rustbook/examples/ex03/src/file_ops.rs

use std::fs::{self, File};
use std::io::{self, Read, Write};
use std::path::Path;

use crate::error::FileError;
use crate::traits::{ContentAnalyzer, ContentTransformer, FileProcessor, LineFilter};

/// 安全的文件读取器
pub struct SafeFileReader {
    path: String,
}

impl SafeFileReader {
    /// 创建新的文件读取器
    /// 
    /// # 参数
    /// * `path` - 文件路径
    pub fn new(path: String) -> Self {
        SafeFileReader { path }
    }
    
    /// 读取文件内容
    /// 
    /// # 返回
    /// * `Result<String, FileError>` - 文件内容或错误
    pub fn read(&self) -> Result<String, FileError> {
        let path = Path::new(&self.path);
        
        if !path.exists() {
            return Err(FileError::NotFound(self.path.clone()));
        }
        
        fs::read_to_string(path)
            .map_err(|e| match e.kind() {
                io::ErrorKind::PermissionDenied => FileError::PermissionDenied(self.path.clone()),
                _ => FileError::ReadError(e.to_string()),
            })
    }
    
    /// 读取并处理文件内容
    /// 
    /// # 参数
    /// * `processor` - 实现了FileProcessor trait的处理器
    /// 
    /// # 返回
    /// * `Result<String, FileError>` - 处理后的内容或错误
    pub fn read_and_process<P>(&self, processor: &P) -> Result<String, FileError>
    where
        P: FileProcessor,
    {
        let content = self.read()?;
        
        processor.process(&content)
            .map_err(|e| FileError::ProcessError(format!("{:?}", e)))
    }
    
    /// 读取并分析文件内容
    /// 
    /// # 参数
    /// * `analyzer` - 实现了ContentAnalyzer trait的分析器
    /// 
    /// # 返回
    /// * `Result<T, FileError>` - 分析结果或错误
    pub fn read_and_analyze<A, T>(&self, analyzer: &A) -> Result<T, FileError>
    where
        A: ContentAnalyzer<T>,
    {
        let content = self.read()?;
        
        analyzer.analyze(&content)
            .map_err(|e| FileError::ProcessError(format!("{:?}", e)))
    }
    
    /// 读取并过滤文件内容
    /// 
    /// # 参数
    /// * `filter` - 实现了LineFilter trait的过滤器
    /// 
    /// # 返回
    /// * `Result<String, FileError>` - 过滤后的内容或错误
    pub fn read_and_filter<F>(&self, filter: &F) -> Result<String, FileError>
    where
        F: LineFilter,
    {
        let content = self.read()?;
        
        let filtered = content
            .lines()
            .filter(|line| filter.should_keep(line))
            .collect::<Vec<&str>>()
            .join("\n");
            
        Ok(filtered)
    }
}

/// 安全的文件写入器
pub struct SafeFileWriter {
    path: String,
}

impl SafeFileWriter {
    /// 创建新的文件写入器
    /// 
    /// # 参数
    /// * `path` - 文件路径
    pub fn new(path: String) -> Self {
        SafeFileWriter { path }
    }
    
    /// 写入内容到文件
    /// 
    /// # 参数
    /// * `content` - 要写入的内容
    /// 
    /// # 返回
    /// * `Result<(), FileError>` - 成功或错误
    pub fn write(&self, content: &str) -> Result<(), FileError> {
        let mut file = File::create(&self.path)
            .map_err(|e| match e.kind() {
                io::ErrorKind::PermissionDenied => FileError::PermissionDenied(self.path.clone()),
                _ => FileError::WriteError(e.to_string()),
            })?;
            
        file.write_all(content.as_bytes())
            .map_err(|e| FileError::WriteError(e.to_string()))?;
            
        Ok(())
    }
    
    /// 转换并写入内容到文件
    /// 
    /// # 参数
    /// * `content` - 原始内容
    /// * `transformer` - 实现了ContentTransformer trait的转换器
    /// 
    /// # 返回
    /// * `Result<(), FileError>` - 成功或错误
    pub fn transform_and_write<T>(&self, content: &str, transformer: &T) -> Result<(), FileError>
    where
        T: ContentTransformer,
    {
        let transformed = transformer.transform(content)
            .map_err(|e| FileError::ProcessError(format!("{:?}", e)))?;
            
        self.write(&transformed)
    }
}

/// 文件处理管道
/// 
/// 允许链式调用多个处理器
pub struct ProcessingPipeline<'a> {
    processors: Vec<&'a dyn FileProcessor<Error = String>>,
}

impl<'a> ProcessingPipeline<'a> {
    /// 创建新的处理管道
    pub fn new() -> Self {
        ProcessingPipeline {
            processors: Vec::new(),
        }
    }
    
    /// 添加处理器到管道
    /// 
    /// # 参数
    /// * `processor` - 实现了FileProcessor trait的处理器
    pub fn add_processor(&mut self, processor: &'a dyn FileProcessor<Error = String>) -> &mut Self {
        self.processors.push(processor);
        self
    }
    
    /// 执行处理管道
    /// 
    /// # 参数
    /// * `content` - 要处理的内容
    /// 
    /// # 返回
    /// * `Result<String, FileError>` - 处理后的内容或错误
    pub fn process(&self, content: &str) -> Result<String, FileError> {
        let mut result = content.to_string();
        
        for processor in &self.processors {
            result = processor.process(&result)
                .map_err(|e| FileError::ProcessError(e))?;
        }
        
        Ok(result)
    }
}

impl<'a> Default for ProcessingPipeline<'a> {
    fn default() -> Self {
        Self::new()
    }
}