; Copyright (c) Nicolas Buduroi. All rights reserved.
; The use and distribution terms for this software are covered by the
; Eclipse Public License 1.0 which can be found in the file
; epl-v10.html at the root of this distribution. By using this software
; in any fashion, you are agreeing to be bound by the terms of this
; license.
; You must not remove this notice, or any other, from this software.

(ns lobos.backends.postgresql
  "Compiler implementation for PostgreSQL."
  (:refer-clojure :exclude [compile defonce])
  (:require (lobos [schema :as schema]))
  (:use lobos.analyzer
        lobos.compiler
        lobos.utils)
  (:import (lobos.ast AlterRenameAction
                      ColumnDefinition
                      DataTypeClause)
           (lobos.schema DataType
                         Schema)))

;; -----------------------------------------------------------------------------

;; ## Analyzer

(def ^{:private true} analyzer-data-type-aliases
  {:bool :boolean
   :bpchar :char
   :bytea :blob
   :float4 :real
   :float8 :double
   :int2 :smallint
   :int4 :integer
   :int8 :bigint
   :text :nclob
   :timestamptz :timestamp
   :timetz :time})

(defmethod analyze [:postgresql DataType]
  [_ column-meta]
  (let [dtype (-> column-meta :type_name as-keyword)
        options {:time-zone (#{:timetz :timestamptz} dtype)}
        dtype (first (replace analyzer-data-type-aliases
                              [dtype]))]
    (schema/data-type
     dtype
     (analyze-data-type-args dtype column-meta)
     options)))

(defmethod analyze [:postgresql Schema]
  [_ sname]
  (analyze [:lobos.analyzer/standard Schema] (or sname :public)))

;; -----------------------------------------------------------------------------

;; ## Compiler

(def ^{:private true} compiler-data-type-aliases
  {:blob :bytea
   :clob :text
   :double :double-precision
   :nclob :text
   :nvarchar :varchar})

(defmethod compile [:postgresql DataTypeClause]
  [expression]
  (let [{:keys [dtype args options]} expression
        {:keys [time-zone]} options
        dtype (first (replace compiler-data-type-aliases [dtype]))
        args (if (#{:bytea :text} dtype) [] args)]
    (unsupported (#{:binary :varbinary} dtype)
      "Use blob instead.")
    (join \space
      (str (as-sql-keyword dtype) (as-list args))
      (when time-zone "WITH TIME ZONE"))))

(defmethod compile [:postgresql ColumnDefinition]
  [definition]
  (let [{:keys [db-spec cname data-type default
                auto-inc not-null others]} definition]
    (apply join \space
      (as-identifier db-spec cname)
      (if auto-inc
        (if (= :bigint (:dtype data-type))
          "BIGSERIAL"
          "SERIAL")
        (compile data-type))
      (when default (str "DEFAULT " (compile default)))
      (not-null-option not-null)
      others)))

(defmethod compile [:postgresql AlterRenameAction]
  [action]
  (let [{:keys [db-spec element]} action
        old-name (:cname element)
        new-name (:others element)]
    (format "RENAME COLUMN %s TO %s"
            (as-identifier db-spec old-name)
            (as-identifier db-spec new-name))))