grindlemire/go-tui code browser

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package tui

import (
	"bytes"
	"io"
	"os"
)

// ANSITerminal implements Terminal using ANSI escape sequences.
// It works with any terminal emulator that supports ANSI codes.
type ANSITerminal struct {
	out           io.Writer     // Output destination (usually os.Stdout)
	in            io.Reader     // Input source (usually os.Stdin)
	caps          Capabilities  // Terminal capabilities
	lastStyle     Style         // Last emitted style (for optimization)
	esc           *escBuilder   // Escape sequence builder
	inFd          uintptr       // File descriptor for input (needed for raw mode)
	outFd         uintptr       // File descriptor for output (needed for size query)
	rawState      *rawModeState // Platform-specific raw mode state
	kittyKeyboard bool          // true if Kitty keyboard protocol was successfully negotiated
}

// NewANSITerminal creates a new ANSI terminal with auto-detected capabilities.
// The output writer is typically os.Stdout and the input reader is os.Stdin.
func NewANSITerminal(out io.Writer, in io.Reader) (*ANSITerminal, error) {
	caps := DetectCapabilities()

	t := &ANSITerminal{
		out:  out,
		in:   in,
		caps: caps,
		esc:  newEscBuilder(4096),
	}

	// Try to get file descriptors for size queries and raw mode
	if f, ok := out.(*os.File); ok {
		t.outFd = f.Fd()
	}
	if f, ok := in.(*os.File); ok {
		t.inFd = f.Fd()
	}

	return t, nil
}

// NewANSITerminalWithCaps creates a new ANSI terminal with explicit capabilities.
// Use this when you want to override auto-detection.
func NewANSITerminalWithCaps(out io.Writer, in io.Reader, caps Capabilities) *ANSITerminal {
	t := &ANSITerminal{
		out:  out,
		in:   in,
		caps: caps,
		esc:  newEscBuilder(4096),
	}

	if f, ok := out.(*os.File); ok {
		t.outFd = f.Fd()
	}
	if f, ok := in.(*os.File); ok {
		t.inFd = f.Fd()
	}

	return t
}

// Size returns the terminal dimensions.
// Returns a default of 80x24 if the size cannot be determined.
func (t *ANSITerminal) Size() (width, height int) {
	w, h, err := getTerminalSize(int(t.outFd))
	if err != nil {
		return 80, 24 // Sensible default
	}
	return w, h
}

// Flush writes the given cell changes to the terminal.
// It optimizes cursor movement and style changes for efficiency.
func (t *ANSITerminal) Flush(changes []CellChange) {
	if len(changes) == 0 {
		return
	}

	t.esc.Reset()
	lastX, lastY := -1, -1
	openLink := "" // currently-open OSC 8 hyperlink ("" = none)

	for _, ch := range changes {
		// Erase-to-end-of-line: clear the row's tail with ESC[K. Reset style
		// first so the erased cells take the default background and stay blank
		// (terminals trim such cells when copying a selection). Checked before
		// the continuation guard below, since this change carries a zero Cell
		// (Width 0) that would otherwise be mistaken for a continuation cell.
		if ch.EraseToEOL {
			if t.caps.Hyperlinks {
				openLink = linkTransition(t.esc, openLink, "")
			}
			t.esc.MoveTo(ch.X, ch.Y)
			if !t.lastStyle.Equal(NewStyle()) {
				t.esc.ResetStyle()
				t.lastStyle = NewStyle()
			}
			t.esc.EraseToEndOfLine()
			lastX, lastY = -1, -1
			continue
		}

		// Skip continuation cells entirely - they represent the second column
		// of a wide character, which was already rendered by the primary cell.
		// Processing them would incorrectly move the cursor backwards.
		if ch.Cell.IsContinuation() {
			continue
		}

		// Optimize cursor movement
		needsMove := false
		if ch.Y != lastY {
			needsMove = true
		} else if ch.X != lastX+1 {
			// Not sequential on the same row
			needsMove = true
		}

		if needsMove {
			// A non-contiguous jump ends any open hyperlink run.
			if t.caps.Hyperlinks {
				openLink = linkTransition(t.esc, openLink, "")
			}
			t.esc.MoveTo(ch.X, ch.Y)
		}

		// Open/close OSC 8 hyperlinks around contiguous same-link runs.
		if t.caps.Hyperlinks {
			openLink = linkTransition(t.esc, openLink, ch.Cell.Link)
		}

		// Only emit style changes when style differs
		if !ch.Cell.Style.Equal(t.lastStyle) {
			t.esc.SetStyle(ch.Cell.Style, t.caps)
			t.lastStyle = ch.Cell.Style
		}

		// Write the cluster glyph (empty cell renders as a space).
		r := ch.Cell.Rune
		if r == 0 {
			r = ' '
		}
		t.esc.WriteRune(r)
		if ch.Cell.Combining != "" {
			t.esc.WriteString(ch.Cell.Combining)
		}

		lastX = ch.X
		if ch.Cell.Width > 1 {
			// Wide character advances cursor by its width
			lastX = ch.X + int(ch.Cell.Width) - 1
		}
		lastY = ch.Y
	}

	if t.caps.Hyperlinks {
		linkTransition(t.esc, openLink, "")
	}

	t.out.Write(t.esc.Bytes())
}

// Clear clears the entire terminal screen.
func (t *ANSITerminal) Clear() {
	t.esc.Reset()
	t.esc.ResetStyle()
	t.esc.MoveTo(0, 0)      // Home first
	t.esc.ClearScreen()     // ESC[2J - clear visible screen
	t.esc.ClearScrollback() // ESC[3J - also clear scrollback (helps with resize)
	t.esc.MoveTo(0, 0)      // Ensure cursor at home after clear
	t.out.Write(t.esc.Bytes())
	t.lastStyle = NewStyle()
}

// ClearToEnd clears from cursor position to end of screen.
func (t *ANSITerminal) ClearToEnd() {
	t.esc.Reset()
	t.esc.ClearToEndOfScreen()
	t.out.Write(t.esc.Bytes())
}

// SetCursor moves the cursor to the specified position (0-indexed).
func (t *ANSITerminal) SetCursor(x, y int) {
	t.esc.Reset()
	t.esc.MoveTo(x, y)
	t.out.Write(t.esc.Bytes())
}

// HideCursor makes the cursor invisible.
func (t *ANSITerminal) HideCursor() {
	t.esc.Reset()
	t.esc.HideCursor()
	t.out.Write(t.esc.Bytes())
}

// ShowCursor makes the cursor visible.
func (t *ANSITerminal) ShowCursor() {
	t.esc.Reset()
	t.esc.ShowCursor()
	t.out.Write(t.esc.Bytes())
}

// EnterRawMode puts the terminal into raw mode.
// This is implemented in platform-specific files.
func (t *ANSITerminal) EnterRawMode() error {
	state, err := enableRawMode(int(t.inFd))
	if err != nil {
		return err
	}
	t.rawState = state
	return nil
}

// ExitRawMode restores the terminal to its previous mode.
// This is implemented in platform-specific files.
func (t *ANSITerminal) ExitRawMode() error {
	if t.rawState == nil {
		return nil
	}
	err := disableRawMode(t.rawState)
	t.rawState = nil
	return err
}

// EnterAltScreen switches to the alternate screen buffer.
func (t *ANSITerminal) EnterAltScreen() {
	t.esc.Reset()
	t.esc.EnterAltScreen()
	t.out.Write(t.esc.Bytes())
}

// ExitAltScreen switches back to the main screen buffer.
func (t *ANSITerminal) ExitAltScreen() {
	t.esc.Reset()
	t.esc.ExitAltScreen()
	t.out.Write(t.esc.Bytes())
}

// EnableMouse enables mouse event reporting.
func (t *ANSITerminal) EnableMouse() {
	t.esc.Reset()
	t.esc.EnableMouse()
	t.out.Write(t.esc.Bytes())
}

// DisableMouse disables mouse event reporting.
func (t *ANSITerminal) DisableMouse() {
	t.esc.Reset()
	t.esc.DisableMouse()
	t.out.Write(t.esc.Bytes())
}

// EnableAltScroll enables alternate-scroll mode (mouse wheel -> cursor keys).
func (t *ANSITerminal) EnableAltScroll() {
	t.esc.Reset()
	t.esc.EnableAltScroll()
	t.out.Write(t.esc.Bytes())
}

// DisableAltScroll disables alternate-scroll mode.
func (t *ANSITerminal) DisableAltScroll() {
	t.esc.Reset()
	t.esc.DisableAltScroll()
	t.out.Write(t.esc.Bytes())
}

// EnableKittyKeyboard pushes Kitty keyboard protocol mode onto the terminal's
// stack without querying. Use this on resume when the terminal is already known
// to support the protocol.
func (t *ANSITerminal) EnableKittyKeyboard() {
	t.esc.Reset()
	t.esc.KittyKeyboardPush(1)
	t.out.Write(t.esc.Bytes())
	t.kittyKeyboard = true
	t.caps.KittyKeyboard = true
}

// DisableKittyKeyboard pops the Kitty keyboard protocol mode from the stack.
func (t *ANSITerminal) DisableKittyKeyboard() {
	if !t.kittyKeyboard {
		return
	}
	t.popKittyKeyboard()
	t.kittyKeyboard = false
	t.caps.KittyKeyboard = false
}

// popKittyKeyboard sends the pop escape sequence to undo a Kitty push.
func (t *ANSITerminal) popKittyKeyboard() {
	t.esc.Reset()
	t.esc.KittyKeyboardPop()
	t.out.Write(t.esc.Bytes())
}

// parseKittyQueryResponse checks if the response bytes contain a valid
// Kitty keyboard protocol query response (CSI ? flags u) where flags
// includes bit 1 (disambiguate).
func parseKittyQueryResponse(data []byte) bool {
	// Look for: \x1b [ ? <digits> u
	// Loop bound ensures i+3 is always in bounds.
	for i := 0; i < len(data)-3; i++ {
		if data[i] == 0x1b && data[i+1] == '[' && data[i+2] == '?' {
			// Parse digits after '?'
			j := i + 3
			flags := 0
			hasDigit := false
			for j < len(data) && data[j] >= '0' && data[j] <= '9' {
				flags = flags*10 + int(data[j]-'0')
				hasDigit = true
				j++
			}
			// Check for 'u' terminator and that flag 1 (disambiguate) is set
			if hasDigit && j < len(data) && data[j] == 'u' && flags&1 != 0 {
				return true
			}
		}
	}
	return false
}

// BeginSyncUpdate starts a synchronized update block.
// Output is buffered until EndSyncUpdate, then displayed atomically.
func (t *ANSITerminal) BeginSyncUpdate() {
	t.esc.Reset()
	t.esc.BeginSyncUpdate()
	t.out.Write(t.esc.Bytes())
}

// EndSyncUpdate ends a synchronized update block.
func (t *ANSITerminal) EndSyncUpdate() {
	t.esc.Reset()
	t.esc.EndSyncUpdate()
	t.out.Write(t.esc.Bytes())
}

// Caps returns the terminal's capabilities.
func (t *ANSITerminal) Caps() Capabilities {
	return t.caps
}

// SetCaps updates the terminal's capabilities.
// This is useful after detecting capabilities at runtime.
func (t *ANSITerminal) SetCaps(caps Capabilities) {
	t.caps = caps
}

// ResetStyle resets the style tracking, forcing the next Flush to emit style codes.
func (t *ANSITerminal) ResetStyle() {
	t.lastStyle = Style{Fg: RGBColor(255, 255, 255)} // Use something that won't match
}

// Writer returns the underlying writer for direct output.
// Use with caution as it bypasses the terminal's buffering.
func (t *ANSITerminal) Writer() io.Writer {
	return t.out
}

// WriteDirect writes raw bytes directly to the terminal output.
// Use for escape sequences or content that doesn't need processing.
func (t *ANSITerminal) WriteDirect(b []byte) (int, error) {
	return t.out.Write(b)
}

// BufferedWriter provides a buffered writer for efficient batch writes.
type BufferedWriter struct {
	buf bytes.Buffer
	out io.Writer
}

// NewBufferedWriter creates a buffered writer wrapping the given writer.
func NewBufferedWriter(out io.Writer) *BufferedWriter {
	return &BufferedWriter{out: out}
}

// Write writes bytes to the buffer.
func (w *BufferedWriter) Write(p []byte) (int, error) {
	return w.buf.Write(p)
}

// Flush writes the buffer contents to the underlying writer and clears the buffer.
func (w *BufferedWriter) Flush() error {
	_, err := w.out.Write(w.buf.Bytes())
	w.buf.Reset()
	return err
}