<?php

namespace App\Actions\Tickets\Support;

use Illuminate\Support\Arr;

class TicketAcceptanceCriteriaData
{
    public const MAX_INDENT_LEVEL = 8;

    /**
     * @return array{
     *     summary: string|null,
     *     items: array<int, array{
     *         checked: bool,
     *         indent: int,
     *         text: string
     *     }>
     * }
     */
    public static function fromStored(mixed $storedData, ?string $legacyText): array
    {
        $normalizedStoredData = is_array($storedData)
            ? self::normalize($storedData)
            : self::empty();

        if (self::hasContent($normalizedStoredData)) {
            return $normalizedStoredData;
        }

        return self::normalize($legacyText);
    }

    /**
     * @return array{
     *     summary: string|null,
     *     items: array<int, array{
     *         checked: bool,
     *         indent: int,
     *         text: string
     *     }>
     * }
     */
    public static function normalize(mixed $value): array
    {
        if (is_array($value)) {
            return self::normalizeFromArray($value);
        }

        if (is_string($value) || $value === null) {
            return self::normalizeFromString($value);
        }

        return self::empty();
    }

    /**
     * @param  array{
     *     summary: string|null,
     *     items: array<int, array{
     *         checked: bool,
     *         indent: int,
     *         text: string
     *     }>
     * }  $acceptanceCriteria
     */
    public static function hasContent(array $acceptanceCriteria): bool
    {
        return $acceptanceCriteria['summary'] !== null
            || $acceptanceCriteria['items'] !== [];
    }

    /**
     * @param  array{
     *     summary: string|null,
     *     items: array<int, array{
     *         checked: bool,
     *         indent: int,
     *         text: string
     *     }>
     * }  $acceptanceCriteria
     * @return array{
     *     summary: string|null,
     *     items: array<int, array{
     *         checked: bool,
     *         indent: int,
     *         text: string
     *     }>
     * }|null
     */
    public static function forStorage(array $acceptanceCriteria): ?array
    {
        $normalized = self::normalize($acceptanceCriteria);

        return self::hasContent($normalized)
            ? $normalized
            : null;
    }

    /**
     * @param  array{
     *     summary: string|null,
     *     items: array<int, array{
     *         checked: bool,
     *         indent: int,
     *         text: string
     *     }>
     * }  $acceptanceCriteria
     */
    public static function toLegacyText(array $acceptanceCriteria): ?string
    {
        $normalized = self::normalize($acceptanceCriteria);
        $lines = [];

        if ($normalized['summary'] !== null) {
            $lines[] = $normalized['summary'];
        }

        if ($normalized['items'] !== []) {
            if ($normalized['summary'] !== null) {
                $lines[] = '';
            }

            foreach ($normalized['items'] as $item) {
                $lines[] = sprintf(
                    '%s- [%s] %s',
                    str_repeat('  ', $item['indent']),
                    $item['checked'] ? 'x' : ' ',
                    $item['text'],
                );
            }
        }

        $legacyText = trim(implode("\n", $lines));

        return $legacyText === '' ? null : $legacyText;
    }

    /**
     * @return array{
     *     summary: string|null,
     *     items: array<int, array{
     *         checked: bool,
     *         indent: int,
     *         text: string
     *     }>
     * }
     */
    private static function empty(): array
    {
        return [
            'summary' => null,
            'items' => [],
        ];
    }

    /**
     * @param  array<string, mixed>  $value
     * @return array{
     *     summary: string|null,
     *     items: array<int, array{
     *         checked: bool,
     *         indent: int,
     *         text: string
     *     }>
     * }
     */
    private static function normalizeFromArray(array $value): array
    {
        $summary = trim((string) Arr::get($value, 'summary', ''));
        $rawItems = Arr::get($value, 'items', []);

        if (! is_array($rawItems)) {
            $rawItems = [];
        }

        $items = [];

        foreach ($rawItems as $rawItem) {
            if (! is_array($rawItem)) {
                continue;
            }

            $text = trim((string) Arr::get($rawItem, 'text', ''));

            if ($text === '') {
                continue;
            }

            $rawChecked = Arr::get($rawItem, 'checked', false);
            $rawIndent = Arr::get($rawItem, 'indent', 0);

            $items[] = [
                'checked' => filter_var($rawChecked, FILTER_VALIDATE_BOOLEAN),
                'indent' => self::clampIndent((int) $rawIndent),
                'text' => $text,
            ];
        }

        return [
            'summary' => $summary === '' ? null : $summary,
            'items' => $items,
        ];
    }

    /**
     * @return array{
     *     summary: string|null,
     *     items: array<int, array{
     *         checked: bool,
     *         indent: int,
     *         text: string
     *     }>
     * }
     */
    private static function normalizeFromString(?string $value): array
    {
        $text = trim((string) $value);

        if ($text === '') {
            return self::empty();
        }

        $lines = preg_split('/\R/u', $text);

        if (! is_array($lines)) {
            return [
                'summary' => $text,
                'items' => [],
            ];
        }

        $summary = null;
        $items = [];

        foreach ($lines as $line) {
            $trimmedLine = trim($line);

            if ($trimmedLine === '') {
                continue;
            }

            if ($summary === null) {
                $summary = $trimmedLine;

                continue;
            }

            $parsedItem = self::parseChecklistItem($line);

            if ($parsedItem === null) {
                continue;
            }

            $items[] = $parsedItem;
        }

        return [
            'summary' => $summary,
            'items' => $items,
        ];
    }

    /**
     * @return array{checked: bool, indent: int, text: string}|null
     */
    private static function parseChecklistItem(string $line): ?array
    {
        $line = rtrim(str_replace("\t", '  ', $line));

        if ($line === '') {
            return null;
        }

        if (! preg_match('/^(?<indent>\s*)(?<content>.+)$/u', $line, $matches)) {
            return null;
        }

        $content = trim((string) Arr::get($matches, 'content', ''));

        if ($content === '') {
            return null;
        }

        $checked = false;

        if (preg_match('/^(?:[-*+]\s+)?\[(?<state>[xX ])\]\s*(?<text>.+)$/u', $content, $checkboxMatches)) {
            $checked = strtolower((string) Arr::get($checkboxMatches, 'state', '')) === 'x';
            $content = trim((string) Arr::get($checkboxMatches, 'text', ''));
        } elseif (preg_match('/^[-*+]\s+(?<text>.+)$/u', $content, $bulletMatches)) {
            $content = trim((string) Arr::get($bulletMatches, 'text', ''));
        }

        if ($content === '') {
            return null;
        }

        return [
            'checked' => $checked,
            'indent' => self::indentLevel((string) Arr::get($matches, 'indent', '')),
            'text' => $content,
        ];
    }

    private static function indentLevel(string $leadingWhitespace): int
    {
        $normalizedWhitespace = str_replace("\t", '  ', $leadingWhitespace);

        return self::clampIndent(intdiv(strlen($normalizedWhitespace), 2));
    }

    private static function clampIndent(int $indent): int
    {
        return max(0, min(self::MAX_INDENT_LEVEL, $indent));
    }
}