<?php
/**
 * Turns one request into Human, a named agent, or Unknown.
 *
 * @package AgentStamp
 */

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

class AgentStamp_Classifier {

	/** @var AgentStamp_Signature */
	private $signature;

	public function __construct( AgentStamp_Signature $signature ) {
		$this->signature = $signature;
	}

	/**
	 * @param int $now
	 * @return array{verdict:string,name:string,confidence:string,detail:string}
	 */
	public function classify( AgentStamp_Request $request, $now ) {
		$signed = $this->signature->check( $request, $now );
		if ( 'valid' === $signed['status'] ) {
			$detail = $signed['detail'];
			$claimed = self::claimed_name( $request->user_agent );
			if ( '' !== $claimed && $claimed !== $signed['name'] ) {
				$detail .= ' User-agent claimed ' . $claimed . '.';
			}
			return array(
				'verdict'    => 'agent',
				'name'       => $signed['name'],
				'confidence' => 'signed',
				'detail'     => $detail,
			);
		}

		if ( 'invalid' === $signed['status'] ) {
			$claimed = self::claimed_name( $request->user_agent );
			$detail  = $signed['detail'];
			if ( '' !== $claimed ) {
				$detail .= ' User-agent claimed ' . $claimed . ', which was not treated as proof.';
			}
			return array(
				'verdict'    => 'unknown',
				'name'       => '',
				'confidence' => 'none',
				'detail'     => $detail,
			);
		}

		$ai = AgentStamp_Agents::match_ai_ua( $request->user_agent );
		if ( '' !== $ai ) {
			return array(
				'verdict'    => 'agent',
				'name'       => $ai,
				'confidence' => 'declared',
				'detail'     => 'User-agent matches ' . $ai . '. The request was not signed.',
			);
		}

		$crawler = AgentStamp_Agents::match_ai_crawler( $request->user_agent );
		if ( '' !== $crawler ) {
			return array(
				'verdict'    => 'unknown',
				'name'       => '',
				'confidence' => 'none',
				'detail'     => 'User-agent names ' . $crawler . ', a crawler. Crawlers do not check out, so the name was not used.',
			);
		}

		if ( AgentStamp_Agents::is_other_bot( $request->user_agent ) ) {
			return array(
				'verdict'    => 'unknown',
				'name'       => '',
				'confidence' => 'none',
				'detail'     => 'A crawler user-agent that is not a named shopping agent.',
			);
		}

		if ( AgentStamp_Agents::is_human_browser( $request->user_agent ) ) {
			return array(
				'verdict'    => 'human',
				'name'       => '',
				'confidence' => 'browser',
				'detail'     => 'Ordinary browser user-agent, no agent signature.',
			);
		}

		$detail = '' === trim( $request->user_agent )
			? 'No user-agent on the checkout request.'
			: 'User-agent is not a browser and not a published AI agent.';

		return array(
			'verdict'    => 'unknown',
			'name'       => '',
			'confidence' => 'none',
			'detail'     => $detail,
		);
	}

	/**
	 * An order source that is an API client or a commerce protocol, not the checkout page.
	 *
	 * @param string $via WooCommerce created_via.
	 * @return bool
	 */
	public static function is_api_channel( $via ) {
		$via = (string) $via;
		if ( 'rest-api' === $via ) {
			return true;
		}
		return 1 === preg_match( '/(?:^|[-_])(?:ucp|acp|ap2|mcp|agent|agentic|chatgpt|openai|gemini|copilot|perplexity)(?:$|[-_])/i', $via );
	}

	/**
	 * Orders that did not come through the store's checkout page.
	 *
	 * A signed or declared agent keeps its name. Anything else is API, named by
	 * the client's user-agent product, or by the channel when there is none.
	 *
	 * @param array{verdict:string,name:string,confidence:string,detail:string} $result
	 * @param string $user_agent
	 * @param string $via WooCommerce created_via.
	 * @return array{verdict:string,name:string,confidence:string,detail:string}
	 */
	public static function for_channel( array $result, $user_agent, $via ) {
		$via = (string) $via;
		if ( in_array( $via, array( '', 'checkout', 'store-api', 'admin' ), true ) ) {
			return $result;
		}
		if ( 'agent' === $result['verdict'] ) {
			$result['detail'] .= ' Created through ' . $via . ', not the checkout page.';
			return $result;
		}
		if ( 'unknown' === $result['verdict'] && false !== stripos( $result['detail'], 'Signature' ) ) {
			return $result;
		}

		$client = '';
		$first  = strtok( trim( (string) $user_agent ), ' ' );
		if ( false !== $first && 0 !== strpos( $first, 'Mozilla/' ) && preg_match( '/^([A-Za-z][A-Za-z0-9._-]{0,40})(?:\/|$)/', $first, $match ) ) {
			$client = $match[1];
		}
		$name = '' !== $client ? $client : $via;

		return array(
			'verdict'    => 'api',
			'name'       => $name,
			'confidence' => 'channel',
			'detail'     => 'Created through ' . $via . ', not the checkout page. ' . ( '' !== $client ? 'The client called itself ' . $client . '.' : 'The client gave no product name.' ) . ' No agent signature.',
		);
	}

	/**
	 * @param string $user_agent
	 * @return string
	 */
	private static function claimed_name( $user_agent ) {
		$claimed = AgentStamp_Agents::match_ai_ua( $user_agent );
		return '' !== $claimed ? $claimed : AgentStamp_Agents::match_ai_crawler( $user_agent );
	}

	/**
	 * Short label for the order list.
	 *
	 * @param array{verdict:string,name:string,confidence:string,detail:string} $result
	 * @return string
	 */
	public static function label( array $result ) {
		if ( 'human' === $result['verdict'] ) {
			return 'Human';
		}
		if ( 'agent' === $result['verdict'] ) {
			$how = ( 'signed' === $result['confidence'] ) ? 'signed' : ( 'payment' === $result['confidence'] ? 'payment' : 'declared' );
			return $result['name'] . ' (' . $how . ')';
		}
		if ( 'unattended' === $result['verdict'] ) {
			return 'Unattended';
		}
		if ( 'likely' === $result['verdict'] ) {
			return 'Likely agent';
		}
		if ( 'api' === $result['verdict'] ) {
			return 'API (' . $result['name'] . ')';
		}
		return 'Unknown';
	}
}