clojure-101

db.clj

(def people (atom {:persons
                    {"Peter"
                     {:name "Peter"
                      :address "SG"
                      :phone "911"}
                     "John"
                     {:name "John"
                      :address "HK"
                      :phone "852911"}
                     "Mary"
                     {:name "Mary"
                      :address "CN"
                      :phone "86911"}}
                   :companies
                    {"Palo"
                     {:name "Palo"
                      :address "SG"
                      :phone "911"}
                     "Dokmee"
                     {:name "Dokmee"
                      :address "US"
                      :phone "852911"}}
                   :work-for
                    [{:person-name "Peter"
                      :company-name "Palo"}]
                   :roles
                    [{:name "Admin"}
                     {:name "Accountant"}
                     {:name "User"}]
                   :role-in-company
                    [{:person-name "Peter"
                      :company-name "Palo"
                      :role "Accountant"}]}))

(defn add-person [db person]
  (update-in db [:persons] conj [(:name person) person]))

(defn add-company [db company]
  (update-in db [:companies] conj [(:name company) company]))

(defn person-exists? [db person-name]
  (some? (get-in db [:persons person-name])))

(defn company-exists? [db company-name]
  (some? (get-in db [:companies company-name])))

(defn role-exists? [db role]
  (some? (seq (filter #(= role %) (map #(:name %) (:roles db))))))

(defn update-person [db person]
  (if (person-exists? db (:name person))
    (assoc-in db [:persons] person)
    (throw (Exception. "Person not found"))))

(defn delete-person [db person-name]
  ; (assoc db :persons (dissoc (:persons db) person-name)))
  (update-in db [:persons] dissoc person-name))

(defn add-work-for [db person-name company-name]
  (if (and (company-exists? db company-name)
           (person-exists? db person-name))
    (update-in db [:work-for]
               #(into [] (conj % {:person-name person-name :company-name company-name})))
    (throw (Exception. "Error adding work-for"))))

(defn add-role-for [db person-name company-name role]
  (if (and (company-exists? db company-name)
           (person-exists? db person-name)
           (role-exists? db role))
    (update-in db [:role-in-company]
               #(into [] (conj % {:person-name person-name :company-name company-name :role role})))
    (throw (Exception. "Error adding role-for"))))