use crate::registry::{self, SYS_REG_PATH, USER_REG_PATH};
use chrono::Local;
use std::path::PathBuf;
use winreg::enums::*;

fn backup_base_dir() -> PathBuf {
    dirs::home_dir()
        .unwrap_or_else(|| PathBuf::from("."))
        .join(".patheditor")
        .join("backups")
}

/// 获取备份目录路径
pub fn get_appdata_dir() -> String {
    backup_base_dir().to_string_lossy().to_string()
}

/// 备份当前注册表中的系统 PATH 和用户 PATH
/// 在保存前调用，备份的是注册表中的当前值（保存前的状态）
pub fn backup_registry(custom_dir: Option<String>) -> Result<String, String> {
    let backup_dir = match custom_dir {
        Some(ref dir) if !dir.is_empty() => {
            let p = std::path::PathBuf::from(dir);
            let normalized = dir.replace('/', "\\").to_lowercase();
            if normalized.starts_with("c:\\windows\\") || normalized.starts_with("c:\\program files\\") {
                return Err("不允许备份到系统目录".into());
            }
            p
        }
        _ => backup_base_dir(),
    };

    std::fs::create_dir_all(&backup_dir).map_err(|e| format!("无法创建备份目录: {}", e))?;

    // 读取当前注册表中的值（保存前的旧值）
    let sys_paths = registry::load_paths(HKEY_LOCAL_MACHINE, SYS_REG_PATH, "系统")?;
    let user_paths = registry::load_paths(HKEY_CURRENT_USER, USER_REG_PATH, "用户")?;

    let timestamp = Local::now().format("%Y%m%d_%H%M%S_%3f");
    let filename = format!("path_backup_{}.txt", timestamp);
    let filepath = backup_dir.join(&filename);

    let mut content = String::new();
    content.push_str(&format!(
        "PathEditor Backup - {}\n",
        Local::now().format("%Y-%m-%d %H:%M:%S")
    ));
    content.push_str("\n[System PATH]\n");
    for path in &sys_paths {
        content.push_str(&format!("{}\n", path));
    }
    content.push_str("\n[User PATH]\n");
    for path in &user_paths {
        content.push_str(&format!("{}\n", path));
    }

    std::fs::write(&filepath, &content).map_err(|e| format!("无法写入备份文件: {}", e))?;

    let result = filepath.to_string_lossy().to_string();
    log::info!("备份已保存到: {}", result);
    Ok(result)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn get_appdata_dir_returns_non_empty() {
        assert!(!get_appdata_dir().is_empty());
    }

    #[test]
    fn backup_registry_with_custom_dir() {
        let dir = std::env::temp_dir().join("patheditor_test_backup_custom");
        let _ = std::fs::remove_dir_all(&dir);
        std::fs::create_dir_all(&dir).unwrap();

        let result = backup_registry(Some(dir.to_string_lossy().to_string()));
        // 可能因无权限读取注册表而失败，但不应 panic
        if let Ok(path) = result {
            assert!(path.contains("patheditor_test_backup_custom"));
            let _ = std::fs::remove_dir_all(&dir);
        }
    }

    #[test]
    fn backup_registry_default_dir_no_panic() {
        // 验证不传参时不会 panic
        let _ = backup_registry(None);
    }
}