<?php

namespace WP_CLI;

use Mustangostang\Spyc;

/**
 * Parse command attributes from its PHPdoc.
 * Used to determine execution characteristics (arguments, etc.).
 */
class DocParser {

    /**
     * PHPdoc command for the command.
     *
     * @var string
     */
    protected $doc_comment;

    /**
     * @param string $doc_comment
     */
    public function __construct( $doc_comment ) {
        /* Make sure we have a known line ending in document */
        $doc_comment       = str_replace( "\r\n", "\n", $doc_comment );
        $this->doc_comment = self::remove_decorations( $doc_comment );
    }

    /**
     * Remove unused cruft from PHPdoc comment.
     *
     * @param string $comment PHPdoc comment.
     * @return string
     */
    private static function remove_decorations( $comment ) {
        $comment = preg_replace( '|^/\*\*[\r\n]+|', '', $comment );
        $comment = preg_replace( '|\n[\t ]*\*/$|', '', $comment );
        $comment = preg_replace( '|^[\t ]*\* ?|m', '', $comment );

        return $comment;
    }

    /**
     * Get the command's short description (e.g. summary).
     *
     * @return string
     */
    public function get_shortdesc() {
        if ( ! preg_match( '|^([^@][^\n]+)\n*|', $this->doc_comment, $matches ) ) {
            return '';
        }

        return $matches[1];
    }

    /**
     * Get the command's full description
     *
     * @return string
     */
    public function get_longdesc() {
        $shortdesc = $this->get_shortdesc();
        if ( ! $shortdesc ) {
            return '';
        }

        $longdesc = substr( $this->doc_comment, strlen( $shortdesc ) );

        $lines = [];
        foreach ( explode( "\n", $longdesc ) as $line ) {
            if ( 0 === strpos( $line, '@' ) ) {
                break;
            }

            $lines[] = $line;
        }

        return trim( implode( "\n", $lines ) );
    }

    /**
     * Get the value for a given tag (e.g. "@alias" or "@subcommand")
     *
     * @param string $name Name for the tag, without '@'
     * @return string
     */
    public function get_tag( $name ) {
        if ( preg_match( '|^@' . $name . '\s+([a-z-_0-9]+)|m', $this->doc_comment, $matches ) ) {
            return $matches[1];
        }

        return '';
    }

    /**
     * Get the command's synopsis.
     *
     * @return string
     */
    public function get_synopsis() {
        if ( ! preg_match( '|^@synopsis\s+(.+)|m', $this->doc_comment, $matches ) ) {
            return '';
        }

        return $matches[1];
    }

    /**
     * Get the description for a given argument.
     *
     * @param string $name Argument's doc name.
     * @return string
     */
    public function get_arg_desc( $name ) {

        if ( preg_match( "/\[?<{$name}>.+\n: (.+?)(\n|$)/", $this->doc_comment, $matches ) ) {
            return $matches[1];
        }

        return '';
    }

    /**
     * Get the arguments for a given argument.
     *
     * @param string $name Argument's doc name.
     * @return mixed|null
     */
    public function get_arg_args( $name ) {
        return $this->get_arg_or_param_args( "/^\[?<{$name}>.*/" );
    }

    /**
     * Get the description for a given parameter.
     *
     * @param string $key Parameter's key.
     * @return string
     */
    public function get_param_desc( $key ) {

        if ( preg_match( "/\[?--{$key}=.+\n: (.+?)(\n|$)/", $this->doc_comment, $matches ) ) {
            return $matches[1];
        }

        return '';
    }

    /**
     * Get the arguments for a given parameter.
     *
     * @param string $key Parameter's key.
     * @return mixed|null
     */
    public function get_param_args( $key ) {
        return $this->get_arg_or_param_args( "/^\[?--{$key}=.*/" );
    }

    /**
     * Get the args for an arg or param
     *
     * @param string $regex Pattern to match against
     * @return array|null Interpreted YAML document, or null.
     */
    private function get_arg_or_param_args( $regex ) {
        $bits       = explode( "\n", $this->doc_comment );
        $within_arg = false;
        $within_doc = false;
        $document   = [];
        foreach ( $bits as $bit ) {
            if ( preg_match( $regex, $bit ) ) {
                $within_arg = true;
            }

            if ( $within_arg && $within_doc && '---' === $bit ) {
                $within_doc = false;
            }

            if ( $within_arg && ! $within_doc && '---' === $bit ) {
                $within_doc = true;
            }

            if ( $within_doc ) {
                $document[] = $bit;
            }

            if ( $within_arg && '' === $bit ) {
                $within_arg = false;
                break;
            }
        }

        if ( $document ) {
            return Spyc::YAMLLoadString( implode( "\n", $document ) );
        }
        return null;
    }
}