71 lines
2.4 KiB
JavaScript
71 lines
2.4 KiB
JavaScript
const cloud = require('wx-server-sdk')
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cloud.init({ env: cloud.DYNAMIC_CURRENT_ENV })
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const db = cloud.database()
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function hashId(id) {
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let h = 5381
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for (let i = 0; i < id.length; i++) {
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h = ((h << 5) + h) ^ id.charCodeAt(i)
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h = h >>> 0 // keep as unsigned 32-bit
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}
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return h
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}
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// Generate a stable map pin position from pet id (fallback abstract layer)
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function stablePin(id) {
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const h = hashId(id)
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const left = 10 + (h % 70)
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const top = 15 + ((h >> 8) % 55)
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return { left, top }
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}
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// Scatter a pet deterministically within roughly ±0.9km of the user, so on a
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// real map markers cluster nearby (stable per pet id across requests).
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function syntheticCoord(id, userLoc) {
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const h = hashId(id)
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const dLat = ((h % 1600) - 800) / 100000 // ±0.008° ≈ ±0.9km
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const dLng = (((h >> 8) % 1600) - 800) / 100000
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return { latitude: userLoc.latitude + dLat, longitude: userLoc.longitude + dLng }
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}
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// Rough distance text from coordinate delta (fallback when no real distance)
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function distanceText(petLoc, userLoc) {
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if (!petLoc || !userLoc) return null
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const R = 6371000
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const dLat = ((petLoc.latitude - userLoc.latitude) * Math.PI) / 180
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const dLon = ((petLoc.longitude - userLoc.longitude) * Math.PI) / 180
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const a =
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Math.sin(dLat / 2) ** 2 +
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Math.cos((userLoc.latitude * Math.PI) / 180) *
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Math.cos((petLoc.latitude * Math.PI) / 180) *
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Math.sin(dLon / 2) ** 2
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const meters = Math.round(R * 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a)))
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if (meters < 1000) return `${meters}m`
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return `${(meters / 1000).toFixed(1)}km`
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}
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exports.main = async event => {
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const filter = event.filters?.type || 'all'
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const userLoc = event.location || null
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const query = {}
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if (filter === 'dog' || filter === 'cat') query.species = filter
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if (filter === 'online') query.online = true
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const res = await db.collection('pets').where(query).limit(50).get()
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const list = res.data.map(pet => {
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const realCoord = pet.location && typeof pet.location.latitude === 'number' ? pet.location : null
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const coord = realCoord || (userLoc ? syntheticCoord(pet._id, userLoc) : null)
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return {
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...pet,
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latitude: coord ? coord.latitude : undefined,
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longitude: coord ? coord.longitude : undefined,
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distanceText: distanceText(coord, userLoc) || pet.distanceText || null,
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pin: stablePin(pet._id)
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}
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})
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return { list }
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}
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