<?php
/**
 * Shared request loop for AI providers called over HTTPS.
 *
 * @package TurtleReport
 */

namespace TurtleReport\Advisor;

use TurtleReport\Support\Text;

defined( 'ABSPATH' ) || exit;

/**
 * What every bring-your-own-key provider does the same way: one HTTPS request
 * from the server with the agency's key, a short automatic retry for rate
 * limits and server errors, and errors that name the real problem without
 * ever repeating the key. Each provider only says how to build its request,
 * read its answer and recognise its errors.
 */
abstract class HttpProvider implements Provider {

	/**
	 * Drops malformed scalar fields from an external error envelope.
	 *
	 * @param array $data Decoded provider reply.
	 * @return array
	 */
	public static function error_data( array $data ) {
		if ( isset( $data['error'] ) && is_array( $data['error'] ) ) {
			foreach ( array( 'message', 'type', 'status', 'param' ) as $field ) {
				if ( isset( $data['error'][ $field ] ) && ! is_string( $data['error'][ $field ] ) ) {
					unset( $data['error'][ $field ] );
				}
			}
			if ( isset( $data['error']['code'] ) && ! is_string( $data['error']['code'] ) && ! is_int( $data['error']['code'] ) ) {
				unset( $data['error']['code'] );
			}
		}
		if ( isset( $data['code'] ) && ! is_string( $data['code'] ) && ! is_int( $data['code'] ) ) {
			unset( $data['code'] );
		}
		return $data;
	}

	/** Automatic retries for temporary problems (rate limits, server errors). */
	const RETRIES = 2;

	/** Longest single wait before a retry, in seconds. */
	const MAX_WAIT = 8;

	/** Longest total waiting across retries, in seconds. */
	const MAX_TOTAL_WAIT = 12;

	/** Room for the model's own thinking on top of the longest answer. */
	const THINKING_ROOM = 2000;

	/**
	 * How to wait between retries (tests replace it).
	 *
	 * @var callable|null
	 */
	public static $sleep = null;

	/**
	 * The model used when none is chosen.
	 *
	 * @return string
	 */
	abstract public function default_model();

	/**
	 * Where keys and billing live, e.g. "console.anthropic.com".
	 *
	 * @return string
	 */
	abstract public function console();

	/**
	 * How a key starts, for the key field's placeholder.
	 *
	 * @return string
	 */
	abstract public function key_placeholder();

	/**
	 * The request: URL, headers and body.
	 *
	 * @param string  $key          API key.
	 * @param string  $model        Model.
	 * @param string  $instructions Instructions.
	 * @param array[] $messages     Turns, oldest first.
	 * @param int     $max_tokens   Longest answer.
	 * @return array{url:string,headers:array,body:array}
	 */
	abstract protected function request( $key, $model, $instructions, array $messages, $max_tokens );

	/**
	 * Reads a successful reply.
	 *
	 * @param array $data Decoded reply.
	 * @return array{text:string,in:int,out:int,cut:bool} cut: stopped at the token limit.
	 */
	abstract protected function parse( array $data );

	/**
	 * What kind of failure an error reply is.
	 *
	 * @param int   $code HTTP status.
	 * @param array $data Decoded reply.
	 * @return string auth|quota|rate_limit|too_large|model|region|permission|server|bad_request
	 */
	abstract public function classify( $code, array $data );

	/**
	 * The provider's own explanation and error code, from an error reply.
	 *
	 * @param array $data Decoded reply.
	 * @return array{0:string,1:string} Message and code.
	 */
	abstract protected function said( array $data );

	/**
	 * The request that lists the models this key can use.
	 *
	 * @param string $key API key.
	 * @return array{url:string,headers:array}
	 */
	abstract protected function models_request( $key );

	/**
	 * Model IDs from the list reply, chat models only.
	 *
	 * @param array $data Decoded reply.
	 * @return string[]
	 */
	abstract protected function models_parse( array $data );

	/**
	 * {@inheritDoc}
	 *
	 * @param string  $key          API key.
	 * @param string  $model        Model ID.
	 * @param string  $instructions Instructions.
	 * @param array[] $messages     Turns.
	 * @param int     $max_tokens   Longest answer.
	 * @return array|\WP_Error
	 */
	public function ask( $key, $model, $instructions, array $messages, $max_tokens ) {
		$start   = microtime( true );
		$attempt = 0;
		$waited  = 0.0;
		while ( true ) {
			++$attempt;
			$req      = $this->request( $key, $model, $instructions, $messages, $max_tokens );
			$response = wp_remote_post(
				$req['url'],
				array(
					'timeout'     => 90,
					'redirection' => 0,
					'headers'     => array_merge( array( 'Content-Type' => 'application/json' ), $req['headers'] ),
					'body'        => wp_json_encode( $req['body'] ),
				)
			);
			$diag     = array(
				'attempts' => $attempt,
				'waited'   => round( $waited, 1 ),
				'ms'       => (int) round( ( microtime( true ) - $start ) * 1000 ),
			);
			if ( is_wp_error( $response ) ) {
				return $this->network_error( $response, $diag );
			}
			$code = (int) wp_remote_retrieve_response_code( $response );
			$data = json_decode( (string) wp_remote_retrieve_body( $response ), true );
			$data = self::error_data( is_array( $data ) ? $data : array() );
			$rid  = Text::substr( preg_replace( '/[^A-Za-z0-9_\-]/', '', (string) wp_remote_retrieve_header( $response, 'request-id' ) . (string) wp_remote_retrieve_header( $response, 'x-request-id' ) ), 0, 64 );
			$diag = array_merge(
				$diag,
				array(
					'http'       => $code,
					'request_id' => $rid,
				)
			);
			if ( 200 === $code ) {
				if ( isset( $data['error'] ) ) {
					return $this->error( $code, $data, $model, array_merge( $diag, array( 'kind' => 'bad_request' ) ) );
				}
				break;
			}
			$kind = $this->classify( $code, $data );
			if ( in_array( $kind, array( 'rate_limit', 'server' ), true ) && $attempt <= self::RETRIES ) {
				$wait = self::wait( $response, $attempt );
				if ( null !== $wait && $waited + $wait <= self::MAX_TOTAL_WAIT ) {
					self::pause( $wait );
					$waited += $wait;
					continue;
				}
			}
			return $this->error( $code, $data, $model, array_merge( $diag, array( 'kind' => $kind ) ) );
		}

		$out  = $this->parse( $data );
		$diag = array_merge( $diag, array( 'kind' => 'ok' ) );
		if ( '' === trim( $out['text'] ) ) {
			if ( $out['cut'] ) {
				return new \WP_Error(
					'turtlereport_ai_short',
					__( 'The answer ran out of room before it was finished. Raise "Longest answer" in Settings → AI Advisor, or ask a narrower question.', 'turtlereport' ),
					array(
						'status'     => 502,
						'diagnostic' => array_merge( $diag, array( 'kind' => 'too_short' ) ),
					)
				);
			}
			return new \WP_Error(
				'turtlereport_ai_empty',
				/* translators: %s: AI provider name. */
				sprintf( __( '%s sent back an empty answer. Try again.', 'turtlereport' ), $this->label() ),
				array(
					'status'     => 502,
					'diagnostic' => array_merge( $diag, array( 'kind' => 'empty' ) ),
				)
			);
		}
		return array(
			'text' => $out['text'],
			'in'   => (int) $out['in'],
			'out'  => (int) $out['out'],
			'meta' => $diag,
		);
	}

	/**
	 * The chat models this key can use, straight from the provider.
	 *
	 * @param string $key API key.
	 * @return string[]|\WP_Error
	 */
	public function list_models( $key ) {
		$req      = $this->models_request( $key );
		$response = wp_remote_get(
			$req['url'],
			array(
				'timeout'     => 15,
				'redirection' => 0,
				'headers'     => $req['headers'],
			)
		);
		if ( is_wp_error( $response ) ) {
			return $this->network_error( $response, array() );
		}
		$code = (int) wp_remote_retrieve_response_code( $response );
		$data = json_decode( (string) wp_remote_retrieve_body( $response ), true );
		$data = self::error_data( is_array( $data ) ? $data : array() );
		if ( 200 !== $code || isset( $data['error'] ) ) {
			return $this->error( $code, $data, '', array( 'kind' => $this->classify( $code, $data ) ) );
		}
		$ids = array_values( array_unique( array_filter( array_map( 'strval', $this->models_parse( $data ) ) ) ) );
		sort( $ids, SORT_NATURAL );
		return $ids;
	}

	/**
	 * A network or timeout failure.
	 *
	 * @param \WP_Error $e    Error.
	 * @param array     $diag Diagnostics.
	 * @return \WP_Error
	 */
	private function network_error( \WP_Error $e, array $diag ) {
		$said = self::clean( $e->get_error_message() );
		$late = false !== stripos( $said, 'timed out' ) || false !== stripos( $said, 'timeout' );
		return new \WP_Error(
			$late ? 'turtlereport_ai_timeout' : 'turtlereport_ai_network',
			$late
				/* translators: %s: AI provider name. */
				? sprintf( __( '%s took too long to answer. Try again, or ask about one client for a smaller question.', 'turtlereport' ), $this->label() )
				/* translators: 1: AI provider name, 2: network error. */
				: sprintf( __( 'Couldn\'t reach %1$s from this server: %2$s', 'turtlereport' ), $this->label(), $said ),
			array(
				'status'     => 504,
				'diagnostic' => array_merge(
					$diag,
					array(
						'kind' => $late ? 'timeout' : 'network',
						'http' => 0,
					)
				),
			)
		);
	}

	/**
	 * A message for an error reply. Never repeats the key.
	 *
	 * @param int    $code  HTTP status.
	 * @param array  $data  Decoded reply.
	 * @param string $model Model.
	 * @param array  $diag  Diagnostics (kind, attempts…).
	 * @return \WP_Error
	 */
	public function error( $code, array $data, $model, array $diag = array() ) {
		$kind   = isset( $diag['kind'] ) ? (string) $diag['kind'] : $this->classify( $code, $data );
		$said   = $this->said( $data );
		$text   = self::clean( $said[0] );
		$name   = $this->label();
		$where  = $this->console();
		$tries  = isset( $diag['attempts'] ) ? (int) $diag['attempts'] : 1;
		$status = 502;
		switch ( $kind ) {
			case 'auth':
				/* translators: %s: AI provider name. */
				$msg = sprintf( __( '%s didn\'t accept the API key: it\'s wrong or was revoked. Paste a new key in Settings → AI Advisor.', 'turtlereport' ), $name );
				break;
			case 'quota':
				/* translators: 1: AI provider name, 2: the provider's console address. */
				$msg = sprintf( __( 'Your %1$s account has no credit left or reached its spending limit, so this question wasn\'t answered. Add credit or raise the limit at %2$s. TurtleReport doesn\'t retry this automatically.', 'turtlereport' ), $name, $where );
				break;
			case 'rate_limit':
				$status = 429;
				/* translators: 1: AI provider name, 2: number of attempts. */
				$msg = sprintf( __( '%1$s\'s rate limit for this API key was reached (too many requests or tokens per minute). TurtleReport tried %2$d times. Wait a minute and ask again.', 'turtlereport' ), $name, $tries );
				break;
			case 'too_large':
				/* translators: %s: AI provider name. */
				$msg = sprintf( __( 'This question needs more data than %s accepts in one request for this key. Ask about one client, or choose a shorter date range.', 'turtlereport' ), $name );
				break;
			case 'model':
				/* translators: 1: model ID, 2: AI provider name, 3: a model that works. */
				$msg = sprintf( __( 'The model “%1$s” isn\'t available to this %2$s API key: it doesn\'t exist, or the account can\'t use it. Pick another model in Settings → AI Advisor, for example %3$s.', 'turtlereport' ), $model, $name, $this->default_model() );
				break;
			case 'region':
				/* translators: %s: AI provider name. */
				$msg = sprintf( __( '%s doesn\'t accept requests from the country or region this server is in.', 'turtlereport' ), $name );
				break;
			case 'permission':
				/* translators: 1: AI provider name, 2: the provider's console address. */
				$msg = sprintf( __( 'This %1$s API key isn\'t allowed to do this (its permissions are restricted). Check the key at %2$s.', 'turtlereport' ), $name, $where );
				break;
			case 'server':
				/* translators: 1: AI provider name, 2: HTTP status, 3: number of attempts. */
				$msg = sprintf( __( '%1$s is having problems right now (error %2$d, tried %3$d times). Try again in a few minutes.', 'turtlereport' ), $name, $code, $tries );
				break;
			default:
				$msg = '' !== $text
					/* translators: 1: AI provider name, 2: the provider's explanation. */
					? sprintf( __( '%1$s couldn\'t answer: %2$s', 'turtlereport' ), $name, $text )
					/* translators: %s: AI provider name. */
					: sprintf( __( '%s couldn\'t answer this request.', 'turtlereport' ), $name );
		}
		$names = array(
			'auth'        => 'invalid_key',
			'quota'       => 'no_credit',
			'rate_limit'  => 'rate_limit',
			'too_large'   => 'too_large',
			'model'       => 'model',
			'region'      => 'region',
			'permission'  => 'permission',
			'server'      => 'unavailable',
			'bad_request' => 'bad_request',
		);
		return new \WP_Error(
			'turtlereport_ai_' . ( isset( $names[ $kind ] ) ? $names[ $kind ] : 'bad_request' ),
			$msg,
			array(
				'status'     => $status,
				'diagnostic' => array_merge(
					$diag,
					array(
						'kind' => $kind,
						'http' => (int) $code,
						'code' => Text::substr( preg_replace( '/[^a-z0-9_\.\-]/i', '', $said[1] ), 0, 60 ),
					)
				),
			)
		);
	}

	/**
	 * Seconds to wait before retry number $attempt, or null when the provider asks for longer than we wait.
	 *
	 * @param array|\WP_Error $response Response.
	 * @param int             $attempt  Attempt that failed (1-based).
	 * @return float|null
	 */
	public static function wait( $response, $attempt ) {
		$sec = (string) wp_remote_retrieve_header( $response, 'retry-after' );
		if ( is_numeric( $sec ) ) {
			return (float) $sec > self::MAX_WAIT ? null : max( 0.5, (float) $sec );
		}
		return min( self::MAX_WAIT, 1.5 * pow( 2, $attempt - 1 ) );
	}

	/**
	 * Waits.
	 *
	 * @param float $seconds Seconds.
	 * @return void
	 */
	private static function pause( $seconds ) {
		if ( is_callable( self::$sleep ) ) {
			call_user_func( self::$sleep, $seconds );
			return;
		}
		usleep( (int) round( $seconds * 1000000 ) );
	}

	/**
	 * Turns as user/assistant pairs.
	 *
	 * @param array[] $messages Turns.
	 * @return array[] Items with role (user|assistant) and text.
	 */
	protected static function turns( array $messages ) {
		$out = array();
		foreach ( $messages as $m ) {
			$out[] = array(
				'role' => isset( $m['role'] ) && 'assistant' === $m['role'] ? 'assistant' : 'user',
				'text' => isset( $m['text'] ) ? (string) $m['text'] : '',
			);
		}
		return $out;
	}

	/**
	 * Strips anything that looks like a key from a message, and shortens it.
	 *
	 * @param string $text Text.
	 * @return string
	 */
	public static function clean( $text ) {
		$text = (string) preg_replace( '/\b(sk-ant-|sk-|rk-|pk-|xai-)[A-Za-z0-9_\-*]{6,}/', '[key hidden]', (string) $text );
		$text = (string) preg_replace( '/\bAIza[0-9A-Za-z_\-]{20,}/', '[key hidden]', $text );
		$text = (string) preg_replace( '/([?&]key=)[^&\s]+/', '$1[key hidden]', $text );
		return Text::truncate( wp_strip_all_tags( $text ), 240 );
	}
}