<?php
/**
 * AKSRT Download State
 *
 * Unified download state resolver for resource pages.
 * Driven by AKSRT_Content_Visibility (cashier unlock), not per-download credits.
 *
 * @package AKSRT
 */

defined('ABSPATH') || exit;

class AKSRT_Download_State {

    private static $instance = null;

    const STATE_NOT_LOGGED_IN      = 'not_logged_in';
    const STATE_NO_PERMISSION      = 'no_permission';
    const STATE_NEED_PURCHASE      = 'need_purchase';
    const STATE_NEED_VIP           = 'need_vip';
    const STATE_OWNED              = 'owned';
    const STATE_AVAILABLE          = 'available';
    const STATE_PENDING_DELIVERY   = 'pending_delivery';
    /** @deprecated use STATE_NEED_PURCHASE — kept for old templates */
    const STATE_INSUFFICIENT_CREDITS = 'need_purchase';

    private function __construct() {}

    public static function get_instance(): self {
        if (null === self::$instance) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    /**
     * Resolve the current user's download state for a given resource post.
     *
     * @param int $post_id Resource post ID.
     * @return array{
     *   state:string,can_download:bool,message:string,action_label:string,
     *   action_url:string,cost:int,balance:int,login_url:string,pay_modo:string,
     *   amount:float,need_purchase:bool,need_vip:bool,has_paid_access:bool
     * }
     */
    public function resolve(int $post_id): array {
        $login_url = wp_login_url(get_permalink($post_id));
        $is_logged_in = is_user_logged_in();
        $user_id = $is_logged_in ? get_current_user_id() : 0;

        $meta = function_exists('aksrt_get_download_box_meta')
            ? aksrt_get_download_box_meta($post_id)
            : (function_exists('aksrt_get_resource_meta') ? aksrt_get_resource_meta($post_id) : []);
        $downloads = is_array($meta['downloads'] ?? null) ? $meta['downloads'] : [];

        if ($downloads === []) {
            return $this->build_result(
                self::STATE_NO_PERMISSION,
                false,
                __('该资源暂未提供下载链接。', 'aksrt'),
                __('暂无下载', 'aksrt'),
                '',
                0,
                0,
                $login_url
            );
        }

        $access = class_exists('AKSRT_Content_Visibility')
            ? AKSRT_Content_Visibility::get_post_access_state($post_id, $user_id)
            : [];
        $priced = function_exists('aksrt_get_user_pay_price')
            ? aksrt_get_user_pay_price($post_id, $user_id)
            : null;
        $pay_modo = is_array($priced)
            ? ((($priced['modo'] ?? '0') === 'points') ? 'points' : '0')
            : '0';
        $amount = is_array($priced) ? (float) ($priced['amount'] ?? 0) : 0.0;
        $cost = function_exists('aksrt_resource_download_cost')
            ? (int) aksrt_resource_download_cost($post_id)
            : 0;
        $balance = ($user_id > 0 && class_exists('AKSRT_Credits'))
            ? AKSRT_Credits::balance($user_id)
            : 0;

        $gate = function_exists('aksrt_can_download') ? aksrt_can_download($post_id, $user_id) : true;
        if (is_wp_error($gate)) {
            $code = $gate->get_error_code();
            $data = (array) $gate->get_error_data();
            $msg  = $gate->get_error_message() ?: __('无下载权限。', 'aksrt');

            if ($code === 'aksrt_need_login') {
                return $this->build_result(
                    self::STATE_NOT_LOGGED_IN,
                    false,
                    __('登录后可下载此资源。', 'aksrt'),
                    __('登录下载', 'aksrt'),
                    (string) ($data['login_url'] ?? $login_url),
                    $cost,
                    $balance,
                    (string) ($data['login_url'] ?? $login_url),
                    [
                        'pay_modo' => $pay_modo,
                        'amount'   => $amount,
                        'need_purchase' => false,
                        'need_vip' => false,
                        'has_paid_access' => !empty($access['has_paid_access']),
                    ]
                );
            }

            if ($code === 'aksrt_need_vip') {
                $vip_url = function_exists('aksrt_get_user_center_tab_url')
                    ? aksrt_get_user_center_tab_url('credits')
                    : $login_url;
                return $this->build_result(
                    self::STATE_NEED_VIP,
                    false,
                    $msg,
                    __('开通会员', 'aksrt'),
                    $vip_url,
                    $cost,
                    $balance,
                    $login_url,
                    [
                        'pay_modo' => $pay_modo,
                        'amount'   => $amount,
                        'need_purchase' => false,
                        'need_vip' => true,
                        'has_paid_access' => false,
                    ]
                );
            }

            // need_purchase / legacy insufficient credits → cashier.
            if (in_array($code, ['aksrt_need_purchase', 'aksrt_credits_insufficient'], true)) {
                $label = $pay_modo === 'points'
                    ? sprintf(__('购买（%s 积分）', 'aksrt'), (string) (int) ceil($amount > 0 ? $amount : $cost))
                    : __('去购买', 'aksrt');
                return $this->build_result(
                    self::STATE_NEED_PURCHASE,
                    false,
                    $msg ?: __('请先购买后再下载。', 'aksrt'),
                    $label,
                    '',
                    $cost,
                    $balance,
                    $login_url,
                    [
                        'pay_modo' => $pay_modo,
                        'amount'   => $amount > 0 ? $amount : (float) $cost,
                        'need_purchase' => true,
                        'need_vip' => false,
                        'has_paid_access' => false,
                    ]
                );
            }

            return $this->build_result(
                self::STATE_NO_PERMISSION,
                false,
                $msg,
                __('无权限', 'aksrt'),
                '',
                $cost,
                $balance,
                $login_url,
                [
                    'pay_modo' => $pay_modo,
                    'amount'   => $amount,
                    'need_purchase' => !empty($access['need_purchase']),
                    'need_vip' => !empty($access['need_vip']),
                    'has_paid_access' => !empty($access['has_paid_access']),
                ]
            );
        }

        // Paid / free unlock.
        $has_paid = !empty($access['has_paid_access']);
        if ($has_paid || $amount <= 0) {
            $owned = $has_paid && $amount > 0;
            return $this->build_result(
                $owned ? self::STATE_OWNED : self::STATE_AVAILABLE,
                true,
                $owned
                    ? __('已购买，可下载。', 'aksrt')
                    : __('此资源可免费下载。', 'aksrt'),
                $owned ? __('立即下载', 'aksrt') : __('立即下载', 'aksrt'),
                '',
                0,
                $balance,
                $login_url,
                [
                    'pay_modo' => $pay_modo,
                    'amount'   => 0.0,
                    'need_purchase' => false,
                    'need_vip' => false,
                    'has_paid_access' => true,
                ]
            );
        }

        // Gate true but still priced unpaid (should be rare).
        return $this->build_result(
            self::STATE_NEED_PURCHASE,
            false,
            __('请先购买后再下载。', 'aksrt'),
            __('去购买', 'aksrt'),
            '',
            $cost,
            $balance,
            $login_url,
            [
                'pay_modo' => $pay_modo,
                'amount'   => $amount,
                'need_purchase' => true,
                'need_vip' => false,
                'has_paid_access' => false,
            ]
        );
    }

    /**
     * @param array<string,mixed> $extra
     */
    private function build_result(
        string $state,
        bool $can_download,
        string $message,
        string $action_label,
        string $action_url,
        int $cost,
        int $balance,
        string $login_url,
        array $extra = []
    ): array {
        return array_merge([
            'state'           => $state,
            'can_download'    => $can_download,
            'message'         => $message,
            'action_label'    => $action_label,
            'action_url'      => $action_url,
            'cost'            => $cost,
            'balance'         => $balance,
            'login_url'       => $login_url,
            'pay_modo'        => '0',
            'amount'          => 0.0,
            'need_purchase'   => false,
            'need_vip'        => false,
            'has_paid_access' => false,
        ], $extra);
    }
}