var db = require('../../common/db')
var auth = require('../../common/auth')
var log = require('../../common/log')
var RESPONSE = require('../../common/response').RESPONSE
var ERROR_CODES = require('../../common/response').ERROR_CODES

exports.main_handler = async function (event) {
  try {
    var method = event.httpMethod || 'GET'
    var path = event.path || ''
    var body = parseBody(event)

    if (method === 'GET' && path === '/api/v1/subscription') {
      return await getSubscription(event)
    }
    if (method === 'POST' && path === '/api/v1/subscription/purchase') {
      return await purchaseSubscription(event, body)
    }
    if (method === 'POST' && path === '/api/v1/subscription/verify') {
      return await verifyPayment(event, body)
    }

    return RESPONSE.error(ERROR_CODES.PARAM_ERROR.code, 'unknown route')
  } catch (err) {
    console.error('subscription error:', err)
    return RESPONSE.error(ERROR_CODES.SERVER_ERROR.code, err.message)
  }
}

async function getSubscription(event) {
  var user = auth.extractUser(event)
  if (!user) return RESPONSE.error(ERROR_CODES.INVALID_TOKEN.code, ERROR_CODES.INVALID_TOKEN.message)

  var subs = await db.query(
    'SELECT id, type, plan, status, trial_used, started_at AS start_time, expired_at AS expire_time ' +
    'FROM subscriptions ' +
    'WHERE user_id = ? AND status = 1 AND expired_at > NOW() ' +
    'ORDER BY expired_at DESC LIMIT 1',
    [user.user_id]
  )

  if (subs.length === 0) {
    return RESPONSE.success({
      status: 0,
      plan: null,
      start_time: null,
      expire_time: null,
      remaining_days: 0
    })
  }

  var sub = subs[0]
  var remainingMs = new Date(sub.expire_time) - new Date()
  var remainingDays = Math.ceil(remainingMs / 86400000)

  return RESPONSE.success({
    status: sub.type === 1 ? 1 : 2,
    plan: sub.plan,
    start_time: sub.start_time,
    expire_time: sub.expire_time,
    remaining_days: remainingDays
  })
}

async function purchaseSubscription(event, body) {
  var user = auth.extractUser(event)
  if (!user) return RESPONSE.error(ERROR_CODES.INVALID_TOKEN.code, ERROR_CODES.INVALID_TOKEN.message)

  if (!body.plan) {
    return RESPONSE.error(ERROR_CODES.PARAM_ERROR.code, 'missing plan')
  }

  var planDays = { monthly: 30, quarterly: 90, yearly: 365 }
  var days = planDays[body.plan] || 30
  var orderId = 'ORD' + Date.now() + Math.random().toString(36).substring(2, 8)

  return RESPONSE.success({
    order_id: orderId,
    payment_params: {
      plan: body.plan,
      days: days,
      amount: 0,
      channel: body.payment_method || 'wechat'
    }
  })
}

async function verifyPayment(event, body) {
  var user = auth.extractUser(event)
  if (!user) return RESPONSE.error(ERROR_CODES.INVALID_TOKEN.code, ERROR_CODES.INVALID_TOKEN.message)

  if (!body.order_id) {
    return RESPONSE.error(ERROR_CODES.PARAM_ERROR.code, 'missing order_id')
  }

  var planDays = { monthly: 30, quarterly: 90, yearly: 365 }

  var currentSub = await db.query(
    'SELECT id, expired_at FROM subscriptions WHERE user_id = ? AND status = 1 AND expired_at > NOW() ORDER BY expired_at DESC LIMIT 1',
    [user.user_id]
  )

  var startDate = new Date()
  if (currentSub.length > 0 && new Date(currentSub[0].expired_at) > startDate) {
    startDate = new Date(currentSub[0].expired_at)
  }

  var plan = body.plan || 'monthly'
  var days = planDays[plan] || 30
  var expiredAt = new Date(startDate.getTime() + days * 86400000)

  await db.insert(
    'INSERT INTO subscriptions (user_id, type, plan, status, started_at, expired_at, source, source_id) VALUES (?, 2, ?, 1, ?, ?, ?, ?)',
    [user.user_id, plan, startDate.toISOString().slice(0, 19).replace('T', ' '), expiredAt.toISOString().slice(0, 19).replace('T', ' '), 'purchase', body.order_id]
  )

  await log.writeLog({
    operator_type: 2,
    operator_id: user.user_id,
    target_type: 'subscription',
    target_id: body.order_id,
    action: 'purchase',
    remark: 'plan=' + plan + ',days=' + days
  })

  return RESPONSE.success({
    status: 2,
    plan: plan,
    expire_time: expiredAt.toISOString().slice(0, 19).replace('T', ' ')
  })
}

function parseBody(event) {
  if (event.body) {
    try { return JSON.parse(event.body) } catch (e) { return {} }
  }
  return event.queryStringParameters || {}
}