package runner

import (
	"context"
	_ "embed"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"time"
)

//go:embed scan.jsx
var scanScript []byte

// WriteScanScript writes the embedded scanner JSX into workDir and returns its path.
func WriteScanScript(workDir string) (string, error) {
	dir := filepath.Join(workDir, "scripts")
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return "", err
	}
	p := filepath.Join(dir, "scan.jsx")
	if err := os.WriteFile(p, scanScript, 0o644); err != nil {
		return "", err
	}
	return p, nil
}

// RunScan runs the After Effects template scanner against aepPath and returns the
// JSON the script writes to outPath. afterfxPath must be afterfx.exe (the AE app,
// not aerender.exe — only the app can run ScriptUI/ExtendScript).
//
// afterfx -r runs the script and the script calls app.quit(); we still poll for the
// output file because afterfx can return before the file is flushed.
func RunScan(ctx context.Context, afterfxPath, aepPath, workDir, outPath string) ([]byte, error) {
	scriptPath, err := WriteScanScript(workDir)
	if err != nil {
		return nil, fmt.Errorf("write scan script: %w", err)
	}
	if err := os.MkdirAll(filepath.Dir(outPath), 0o755); err != nil {
		return nil, err
	}
	_ = os.Remove(outPath)
	_ = os.Remove(outPath + ".error")

	cmd := exec.CommandContext(ctx, afterfxPath, "-r", scriptPath)
	cmd.Env = append(os.Environ(), "FR_SCAN_AEP="+aepPath, "FR_SCAN_OUT="+outPath)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	// afterfx may exit non-zero on app.quit() — don't treat the exit code as fatal;
	// success is determined by the presence of the output JSON file.
	_ = cmd.Run()

	for {
		if eb, rerr := os.ReadFile(outPath + ".error"); rerr == nil && len(eb) > 0 {
			return nil, fmt.Errorf("scan script error: %s", string(eb))
		}
		if b, rerr := os.ReadFile(outPath); rerr == nil && len(b) > 0 {
			return b, nil
		}
		select {
		case <-ctx.Done():
			return nil, fmt.Errorf("scan timed out waiting for %s", outPath)
		case <-time.After(2 * time.Second):
		}
	}
}