<?php

use cli\Shell;
use WP_CLI\Dispatcher;
use WP_CLI\Utils;

class Help_Command extends WP_CLI_Command {

    /**
     * Gets help on WP-CLI, or on a specific command.
     *
     * ## OPTIONS
     *
     * [<command>...]
     * : Get help on a specific command.
     *
     * ## EXAMPLES
     *
     *     # get help for `core` command
     *     wp help core
     *
     *     # get help for `core download` subcommand
     *     wp help core download
     */
    public function __invoke( $args, $assoc_args ) {
        $r = WP_CLI::get_runner()->find_command_to_run( $args );

        if ( is_array( $r ) ) {
            list( $command ) = $r;

            self::show_help( $command );
            exit;
        }
    }

    private static function show_help( $command ) {
        $out = self::get_initial_markdown( $command );

        // Remove subcommands if in columns - will wordwrap separately.
        $subcommands       = '';
        $column_subpattern = '[ \t]+[^\t]+\t+';
        if ( preg_match( '/(^## SUBCOMMANDS[^\n]*\n+' . $column_subpattern . '.+?)(?:^##|\z)/ms', $out, $matches, PREG_OFFSET_CAPTURE ) ) {
            $subcommands        = $matches[1][0];
            $subcommands_header = "## SUBCOMMANDS\n";
            $out                = substr_replace( $out, $subcommands_header, $matches[1][1], strlen( $subcommands ) );
        }

        $out .= self::parse_reference_links( $command->get_longdesc() );

        // Definition lists.
        $out = preg_replace_callback( '/([^\n]+)\n: (.+?)(\n\n|$)/s', [ __CLASS__, 'rewrap_param_desc' ], $out );

        // Ensure lines with no leading whitespace that aren't section headers are indented.
        $out = preg_replace( '/^((?! |\t|##).)/m', "\t$1", $out );

        $tab = str_repeat( ' ', 2 );

        // Need to de-tab for wordwrapping to work properly.
        $out = str_replace( "\t", $tab, $out );

        $wordwrap_width = Shell::columns();

        // Wordwrap with indent.
        $out = preg_replace_callback(
            '/^( *)([^\n]+)\n/m',
            function ( $matches ) use ( $wordwrap_width ) {
                return $matches[1] . str_replace( "\n", "\n{$matches[1]}", wordwrap( $matches[2], $wordwrap_width - strlen( $matches[1] ) ) ) . "\n";
            },
            $out
        );

        if ( $subcommands ) {
            // Wordwrap with column indent.
            $subcommands = preg_replace_callback(
                '/^(' . $column_subpattern . ')([^\n]+)\n/m',
                function ( $matches ) use ( $wordwrap_width, $tab ) {
                    // Need to de-tab for wordwrapping to work properly.
                    $matches[1]  = str_replace( "\t", $tab, $matches[1] );
                    $matches[2]  = str_replace( "\t", $tab, $matches[2] );
                    $padding_len = strlen( $matches[1] );
                    $padding     = str_repeat( ' ', $padding_len );
                    return $matches[1] . str_replace( "\n", "\n$padding", wordwrap( $matches[2], $wordwrap_width - $padding_len ) ) . "\n";
                },
                $subcommands
            );

            // Put subcommands back.
            $out = str_replace( $subcommands_header, $subcommands, $out );
        }

        // Section headers.
        $out = preg_replace( '/^## ([A-Z ]+)/m', WP_CLI::colorize( '%9\1%n' ), $out );

        self::pass_through_pager( $out );
    }

    private static function rewrap_param_desc( $matches ) {
        $param = $matches[1];
        $desc  = self::indent( "\t\t", $matches[2] );
        return "\t$param\n$desc\n\n";
    }

    private static function indent( $whitespace, $text ) {
        $lines = explode( "\n", $text );
        foreach ( $lines as &$line ) {
            $line = $whitespace . $line;
        }
        return implode( "\n", $lines );
    }

    private static function pass_through_pager( $out ) {

        if ( ! Utils\check_proc_available( null /*context*/, true /*return*/ ) ) {
            WP_CLI::line( $out );
            WP_CLI::debug( 'Warning: check_proc_available() failed in pass_through_pager().', 'help' );
            return -1;
        }

        $pager = getenv( 'PAGER' );
        if ( false === $pager ) {
            $pager = Utils\is_windows() ? 'more' : 'less -R';
        }

        // For Windows 7 need to set code page to something other than Unicode (65001) to get around "Not enough memory." error with `more.com` on PHP 7.1+.
        if ( 'more' === $pager && defined( 'PHP_WINDOWS_VERSION_MAJOR' ) && PHP_WINDOWS_VERSION_MAJOR < 10 && function_exists( 'sapi_windows_cp_set' ) ) {
            // Note will also apply to Windows 8 (see https://msdn.microsoft.com/en-us/library/windows/desktop/ms724832.aspx) but probably harmless anyway.
            $cp = getenv( 'WP_CLI_WINDOWS_CODE_PAGE' ) ?: 1252; // Code page 1252 is the most used so probably the most compat.
            // phpcs:ignore PHPCompatibility.FunctionUse.NewFunctions -- Wrapped in function_exists() call.
            sapi_windows_cp_set( $cp ); // `sapi_windows_cp_set()` introduced PHP 7.1.
        }

        // Convert string to file handle.
        $fd = fopen( 'php://temp', 'r+b' );
        fwrite( $fd, $out );
        rewind( $fd );

        $descriptorspec = [
            0 => $fd,
            1 => STDOUT,
            2 => STDERR,
        ];

        return proc_close( Utils\proc_open_compat( $pager, $descriptorspec, $pipes ) );
    }

    private static function get_initial_markdown( $command ) {
        $name = implode( ' ', Dispatcher\get_path( $command ) );

        $binding = [
            'name'      => $name,
            'shortdesc' => $command->get_shortdesc(),
        ];

        $binding['synopsis'] = "$name " . $command->get_synopsis();

        $alias = $command->get_alias();
        if ( $alias ) {
            $binding['alias'] = $alias;
        }
        $hook_name        = $command->get_hook();
        $hook_description = $hook_name ? Utils\get_hook_description( $hook_name ) : null;
        if ( $hook_description && 'after_wp_load' !== $hook_name ) {
            if ( $command->can_have_subcommands() ) {
                $binding['shortdesc'] .= "\n\nUnless overridden, these commands run on the '$hook_name' hook, $hook_description";
            } else {
                $binding['shortdesc'] .= "\n\nThis command runs on the '$hook_name' hook, $hook_description";
            }
        }

        if ( $command->can_have_subcommands() ) {
            $binding['has-subcommands']['subcommands'] = self::render_subcommands( $command );
        }

        return Utils\mustache_render( 'man.mustache', $binding );
    }

    private static function render_subcommands( $command ) {
        $subcommands = [];
        foreach ( $command->get_subcommands() as $subcommand ) {

            if ( WP_CLI::get_runner()->is_command_disabled( $subcommand ) ) {
                continue;
            }

            $subcommands[ $subcommand->get_name() ] = $subcommand->get_shortdesc();
        }

        $max_len = self::get_max_len( array_keys( $subcommands ) );

        $lines = [];
        foreach ( $subcommands as $name => $desc ) {
            $lines[] = str_pad( $name, $max_len ) . "\t\t\t" . $desc;
        }

        return $lines;
    }

    private static function get_max_len( $strings ) {
        $max_len = 0;
        foreach ( $strings as $str ) {
            $len = strlen( $str );
            if ( $len > $max_len ) {
                $max_len = $len;
            }
        }

        return $max_len;
    }

    /**
     * Parse reference links from longdescription.
     *
     * @param  string $longdesc The longdescription from the `$command->get_longdesc()`.
     * @return string The longdescription which has links as footnote.
     */
    private static function parse_reference_links( $longdesc ) {
        $description = '';
        foreach ( explode( "\n", $longdesc ) as $line ) {
            if ( 0 === strpos( $line, '#' ) ) {
                break;
            }
            $description .= $line . "\n";
        }

        // Fires if it has description text at the head of `$longdesc`.
        if ( $description ) {
            $links   = []; // An array of URLs from the description.
            $pattern = '/\[.+?\]\((https?:\/\/.+?)\)/';
            $newdesc = preg_replace_callback(
                $pattern,
                function ( $matches ) use ( &$links ) {
                    static $count = 0;
                    $count++;
                    $links[] = $matches[1];
                    return str_replace( '(' . $matches[1] . ')', '[' . $count . ']', $matches[0] );
                },
                $description
            );

            $footnote   = '';
            $link_count = count( $links );
            for ( $i = 0; $i < $link_count; $i++ ) {
                $n         = $i + 1;
                $footnote .= '[' . $n . '] ' . $links[ $i ] . "\n";
            }

            if ( $footnote ) {
                $newdesc  = trim( $newdesc ) . "\n\n---\n" . $footnote;
                $longdesc = str_replace( trim( $description ), trim( $newdesc ), $longdesc );
            }
        }

        return $longdesc;
    }
}