<?php
declare(strict_types=1);

namespace PrinsFrank\PdfParser\Document\Dictionary;

use PrinsFrank\PdfParser\Document\Dictionary\DictionaryParseContext\DictionaryParseContext;
use PrinsFrank\PdfParser\Document\Dictionary\DictionaryParseContext\NestingContext;
use PrinsFrank\PdfParser\Document\Generic\Character\DelimiterCharacter;
use PrinsFrank\PdfParser\Document\Generic\Character\LiteralStringEscapeCharacter;
use PrinsFrank\PdfParser\Document\Generic\Character\WhitespaceCharacter;
use PrinsFrank\PdfParser\Document\Generic\Parsing\RollingCharBuffer;
use PrinsFrank\PdfParser\Exception\PdfParserException;
use PrinsFrank\PdfParser\Stream\Stream;

/** @internal */
class DictionaryParser {
    /**
     * @phpstan-assert int<0, max> $startPos
     * @phpstan-assert int<1, max> $nrOfBytes
     *
     * @throws PdfParserException
     */
    public static function parse(Stream $stream, int $startPos, int $nrOfBytes): Dictionary {
        $dictionaryArray = [];
        $rollingCharBuffer = new RollingCharBuffer(6);
        $nestingContext = (new NestingContext())->setContext(DictionaryParseContext::ROOT);
        $arrayNestingLevel = 0;
        foreach ($stream->chars($startPos, $nrOfBytes) as $char) {
            $rollingCharBuffer->next($char);
            if ($char === DelimiterCharacter::LESS_THAN_SIGN->value && $rollingCharBuffer->getPreviousCharacter() === DelimiterCharacter::LESS_THAN_SIGN->value && $rollingCharBuffer->getPreviousCharacter(2) !== LiteralStringEscapeCharacter::REVERSE_SOLIDUS->value && $nestingContext->getContext() !== DictionaryParseContext::VALUE_IN_SQUARE_BRACKETS) {
                if ($nestingContext->getContext() === DictionaryParseContext::KEY) {
                    $nestingContext->removeFromKeyBuffer();
                }

                $nestingContext->setContext(DictionaryParseContext::DICTIONARY)->incrementNesting()->setContext(DictionaryParseContext::DICTIONARY);
            } elseif ($char === DelimiterCharacter::LESS_THAN_SIGN->value && $nestingContext->getContext() === DictionaryParseContext::KEY) {
                $nestingContext->setContext(DictionaryParseContext::VALUE);
            } elseif ($char === DelimiterCharacter::GREATER_THAN_SIGN->value && $rollingCharBuffer->getPreviousCharacter() === DelimiterCharacter::GREATER_THAN_SIGN->value && $rollingCharBuffer->getPreviousCharacter(2) !== LiteralStringEscapeCharacter::REVERSE_SOLIDUS->value && $nestingContext->getContext() !== DictionaryParseContext::VALUE_IN_SQUARE_BRACKETS) {
                $nestingContext->removeFromValueBuffer();
                self::flush($dictionaryArray, $nestingContext);
                $nestingContext->decrementNesting()->flush();
            } elseif ($char === DelimiterCharacter::SOLIDUS->value && $rollingCharBuffer->getPreviousCharacter() !== LiteralStringEscapeCharacter::REVERSE_SOLIDUS->value && $nestingContext->getContext() !== DictionaryParseContext::VALUE_IN_SQUARE_BRACKETS) {
                if ($nestingContext->getContext() === DictionaryParseContext::DICTIONARY) {
                    $nestingContext->setContext(DictionaryParseContext::KEY);
                } elseif ($nestingContext->getContext() === DictionaryParseContext::VALUE) {
                    self::flush($dictionaryArray, $nestingContext);
                    $nestingContext->setContext(DictionaryParseContext::KEY);
                } elseif ($nestingContext->getContext() === DictionaryParseContext::KEY || $nestingContext->getContext() === DictionaryParseContext::KEY_VALUE_SEPARATOR) {
                    $nestingContext->setContext(DictionaryParseContext::VALUE);
                }
            } elseif ($char === WhitespaceCharacter::LINE_FEED->value && $nestingContext->getContext() !== DictionaryParseContext::VALUE_IN_SQUARE_BRACKETS) {
                if ($nestingContext->getContext() === DictionaryParseContext::KEY) {
                    $nestingContext->setContext(DictionaryParseContext::KEY_VALUE_SEPARATOR);
                } elseif ($nestingContext->getContext() === DictionaryParseContext::VALUE) {
                    self::flush($dictionaryArray, $nestingContext);
                } elseif ($nestingContext->getContext() === DictionaryParseContext::COMMENT) {
                    $nestingContext->setContext(DictionaryParseContext::DICTIONARY);
                }
            } elseif (WhitespaceCharacter::tryFrom($char) !== null && $nestingContext->getContext() === DictionaryParseContext::KEY) {
                $nestingContext->setContext(DictionaryParseContext::KEY_VALUE_SEPARATOR);
            } elseif ($char === DelimiterCharacter::LEFT_PARENTHESIS->value && (in_array($nestingContext->getContext(), [DictionaryParseContext::KEY, DictionaryParseContext::KEY_VALUE_SEPARATOR, DictionaryParseContext::VALUE], true))) {
                $nestingContext->setContext(DictionaryParseContext::VALUE_IN_PARENTHESES);
            } elseif ($char === DelimiterCharacter::RIGHT_PARENTHESIS->value && $rollingCharBuffer->getPreviousCharacter() !== LiteralStringEscapeCharacter::REVERSE_SOLIDUS->value && $nestingContext->getContext() === DictionaryParseContext::VALUE_IN_PARENTHESES) {
                $nestingContext->setContext(DictionaryParseContext::VALUE);
            } elseif ($char === DelimiterCharacter::LEFT_SQUARE_BRACKET->value && (in_array($nestingContext->getContext(), [DictionaryParseContext::KEY, DictionaryParseContext::KEY_VALUE_SEPARATOR, DictionaryParseContext::VALUE, DictionaryParseContext::VALUE_IN_SQUARE_BRACKETS], true))) {
                $nestingContext->setContext(DictionaryParseContext::VALUE_IN_SQUARE_BRACKETS);
                $arrayNestingLevel++;
            } elseif ($char === DelimiterCharacter::RIGHT_SQUARE_BRACKET->value && $nestingContext->getContext() === DictionaryParseContext::VALUE_IN_SQUARE_BRACKETS) {
                $arrayNestingLevel--;
                if ($arrayNestingLevel === 0) {
                    $nestingContext->setContext(DictionaryParseContext::VALUE);
                }
            } elseif (trim($char) !== '' && $nestingContext->getContext() === DictionaryParseContext::KEY_VALUE_SEPARATOR) {
                $nestingContext->setContext(DictionaryParseContext::VALUE);
            } elseif ($char === DelimiterCharacter::PERCENT_SIGN->value && $rollingCharBuffer->getPreviousCharacter() !== LiteralStringEscapeCharacter::REVERSE_SOLIDUS->value && $nestingContext->getContext() !== DictionaryParseContext::VALUE_IN_PARENTHESES) {
                $nestingContext->setContext(DictionaryParseContext::COMMENT);
            }

            match ($nestingContext->getContext()) {
                DictionaryParseContext::KEY => $nestingContext->addToKeyBuffer($char),
                DictionaryParseContext::VALUE_IN_PARENTHESES,
                DictionaryParseContext::VALUE_IN_SQUARE_BRACKETS,
                DictionaryParseContext::VALUE => $nestingContext->addToValueBuffer($char),
                default => null,
            };
        }

        return DictionaryFactory::fromArray($dictionaryArray);
    }

    /** @param array<string, mixed> $dictionaryArray */
    private static function flush(array &$dictionaryArray, NestingContext $nestingContext): void {
        if ($nestingContext->getValueBuffer()->isEmpty() || $nestingContext->getKeyBuffer()->isEmpty()) {
            return;
        }

        $dictionaryArrayPointer = &$dictionaryArray;
        $keys = $nestingContext->getKeysFromRoot();
        foreach ($keys as $index => $key) {
            if ($key === (string) $nestingContext->getKeyBuffer() && $index === array_key_last($keys)) {
                break;
            }

            /** @phpstan-ignore offsetAccess.nonOffsetAccessible */
            $dictionaryArrayPointer = &$dictionaryArrayPointer[trim($key)];
        }

        /** @phpstan-ignore offsetAccess.nonOffsetAccessible */
        $dictionaryArrayPointer[(string) $nestingContext->getKeyBuffer()] = trim((string) $nestingContext->getValueBuffer());
        $nestingContext->flush();
    }
}