<?php

declare(strict_types=1);

/*
 * This file is part of the TYPO3 CMS project.
 *
 * It is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, either version 2
 * of the License, or any later version.
 *
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 *
 * The TYPO3 project - inspiring people to share!
 */

namespace TYPO3\CMS\Core\TypoScript\AST;

use Psr\EventDispatcher\EventDispatcherInterface;
use TYPO3\CMS\Core\TypoScript\AST\CurrentObjectPath\CurrentObjectPath;
use TYPO3\CMS\Core\TypoScript\AST\CurrentObjectPath\CurrentObjectPathStack;
use TYPO3\CMS\Core\TypoScript\AST\Node\NodeInterface;
use TYPO3\CMS\Core\TypoScript\AST\Node\RootNode;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Line\BlockCloseLine;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Line\CommentLine;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Line\EmptyLine;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Line\IdentifierAssignmentLine;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Line\IdentifierBlockOpenLine;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Line\IdentifierCopyLine;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Line\IdentifierFunctionLine;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Line\IdentifierReferenceLine;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Line\IdentifierUnsetLine;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Line\LineStream;
use TYPO3\CMS\Core\TypoScript\Tokenizer\Token\ConstantAwareTokenStream;

/**
 * Secondary TypoScript AST builder.
 *
 * This creates a tree of Nodes, starting with the root node. Each node can have
 * children. The implementation basically iterates a LineStream created by the
 * tokenizers, and creates AST depending on the line type. It handles all the
 * different operator lines like "=", "<" and so on.
 *
 * This AST builder is comment aware: Comments are assigned to nodes. This is used
 * in ext:tstemplate and page TSconfig backend modules to add the comment related
 * TypoScript functionality.
 *
 * This AST builder variant adds runtime overhead and is slower than the main
 * AstBuilder class.
 *
 * @internal: Internal AST structure.
 */
final class CommentAwareAstBuilder extends AbstractAstBuilder implements AstBuilderInterface
{
    public function __construct(
        EventDispatcherInterface $eventDispatcher,
    ) {
        $this->eventDispatcher = $eventDispatcher;
    }

    /**
     * @param array<string, string> $flatConstants
     */
    public function build(LineStream $lineStream, RootNode $ast, array $flatConstants = []): RootNode
    {
        $this->flatConstants = $flatConstants;

        $currentObjectPath = new CurrentObjectPath($ast);
        $currentObjectPathStack = new CurrentObjectPathStack();
        $currentObjectPathStack->push($currentObjectPath);

        $previousLineComments = [];
        while ($line = $lineStream->getNext()) {
            $node = null;
            if ($line instanceof IdentifierAssignmentLine) {
                // "foo = bar" and "foo ( bar )": Single and multi line assignments
                $node = $this->handleIdentifierAssignmentLine($line, $currentObjectPath);
                if ($previousLineComments) {
                    foreach ($previousLineComments as $previousLineComment) {
                        $node->addComment($previousLineComment);
                    }
                    $previousLineComments = [];
                }
            } elseif ($line instanceof IdentifierBlockOpenLine) {
                // "foo {": Opening a block - push to object path stack
                $node = $this->getOrAddNodeFromIdentifierStream($currentObjectPath, $line->getIdentifierTokenStream());
                if ($previousLineComments) {
                    foreach ($previousLineComments as $previousLineComment) {
                        $node->addComment($previousLineComment);
                    }
                    $previousLineComments = [];
                }
                $currentObjectPath = (new CurrentObjectPath($node));
                $currentObjectPathStack->push($currentObjectPath);
            } elseif ($line instanceof BlockCloseLine) {
                // "}": Closing a block - pop from object path stack
                $currentObjectPath = $currentObjectPathStack->pop();
            } elseif ($line instanceof IdentifierUnsetLine) {
                // "foo >": Remove a path
                $this->handleIdentifierUnsetLine($line, $currentObjectPath);
            } elseif ($line instanceof IdentifierCopyLine) {
                // "foo < bar": Copy a node source path to a target path
                $node = $this->handleIdentifierCopyLine($line, $ast, $currentObjectPath);
                if ($node && $previousLineComments) {
                    foreach ($previousLineComments as $previousLineComment) {
                        $node->addComment($previousLineComment);
                    }
                    $previousLineComments = [];
                }
            } elseif ($line instanceof IdentifierFunctionLine) {
                // "foo := addToList(42)": Evaluate functions
                $node = $this->getOrAddNodeFromIdentifierStream($currentObjectPath, $line->getIdentifierTokenStream());
                $functionValueTokenStream = $line->getFunctionValueTokenStream();
                $node->setValue($this->evaluateValueModifier($line->getFunctionNameToken(), clone $functionValueTokenStream, $node->getValue()));
                if ($functionValueTokenStream instanceof ConstantAwareTokenStream) {
                    // @todo: This is a bit unfortunate. When multiple functions manipulate a value after each other,
                    //        only the stream of the last one is preserved, previous ones are lost. This way, the BE modules
                    //        can not reflect when previous functions used constants. One idea to solve this is to turn existing
                    //        nodes into special "function" nodes that park single operations, which are then executed lazy when
                    //        a node value is string'ified. The BE modules could then render full lists of value manipulations and
                    //        show how values evolve. Another idea is to change setOriginalValueTokenStream() to gather multiple
                    //        streams - probably together with the current value at this point in time, which would also allow
                    //        rendering how a value evolves over time as well.
                    $node->setOriginalValueTokenStream($functionValueTokenStream);
                }
                if ($previousLineComments) {
                    foreach ($previousLineComments as $previousLineComment) {
                        $node->addComment($previousLineComment);
                    }
                    $previousLineComments = [];
                }
            } elseif ($line instanceof IdentifierReferenceLine) {
                // "foo =< bar": Prepare a reference resolving
                $node = $this->handleIdentifierReferenceLine($line, $currentObjectPath);
                if ($previousLineComments) {
                    foreach ($previousLineComments as $previousLineComment) {
                        $node->addComment($previousLineComment);
                    }
                    $previousLineComments = [];
                }
            } elseif ($line instanceof CommentLine) {
                $nextLine = $lineStream->peekNext();
                if ($currentObjectPath->getLast() instanceof RootNode && ($nextLine === null || $nextLine instanceof EmptyLine)) {
                    $previousLineComments[] = $line->getTokenStream();
                    foreach ($previousLineComments as $commentLineTokenStream) {
                        $ast->addComment($commentLineTokenStream);
                    }
                    $previousLineComments = [];
                }
                if ($nextLine instanceof CommentLine) {
                    $previousLineComments[] = $line->getTokenStream();
                }
                if ($nextLine instanceof IdentifierAssignmentLine
                    || $nextLine instanceof IdentifierBlockOpenLine
                    || $nextLine instanceof IdentifierCopyLine
                    || $nextLine instanceof IdentifierFunctionLine
                    || $nextLine instanceof IdentifierReferenceLine
                ) {
                    $previousLineComments[] = $line->getTokenStream();
                }
            }
        }

        return $ast;
    }

    /**
     * Slightly different from AstBuilder since it sets 'previousValue'
     */
    private function handleIdentifierAssignmentLine(IdentifierAssignmentLine $line, CurrentObjectPath $currentObjectPath): NodeInterface
    {
        $node = $this->getOrAddNodeFromIdentifierStream($currentObjectPath, $line->getIdentifierTokenStream());
        $valueTokenStream = $line->getValueTokenStream();
        if ($valueTokenStream instanceof ConstantAwareTokenStream) {
            $node->setOriginalValueTokenStream($valueTokenStream);
            $valueTokenStream = clone $valueTokenStream;
            $valueTokenStream->setFlatConstants($this->flatConstants);
            $node->setPreviousValue($node->getValue());
            $node->setValue((string)$valueTokenStream);
            return $node;
        }
        $node->setPreviousValue($node->getValue());
        $node->setValue((string)$valueTokenStream);
        return $node;
    }
}
