//go:build linux

// Headless Linux hosts (Docker, CI, VPS) have no DISPLAY. Install Xvfb + scrot:
//
//	apt-get install -y xvfb scrot
//	Xvfb :99 -screen 0 1280x720x24 &
//	export DISPLAY=:99
//
// Or pass a one-shot custom command via Crucible screenshot (command field), e.g.:
//
//	DISPLAY=:99 scrot -q 55 -o /tmp/s.jpg && base64 -w0 /tmp/s.jpg
//
// See docs/E2E_VALIDATION.md § Linux headless screenshot.

package client

import (
	"encoding/base64"
	"fmt"
	"os"
	"os/exec"
	"strings"
)

func capturePlatformScreenshot(customCmd string) (string, error) {
	if strings.TrimSpace(customCmd) != "" {
		out, err := exec.Command("/bin/sh", "-c", customCmd).CombinedOutput()
		if err != nil {
			return "", fmt.Errorf("%w: %s", err, strings.TrimSpace(string(out)))
		}
		if b64 := extractScreenshotBase64(out); len(b64) >= 100 {
			return b64, nil
		}
		return "", fmt.Errorf("custom screenshot command returned no image data")
	}

	if raw, err := captureLinuxScreenshotJPEG(); err == nil && len(raw) >= 100 {
		return base64.StdEncoding.EncodeToString(raw), nil
	} else if err != nil {
		return "", err
	}
	return "", fmt.Errorf("screenshot failed: install scrot, imagemagick (import), or gnome-screenshot")
}

func captureLinuxScreenshotJPEG() ([]byte, error) {
	if scrot, err := exec.LookPath("scrot"); err == nil {
		tmp, err := os.CreateTemp("", "af-scr-*.jpg")
		if err != nil {
			return nil, err
		}
		path := tmp.Name()
		_ = tmp.Close()
		defer os.Remove(path)
		out, runErr := exec.Command(scrot, "-q", "55", path).CombinedOutput()
		if runErr != nil {
			return nil, fmt.Errorf("scrot: %v (%s)", runErr, strings.TrimSpace(string(out)))
		}
		return os.ReadFile(path)
	}

	if importCmd, err := exec.LookPath("import"); err == nil {
		tmp, err := os.CreateTemp("", "af-scr-*.jpg")
		if err != nil {
			return nil, err
		}
		path := tmp.Name()
		_ = tmp.Close()
		defer os.Remove(path)
		out, runErr := exec.Command(importCmd, "-window", "root", "-quality", "55", path).CombinedOutput()
		if runErr != nil {
			return nil, fmt.Errorf("import: %v (%s)", runErr, strings.TrimSpace(string(out)))
		}
		return os.ReadFile(path)
	}

	if gnome, err := exec.LookPath("gnome-screenshot"); err == nil {
		tmp, err := os.CreateTemp("", "af-scr-*.jpg")
		if err != nil {
			return nil, err
		}
		path := tmp.Name()
		_ = tmp.Close()
		defer os.Remove(path)
		out, runErr := exec.Command(gnome, "-f", path).CombinedOutput()
		if runErr != nil {
			return nil, fmt.Errorf("gnome-screenshot: %v (%s)", runErr, strings.TrimSpace(string(out)))
		}
		return os.ReadFile(path)
	}

	return nil, fmt.Errorf("no screenshot tool found (scrot, import, gnome-screenshot); headless hosts need xvfb — see docs/E2E_VALIDATION.md")
}