<?php
/**
 * Chat History logging manager.
 *
 * @package AISupportAssistant\Chat
 */

// phpcs:disable WordPress.DB.DirectDatabaseQuery

namespace AISupportAssistant\Chat;

use AISupportAssistant\Database\DatabaseManager;
use AISupportAssistant\Helpers\Logger;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Class ChatHistory
 */
class ChatHistory {

	/**
	 * Log a chat conversation turn in the database.
	 *
	 * @param string $session_id User session ID.
	 * @param string $question   User query.
	 * @param string $answer     AI response.
	 * @param string $provider   AI provider (openai, gemini).
	 * @param string $model      AI model.
	 * @return bool True on success.
	 */
	public static function add_log( string $session_id, string $question, string $answer, string $provider, string $model, string $outcome = 'completed' ): bool {
		if ( ! \AISupportAssistant\Admin\Settings::get_instance()->get( 'enable_chat_history', 1 ) ) { return true; }
		return SessionLock::run( $session_id, static function () use ( $session_id, $question, $answer, $provider, $model, $outcome ) {
			return self::append_log( $session_id, $question, $answer, $provider, $model, $outcome );
		} );
	}

	private static function append_log( string $session_id, string $question, string $answer, string $provider, string $model, string $outcome ): bool {
		if ( ! \AISupportAssistant\Admin\Settings::get_instance()->get( 'enable_chat_history', 1 ) ) {
			return true;
		}
		self::purge_expired();
		global $wpdb;
		DatabaseManager::maybe_upgrade_chat_table();
		$table = DatabaseManager::get_chat_history_table();

		$now      = current_time( 'mysql' );
		$existing = $wpdb->get_row(
			$wpdb->prepare( 'SELECT * FROM %i WHERE session_id = %s LIMIT 1', $table, $session_id )
		);

		if ( $existing ) {
			$messages = array();
			if ( ! empty( $existing->messages ) ) {
				$decoded = json_decode( $existing->messages, true );
				if ( is_array( $decoded ) ) {
					$messages = $decoded;
				}
			}

			// If messages array is empty, populate from the existing initial question/answer.
			if ( empty( $messages ) && ( ! empty( $existing->question ) || ! empty( $existing->answer ) ) ) {
				if ( ! empty( $existing->question ) ) {
					$messages[] = array(
						'role'    => 'user',
						'content' => $existing->question,
						'time'    => $existing->created_at,
					);
				}
				if ( ! empty( $existing->answer ) ) {
					$messages[] = array(
						'role'    => 'assistant',
						'content' => $existing->answer,
						'time'    => $existing->created_at,
					);
				}
			}

			// Append new user turn and AI response.
			$messages[] = array(
				'role'    => 'user',
				'content' => $question,
				'time'    => $now,
			);
			$messages = array_slice( $messages, -100 );
			$messages[] = array(
				'role'    => 'assistant',
				'content' => $answer,
				'outcome' => $outcome,
				'provider' => $provider,
				'model' => $model,
				'time'    => $now,
			);

			$result = $wpdb->update(
				$table,
				array(
					'question'      => $question,
					'answer'        => $answer,
					'messages'      => wp_json_encode( $messages ),
					'provider'      => $provider,
					'model'         => $model,
					'status'        => 'completed',
					'error_message' => null,
					'updated_at'    => $now,
				),
				array( 'id' => $existing->id ),
				array( '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s' ),
				array( '%d' )
			);

			return false !== $result;
		}

		$messages = array(
			array(
				'role'    => 'user',
				'content' => $question,
				'time'    => $now,
			),
			array(
				'role'    => 'assistant',
				'content' => $answer,
				'outcome' => $outcome,
				'provider' => $provider,
				'model' => $model,
				'time'    => $now,
			),
		);

		$result = $wpdb->insert(
			$table,
			array(
				'session_id'    => $session_id,
				'question'      => $question,
				'answer'        => $answer,
				'messages'      => wp_json_encode( $messages ),
				'provider'      => $provider,
				'model'         => $model,
				'status'        => 'completed',
				'error_message' => null,
				'created_at'    => $now,
				'updated_at'    => $now,
			),
			array( '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s' )
		);

		return false !== $result;
	}

	/**
	 * Record a failed chat request for administrator diagnostics.
	 *
	 * @param string $session_id User session ID.
	 * @param string $question   User query.
	 * @param string $provider   AI provider.
	 * @param string $model      AI model.
	 * @param string $error      Internal failure detail.
	 * @return bool True if the failure record was saved.
	 */
	public static function log_failure( string $session_id, string $question, string $provider, string $model, string $error ): bool {
		if ( ! \AISupportAssistant\Admin\Settings::get_instance()->get( 'enable_chat_history', 1 ) ) { return true; }
		return SessionLock::run( $session_id, static function () use ( $session_id, $question, $provider, $model, $error ) {
			return self::append_failure( $session_id, $question, $provider, $model, $error );
		} );
	}

	private static function append_failure( string $session_id, string $question, string $provider, string $model, string $error ): bool {
		if ( ! \AISupportAssistant\Admin\Settings::get_instance()->get( 'enable_chat_history', 1 ) ) {
			return true;
		}
		self::purge_expired();
		global $wpdb;

		DatabaseManager::maybe_upgrade_chat_table();
		$table    = DatabaseManager::get_chat_history_table();
		$now      = current_time( 'mysql' );
		$error    = self::redact_api_keys( sanitize_textarea_field( $error ) );
		$error    = substr( $error, 0, 4000 );
		$existing = $wpdb->get_row(
			$wpdb->prepare( 'SELECT * FROM %i WHERE session_id = %s LIMIT 1', $table, $session_id )
		);
		$messages = array();

		if ( $existing && ! empty( $existing->messages ) ) {
			$decoded = json_decode( $existing->messages, true );
			if ( is_array( $decoded ) ) {
				$messages = $decoded;
			}
		}
		if ( $existing && empty( $messages ) ) {
			if ( ! empty( $existing->question ) ) {
				$messages[] = array(
					'role'    => 'user',
					'content' => $existing->question,
					'time'    => $existing->created_at,
				);
			}
			if ( ! empty( $existing->answer ) ) {
				$messages[] = array(
					'role'    => 'assistant',
					'content' => $existing->answer,
					'time'    => $existing->created_at,
				);
			}
		}
		$messages[] = array(
			'role'    => 'user',
			'content' => $question,
			'outcome' => 'failed',
			'provider' => $provider,
			'model' => $model,
			'time'    => $now,
		);
		$messages = array_slice( $messages, -100 );

		$data = array(
			'question'      => $question,
			'answer'        => '',
			'messages'      => wp_json_encode( $messages ),
			'provider'      => $provider,
			'model'         => $model,
			'status'        => 'failed',
			'error_message' => $error,
			'updated_at'    => $now,
		);

		if ( $existing ) {
			$result = $wpdb->update( $table, $data, array( 'id' => $existing->id ) );
		} else {
			$data['session_id'] = $session_id;
			$data['created_at'] = $now;
			$result             = $wpdb->insert( $table, $data );
		}

		if ( false === $result ) {
			Logger::error( 'Unable to save failed chat request to admin history.', array( 'error' => $wpdb->last_error ) );
			return false;
		}

		return true;
	}

	/**
	 * Remove configured API credentials from provider error details.
	 *
	 * @param string $message Error detail.
	 * @return string Redacted error detail.
	 */
	private static function redact_api_keys( string $message ): string {
		$settings = \AISupportAssistant\Admin\Settings::get_instance();
		$keys     = array(
			(string) $settings->get_secret( 'openai_api_key' ),
			(string) $settings->get_secret( 'gemini_api_key' ),
			(string) \AISupportAssistant\Helpers\ConnectorHelper::get_connector_api_key( 'openai' ),
			(string) \AISupportAssistant\Helpers\ConnectorHelper::get_connector_api_key( 'google' ),
			(string) \AISupportAssistant\Helpers\ConnectorHelper::get_connector_api_key( 'gemini' ),
		);
		foreach ( array_filter( $keys ) as $key ) {
			$message = str_replace( $key, '[redacted]', $message );
		}
		return $message;
	}

	/**
	 * Log a chat conversation turn in the database (alias for add_log).
	 *
	 * @param string $session_id User session ID.
	 * @param string $question   User query.
	 * @param string $answer     AI response.
	 * @param string $provider   AI provider (openai, gemini).
	 * @param string $model      AI model.
	 * @return bool True on success.
	 */
	public static function log( string $session_id, string $question, string $answer, string $provider, string $model, string $outcome = 'completed' ): bool {
		return self::add_log( $session_id, $question, $answer, $provider, $model, $outcome );
	}

	/**
	 * Retrieve dialogue history for a session ID.
	 *
	 * @param string $session_id User session ID.
	 * @param int    $limit      Max turns to fetch.
	 * @return array Dialogue turns.
	 */
	public static function get_history( string $session_id, int $limit = 5 ): array {
		self::purge_expired();
		global $wpdb;
		$table = DatabaseManager::get_chat_history_table();

		$existing = $wpdb->get_row(
			$wpdb->prepare( 'SELECT * FROM %i WHERE session_id = %s LIMIT 1', $table, $session_id )
		);

		if ( ! $existing ) {
			return array();
		}

		$history = array();
		if ( ! empty( $existing->messages ) ) {
			$messages = json_decode( $existing->messages, true );
			if ( is_array( $messages ) ) {
				$temp_user = '';
				foreach ( $messages as $msg ) {
					if ( ( $msg['role'] ?? '' ) === 'user' ) {
						$temp_user = $msg['content'] ?? '';
					} elseif ( ( $msg['role'] ?? '' ) === 'assistant' && ! empty( $temp_user ) ) {
						$history[] = array(
							'question' => $temp_user,
							'answer'   => $msg['content'] ?? '',
						);
						$temp_user = '';
					}
				}
			}
		}

		if ( empty( $history ) && ! empty( $existing->question ) ) {
			$history[] = array(
				'question' => $existing->question,
				'answer'   => $existing->answer,
			);
		}

		if ( count( $history ) > $limit ) {
			$history = array_slice( $history, -$limit );
		}

		return $history;
	}

	/**
	 * Stream chat logs as a download CSV file.
	 *
	 * @return void
	 */
	public static function export_csv(): void {
		if ( ! current_user_can( 'manage_options' ) ) {
			wp_die( esc_html__( 'Unauthorized access.', 'ai-support-assistant' ) );
		}

		self::purge_expired();
		global $wpdb;
		$table = DatabaseManager::get_chat_history_table();
		$logs  = $wpdb->get_results(
			$wpdb->prepare(
				'SELECT * FROM %i ORDER BY created_at DESC',
				$table
			),
			ARRAY_A
		);

		// Clean headers.
		header( 'Content-Type: text/csv; charset=utf-8' );
		header( 'Content-Disposition: attachment; filename="ai-support-assistant-history-' . gmdate( 'Y-m-d' ) . '.csv"' );
		header( 'Pragma: no-cache' );
		header( 'Expires: 0' );

		$output = fopen( 'php://output', 'w' );
		if ( false === $output ) {
			exit;
		}

		// Write column headers.
		fputcsv( $output, array( 'ID', 'Session ID', 'Question', 'Answer', 'Provider', 'Model', 'Status', 'Error', 'Asked At' ), ',', '"', '' );

		if ( ! empty( $logs ) ) {
			foreach ( $logs as $row ) {
				fputcsv(
					$output,
					array_map(
						array( self::class, 'sanitize_csv_cell' ),
						array(
							$row['id'],
							$row['session_id'],
							$row['question'],
							$row['answer'],
							$row['provider'],
							$row['model'],
							$row['status'] ?? 'completed',
							$row['error_message'] ?? '',
							$row['created_at'],
						)
					),
					',',
					'"',
					''
				);
			}
		}

		fclose( $output ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fclose
		exit;
	}

	/** Remove inactive conversations after 30 days. */
	public static function purge_expired(): void {
		global $wpdb;
		$wpdb->query(
			$wpdb->prepare(
				'DELETE FROM %i WHERE COALESCE(updated_at, created_at) < %s',
				DatabaseManager::get_chat_history_table(),
				wp_date( 'Y-m-d H:i:s', time() - 30 * DAY_IN_SECONDS, wp_timezone() )
			)
		);
	}

	/**
	 * Keep untrusted CSV values from being evaluated as spreadsheet formulas.
	 *
	 * @param mixed $value Exported cell value.
	 * @return string Safe spreadsheet cell.
	 */
	public static function sanitize_csv_cell( $value ): string {
		$value = (string) $value;
		return preg_match( '/^[\s\x00-\x20]*[=+@-]/u', $value ) ? "'" . $value : $value;
	}
}