<?php
// SPDX-License-Identifier: GPL-3.0-or-later
declare(strict_types=1);

namespace Aiwend\Pricing;

use Aiwend\Support\Clock;
use Aiwend\Support\OptionStore;

/**
 * The rates an administrator entered for this site: one option, at most 50 entries, each validated on the way in and again on the
 * way out (a stored value that is malformed or was edited by hand is ignored). A rate states what the administrator's own provider
 * account charges; it is labelled custom and dated everywhere it is used.
 */
final class PriceOverrides
{
    public const OPTION = 'aiwend_price_overrides';
    public const MAX = 50;
    public const PROVIDERS = ['openai', 'anthropic', 'gemini'];
    private const MODEL = '/^[A-Za-z0-9][A-Za-z0-9._:\/@+-]{0,190}$/D';

    public function __construct(private OptionStore $options, private Clock $clock)
    {
    }

    /** @return list<array{provider:string, model:string, currency:string, input:string, cached_input:?string, output:string, entered_at:int}> */
    public function all(): array
    {
        $stored = $this->options->get(self::OPTION, []);
        $out = [];
        foreach (is_array($stored) ? $stored : [] as $e) {
            $clean = is_array($e) ? self::clean($e) : null;
            if ($clean !== null && isset($e['entered_at']) && is_int($e['entered_at']) && $e['entered_at'] > 0) {
                $out[] = $clean + ['entered_at' => $e['entered_at']];
            }
        }
        return $out;
    }

    /**
     * @param array<string, mixed> $in provider, model, currency, input, cached_input, output, confirm
     * @return array{ok:bool, error:?string} error: provider, model, currency, rate, confirm or limit
     */
    public function save(array $in): array
    {
        if ((string) ($in['confirm'] ?? '') !== '1') {
            return ['ok' => false, 'error' => 'confirm'];
        }
        $provider = (string) ($in['provider'] ?? '');
        if (!in_array($provider, self::PROVIDERS, true)) {
            return ['ok' => false, 'error' => 'provider'];
        }
        $model = (string) ($in['model'] ?? '');
        if (preg_match(self::MODEL, $model) !== 1) {
            return ['ok' => false, 'error' => 'model'];
        }
        $currency = (string) ($in['currency'] ?? '');
        if (preg_match('/^[A-Z]{3}$/D', $currency) !== 1) {
            return ['ok' => false, 'error' => 'currency'];
        }
        $cachedText = trim((string) ($in['cached_input'] ?? ''));
        $entry = self::clean([
            'provider' => $provider, 'model' => $model, 'currency' => $currency,
            'input' => trim((string) ($in['input'] ?? '')), 'cached_input' => $cachedText === '' ? null : $cachedText, 'output' => trim((string) ($in['output'] ?? '')),
        ]);
        if ($entry === null) {
            return ['ok' => false, 'error' => 'rate'];
        }
        $list = array_values(array_filter($this->all(), static fn(array $e): bool => !($e['provider'] === $provider && $e['model'] === $model)));
        if (count($list) >= self::MAX) {
            return ['ok' => false, 'error' => 'limit'];
        }
        $list[] = $entry + ['entered_at' => $this->clock->now()];
        $this->options->set(self::OPTION, $list);
        return ['ok' => true, 'error' => null];
    }

    public function remove(string $provider, string $model): bool
    {
        $all = $this->all();
        $kept = array_values(array_filter($all, static fn(array $e): bool => !($e['provider'] === $provider && $e['model'] === $model)));
        if (count($kept) === count($all)) {
            return false;
        }
        $this->options->set(self::OPTION, $kept);
        return true;
    }

    /**
     * @param array<string, mixed> $e
     * @return array{provider:string, model:string, currency:string, input:string, cached_input:?string, output:string}|null
     */
    private static function clean(array $e): ?array
    {
        $provider = $e['provider'] ?? null;
        $model = $e['model'] ?? null;
        $currency = $e['currency'] ?? null;
        $input = $e['input'] ?? null;
        $output = $e['output'] ?? null;
        $cached = $e['cached_input'] ?? null;
        if (!is_string($provider) || !in_array($provider, self::PROVIDERS, true) || !is_string($model) || preg_match(self::MODEL, $model) !== 1
            || !is_string($currency) || preg_match('/^[A-Z]{3}$/D', $currency) !== 1 || !is_string($input) || !is_string($output) || ($cached !== null && !is_string($cached))) {
            return null;
        }
        $in = Decimal::toMicro($input);
        $out = Decimal::toMicro($output);
        $ca = $cached === null ? null : Decimal::toMicro($cached);
        // a price of zero would claim the model is free; a cached read dearer than fresh input is a typing mistake
        if ($in === null || $out === null || $in === 0 || $out === 0 || ($cached !== null && ($ca === null || $ca === 0 || $ca > $in))) {
            return null;
        }
        return ['provider' => $provider, 'model' => $model, 'currency' => $currency, 'input' => $input, 'cached_input' => $cached, 'output' => $output];
    }
}