<?php

declare(strict_types=1);

namespace app\adminapi\service;

/** Repeated JSON keys only: no text summarization, row filtering or value coercion. */
final class AiLosslessSourceEncoding
{
    public const VERSION = 'clinical-row-tables-v1';

    public static function encode(array $snapshot): string
    {
        $paths = [];
        $data = self::pack($snapshot, [], $paths);
        return json_encode([
            'encoding' => self::VERSION,
            'reading_rule' => 'table_paths指定的节点使用columns和rows：每行各值按columns的同序字段对应。'
                . '这是完整原始记录的无损表示，不是摘要；所有行、日期、数值、原文、null和空项均保留。'
                . '表外对象照常读取；历史记录不能当成本次查体，空项不能当成患者否认或正常。',
            'table_paths' => $paths,
            'data' => $data,
        ], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES | JSON_PRESERVE_ZERO_FRACTION
            | JSON_INVALID_UTF8_SUBSTITUTE | JSON_THROW_ON_ERROR);
    }

    /** Reversible verification helper. Table paths also disambiguate literal columns/rows objects. */
    public static function decode(string $encoded): array
    {
        $wire = json_decode($encoded, true, 512, JSON_THROW_ON_ERROR);
        if (($wire['encoding'] ?? null) !== self::VERSION || !is_array($wire['table_paths'] ?? null)
            || !is_array($wire['data'] ?? null)) {
            throw new \InvalidArgumentException('Invalid clinical row encoding');
        }
        $tables = [];
        foreach ($wire['table_paths'] as $path) {
            if (!is_array($path) || !array_is_list($path)) throw new \InvalidArgumentException('Invalid table path');
            $tables[serialize($path)] = true;
        }
        return self::unpack($wire['data'], [], $tables);
    }

    private static function pack($node, array $path, array &$paths)
    {
        if (!is_array($node)) return $node;
        if (array_is_list($node) && count($node) > 1 && is_array($node[0]) && !array_is_list($node[0])) {
            $columns = array_keys($node[0]);
            $sameShape = true;
            foreach ($node as $row) {
                if (!is_array($row) || array_keys($row) !== $columns) { $sameShape = false; break; }
            }
            if ($sameShape) {
                $paths[] = $path;
                $rows = [];
                foreach ($node as $r => $row) {
                    $values = [];
                    foreach (array_values($row) as $c => $value) {
                        $values[] = self::pack($value, [...$path, 'rows', $r, $c], $paths);
                    }
                    $rows[] = $values;
                }
                return ['columns' => $columns, 'rows' => $rows];
            }
        }
        $result = [];
        foreach ($node as $key => $value) $result[$key] = self::pack($value, [...$path, $key], $paths);
        return $result;
    }

    private static function unpack($node, array $path, array $tables)
    {
        if (!is_array($node)) return $node;
        if (isset($tables[serialize($path)])) {
            if (!is_array($node['columns'] ?? null) || !is_array($node['rows'] ?? null)) {
                throw new \InvalidArgumentException('Invalid clinical row table');
            }
            $result = [];
            foreach ($node['rows'] as $r => $row) {
                if (!is_array($row) || count($row) !== count($node['columns'])) {
                    throw new \InvalidArgumentException('Invalid clinical row width');
                }
                $values = [];
                foreach ($row as $c => $value) $values[] = self::unpack($value, [...$path, 'rows', $r, $c], $tables);
                $result[] = array_combine($node['columns'], $values);
            }
            return $result;
        }
        $result = [];
        foreach ($node as $key => $value) $result[$key] = self::unpack($value, [...$path, $key], $tables);
        return $result;
    }
}