package skills

import (
	"bytes"
	"crypto/sha256"
	"fmt"
	"io/fs"
	"os"
	"path"
	"path/filepath"
	"strings"
	"sync"

	"cursor/internal/appdata"
	"cursor/internal/securefile"
)

var operationMu sync.Mutex

func checkManagedPaths(project, name string) error {
	paths := []string{filepath.Join(project, ".cursor"), skillsDir(project), skillTargetDir(project, name), projectCommandsDir(project)}
	for _, file := range commandFileNames(name) {
		paths = append(paths, filepath.Join(projectCommandsDir(project), file))
	}
	for _, entry := range paths {
		info, err := os.Lstat(entry)
		if os.IsNotExist(err) {
			continue
		}
		if err != nil {
			return err
		}
		if info.Mode()&os.ModeSymlink != 0 {
			return fmt.Errorf("安全保护：拒绝通过符号链接修改 %s", entry)
		}
	}
	target := skillTargetDir(project, name)
	if _, err := os.Stat(target); os.IsNotExist(err) {
		return nil
	}
	return filepath.WalkDir(target, func(p string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.Type()&os.ModeSymlink != 0 {
			return fmt.Errorf("安全保护：skill 内含符号链接 %s", p)
		}
		return nil
	})
}

func backupBeforeReplace(target string, next []byte) error {
	previous, err := os.ReadFile(target)
	if os.IsNotExist(err) {
		return nil
	}
	if err != nil {
		return err
	}
	if bytes.Equal(previous, next) {
		return nil
	}
	id := fmt.Sprintf("%x", sha256.Sum256([]byte(target)))
	dir := filepath.Join(appdata.DataRootPath(), "skill-backups", id[:16])
	if err = securefile.PrivateDir(dir); err != nil {
		return err
	}
	file, err := os.CreateTemp(dir, filepath.Base(target)+"-*.bak")
	if err != nil {
		return err
	}
	name := file.Name()
	if err = file.Close(); err != nil {
		return err
	}
	return securefile.Write(name, previous)
}

func ensureNoCustomSkillFiles(project, name string) error {
	allowed := map[string]bool{}
	err := fs.WalkDir(builtinFS, path.Join(builtinRoot, name), func(p string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if !d.IsDir() {
			rel := strings.TrimPrefix(p, path.Join(builtinRoot, name)+"/")
			allowed[rel] = true
		}
		return nil
	})
	if err != nil {
		return err
	}
	for _, file := range retiredSkillFiles[name] {
		allowed[file] = true
	}
	target := skillTargetDir(project, name)
	if _, err = os.Stat(target); os.IsNotExist(err) {
		return nil
	}
	return filepath.WalkDir(target, func(p string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if !d.IsDir() {
			rel, _ := filepath.Rel(target, p)
			if !allowed[filepath.ToSlash(rel)] {
				return fmt.Errorf("skill 含自建文件 %s，已保留；请先备份后手动移除", strings.TrimPrefix(p, target))
			}
		}
		return nil
	})
}