<?php
/**
 * 招新“学期”数据层：把原本单一的 itstudio_join_settings 配置扩展为可存档的多学期集合。
 *
 * 存储：
 *   option itstudio_join_terms         —— array，键为学期 id，值为 { id, academic_year, season, label, created, settings }
 *   option itstudio_join_active_term_id —— string，当前生效学期的 id
 *   option itstudio_join_terms_migrated —— 迁移完成标记
 *
 * 兼容：旧的 itstudio_join_settings 选项保留，作为迁移来源与兜底。
 * 迁移铁律沿用：各字段/选项标识不变，老数据不丢。
 */

if (!defined('ABSPATH')) {
    exit;
}

/**
 * 可选的季节及其中文名。
 */
function itstudio_join_get_seasons() {
    return array(
        'fall' => '秋季',
        'spring' => '春季',
    );
}

/**
 * 读取全部学期（id => term 的关联数组）。
 */
function itstudio_join_get_terms() {
    $terms = get_option('itstudio_join_terms', array());
    return is_array($terms) ? $terms : array();
}

/**
 * 当前生效学期 id。
 */
function itstudio_join_get_active_term_id() {
    $id = (string) get_option('itstudio_join_active_term_id', '');
    if ($id !== '') {
        $terms = itstudio_join_get_terms();
        if (isset($terms[$id])) {
            return $id;
        }
    }

    // 生效指针失效时，回退到第一个存在的学期。
    $terms = itstudio_join_get_terms();
    if (!empty($terms)) {
        return (string) array_key_first($terms);
    }

    return '';
}

/**
 * 取单个学期结构（不存在返回 null）。
 */
function itstudio_join_get_term($term_id) {
    $term_id = (string) $term_id;
    $terms = itstudio_join_get_terms();
    return isset($terms[$term_id]) ? $terms[$term_id] : null;
}

/**
 * 学期的展示名：优先自定义 label，否则“学年 + 季节招新”。
 */
function itstudio_join_term_label($term) {
    if (!is_array($term)) {
        return '';
    }

    $custom = trim((string) ($term['label'] ?? ''));
    if ($custom !== '') {
        return $custom;
    }

    $seasons = itstudio_join_get_seasons();
    $season_cn = $seasons[$term['season'] ?? ''] ?? '';
    $year = trim((string) ($term['academic_year'] ?? ''));
    $label = trim($year . ' ' . $season_cn . '招新');
    return $label !== '招新' ? $label : '未命名招新期';
}

/**
 * 由学年 + 季节生成稳定且唯一的学期 id（冲突时追加 -2、-3…）。
 */
function itstudio_join_make_term_id($academic_year, $season, array $existing = array()) {
    $base = sanitize_title($academic_year . '-' . $season);
    if ($base === '') {
        $base = 'term';
    }

    $id = $base;
    $suffix = 2;
    while (isset($existing[$id])) {
        $id = $base . '-' . $suffix;
        $suffix++;
    }

    return $id;
}

/**
 * 新建学期。$settings 省略时用默认空配置。返回新学期 id。
 */
function itstudio_join_create_term($academic_year, $season, $label = '', $settings = null) {
    $terms = itstudio_join_get_terms();

    $season = array_key_exists($season, itstudio_join_get_seasons()) ? $season : 'fall';
    $academic_year = itstudio_join_sanitize_shortcode_value($academic_year);
    $label = itstudio_join_sanitize_shortcode_value($label);

    $id = itstudio_join_make_term_id($academic_year, $season, $terms);

    $terms[$id] = array(
        'id' => $id,
        'academic_year' => $academic_year,
        'season' => $season,
        'label' => $label,
        'created' => current_time('mysql'),
        'settings' => is_array($settings)
            ? itstudio_join_sanitize_settings($settings)
            : itstudio_join_get_default_settings(),
    );

    update_option('itstudio_join_terms', $terms);

    // 若尚无“显式”生效学期（读原始选项，不走会兜底的 getter），新建的即为生效。
    $active_raw = (string) get_option('itstudio_join_active_term_id', '');
    if ($active_raw === '' || !isset($terms[$active_raw])) {
        itstudio_join_set_active_term($id);
    }

    return $id;
}

/**
 * 更新某学期的元信息（学年/季节/自定义名）。
 */
function itstudio_join_update_term_meta($term_id, $academic_year, $season, $label = '') {
    $terms = itstudio_join_get_terms();
    $term_id = (string) $term_id;
    if (!isset($terms[$term_id])) {
        return false;
    }

    $terms[$term_id]['academic_year'] = itstudio_join_sanitize_shortcode_value($academic_year);
    $terms[$term_id]['season'] = array_key_exists($season, itstudio_join_get_seasons()) ? $season : 'fall';
    $terms[$term_id]['label'] = itstudio_join_sanitize_shortcode_value($label);

    update_option('itstudio_join_terms', $terms);
    return true;
}

/**
 * 把一份配置写入指定学期。
 */
function itstudio_join_save_term_settings($term_id, $raw_settings) {
    $terms = itstudio_join_get_terms();
    $term_id = (string) $term_id;
    if (!isset($terms[$term_id])) {
        return false;
    }

    $terms[$term_id]['settings'] = itstudio_join_sanitize_settings($raw_settings);
    update_option('itstudio_join_terms', $terms);
    return true;
}

/**
 * 设为当前生效学期。
 */
function itstudio_join_set_active_term($term_id) {
    $term_id = (string) $term_id;
    $terms = itstudio_join_get_terms();
    if (!isset($terms[$term_id])) {
        return false;
    }

    update_option('itstudio_join_active_term_id', $term_id);
    return true;
}

/**
 * 删除学期。不允许删“当前生效”或最后一个。
 */
function itstudio_join_delete_term($term_id) {
    $term_id = (string) $term_id;
    $terms = itstudio_join_get_terms();

    if (!isset($terms[$term_id])) {
        return false;
    }
    if (count($terms) <= 1) {
        return false;
    }
    if (itstudio_join_get_active_term_id() === $term_id) {
        return false;
    }

    unset($terms[$term_id]);
    update_option('itstudio_join_terms', $terms);
    return true;
}

/**
 * 由旧的单一配置推断学年与季节（报名开始月份 >= 7 视为秋季）。
 */
function itstudio_join_guess_term_from_settings($settings) {
    $settings = is_array($settings) ? $settings : array();
    $anchor = '';
    foreach (array('registration_start', 'notice_start_date', 'first_interview_date') as $key) {
        if (!empty($settings[$key])) {
            $anchor = (string) $settings[$key];
            break;
        }
    }

    if ($anchor === '' || !preg_match('/(\d{4})-(\d{2})/', $anchor, $m)) {
        return array('academic_year' => '', 'season' => 'fall');
    }

    $year = (int) $m[1];
    $month = (int) $m[2];
    if ($month >= 7) {
        return array('academic_year' => $year . '-' . ($year + 1), 'season' => 'fall');
    }

    return array('academic_year' => ($year - 1) . '-' . $year, 'season' => 'spring');
}

/**
 * 一次性迁移：把旧的单一 itstudio_join_settings 归入首个学期并设为生效。
 * 前后台每个请求都会触发，但有标记，已迁移则立即返回。
 */
function itstudio_join_maybe_migrate_terms() {
    if (get_option('itstudio_join_terms_migrated')) {
        return;
    }

    $terms = itstudio_join_get_terms();
    if (empty($terms)) {
        $legacy = get_option('itstudio_join_settings', array());
        $legacy = is_array($legacy) ? $legacy : array();

        if (!empty($legacy)) {
            $guess = itstudio_join_guess_term_from_settings($legacy);
            $label = $guess['academic_year'] === '' ? '初始招新期' : '';
            itstudio_join_create_term($guess['academic_year'], $guess['season'], $label, $legacy);
        } else {
            // 全新安装：建一个空的当前学期占位。
            $now_year = (int) current_time('Y');
            itstudio_join_create_term($now_year . '-' . ($now_year + 1), 'fall', '', null);
        }
    }

    update_option('itstudio_join_terms_migrated', 1);
}
add_action('init', 'itstudio_join_maybe_migrate_terms', 1);