<?php
namespace BavarianRankEngine\Helpers;

class TokenEstimator {
	/**
	 * Pricing per 1k tokens [provider][model][input|output]
	 * Update these when provider pricing changes.
	 */
	private const PRICING = array(
		'openai'    => array(
			'gpt-4.1'       => array(
				'input'  => 0.002,
				'output' => 0.008,
			),
			'gpt-4o'        => array(
				'input'  => 0.0025,
				'output' => 0.01,
			),
			'gpt-4o-mini'   => array(
				'input'  => 0.00015,
				'output' => 0.0006,
			),
			'gpt-3.5-turbo' => array(
				'input'  => 0.0005,
				'output' => 0.0015,
			),
		),
		'anthropic' => array(
			'claude-sonnet-4-6'         => array(
				'input'  => 0.003,
				'output' => 0.015,
			),
			'claude-opus-4-6'           => array(
				'input'  => 0.015,
				'output' => 0.075,
			),
			'claude-haiku-4-5-20251001' => array(
				'input'  => 0.00025,
				'output' => 0.00125,
			),
		),
		'gemini'    => array(
			'gemini-2.0-flash'      => array(
				'input'  => 0.00010,
				'output' => 0.00040,
			),
			'gemini-2.0-flash-lite' => array(
				'input'  => 0.000038,
				'output' => 0.00015,
			),
			'gemini-1.5-pro'        => array(
				'input'  => 0.00125,
				'output' => 0.005,
			),
		),
		'grok'      => array(
			'grok-3'      => array(
				'input'  => 0.003,
				'output' => 0.015,
			),
			'grok-3-mini' => array(
				'input'  => 0.0003,
				'output' => 0.0005,
			),
		),
	);

	/** Estimate token count (~4 chars per token) */
	public static function estimate( string $text ): int {
		return (int) ceil( mb_strlen( $text ) / 4 );
	}

	/** Truncate text to approximately $max_tokens */
	public static function truncate( string $text, int $max_tokens ): string {
		$max_chars = $max_tokens * 4;
		if ( mb_strlen( $text ) <= $max_chars ) {
			return $text;
		}
		return mb_substr( $text, 0, $max_chars );
	}

	/**
	 * Estimate cost in USD.
	 *
	 * @param int    $tokens   Number of tokens
	 * @param string $provider Provider ID
	 * @param string $model    Model ID
	 * @param string $type     'input' or 'output'
	 */
	public static function estimateCost( int $tokens, string $provider, string $model, string $type = 'input' ): float {
		$price_per_1k = self::PRICING[ $provider ][ $model ][ $type ] ?? 0.002;
		return round( ( $tokens / 1000 ) * $price_per_1k, 6 );
	}

	/** Human-readable cost string e.g. "~0,05 €" */
	public static function formatCost( float $usd ): string {
		$eur = $usd * 0.92;
		if ( $eur < 0.01 ) {
			return '< 0,01 €';
		}
		return '~' . number_format( $eur, 2, ',', '.' ) . ' €';
	}
}