<?php
namespace Elastica\Suggest;

use Elastica\Suggest\CandidateGenerator\AbstractCandidateGenerator;

/**
 * Class Phrase.
 *
 * @link http://www.elastic.co/guide/en/elasticsearch/reference/current/search-suggesters-phrase.html
 */
class Phrase extends AbstractSuggest
{
    /**
     * @param string $analyzer
     *
     * @return $this
     */
    public function setAnalyzer($analyzer)
    {
        return $this->setParam('analyzer', $analyzer);
    }

    /**
     * Set the max size of the n-grams (shingles) in the field.
     *
     * @param int $size
     *
     * @return $this
     */
    public function setGramSize($size)
    {
        return $this->setParam('gram_size', $size);
    }

    /**
     * Set the likelihood of a term being misspelled even if the term exists in the dictionary.
     *
     * @param float $likelihood Defaults to 0.95, meaning 5% of the words are misspelled.
     *
     * @return $this
     */
    public function setRealWordErrorLikelihood($likelihood)
    {
        return $this->setParam('real_word_error_likelihood', $likelihood);
    }

    /**
     * Set the factor applied to the input phrases score to be used as a threshold for other suggestion candidates.
     * Only candidates which score higher than this threshold will be included in the result.
     *
     * @param float $confidence Defaults to 1.0.
     *
     * @return $this
     */
    public function setConfidence($confidence)
    {
        return $this->setParam('confidence', $confidence);
    }

    /**
     * Set the maximum percentage of the terms considered to be misspellings in order to form a correction.
     *
     * @param float $max
     *
     * @return $this
     */
    public function setMaxErrors($max)
    {
        return $this->setParam('max_errors', $max);
    }

    /**
     * @param string $separator
     *
     * @return $this
     */
    public function setSeparator($separator)
    {
        return $this->setParam('separator', $separator);
    }

    /**
     * Set suggestion highlighting.
     *
     * @param string $preTag
     * @param string $postTag
     *
     * @return $this
     */
    public function setHighlight($preTag, $postTag)
    {
        return $this->setParam('highlight', array(
            'pre_tag' => $preTag,
            'post_tag' => $postTag,
        ));
    }

    /**
     * @param float $discount
     *
     * @return $this
     */
    public function setStupidBackoffSmoothing($discount = 0.4)
    {
        return $this->setSmoothingModel('stupid_backoff', array(
            'discount' => $discount,
        ));
    }

    /**
     * @param float $alpha
     *
     * @return $this
     */
    public function setLaplaceSmoothing($alpha = 0.5)
    {
        return $this->setSmoothingModel('laplace', array(
            'alpha' => $alpha,
        ));
    }

    /**
     * @param float $trigramLambda
     * @param float $bigramLambda
     * @param float $unigramLambda
     *
     * @return $this
     */
    public function setLinearInterpolationSmoothing($trigramLambda, $bigramLambda, $unigramLambda)
    {
        return $this->setSmoothingModel('linear_interpolation', array(
            'trigram_lambda' => $trigramLambda,
            'bigram_lambda' => $bigramLambda,
            'unigram_lambda' => $unigramLambda,
        ));
    }

    /**
     * @param string $model  the name of the smoothing model
     * @param array  $params
     *
     * @return $this
     */
    public function setSmoothingModel($model, array $params)
    {
        return $this->setParam('smoothing', array(
            $model => $params,
        ));
    }

    /**
     * @param AbstractCandidateGenerator $generator
     *
     * @return $this
     */
    public function addCandidateGenerator(AbstractCandidateGenerator $generator)
    {
        $generator = $generator->toArray();
        $keys = array_keys($generator);
        $values = array_values($generator);

        return $this->addParam($keys[0], $values[0]);
    }
}