package injection

import (
	"context"
	"fmt"
	"os"
	"os/exec"
	"strings"
	"time"
)

// clipboardPasteBackend copies text to the primary selection and pastes it
// with ydotool's layout-independent Shift+Insert key codes.
//
// This preserves the regular clipboard, is independent of the active keyboard
// layout, and delivers the whole string at once.
type clipboardPasteBackend struct {
	clipboard *clipboardBackend
	ydotool   *ydotoolBackend
}

func NewClipboardPasteBackend() Backend {
	return &clipboardPasteBackend{
		clipboard: NewClipboardBackend().(*clipboardBackend),
		ydotool:   NewYdotoolBackend().(*ydotoolBackend),
	}
}

func (c *clipboardPasteBackend) Name() string {
	return "clipboard-paste"
}

func (c *clipboardPasteBackend) Available() error {
	if err := c.clipboard.Available(); err != nil {
		return err
	}
	if err := c.ydotool.Available(); err != nil {
		return err
	}
	return nil
}

func (c *clipboardPasteBackend) Inject(ctx context.Context, text string, timeout time.Duration) error {
	ctx, cancel := context.WithTimeout(ctx, timeout)
	defer cancel()

	if err := c.Available(); err != nil {
		return err
	}
	// Shift+Insert pastes the primary selection, leaving the user's regular
	// clipboard untouched.
	primaryCopy := exec.CommandContext(ctx, "wl-copy", "--primary")
	primaryCopy.Stdin = strings.NewReader(text)
	if err := primaryCopy.Run(); err != nil {
		return fmt.Errorf("copy transcription to primary selection: %w", err)
	}
	// wl-copy returns before every client has observed the new selection. Give
	// the compositor a short chance to publish it; this is still perceived as
	// an immediate paste and avoids inserting the previous clipboard contents.
	select {
	case <-time.After(150 * time.Millisecond):
	case <-ctx.Done():
		return ctx.Err()
	}

	// Linux input event codes: KEY_LEFTSHIFT=42, KEY_INSERT=110. These keys do
	// not depend on the alphabetic layout, and Shift+Insert is widely supported.
	cmd := exec.CommandContext(ctx, "ydotool", "key", "42:1", "110:1", "110:0", "42:0")
	if socketPath := c.ydotool.getSocketPath(); socketPath != "" {
		cmd.Env = append(os.Environ(), "YDOTOOL_SOCKET="+socketPath)
	}
	if err := cmd.Run(); err != nil {
		return fmt.Errorf("paste primary selection with ydotool: %w", err)
	}
	return nil
}