package app

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

func validateScopedTarget(root, target, policy string, requireDir bool) (scopedDir, error) {
	cleanRoot := strings.TrimSpace(root)
	cleanTarget := strings.TrimSpace(target)
	if cleanRoot == "" {
		return scopedDir{}, fmt.Errorf("cleanup policy %s: root path is required", policy)
	}
	if cleanTarget == "" {
		return scopedDir{}, fmt.Errorf("cleanup policy %s: target path is required", policy)
	}

	rootAbs, err := filepath.Abs(cleanRoot)
	if err != nil {
		return scopedDir{}, fmt.Errorf("cleanup policy %s: resolve root %q: %w", policy, cleanRoot, err)
	}
	targetAbs, err := filepath.Abs(cleanTarget)
	if err != nil {
		return scopedDir{}, fmt.Errorf("cleanup policy %s: resolve target %q: %w", policy, cleanTarget, err)
	}

	rel, err := filepath.Rel(rootAbs, targetAbs)
	if err != nil {
		return scopedDir{}, fmt.Errorf("cleanup policy %s: relative path from %q to %q: %w", policy, rootAbs, targetAbs, err)
	}
	if rel == "." {
		return scopedDir{}, fmt.Errorf("cleanup policy %s: refusing to delete root directory %q", policy, rootAbs)
	}
	if rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) {
		return scopedDir{}, fmt.Errorf("cleanup policy %s: refusing to delete path outside root: root=%q target=%q", policy, rootAbs, targetAbs)
	}

	info, err := os.Lstat(targetAbs)
	if err != nil {
		if os.IsNotExist(err) {
			return scopedDir{RootAbs: rootAbs, TargetAbs: targetAbs, Exists: false}, nil
		}
		return scopedDir{}, fmt.Errorf("cleanup policy %s: stat target %q: %w", policy, targetAbs, err)
	}
	if info.Mode()&os.ModeSymlink != 0 {
		return scopedDir{}, fmt.Errorf("cleanup policy %s: refusing to delete symlink path %q", policy, targetAbs)
	}
	if requireDir && !info.IsDir() {
		return scopedDir{}, fmt.Errorf("cleanup policy %s: target %q is not a directory", policy, targetAbs)
	}
	if !requireDir && info.IsDir() {
		return scopedDir{}, fmt.Errorf("cleanup policy %s: target %q is a directory", policy, targetAbs)
	}
	return scopedDir{RootAbs: rootAbs, TargetAbs: targetAbs, Exists: true}, nil
}

func validateCleanRoot(root, policy string) (string, bool, error) {
	cleanRoot := strings.TrimSpace(root)
	if cleanRoot == "" {
		return "", false, fmt.Errorf("cleanup policy %s: root path is required", policy)
	}
	rootAbs, err := filepath.Abs(cleanRoot)
	if err != nil {
		return "", false, fmt.Errorf("cleanup policy %s: resolve root %q: %w", policy, cleanRoot, err)
	}
	info, err := os.Lstat(rootAbs)
	if err != nil {
		if os.IsNotExist(err) {
			return rootAbs, false, nil
		}
		return "", false, fmt.Errorf("cleanup policy %s: stat root %q: %w", policy, rootAbs, err)
	}
	if info.Mode()&os.ModeSymlink != 0 {
		return "", false, fmt.Errorf("cleanup policy %s: refusing to clean symlink root %q", policy, rootAbs)
	}
	if !info.IsDir() {
		return "", false, fmt.Errorf("cleanup policy %s: root %q is not a directory", policy, rootAbs)
	}
	return rootAbs, true, nil
}