68 lines
1.9 KiB
Go
68 lines
1.9 KiB
Go
package domain
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import (
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"math"
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"time"
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"github.com/gofrs/uuid/v5"
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)
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const earthRadiusKm = 6371.0
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// HaversineDistance calculates the distance in kilometers between two points
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// using the Haversine formula. The result is approximate (±5km for security).
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func HaversineDistance(lat1, lng1, lat2, lng2 float64) float64 {
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dLat := degreesToRadians(lat2 - lat1)
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dLng := degreesToRadians(lng2 - lng1)
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lat1Rad := degreesToRadians(lat1)
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lat2Rad := degreesToRadians(lat2)
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a := math.Sin(dLat/2)*math.Sin(dLat/2) +
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math.Cos(lat1Rad)*math.Cos(lat2Rad)*
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math.Sin(dLng/2)*math.Sin(dLng/2)
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c := 2 * math.Atan2(math.Sqrt(a), math.Sqrt(1-a))
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distance := earthRadiusKm * c
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// Round to nearest km for approximate distance (security)
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return math.Round(distance)
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}
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func degreesToRadians(degrees float64) float64 {
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return degrees * math.Pi / 180
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}
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// ProductWithDistance extends Product with distance information for search results.
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type ProductWithDistance struct {
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Product
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DistanceKm float64 `json:"distance_km"`
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TenantCity string `json:"tenant_city,omitempty"`
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TenantState string `json:"tenant_state,omitempty"`
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// TenantID is hidden for anonymous browsing, revealed only at checkout
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}
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// ProductSearchFilter captures search constraints.
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type ProductSearchFilter struct {
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Search string
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Category string
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MinPriceCents *int64
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MaxPriceCents *int64
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ExpiresAfter *time.Time
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ExpiresBefore *time.Time
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MaxDistanceKm *float64
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BuyerLat float64
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BuyerLng float64
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ExcludeSellerID *uuid.UUID // Exclude products from buyer's own company
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Limit int
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Offset int
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}
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// ProductSearchPage wraps search results with pagination.
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type ProductSearchPage struct {
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Products []ProductWithDistance `json:"products"`
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Total int64 `json:"total"`
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Page int `json:"page"`
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PageSize int `json:"page_size"`
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}
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