.
// A `~` is a special case of contentChange that is used to indicate a new line.
type contentChange struct {
	Type contentChangeType `json:"type"`
	From string            `json:"from"`
	To   string            `json:"to"`
}

type changeList []contentChange

// hunkLine keeps a normalized, apply-friendly view of a hunk line.
type hunkLine struct {
	Kind       byte   `json:"kind"`
	Text       string `json:"text"`
	HasNewline bool   `json:"has_newline"`
	OldEOF     bool   `json:"old_eof,omitempty"`
	NewEOF     bool   `json:"new_eof,omitempty"`
}

// hunk is a line that starts with @@.
// Each hunk shows one area where the files differ.
// Unified format hunks look like this:
// @@ from-file-line-numbers to-file-line-numbers @@
//
//	line-from-either-file
//	line-from-either-file…
//
// If a hunk contains just one line, only its start line number appears. Otherwise its line numbers look like 'start,count'. An empty hunk is considered to start at the line that follows the hunk.
type hunk struct {
	ChangeList         changeList `json:"change_list"`
	Lines              []hunkLine `json:"lines,omitempty"`
	StartLineNumberOld int        `json:"start_line_number_old"`
	CountOld           int        `json:"count_old"`
	StartLineNumberNew int        `json:"start_line_number_new"`
	CountNew           int        `json:"count_new"`
}

func (l *hunkLine) markNoNewline() {
	l.HasNewline = false
}

func (h *hunk) markEOFMarkers() {
	oldSeen := 0
	newSeen := 0

	for i := range h.Lines {
		line := &h.Lines[i]
		if line.Kind == ' ' || line.Kind == '-' {
			oldSeen++
		}
		if line.Kind == ' ' || line.Kind == '+' {
			newSeen++
		}
		if !line.HasNewline || strings.TrimSuffix(line.Text, "\r") != "" {
			continue
		}

		line.OldEOF = (line.Kind == ' ' || line.Kind == '-') && oldSeen == h.CountOld
		line.NewEOF = (line.Kind == ' ' || line.Kind == '+') && newSeen == h.CountNew
	}
}

func (changes *changeList) isSignificant() bool {
	for _, change := range *changes {
		if change.Type != contentChangeTypeNOOP {
			return true
		}
	}
	return false
}

func (h *hunk) GoString() string {
	return fmt.Sprintf(
		"git_diff_parser.Hunk{ChangeList:%#v, StartLineNumberOld:%d, CountOld:%d, StartLineNumberNew:%d, CountNew:%d}",
		h.ChangeList,
		h.StartLineNumberOld,
		h.CountOld,
		h.StartLineNumberNew,
		h.CountNew,
	)
}

type fileDiffType string

const (
	fileDiffTypeAdded    fileDiffType = "add"
	fileDiffTypeDeleted  fileDiffType = "delete"
	fileDiffTypeModified fileDiffType = "modify"
)

type binaryDeltaType string

const (
	binaryDeltaTypeLiteral binaryDeltaType = "literal"
	binaryDeltaTypeDelta   binaryDeltaType = "delta"
)

type binaryPatch struct {
	Type    binaryDeltaType `json:"type"`
	Count   int
	Content string
}

// fileDiff models the subset of Git patch metadata exposed by this parser.
//
// Git represents generated diff pairs as diff_filepair:
// https://github.com/git/git/blob/aec3f587505a472db67e9462d0702e7d463a449d/diffcore.h#L107-L130
//
// Git emits unified patch file headers in builtin_diff:
// https://github.com/git/git/blob/aec3f587505a472db67e9462d0702e7d463a449d/diff.c#L3838-L3930
type fileDiff struct {
	FromFile           string        `json:"from_file"`
	ToFile             string        `json:"to_file"`
	Type               fileDiffType  `json:"type"`
	IsBinary           bool          `json:"is_binary"`
	OldMode            string        `json:"old_mode,omitempty"`
	NewMode            string        `json:"new_mode,omitempty"`
	IndexOld           string        `json:"index_old,omitempty"`
	IndexNew           string        `json:"index_new,omitempty"`
	IndexMode          string        `json:"index_mode,omitempty"`
	SimilarityIndex    int           `json:"similarity_index,omitempty"`
	DissimilarityIndex int           `json:"dissimilarity_index,omitempty"`
	RenameFrom         string        `json:"rename_from,omitempty"`
	RenameTo           string        `json:"rename_to,omitempty"`
	CopyFrom           string        `json:"copy_from,omitempty"`
	CopyTo             string        `json:"copy_to,omitempty"`
	Hunks              []hunk        `json:"hunks"`
	BinaryPatch        []binaryPatch `json:"binary_patch"`

	// Parser-only paths from the "---" and "+++" file header lines. Git apply
	// validates these against the diff --git/copy/rename names in apply.c:
	// https://github.com/git/git/blob/aec3f587505a472db67e9462d0702e7d463a449d/apply.c#L929-L966
	// https://github.com/git/git/blob/aec3f587505a472db67e9462d0702e7d463a449d/apply.c#L1330-L1453
	//
	// They are intentionally unexported and omitted from JSON because they are
	// input syntax used for validation, not semantic diff metadata.
	oldFileHeaderPath string
	newFileHeaderPath string
}

func (fd *fileDiff) GoString() string {
	var hunksStr string
	if fd.Hunks == nil {
		hunksStr = "[]git_diff_parser.Hunk(nil)"
	} else {
		hunks := make([]string, len(fd.Hunks))
		for i := range fd.Hunks {
			hunks[i] = fd.Hunks[i].GoString()
		}
		hunksStr = "[]git_diff_parser.Hunk{" + strings.Join(hunks, ", ") + "}"
	}
	return fmt.Sprintf(
		"&git_diff_parser.FileDiff{FromFile:%#v, ToFile:%#v, Type:%#v, IsBinary:%t, NewMode:%#v, Hunks:%s, BinaryPatch:%#v}",
		fd.FromFile,
		fd.ToFile,
		fd.Type,
		fd.IsBinary,
		fd.NewMode,
		hunksStr,
		fd.BinaryPatch,
	)
}

type diff struct {
	FileDiff []fileDiff `json:"file_diff"`
}