<?php

namespace App\Services\CardDav;

class VCardParser
{
    public function parse(string $contents): ParsedVCard
    {
        $uid = null;
        $fullName = null;
        $firstName = null;
        $lastName = null;
        $organization = null;
        $email = null;
        $phoneNumbers = [];
        $categories = [];

        foreach ($this->parseLines($contents) as $line) {
            [$name, $params, $value] = $line;

            match ($name) {
                'UID' => $uid = $uid ?? $this->cleanValue($value),
                'FN' => $fullName = $fullName ?? $this->cleanValue($value),
                'N' => [$lastName, $firstName] = $this->parseStructuredName($value, $lastName, $firstName),
                'ORG' => $organization = $organization ?? $this->cleanValue($this->splitEscaped($value, ';')[0] ?? ''),
                'EMAIL' => $email = $email ?? $this->cleanValue($value),
                'TEL' => $phoneNumbers[] = new ParsedVCardPhoneNumber($this->cleanValue($value), $this->phoneLabel($params)),
                'CATEGORIES' => $categories = array_merge($categories, $this->parseCategories($value)),
                default => null,
            };
        }

        $categories = array_values(array_unique(array_filter($categories)));

        return new ParsedVCard(
            uid: $uid,
            fullName: $fullName,
            firstName: $firstName,
            lastName: $lastName,
            organization: $organization,
            email: $email,
            phoneNumbers: array_values(array_filter(
                $phoneNumbers,
                fn (ParsedVCardPhoneNumber $phoneNumber): bool => $phoneNumber->rawNumber !== '',
            )),
            categories: $categories,
        );
    }

    /**
     * @return array<int, array{0: string, 1: array<string, array<int, string>>, 2: string}>
     */
    private function parseLines(string $contents): array
    {
        $contents = str_replace(["\r\n", "\r"], "\n", $contents);
        $contents = preg_replace("/\n[ \t]/", '', $contents) ?? $contents;
        $lines = [];

        foreach (explode("\n", $contents) as $line) {
            $line = trim($line);

            if ($line === '' || ! str_contains($line, ':')) {
                continue;
            }

            [$left, $value] = explode(':', $line, 2);
            $propertyParts = explode(';', $left);
            $name = strtoupper((string) array_shift($propertyParts));

            if ($name === 'BEGIN' || $name === 'END' || $name === 'VERSION') {
                continue;
            }

            $params = [];

            foreach ($propertyParts as $part) {
                if (str_contains($part, '=')) {
                    [$paramName, $paramValue] = explode('=', $part, 2);
                    $paramName = strtoupper($paramName);
                    $params[$paramName] = array_merge(
                        $params[$paramName] ?? [],
                        array_map('strtoupper', $this->splitEscaped($paramValue, ',')),
                    );

                    continue;
                }

                $params['TYPE'][] = strtoupper($part);
            }

            $lines[] = [$name, $params, $value];
        }

        return $lines;
    }

    /**
     * @return array{0: ?string, 1: ?string}
     */
    private function parseStructuredName(string $value, ?string $currentLastName, ?string $currentFirstName): array
    {
        $parts = $this->splitEscaped($value, ';');
        $lastName = $this->cleanValue($parts[0] ?? '') ?: $currentLastName;
        $firstName = $this->cleanValue($parts[1] ?? '') ?: $currentFirstName;

        return [$lastName, $firstName];
    }

    /**
     * @return array<int, string>
     */
    private function parseCategories(string $value): array
    {
        return array_map(
            fn (string $category): string => $this->cleanValue($category),
            $this->splitEscaped($value, ','),
        );
    }

    /**
     * @param  array<string, array<int, string>>  $params
     */
    private function phoneLabel(array $params): ?string
    {
        $types = array_filter($params['TYPE'] ?? []);

        if ($types === []) {
            return null;
        }

        return implode(', ', array_map(
            fn (string $type): string => ucfirst(strtolower($type)),
            array_unique($types),
        ));
    }

    /**
     * @return array<int, string>
     */
    private function splitEscaped(string $value, string $separator): array
    {
        $parts = [];
        $buffer = '';
        $escaped = false;

        foreach (str_split($value) as $char) {
            if ($escaped) {
                $buffer .= '\\'.$char;
                $escaped = false;

                continue;
            }

            if ($char === '\\') {
                $escaped = true;

                continue;
            }

            if ($char === $separator) {
                $parts[] = $buffer;
                $buffer = '';

                continue;
            }

            $buffer .= $char;
        }

        if ($escaped) {
            $buffer .= '\\';
        }

        $parts[] = $buffer;

        return $parts;
    }

    private function cleanValue(string $value): string
    {
        $value = str_replace(
            ['\n', '\N', '\;', '\,', '\\\\'],
            ["\n", "\n", ';', ',', '\\'],
            trim($value),
        );

        return trim($value);
    }
}