yuming
61 lines
2.2 KiB
JavaScript
61 lines
2.2 KiB
JavaScript
/**
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* 订阅消息额度记账
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*
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* ⚠️ balance 是估算值，不是权威数据。真值只存在于微信服务器，且没有接口可查。
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* 我们靠「前端授权成功上报 +1、发送成功 -1」维护，并在发送返回 43101 时归零校正。
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* 任何地方都不要把 balance 当作可信的强校验依据。
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*
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* 额度是「每用户 × 每模板」维度的，所以以 openid 为主键；本项目只有一个模板，故不再分列。
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*/
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const db = require('./db')
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const MAX_GRANT_PER_CALL = 50 // 单次上报上限，防御异常入参
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function getBalance(openid) {
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const row = db.prepare('SELECT balance FROM subscribe_quota WHERE openid = ?').get(openid)
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return row ? row.balance : 0
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}
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// 把任意入参收敛成 1..MAX_GRANT_PER_CALL 的整数
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function _normalize(count) {
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const n = parseInt(count, 10)
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if (!Number.isFinite(n) || n < 1) return 1
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return Math.min(n, MAX_GRANT_PER_CALL)
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}
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// 授权上报：纯累加、不去重——微信侧确实每次授权都 +1，如实记录即可
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function grant(openid, count = 1) {
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const n = _normalize(count)
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db.prepare(`
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INSERT INTO subscribe_quota (openid, balance, grantedTotal, sentTotal, updateTime)
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VALUES (@openid, @n, @n, 0, @now)
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ON CONFLICT(openid) DO UPDATE SET
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balance = balance + @n,
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grantedTotal = grantedTotal + @n,
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updateTime = @now
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`).run({ openid, n, now: Date.now() })
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return getBalance(openid)
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}
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function consume(openid, count = 1) {
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const n = _normalize(count)
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db.prepare(`
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UPDATE subscribe_quota
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SET balance = MAX(0, balance - @n), sentTotal = sentTotal + @n, updateTime = @now
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WHERE openid = @openid
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`).run({ openid, n, now: Date.now() })
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return getBalance(openid)
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}
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// 余额归零：发送返回 43101 时调用，说明微信侧实际已无额度（或用户关了通知总开关）
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function reset(openid) {
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db.prepare(`
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INSERT INTO subscribe_quota (openid, balance, grantedTotal, sentTotal, updateTime)
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VALUES (@openid, 0, 0, 0, @now)
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ON CONFLICT(openid) DO UPDATE SET balance = 0, updateTime = @now
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`).run({ openid, now: Date.now() })
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}
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module.exports = { getBalance, grant, consume, reset }
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