// Copyright (c) 2026 Storm Dragon
// SPDX-License-Identifier: GPL-3.0-or-later
package app

import (
	"context"
	"errors"
	"io"
	"net/url"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"

	"git.stormux.org/storm/cthulhu/internal/tentaclewire"
)

func readClipboardTarget(ctx context.Context, target string) (string, error) {
	command := exec.CommandContext(ctx, "xclip", "-selection", "clipboard", "-out", "-target", target)
	command.WaitDelay = time.Second
	pipe, err := command.StdoutPipe()
	if err != nil {
		return "", err
	}
	if err = command.Start(); err != nil {
		return "", err
	}
	data, readErr := io.ReadAll(io.LimitReader(pipe, 8193))
	if readErr != nil || len(data) > 8192 {
		command.Process.Kill()
		command.Wait()
		return "", errors.New("clipboard too large")
	}
	err = command.Wait()
	return string(data), err
}
func readTentacleClipboard(ctx context.Context) (tentaclewire.Item, error) {
	targets, err := readClipboardTarget(ctx, "TARGETS")
	if err != nil {
		return tentaclewire.Item{}, err
	}
	for _, target := range strings.Fields(targets) {
		if target == "text/uri-list" || target == "x-special/gnome-copied-files" {
			data, err := readClipboardTarget(ctx, target)
			if err != nil {
				return tentaclewire.Item{}, err
			}
			return singleClipboardURI(data)
		}
	}
	for _, target := range []string{"UTF8_STRING", "text/plain;charset=utf-8", "text/plain", "STRING"} {
		for _, available := range strings.Fields(targets) {
			if available == target {
				text, err := readClipboardTarget(ctx, target)
				return tentaclewire.Item{Text: text}, err
			}
		}
	}
	for _, target := range strings.Fields(targets) {
		if target == "image/png" {
			return clipboardPNG(ctx)
		}
	}
	return tentaclewire.Item{}, errors.New("clipboard has no transferable text or file")
}
func singleClipboardURI(data string) (tentaclewire.Item, error) {
	// GTK file managers can include a C-string terminator in the X selection.
	// Remove only that trailing byte; embedded NULs remain invalid URI data.
	data = strings.TrimSuffix(data, "\x00")
	var uris []string
	for _, line := range strings.Split(data, "\n") {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "#") || line == "copy" || line == "cut" {
			continue
		}
		uris = append(uris, line)
	}
	if len(uris) != 1 {
		return tentaclewire.Item{}, errors.New("copy exactly one file or folder")
	}
	parsed, err := url.Parse(uris[0])
	if err != nil || parsed.Scheme != "file" || parsed.Host != "" && parsed.Host != "localhost" || parsed.RawQuery != "" || parsed.Fragment != "" || !filepath.IsAbs(parsed.Path) || strings.ContainsRune(parsed.Path, '\x00') {
		return tentaclewire.Item{}, errors.New("local file path unavailable")
	}
	return tentaclewire.Item{Path: parsed.Path}, nil
}

func clipboardPNG(ctx context.Context) (tentaclewire.Item, error) {
	directory, err := os.MkdirTemp("", "cthulhu-clipboard-*")
	if err != nil {
		return tentaclewire.Item{}, err
	}
	keep := false
	defer func() {
		if !keep {
			os.RemoveAll(directory)
		}
	}()
	path := filepath.Join(directory, "clipboard.png")
	file, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0600)
	if err != nil {
		return tentaclewire.Item{}, err
	}
	defer file.Close()
	command := exec.CommandContext(ctx, "xclip", "-selection", "clipboard", "-out", "-target", "image/png")
	command.WaitDelay = time.Second
	pipe, err := command.StdoutPipe()
	if err != nil {
		return tentaclewire.Item{}, err
	}
	if err = command.Start(); err != nil {
		return tentaclewire.Item{}, err
	}
	count, copyErr := io.Copy(file, io.LimitReader(pipe, 32*1024*1024+1))
	if copyErr != nil || count > 32*1024*1024 {
		command.Process.Kill()
		command.Wait()
		return tentaclewire.Item{}, errors.New("clipboard image too large")
	}
	if err = command.Wait(); err != nil {
		return tentaclewire.Item{}, err
	}
	if count == 0 {
		return tentaclewire.Item{}, errors.New("empty clipboard image")
	}
	if err = file.Close(); err != nil {
		return tentaclewire.Item{}, err
	}
	keep = true
	return tentaclewire.Item{Path: path, Temporary: true}, nil
}
func copyTentacleText(ctx context.Context, value string) error {
	command := exec.CommandContext(ctx, "xclip", "-selection", "clipboard", "-in")
	command.Stdin = strings.NewReader(value)
	return command.Run()
}