#lang racket

;;; dds/rs

;;; Definitions for working with reaction systems.

(require "utils.rkt")

(provide
 ;; Structures
 (struct-out reaction)
 ;; Functions
 (contract-out [enabled? (-> reaction? (set/c symbol?) boolean?)]
               [list-enabled (-> reaction-system/c (set/c species?) (listof symbol?))]
               [union-products (-> reaction-system/c (listof symbol?) (set/c species?))]
               [apply-rs (-> reaction-system/c (set/c species?) (set/c species?))]
               [ht-str-triples->rs (-> (hash/c symbol? (list/c string? string? string?)) reaction-system/c)])
 ;; Predicates
 (contract-out [species? (-> any/c boolean?)])
 ;; Contracts
 (contract-out [reaction-system/c contract?])
 ;; Syntax
 unorg-rs)

;;; =================
;;; Basic definitions
;;; =================

;;; A species is a symbol.
(define species? symbol?)

;;; A reaction is a triple of sets, giving the reactants, the
;;; inhibitors, and the products, respectively.
(struct reaction (reactants inhibitors products) #:transparent)

;;; A reaction is enabled on a set if all of its reactants are in the
;;; set and none of its inhibitors are.
(define/match (enabled? r s)
  [((reaction r i p) s)
   (and (subset? r s) (set-empty? (set-intersect i s)))])

;;; A reaction system is a dictionary mapping reaction names to
;;; reactions.
(define reaction-system/c (hash/c symbol? reaction?))

;;; Returns the list of reaction names enabled on a given set.
(define (list-enabled rs s)
  (for/list ([(name reaction) (in-hash rs)]
             #:when (enabled? reaction s))
    name))

;;; Returns the union of the product sets of the given reactions in a
;;; reaction system.
;;;
;;; This function can be seen as producing the result of the
;;; application of the given reactions to a set.  Clearly, it does not
;;; check whether the reactions are actually enabled.
(define (union-products rs as)
  (apply set-union
         (for/list ([a as])
           (reaction-products (hash-ref rs a)))))

;;; Applies a reaction system to a set.
(define (apply-rs rs s)
  (let ([as (list-enabled rs s)])
    (union-products rs as)))


;;; ====================
;;; Org-mode interaction
;;; ====================

;;; This section contains some useful primitives for Org-mode
;;; interoperability.

;;; Reads a list of species from a string.
(define (read-symbol-list str)
  (string->any (string-append "(" str ")")))

;;; Converts a triple of strings to a reaction.
(define/match (str-triple->reaction lst)
  [((list str-reactants str-inhibitors str-products))
   (reaction (list->set (read-symbol-list str-reactants))
             (list->set (read-symbol-list str-inhibitors))
             (list->set (read-symbol-list str-products)))])

;;; Converts a hash table mapping reaction names to triples of strings
;;; to a reaction system.
(define (ht-str-triples->rs ht)
  (for/hash ([(a triple) (in-hash ht)])
    (values a (str-triple->reaction triple))))

;;; Chains ht-str-triples->rs with unorg.
(define-syntax-rule (unorg-rs str) (ht-str-triples->rs (unorg str)))