<?php
/**
 * Debug Log Handler
 *
 * Handles debug log retrieval and file operations.
 *
 * @package Accessibility_Audio_TTS
 */

namespace Accessibility_Audio_TTS\Admin\Utils;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Debug Log Handler
 *
 * Single Responsibility: Managing debug log files and content.
 */
class Debug_Log_Handler {

	/**
	 * Handle getting debug log via AJAX
	 */
	public function handle_get_debug_log() {
		if ( ! $this->validate_debug_log_request() ) {
			return;
		}

		$lines    = $this->get_requested_lines();
		$log_file = $this->get_log_file_path();

		if ( ! $this->log_file_exists( $log_file ) ) {
			$this->send_file_not_found_response( $lines );
			return;
		}

		$log_content = $this->get_log_content( $log_file, $lines );
		$this->send_log_content_response( $log_content, $lines, $log_file );
	}

	/**
	 * Validates the debug log request permissions and security
	 *
	 * @return bool
	 */
	private function validate_debug_log_request() {
		if ( ! current_user_can( 'manage_options' ) ) {
			wp_send_json_error( __( 'Permission denied', 'accessibility-audio-tts-text-to-speech-for-articles' ) );
			return false;
		}

		$nonce = isset( $_POST['nonce'] ) ? sanitize_text_field( wp_unslash( $_POST['nonce'] ) ) : '';
		if ( ! wp_verify_nonce( $nonce, 'accessibility_audio_tts_debug_nonce' ) ) {
			wp_send_json_error( __( 'Invalid nonce', 'accessibility-audio-tts-text-to-speech-for-articles' ) );
			return false;
		}

		return true;
	}

	/**
	 * Gets the number of lines requested with validation
	 *
	 * @return int
	 */
	private function get_requested_lines() {
        // phpcs:ignore WordPress.Security.NonceVerification.Missing -- Called from methods that verify nonce
		$lines = isset( $_POST['lines'] ) ? absint( wp_unslash( $_POST['lines'] ) ) : 50;
		return max( 10, min( 200, $lines ) ); // Minimum 10, maximum 200 lines.
	}

	/**
	 * Gets the debug log file path
	 *
	 * @return string
	 */
	private function get_log_file_path() {
		return \Accessibility_Audio_TTS\Core\Privacy_Lifecycle::latest_log_file();
	}

	/**
	 * Checks if log file exists
	 *
	 * @param string $log_file Log file path.
	 * @return bool
	 */
	private function log_file_exists( $log_file ) {
		return '' !== $log_file && ! is_link( $log_file ) && is_file( $log_file ) && is_readable( $log_file );
	}

	/**
	 * Sends response when log file doesn't exist
	 *
	 * @param int $lines Number of lines requested.
	 */
	private function send_file_not_found_response( $lines ) {
		wp_send_json_success(
			array(
				'log'             => __( 'Debug log does not exist', 'accessibility-audio-tts-text-to-speech-for-articles' ),
				'lines_requested' => $lines,
				'file_exists'     => false,
			)
		);
	}

	/**
	 * Gets log content from file
	 *
	 * @param string $log_file Log file path.
	 * @param int    $lines Number of lines to retrieve.
	 * @return string
	 */
	private function get_log_content( $log_file, $lines ) {
		return $this->tail_file( $log_file, $lines );
	}

	/**
	 * Sends successful log content response
	 *
	 * @param string $log_content Log content.
	 * @param int    $lines Number of lines requested.
	 * @param string $log_file Log file path.
	 */
	private function send_log_content_response( $log_content, $lines, $log_file ) {
		wp_send_json_success(
			array(
				'log'             => $log_content,
				'lines_requested' => $lines,
				'lines_returned'  => substr_count( $log_content, "\n" ),
				'file_size'       => filesize( $log_file ),
				'file_exists'     => true,
				'timestamp'       => current_time( 'mysql' ),
			)
		);
	}

	/**
	 * Get last N lines from file (like tail in bash)
	 *
	 * @param string $file File path.
	 * @param int    $lines Number of lines.
	 * @return string
	 */
	private function tail_file( $file, $lines = 50 ) {
		return \Accessibility_Audio_TTS\Core\Privacy_Lifecycle::read_log_tail( $file, $lines );
	}

	/**
	 * Reads content from small files
	 *
	 * @param string $file File path.
	 * @param int    $lines Number of lines.
	 * @return string
	 */
	private function read_small_file( $file, $lines ) {
		return $this->tail_file( $file, $lines );
	}

	/**
	 * Reads content from large files by reading backwards
	 *
	 * @param string $file File path.
	 * @param int    $lines Number of lines.
	 * @return string
	 */
	private function read_large_file( $file, $lines ) {
		// Fallback to full read and slice lines (avoids direct fopen/fclose).
		return $this->read_small_file( $file, $lines );
	}
}