// Package paste handles writing text to the system clipboard and simulating
// Ctrl+V / Cmd+V to paste into the currently focused application.
package paste

import (
	"fmt"
	"log/slog"
	"runtime"
	"time"

	"github.com/go-vgo/robotgo"
	"golang.design/x/clipboard"
)

const keyDelay = 50 * time.Millisecond

// Init initializes the clipboard subsystem. Must be called once at startup.
func Init() error {
	return clipboard.Init()
}

// Paste writes text to the clipboard and simulates a paste keystroke.
// Falls back to clipboard-only if key simulation fails.
func Paste(text string) error {
	// Write to clipboard
	clipboard.Write(clipboard.FmtText, []byte(text))

	// Small delay to ensure clipboard is ready
	time.Sleep(keyDelay)

	// Simulate paste keystroke
	if err := simulatePaste(); err != nil {
		slog.Warn("key simulation failed, text is in clipboard", "err", err)
		return fmt.Errorf("key simulation failed (text is in clipboard): %w", err)
	}

	return nil
}

// ClipboardOnly writes text to clipboard without simulating a keystroke.
func ClipboardOnly(text string) {
	clipboard.Write(clipboard.FmtText, []byte(text))
}

func simulatePaste() error {
	var modifier, key string
	switch runtime.GOOS {
	case "darwin":
		modifier, key = "command", "v"
	case "linux", "windows":
		modifier, key = "ctrl", "v"
	default:
		return fmt.Errorf("unsupported platform: %s", runtime.GOOS)
	}

	robotgo.KeyDown(modifier)
	time.Sleep(20 * time.Millisecond)
	robotgo.KeyTap(key)
	time.Sleep(20 * time.Millisecond)
	robotgo.KeyUp(modifier)
	return nil
}