//! Custom File Appender Implementation
//!
//! This module provides custom file appender functionality with enhanced
//! rotation and directory management capabilities.

use crate::{LoggerError, Result};
use std::path::{Path, PathBuf};
use tracing_appender::rolling::{RollingFileAppender, Rotation};

/// Create a custom rolling file appender with enhanced configuration
pub fn create_rolling_appender<P: AsRef<Path>>(
    directory: P,
    file_name_prefix: &str,
    rotation: AppenderRotation,
) -> Result<RollingFileAppender> {
    let directory = directory.as_ref();
    
    // Ensure directory exists
    std::fs::create_dir_all(directory)
        .map_err(|e| LoggerError::DirectoryCreation(
            format!("Failed to create directory {}: {}", directory.display(), e)
        ))?;
    
    let rotation = match rotation {
        AppenderRotation::Hourly => Rotation::HOURLY,
        AppenderRotation::Daily => Rotation::DAILY,
        AppenderRotation::Never => Rotation::NEVER,
    };
    
    let appender = tracing_appender::rolling::Builder::new()
        .rotation(rotation)
        .filename_prefix(file_name_prefix)
        .filename_suffix("log")
        .build(directory)
        .map_err(|e| LoggerError::Config(format!("Failed to create rolling appender: {}", e)))?;
    
    Ok(appender)
}

/// Enhanced rotation configuration
#[derive(Debug, Clone, Copy)]
pub enum AppenderRotation {
    /// Rotate files every hour
    Hourly,
    /// Rotate files every day
    Daily,
    /// Never rotate (single file)
    Never,
}

/// File appender builder for more complex configurations
pub struct FileAppenderBuilder {
    directory: PathBuf,
    file_prefix: String,
    file_suffix: String,
    rotation: AppenderRotation,
    max_files: Option<usize>,
}

impl FileAppenderBuilder {
    /// Create a new file appender builder
    pub fn new<P: AsRef<Path>>(directory: P) -> Self {
        Self {
            directory: directory.as_ref().to_path_buf(),
            file_prefix: "log".to_string(),
            file_suffix: "log".to_string(),
            rotation: AppenderRotation::Hourly,
            max_files: None,
        }
    }
    
    /// Set the file prefix
    pub fn file_prefix<S: Into<String>>(mut self, prefix: S) -> Self {
        self.file_prefix = prefix.into();
        self
    }
    
    /// Set the file suffix
    pub fn file_suffix<S: Into<String>>(mut self, suffix: S) -> Self {
        self.file_suffix = suffix.into();
        self
    }
    
    /// Set the rotation policy
    pub fn rotation(mut self, rotation: AppenderRotation) -> Self {
        self.rotation = rotation;
        self
    }
    
    /// Set maximum number of files to keep (for cleanup)
    pub fn max_files(mut self, max: usize) -> Self {
        self.max_files = Some(max);
        self
    }
    
    /// Build the file appender
    pub fn build(self) -> Result<RollingFileAppender> {
        // Ensure directory exists
        std::fs::create_dir_all(&self.directory)
            .map_err(|e| LoggerError::DirectoryCreation(
                format!("Failed to create directory {}: {}", self.directory.display(), e)
            ))?;
        
        let rotation = match self.rotation {
            AppenderRotation::Hourly => Rotation::HOURLY,
            AppenderRotation::Daily => Rotation::DAILY,
            AppenderRotation::Never => Rotation::NEVER,
        };
        
        let appender = tracing_appender::rolling::Builder::new()
            .rotation(rotation)
            .filename_prefix(&self.file_prefix)
            .filename_suffix(&self.file_suffix)
            .build(&self.directory)
            .map_err(|e| LoggerError::Config(format!("Failed to create rolling appender: {}", e)))?;
        
        // Perform cleanup if max_files is set
        if let Some(max_files) = self.max_files {
            if let Err(e) = cleanup_old_files(&self.directory, &self.file_prefix, max_files) {
                tracing::warn!("Failed to cleanup old log files: {}", e);
            }
        }
        
        Ok(appender)
    }
}

/// Clean up old log files, keeping only the most recent ones
fn cleanup_old_files<P: AsRef<Path>>(
    directory: P,
    file_prefix: &str,
    max_files: usize,
) -> Result<()> {
    let directory = directory.as_ref();
    
    let mut log_files = Vec::new();
    
    // Read directory and collect log files
    let entries = std::fs::read_dir(directory)
        .map_err(|e| LoggerError::Io(e))?;
    
    for entry in entries {
        let entry = entry.map_err(|e| LoggerError::Io(e))?;
        let path = entry.path();
        
        if let Some(file_name) = path.file_name().and_then(|n| n.to_str()) {
            if file_name.starts_with(file_prefix) && file_name.ends_with(".log") {
                if let Ok(metadata) = entry.metadata() {
                    if let Ok(modified) = metadata.modified() {
                        log_files.push((path, modified));
                    }
                }
            }
        }
    }
    
    // Sort by modification time (newest first)
    log_files.sort_by(|a, b| b.1.cmp(&a.1));
    
    // Remove old files if we exceed max_files
    if log_files.len() > max_files {
        for (old_file, _) in log_files.iter().skip(max_files) {
            if let Err(e) = std::fs::remove_file(old_file) {
                tracing::warn!("Failed to remove old log file {}: {}", old_file.display(), e);
            } else {
                tracing::debug!("Removed old log file: {}", old_file.display());
            }
        }
    }
    
    Ok(())
}

/// Utility function to get the current log file path for a given configuration
pub fn get_current_log_file<P: AsRef<Path>>(
    directory: P,
    file_prefix: &str,
    rotation: AppenderRotation,
) -> PathBuf {
    let directory = directory.as_ref();
    
    match rotation {
        AppenderRotation::Hourly => {
            let now = chrono::Utc::now();
            let timestamp = now.format("%Y-%m-%d-%H");
            directory.join(format!("{}.{}.log", file_prefix, timestamp))
        }
        AppenderRotation::Daily => {
            let now = chrono::Utc::now();
            let timestamp = now.format("%Y-%m-%d");
            directory.join(format!("{}.{}.log", file_prefix, timestamp))
        }
        AppenderRotation::Never => {
            directory.join(format!("{}.log", file_prefix))
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use tempfile::TempDir;
    use std::time::Duration;

    #[test]
    fn test_create_rolling_appender() {
        let temp_dir = TempDir::new().unwrap();
        let directory = temp_dir.path().join("logs");
        
        let appender = create_rolling_appender(&directory, "test", AppenderRotation::Hourly).unwrap();
        
        // Verify directory was created
        assert!(directory.exists());
    }

    #[test]
    fn test_file_appender_builder() {
        let temp_dir = TempDir::new().unwrap();
        let directory = temp_dir.path().join("logs");
        
        let appender = FileAppenderBuilder::new(&directory)
            .file_prefix("custom")
            .file_suffix("txt")
            .rotation(AppenderRotation::Daily)
            .max_files(5)
            .build()
            .unwrap();
        
        assert!(directory.exists());
    }

    #[test]
    fn test_get_current_log_file() {
        let temp_dir = TempDir::new().unwrap();
        let directory = temp_dir.path();
        
        // Test hourly rotation
        let hourly_file = get_current_log_file(directory, "test", AppenderRotation::Hourly);
        assert!(hourly_file.to_string_lossy().contains("test."));
        assert!(hourly_file.extension().unwrap() == "log");
        
        // Test daily rotation
        let daily_file = get_current_log_file(directory, "test", AppenderRotation::Daily);
        assert!(daily_file.to_string_lossy().contains("test."));
        assert!(daily_file.extension().unwrap() == "log");
        
        // Test never rotation
        let never_file = get_current_log_file(directory, "test", AppenderRotation::Never);
        assert_eq!(never_file, directory.join("test.log"));
    }

    #[test]
    fn test_cleanup_old_files() {
        let temp_dir = TempDir::new().unwrap();
        let directory = temp_dir.path();
        
        // Create some test log files
        for i in 0..10 {
            let file_path = directory.join(format!("test.{}.log", i));
            std::fs::write(&file_path, "test content").unwrap();
            
            // Sleep briefly to ensure different modification times
            std::thread::sleep(Duration::from_millis(10));
        }
        
        // Cleanup, keeping only 5 files
        cleanup_old_files(directory, "test", 5).unwrap();
        
        // Count remaining files
        let remaining_files: Vec<_> = std::fs::read_dir(directory)
            .unwrap()
            .filter_map(|entry| {
                let entry = entry.ok()?;
                let name = entry.file_name().to_string_lossy().to_string();
                if name.starts_with("test.") && name.ends_with(".log") {
                    Some(name)
                } else {
                    None
                }
            })
            .collect();
        
        assert_eq!(remaining_files.len(), 5);
    }
}