const db = uniCloud.database();
const _ = db.command;
const uniID = require('uni-id-common');

module.exports = {
	_before: function () { // 通用预处理器
		this.uniID = uniID.createInstance({
			context: this.getClientInfo()
		});
	},

	async collectArticle(query) {
		const payload = await this.uniID.checkToken(this.getUniIdToken());
		if (payload.errCode) throw new Error('登录状态失效，请重新登录');
		const user_id = payload.uid; // 以服务端令牌为准，忽略客户端传入
		const article_id = query && query.article_id;
		if (!article_id) {
			return { code: 400, msg: '缺少 article_id' };
		}

		const transaction = await db.startTransaction();
		try {
			// 查重只看「用户 + 文章」。曾把本次请求时间戳也放进条件，
			// 导致每次都查不到已有记录，可以无限重复收藏刷高计数。
			const exist = await transaction.collection('cms-articles-collect')
				.where({
					user_id: user_id,
					article_id: article_id
				}).count();

			if (exist.total > 0) {
				await transaction.rollback();
				return { code: 201, msg: '已点收藏' };
			}

			await transaction.collection('cms-articles-collect').add({
				user_id: user_id,
				article_id: article_id,
				create_time: Date.now()
			});

			await transaction.collection('uni-cms-articles').doc(article_id)
				.update({
					collect_count: _.inc(1)
				});

			await transaction.commit();
			return { code: 200 };
		} catch (e) {
			await transaction.rollback();
			return { code: 500, msg: e.message };
		}
	},

	async recollectArticle(query) {
		const payload = await this.uniID.checkToken(this.getUniIdToken());
		if (payload.errCode) throw new Error('登录状态失效，请重新登录');
		const user_id = payload.uid;
		const article_id = query && query.article_id;
		if (!article_id) {
			return { code: 400, msg: '缺少 article_id' };
		}

		// 删除明细与减计数必须同事务，否则删成功而减失败会让计数永久偏高
		const transaction = await db.startTransaction();
		try {
			const removeRes = await transaction.collection('cms-articles-collect')
				.where({
					user_id: user_id,
					article_id: article_id
				}).remove();

			if (removeRes.deleted === 0) {
				await transaction.rollback();
				return { code: 201, msg: '未找到收藏记录' };
			}

			await transaction.collection('uni-cms-articles').doc(article_id)
				.update({
					collect_count: _.inc(-1)
				});

			await transaction.commit();
			return { code: 200 };
		} catch (e) {
			await transaction.rollback();
			return { code: 500, msg: e.message };
		}
	}
}