package core

type BufferOptions struct {
	// tabstop expandtab
}

type BufferType int

const (
	ScatchBuffer BufferType = iota
	FileBuffer
	DirectoryBuffer
)

type Buffer struct {
	// Buffer data
	Id   int
	Type BufferType

	// File data
	Filename string
	Filetype string
	Lines    []*GapBuffer // Changed from []string to []*GapBuffer

	// Flags (not used yet)
	Modified bool
	Loaded   bool
	Listed   bool
	ReadOnly bool

	// Options BufferOptions
	UndoStack *UndoStack
}

// ==================================================
// Helper methods
// ==================================================

// Buffer.Line: Get the line at an index. Returns an empty string if the index
// is out of bounds.
func (b *Buffer) Line(idx int) string {
	if idx < 0 || idx >= len(b.Lines) {
		return ""
	}
	return b.Lines[idx].String()
}

// Buffer.SetLine: Set the content of the line at an index. Does nothing if the
// index is out of bounds. This function sets the modified flag.
func (b *Buffer) SetLine(idx int, content string) {
	if idx >= 0 && idx < len(b.Lines) {
		// Record set line in undo stack
		if b.UndoStack != nil {
			b.UndoStack.RecordSetLine(idx, b.Lines[idx].String(), content)
		}
		b.Lines[idx].Set(content)
	}
	b.Modified = true
}

// Buffer.InsertLine: Insert a line with content at an index. The index is clamped
// to valid bounds (0 to len(Lines)). The new line is inserted before the line at
// the given index. This function sets the modified flag.
func (b *Buffer) InsertLine(idx int, content string) {
	if idx < 0 {
		idx = 0
	}
	if idx > len(b.Lines) {
		idx = len(b.Lines)
	}

	// Record insert line in undo stack
	if b.UndoStack != nil {
		b.UndoStack.RecordInsertLine(idx, content)
	}

	newLine := NewGapBuffer(content)
	b.Lines = append(b.Lines[:idx], append([]*GapBuffer{newLine}, b.Lines[idx:]...)...)
	b.Modified = true
}

// Buffer.DeleteLine: Delete a line at an index. Does nothing if the index is out
// of bounds. This function sets the modified flag.
func (b *Buffer) DeleteLine(idx int) {
	if idx >= 0 && idx < len(b.Lines) {
		// Record delete line in undo stack
		if b.UndoStack != nil {
			b.UndoStack.RecordDeleteLine(idx, b.Lines[idx].String())
		}
		b.Lines = append(b.Lines[:idx], b.Lines[idx+1:]...)
	}
	b.Modified = true
}

// Buffer.LineCount: Get the number of lines in the buffer.
func (b *Buffer) LineCount() int {
	return len(b.Lines)
}

// ==================================================
// Undo Stack
// ==================================================
func (b *Buffer) Undo(w *Window) bool {
	if b.UndoStack == nil {
		return false
	}

	block := b.UndoStack.Undo()
	if block == nil {
		return false
	}

	// Apply changes in REVERSE order
	for i := len(block.Changes) - 1; i >= 0; i-- {
		change := block.Changes[i]

		// Temporarily disable recording while we undo
		wasRecording := b.UndoStack.recording
		b.UndoStack.recording = false

		switch change.Type {
		case SetLineChange:
			// Restore old data
			if change.Line >= 0 && change.Line < len(b.Lines) {
				b.Lines[change.Line].Set(change.OldData)
			}
		case InsertLineChange:
			// Remove the inserted line
			if change.Line >= 0 && change.Line < len(b.Lines) {
				b.Lines = append(b.Lines[:change.Line], b.Lines[change.Line+1:]...)
			}
		case DeleteLineChange:
			// Re-insert the deleted line
			if change.Line <= len(b.Lines) {
				newLine := NewGapBuffer(change.OldData)
				b.Lines = append(b.Lines[:change.Line], append([]*GapBuffer{newLine}, b.Lines[change.Line:]...)...)
			}
		}

		b.UndoStack.recording = wasRecording
	}

	// Restore cursor position
	w.SetCursorLine(block.OldCursor.Line)
	w.SetCursorCol(block.OldCursor.Col)

	return true
}

func (b *Buffer) Redo(w *Window) bool {
	if b.UndoStack == nil {
		return false
	}

	block := b.UndoStack.Redo()
	if block == nil {
		return false
	}

	// Apply changes in FORWARD order
	for _, change := range block.Changes {
		// Temporarily disable recording while we redo
		wasRecording := b.UndoStack.recording
		b.UndoStack.recording = false

		switch change.Type {
		case SetLineChange:
			// Apply new data
			if change.Line >= 0 && change.Line < len(b.Lines) {
				b.Lines[change.Line].Set(change.NewData)
			}
		case InsertLineChange:
			// Re-insert the line
			if change.Line <= len(b.Lines) {
				newLine := NewGapBuffer(change.NewData)
				b.Lines = append(b.Lines[:change.Line], append([]*GapBuffer{newLine}, b.Lines[change.Line:]...)...)
			}
		case DeleteLineChange:
			// Re-delete the line
			if change.Line >= 0 && change.Line < len(b.Lines) {
				b.Lines = append(b.Lines[:change.Line], b.Lines[change.Line+1:]...)
			}
		}

		b.UndoStack.recording = wasRecording
	}

	// Restore cursor position
	w.SetCursorLine(block.NewCursor.Line)
	w.SetCursorCol(block.NewCursor.Col)

	return true
}

// ==================================================
// Setters
// ==================================================

// Buffer.SetFilename: Set the filename associated with this buffer. This is
// typically the path to the file on disk that this buffer represents.
func (b *Buffer) SetFilename(filename string) {
	b.Filename = filename
}

// Buffer.SetFiletype: Set the filetype of this buffer. The filetype is used
// for syntax highlighting and other language-specific features.
func (b *Buffer) SetFiletype(filetype string) {
	b.Filetype = filetype
}

// Buffer.SetLines: Replace all lines in the buffer with the provided lines.
// This is useful when loading a file or resetting buffer content.
func (b *Buffer) SetLines(lines []string) {
	b.Lines = make([]*GapBuffer, len(lines))
	for i, line := range lines {
		b.Lines[i] = NewGapBuffer(line)
	}
}

// Buffer.SetModified: Set the modified flag for this buffer. A modified buffer
// has unsaved changes that differ from the file on disk.
func (b *Buffer) SetModified(modified bool) {
	b.Modified = modified
}

// Buffer.SetLoaded: Set the loaded flag for this buffer. A loaded buffer has
// its content in memory, while an unloaded buffer exists only as metadata.
func (b *Buffer) SetLoaded(loaded bool) {
	b.Loaded = loaded
}

// Buffer.SetListed: Set the listed flag for this buffer. A listed buffer appears
// in buffer lists (like :ls), while an unlisted buffer is hidden from normal
// buffer navigation.
func (b *Buffer) SetListed(listed bool) {
	b.Listed = listed
}

// Buffer.SetType: Set the buffers type. This type is used to determine handling
// of I/O functions.
func (b *Buffer) SetType(t BufferType) {
	b.Type = t
}