<?php

/** Project-local checks for the OpenAPI schema subset used by the mini API fixtures. */
final class MiniApiContract
{
    public readonly array $document;

    public function __construct()
    {
        $this->document = json_decode(file_get_contents(dirname(__DIR__, 2) . '/docs/openapi/water-mini-v1.json'), true, 512, JSON_THROW_ON_ERROR);
    }

    public function data(string $name, mixed $data): bool
    {
        // Match wire JSON object/array distinctions rather than PHP associative arrays.
        $this->validate($this->document['components']['schemas'][$name], json_decode(json_encode($data, JSON_THROW_ON_ERROR)), $name);

        return true;
    }

    public function resolve(string $reference): array
    {
        if (!str_starts_with($reference, '#/')) {
            throw new RuntimeException('Only local schema references are expected: ' . $reference);
        }
        $node = $this->document;
        foreach (explode('/', substr($reference, 2)) as $part) {
            $node = $node[str_replace(['~1', '~0'], ['/', '~'], $part)] ?? null;
            if (!is_array($node)) {
                throw new RuntimeException('Unresolved reference: ' . $reference);
            }
        }

        return $node;
    }

    public function validate(array $schema, mixed $value, string $path = 'data'): void
    {
        if (isset($schema['$ref'])) {
            $this->validate($this->resolve($schema['$ref']), $value, $path);

            return;
        }
        if ($value === null && ($schema['nullable'] ?? false) && isset($schema['type'])) {
            return;
        }
        foreach ($schema['allOf'] ?? [] as $part) {
            $this->validate($part, $value, $path);
        }
        foreach (['oneOf', 'anyOf'] as $union) {
            if (!isset($schema[$union])) {
                continue;
            }
            $matches = 0;
            foreach ($schema[$union] as $part) {
                try {
                    $this->validate($part, $value, $path);
                    $matches++;
                } catch (RuntimeException) {
                }
            }
            if ($matches === 0 || ($union === 'oneOf' && $matches !== 1)) {
                throw new RuntimeException($path . ': invalid ' . $union);
            }
        }
        $type = $schema['type'] ?? null;
        $valid = match ($type) {
            'object' => $value instanceof stdClass,
            'array' => is_array($value),
            'integer' => is_int($value),
            'number' => is_int($value) || is_float($value),
            'string' => is_string($value),
            'boolean' => is_bool($value),
            null => true,
            default => false,
        };
        if (!$valid || (isset($schema['enum']) && !in_array($value, $schema['enum'], true))) {
            throw new RuntimeException($path . ': expected ' . $type);
        }
        if ($type === 'object') {
            foreach ($schema['required'] ?? [] as $key) {
                if (!property_exists($value, $key)) {
                    throw new RuntimeException($path . ': missing ' . $key);
                }
            }
            foreach (get_object_vars($value) as $key => $item) {
                $child = $schema['properties'][$key] ?? $schema['additionalProperties'] ?? true;
                if ($child === false) {
                    throw new RuntimeException($path . ': unexpected ' . $key);
                }
                if (is_array($child)) {
                    $this->validate($child, $item, $path . '.' . $key);
                }
            }
        }
        if ($type === 'array') {
            if (count($value) < ($schema['minItems'] ?? 0) || count($value) > ($schema['maxItems'] ?? PHP_INT_MAX)) {
                throw new RuntimeException($path . ': array length');
            }
            if (($schema['uniqueItems'] ?? false) && count(array_unique(array_map('serialize', $value))) !== count($value)) {
                throw new RuntimeException($path . ': duplicate item');
            }
            foreach ($value as $index => $item) {
                $this->validate($schema['items'], $item, $path . '[' . $index . ']');
            }
        }
        if ($type === 'string') {
            if (mb_strlen($value) < ($schema['minLength'] ?? 0) || mb_strlen($value) > ($schema['maxLength'] ?? PHP_INT_MAX)
                || (isset($schema['pattern']) && !preg_match('~' . str_replace('~', '\\~', $schema['pattern']) . '~uD', $value))) {
                throw new RuntimeException($path . ': string constraint');
            }
        }
        if (($type === 'integer' || $type === 'number') && ($value < ($schema['minimum'] ?? -INF) || $value > ($schema['maximum'] ?? INF))) {
            throw new RuntimeException($path . ': numeric range');
        }
    }
}