(ns clojure-sql.core
  (:refer-clojure :exclude [sort take drop])
  (:require [clojure.set :as set]
            [clojure-sql.compiler :as c]
            [clojure-sql.dsl :as d]
            [clojure-sql.query :as q]
            [clojure-sql.util :as u]
            [clojure.walk]))


(defmacro pull [ns & vlist]
  `(do ~@(for [i vlist
               :let [sym (symbol (name ns) (name i))]] 
           `(def ~(with-meta i
                    (u/map-vals (fn [x] `(quote ~x)) (meta (resolve sym))))
              ~sym))
       nil))

(pull clojure-sql.dsl
      table join
      project rename
      select
      group having
      sort take drop)


(def ^:private ^:dynamic *database-type* nil)
(defn set-database-type! [new-type]
  (alter-var-root #'*database-type* (constantly new-type))
  nil)

(def ^:private ^:dynamic *query-executor* (comp second vector))
(defn set-query-executor! [exec-fn]
  (alter-var-root #'*query-executor* (constantly exec-fn))
  nil)



(defmethod print-method clojure_sql.query.Query [query writer]
  (binding [*out* writer]
    (pr (c/compile-select *database-type* query))))


(defn run-query [query]
  (assert *query-executor* "Cannot execute a query without a query executor")
  (*query-executor* :select (c/compile-select *database-type* query)))

(defn insert! [query & records]
  (assert *query-executor* "Cannot execute a query without a query executor")
  (let [compiled (apply c/compile-insert *database-type* query records)]
    (*query-executor* :insert compiled)))

(defn update! [query partial-record]
  (assert *query-executor* "Cannot execute a query without a query executor")
  (let [compiled (c/compile-update *database-type* query partial-record)]
    (*query-executor* :update compiled)))

(defn delete! [query]
  (assert *query-executor* "Cannot execute a query without a query executor")
  (let [compiled (c/compile-delete *database-type* query)]
    (*query-executor* :delete compiled)))

(q/set-query-deref-behaviour! run-query)