#lang typed/racket/base
(require sugar/list)
(require/typed racket/list [flatten (All (A) (Rec as (U Any (Listof as))) -> (Listof Any))])
(require (for-syntax racket/syntax racket/base) racket/string (except-in racket/list flatten) sugar/debug racket/bool hyphenate racket/function math/flonum)
(require "quads-typed.rkt" "world-typed.rkt" "measure-typed.rkt")


;; predicate for use below
(: list-of-mergeable-attrs? (Any . -> . Boolean))
(define (list-of-mergeable-attrs? xs)
  (and (list? xs) (andmap (λ(x) (or (quad? x) (quad-attrs? x) (hashable-list? x))) xs)))

;; faster than (listof pair?)
(: pairs? (Any . -> . Boolean))
(define (pairs? x) (and (list? x) (andmap pair? x)))

;; push together multiple attr sources into one list of pairs.
;; mostly a helper function for the two attr functions below.
(provide join-attrs)
(: join-attrs ((Listof (U Quad QuadAttrs HashableList)) . -> . (Listof QuadAttrPair)))
(define (join-attrs quads-or-attrs-or-lists)
  ((inst append-map QuadAttrPair QuadAttrs) (inst hash->list QuadAttrKey QuadAttrValue) (map (λ(x)
                                                   (cond
                                                     [(quad? x) (quad-attrs x)]
                                                     [(quad-attrs? x) (cast x QuadAttrs)]
                                                     [(hashable-list? x) (quadattrs (cast x (Listof Any)))]
                                                     [else ;; something that will have no effect on result 
                                                      (cast (hash) QuadAttrs)])) quads-or-attrs-or-lists)))


;; flatten merges attributes, but applies special logic suitable to flattening
;; for instance, resolving x and y coordinates.
(provide flatten-attrs)
(: flatten-attrs ((U Quad QuadAttrs) * . -> . QuadAttrs))
(define (flatten-attrs . quads-or-attrs-or-falses)
  (define all-attrs (join-attrs quads-or-attrs-or-falses))
  (define-values (x-attrs y-attrs other-attrs-reversed)
    (for/fold ([xas : (Listof QuadAttrPair) null]
               [yas : (Listof QuadAttrPair) null]
               [oas : (Listof QuadAttrPair) null])
              ([attr (in-list all-attrs)])
      (cond
        [(equal? (car attr) world:x-position-key) (values (cons attr xas) yas oas)]
        [(equal? (car attr) world:y-position-key) (values xas (cons attr yas) oas)]
        [else (values xas yas (cons attr oas))])))
  (: make-cartesian-attr (QuadAttrKey (Listof QuadAttrPair) . -> . (Listof QuadAttrPair)))
  (define (make-cartesian-attr key attrs) 
    (if (empty? attrs) 
        empty 
        (list (cons key (apply + (cast ((inst map QuadAttrValue QuadAttrPair) cdr attrs) (Listof Flonum)))))))
  (define x-attr (make-cartesian-attr world:x-position-key x-attrs))
  (define y-attr (make-cartesian-attr world:y-position-key y-attrs))
  (for/hash : QuadAttrs ([kv-pair (in-list (append x-attr y-attr (reverse other-attrs-reversed)))])
      (values (car kv-pair) (cdr kv-pair))))

;; merge concatenates attributes, with later ones overriding earlier.
;; most of the work is done by join-attrs.
(provide merge-attrs)
(: merge-attrs ((U Quad QuadAttrs HashableList) * . -> . QuadAttrs))
(define (merge-attrs . quads-or-attrs-or-lists)
  (for/hash : QuadAttrs ([kv-pair (in-list (join-attrs quads-or-attrs-or-lists))])
      (values (car kv-pair) (cdr kv-pair))))



;; pushes attributes down from parent quads to children, 
;; resulting in a flat list of quads.
(provide flatten-quad)
(: flatten-quad (Quad . -> . (Listof Quad)))
(define (flatten-quad q)
  (cast (flatten 
   (let loop : (Treeof Quad)
     ([x : QuadListItem q][parent : Quad (box)])
     
     (cond       
       [(quad? x)
        (let ([x-with-parent-attrs (quad (quad-name x) 
                                         (flatten-attrs parent x) ; child positioned last so it overrides parent attributes 
                                         (quad-list x))])
          (if (empty? (quad-list x))
              x-with-parent-attrs ; no subelements, so stop here
              ((inst map (Treeof Quad) QuadListItem) (λ(xi) (loop xi x-with-parent-attrs)) (quad-list x))))] ; replace quad with its elements
       [else ;; it's a string
        (quad (quad-name parent) (quad-attrs parent) (list x))]))) (Listof Quad)))