grindlemire/go-tui code browser

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package tui

import (
	"fmt"
	"time"
)

// AppOption is a functional option for configuring an App.
type AppOption func(*App) error

// InlineStartupMode controls how inline mode initializes the visible terminal
// viewport when an app starts.
type InlineStartupMode int

const (
	// InlineStartupPreserveVisible keeps existing visible rows on launch.
	// Unknown history is modeled conservatively so stale rows drain naturally as
	// new PrintAbove/PrintAboveln content is appended.
	InlineStartupPreserveVisible InlineStartupMode = iota

	// InlineStartupFreshViewport clears the visible viewport immediately.
	// Existing visible rows are discarded rather than pushed into scrollback.
	InlineStartupFreshViewport

	// InlineStartupSoftReset clears the visible viewport by pushing rows upward
	// via newline flow, preserving previous visible rows in scrollback.
	InlineStartupSoftReset
)

// WithInputLatency sets the polling timeout for the event reader.
// Default is InputLatencyBlocking (blocks until input arrives).
// Use a positive duration (e.g. 50ms) for polling mode.
// A value of 0 is not allowed and will return an error.
func WithInputLatency(d time.Duration) AppOption {
	return func(a *App) error {
		if d == 0 {
			return fmt.Errorf("input latency of 0 (busy polling) is not allowed; use a positive duration or InputLatencyBlocking")
		}
		a.inputLatency = d
		return nil
	}
}

// WithFrameRate sets the target frame rate for the render loop.
// Default is 60 fps (16ms frame duration). Valid range is 1-240 fps.
func WithFrameRate(fps int) AppOption {
	return func(a *App) error {
		if fps < 1 {
			return fmt.Errorf("frame rate must be at least 1 fps")
		}
		if fps > 240 {
			return fmt.Errorf("frame rate cannot exceed 240 fps")
		}
		a.frameDuration = time.Second / time.Duration(fps)
		return nil
	}
}

// WithEventQueueSize sets the capacity of the event queue buffer.
// Default is 256. Must be at least 1.
//
// Note: keyboard and mouse events use a separate lossless queue.
// Background state updates (from QueueUpdate) use a bounded queue
// that drops the oldest update when full to prevent backpressure.
func WithEventQueueSize(size int) AppOption {
	return func(a *App) error {
		if size < 1 {
			return fmt.Errorf("event queue size must be at least 1")
		}
		a.eventQueueSize = size
		return nil
	}
}

// WithGlobalKeyHandler sets a handler that runs before dispatching to focused element.
// If the handler returns true, the event is consumed and not dispatched further.
// Use this for app-level key bindings like quit.
func WithGlobalKeyHandler(fn func(KeyEvent) bool) AppOption {
	return func(a *App) error {
		a.globalKeyHandler = fn
		return nil
	}
}

// WithRoot sets the root element after app initialization.
func WithRoot(root *Element) AppOption {
	return func(a *App) error {
		a.pendingRootApply = func(app *App) {
			app.SetRoot(root)
		}
		return nil
	}
}

// WithRootView sets a Viewable root after app initialization.
func WithRootView(view Viewable) AppOption {
	return func(a *App) error {
		a.pendingRootApply = func(app *App) {
			app.SetRootView(view)
		}
		return nil
	}
}

// WithRootComponent sets a Component root after app initialization.
func WithRootComponent(component Component) AppOption {
	return func(a *App) error {
		a.pendingRootApply = func(app *App) {
			app.SetRootComponent(component)
		}
		return nil
	}
}

// WithMouse explicitly enables mouse event reporting.
// Use this to enable mouse in inline mode (where it's disabled by default).
func WithMouse() AppOption {
	return func(a *App) error {
		a.mouseEnabled = true
		a.mouseExplicit = true
		return nil
	}
}

// WithPostRenderHook sets a callback that runs after every render cycle.
func WithPostRenderHook(fn func()) AppOption {
	return func(a *App) error {
		a.postRenderHook = fn
		return nil
	}
}

// WithoutMouse explicitly disables mouse event reporting.
// Use this to disable mouse in full screen mode (where it's enabled by default).
func WithoutMouse() AppOption {
	return func(a *App) error {
		a.mouseEnabled = false
		a.mouseExplicit = true
		return nil
	}
}

// WithCursor keeps the cursor visible during app execution.
// By default, the cursor is hidden.
func WithCursor() AppOption {
	return func(a *App) error {
		a.cursorVisible = true
		return nil
	}
}

// WithInlineHeight enables inline widget mode.
// The TUI manages only the bottom N rows of the terminal, allowing normal
// terminal output above. Use PrintAbove() or PrintAboveln() to print
// scrolling content above the widget.
// For goroutine-safe queued writes, use QueuePrintAbove() /
// QueuePrintAboveln().
//
// In inline mode:
//   - Alternate screen is not used, so terminal history is preserved
//   - Mouse events are disabled by default, allowing native terminal scrollback
//   - Use WithMouse() to explicitly enable mouse if needed
//   - Startup behavior can be configured with WithInlineStartupMode()
func WithInlineHeight(rows int) AppOption {
	return func(a *App) error {
		if rows < 1 {
			return fmt.Errorf("inline height must be at least 1 row")
		}
		a.inlineHeight = rows
		return nil
	}
}

// WithInlineStartupMode configures how inline mode handles existing visible
// terminal content at app startup.
func WithInlineStartupMode(mode InlineStartupMode) AppOption {
	return func(a *App) error {
		switch mode {
		case InlineStartupPreserveVisible, InlineStartupFreshViewport, InlineStartupSoftReset:
			a.inlineStartupMode = mode
			return nil
		default:
			return fmt.Errorf("invalid inline startup mode: %d", mode)
		}
	}
}

// WithOnSuspend sets a callback that runs before the app suspends (Ctrl+Z).
// Use this to save state or pause timers before the process stops.
func WithOnSuspend(fn func()) AppOption {
	return func(a *App) error {
		a.onSuspend = fn
		return nil
	}
}

// WithOnResume sets a callback that runs after the app resumes (fg).
// Use this to restart timers or refresh stale data.
func WithOnResume(fn func()) AppOption {
	return func(a *App) error {
		a.onResume = fn
		return nil
	}
}

// WithLegacyKeyboard forces legacy keyboard mode, skipping Kitty keyboard
// protocol negotiation. By default, go-tui attempts the Kitty protocol
// and falls back to legacy if the terminal doesn't support it.
func WithLegacyKeyboard() AppOption {
	return func(a *App) error {
		a.legacyKeyboard = true
		return nil
	}
}