<?php
/**
 * This source file is part of the open source project
 * ExpressionEngine (https://expressionengine.com)
 *
 * @link      https://expressionengine.com/
 * @copyright Copyright (c) 2003-2022, Packet Tide, LLC (https://www.packettide.com)
 * @license   https://expressionengine.com/license Licensed under Apache License, Version 2.0
 */

namespace ExpressionEngine\Library\Parser\Conditional;

use ExpressionEngine\Library\Parser\Conditional\Token\Token;
use ExpressionEngine\Library\Parser\Conditional\Token\Boolean;
use ExpressionEngine\Library\Parser\Conditional\Token\Comment;
use ExpressionEngine\Library\Parser\Conditional\Token\Number;
use ExpressionEngine\Library\Parser\Conditional\Token\Operator;
use ExpressionEngine\Library\Parser\Conditional\Token\Other;
use ExpressionEngine\Library\Parser\Conditional\Token\StringLiteral;
use ExpressionEngine\Library\Parser\Conditional\Token\Tag;
use ExpressionEngine\Library\Parser\Conditional\Token\Variable;

/**
 * Helper function to create the operator pattern which is somewhat
 * complicated.
 */
function compileOperatorPattern()
{
    $pattern = '';
    $operators = array(
        '^=', '*=', '$=', '~',
        '==', '!=', '<=', '>=', '<>', '<', '>',
        '**', '%', '+', '-', '*', '/',
        '.', '!', '^',
        '||', '&&',
        'AND', 'OR', 'XOR'
    );

    foreach ($operators as $operator) {
        $operator = preg_quote($operator, '/');
        $pattern .= $operator . '|';
    }

    return $pattern = '(' . substr($pattern, 0, -1) . ')';
}

/**
 * Conditional Lexer Rules
 *
 * Syntax follows basic lex syntax.
 *
 * All start conditions are exclusive.
 */

return array(

    // comments are valid anywhere
    '/{!--(.*?)--}/' => function ($lexeme, $scanner) {
        return new Token('COMMENT', $lexeme);
    },

    // template strings
    '<INITIAL>/[^{]+/' => function ($lexeme, $scanner) {
        return new Token('TEMPLATE_STRING', $lexeme);
    },

    // conditionals that start an expression
    '<INITIAL>/\{if(:elseif)?\s/' => function ($lexeme, $scanner) {
        $scanner->state = 'EXPRESSION';
        $scanner->index--; // backtrack on the whitespace

        $tokens = array();
        $tokens[] = new Token('LD', '{');

        switch (trim($lexeme)) {
            case '{if': $tokens[] = new Token('IF', 'if');

                break;
            case '{if:elseif': $tokens[] = new Token('ELSEIF', 'if:elseif');

                break;
        }

        return $tokens;
    },

    // other conditional builtins that don't start
    // an expression {/if} and {if:else}
    '<INITIAL>/{(\/if|if:else)\}/' => function ($lexeme, $scanner) {
        $tokens = array();
        $tokens[] = new Token('LD', '{');

        switch ($lexeme) {
            case '{/if}': $tokens[] = new Token('ENDIF', '/if');

                break;
            case '{if:else}': $tokens[] = new Token('ELSE', 'if:else');

                break;
        }

        $tokens[] = new Token('RD', '}');

        return $tokens;
    },

    // valid in expressions

    // whitespace
    '<EXPRESSION>/\s+/' => function ($lexeme, $scanner) {
        return new Token('WHITESPACE', $lexeme);
    },

    // booleans
    '<EXPRESSION>/(TRUE|FALSE)/i' => function ($lexeme, $scanner) {
        return new Token('BOOL', $lexeme);
    },

    // parentheses
    '<EXPRESSION>/[()]/' => function ($lexeme, $scanner) {
        $token = ($lexeme == '(') ? 'LP' : 'RP';

        return new Token($token, $lexeme);
    },

    // numbers
    '<EXPRESSION>/([0-9]*\.[0-9]+|[0-9]+\.[0-9]*|[0-9]+)/' => function ($lexeme, $scanner) {
        return new Token('NUMBER', $lexeme);
    },

    // operators
    '<EXPRESSION>/' . compileOperatorPattern() . '/i' => function ($lexeme, $scanner) {
        return new Token('OPERATOR', $lexeme);
    },

    // variables
    '<EXPRESSION>/\w*([a-zA-Z]+([\w:-]+\w)?|(\w[\w:-]+)?[a-zA-Z]+)\w*/i' => function ($lexeme, $scanner) {
        return new Token('VARIABLE', $lexeme);
    },

    // open tag
    '<EXPRESSION|TAG>/{/' => function ($lexeme, $scanner) {
        if ($scanner->state != 'TAG') {
            $scanner->tag_buffer = '';
            $scanner->state = 'TAG';
            $scanner->tag_depth = 0;
        }

        $scanner->tag_depth++;
        $scanner->tag_buffer .= $lexeme;
    },

    // end expression
    '<EXPRESSION>/}/' => function ($lexeme, $scanner) {
        $scanner->state = 'INITIAL';

        return new Token('RD', $lexeme);
    },

    // seek through tag, avoiding strings and nested
    // tags. They will be handled separately
    '<TAG>/[^{}\'"]+/' => function ($lexeme, $scanner) {
        $scanner->tag_buffer .= $lexeme;
    },

    // end tag
    '<TAG>/}/' => function ($lexeme, $scanner) {
        $scanner->tag_depth--;
        $scanner->tag_buffer .= $lexeme;

        if ($scanner->tag_depth == 0) {
            $scanner->state = 'EXPRESSION';

            return new Token('TAG', $scanner->tag_buffer);
        }
    },

    // strings are valid in tags and expressions

    // single quoted string
    "<TAG|EXPRESSION>/'(\\|\'|[^'])*?'/" => function ($lexeme, $scanner) {
        if ($scanner->state == 'TAG') {
            $scanner->tag_buffer .= $lexeme;
        } else {
            return new Token('STRING', substr($lexeme, 1, -1));
        }
    },

    // double quoted string
    '<TAG|EXPRESSION>/"(\\|\"|[^"])*?"/' => function ($lexeme, $scanner) {
        if ($scanner->state == 'TAG') {
            $scanner->tag_buffer .= $lexeme;
        } else {
            return new Token('STRING', substr($lexeme, 1, -1));
        }
    },

);

// EOF
