zamzam-supply

;; zamzam-supply -- Zamzam water distribution and supply chain
(define-constant CONTRACT-OWNER tx-sender)
(define-constant ERR-AUTH (err u401))
(define-constant ERR-NONE (err u404))
(define-data-var shipment-count uint u0)
(define-data-var total-liters uint u0)
(define-map shipments uint { supplier: principal, destination: (string-utf8 100), liters: uint, verified: bool, block: uint })
(define-map distributor-volume principal uint)

(define-public (create-shipment (destination (string-utf8 100)) (liters uint))
  (let ((id (+ (var-get shipment-count) u1))
        (prev (default-to u0 (map-get? distributor-volume tx-sender))))
    (var-set shipment-count id)
    (var-set total-liters (+ (var-get total-liters) liters))
    (map-set shipments id { supplier: tx-sender, destination: destination, liters: liters, verified: false, block: stacks-block-height })
    (map-set distributor-volume tx-sender (+ prev liters))
    (ok id)))

(define-public (verify-shipment (id uint))
  (let ((s (unwrap! (map-get? shipments id) ERR-NONE)))
    (asserts! (is-eq tx-sender CONTRACT-OWNER) ERR-AUTH)
    (map-set shipments id (merge s { verified: true })) (ok true)))

(define-read-only (get-shipment (id uint)) (map-get? shipments id))
(define-read-only (get-total-liters) (var-get total-liters))
(define-read-only (get-distributor-volume (addr principal)) (default-to u0 (map-get? distributor-volume addr)))