#lang scheme/base

(require (planet cobbe/contract-utils:1/contract-utils)
         (except-in srfi/1/list any)
         scheme/contract
         scheme/match
         "../syntax/ast-core.ss"
         "../syntax/ast-utils.ss"
         "../syntax/token.ss")

(define-struct (FunctionDeclaration/hoisted FunctionDeclaration) (functions variables))
(define-struct (FunctionExpression/hoisted FunctionExpression) (functions variables))
(define-struct (BlockStatement/hoisted BlockStatement) (functions variables))

;; (listof FunctionDeclaration/hoisted) * (listof Identifier) * (listof FunctionDeclaration/hoisted) * (listof Identifier)
(define-struct hoisting (functions vars let-functions let-vars) #:transparent)

;; null-hoisting : hoisting
(define null-hoisting (make-hoisting null null null null))

;; append-hoisting : hoisting * hoisting -> hoisting
(define (append-hoisting . hs)
  (match hs
    [(list (struct hoisting (funss varss let-funss let-varss)) ...)
     (make-hoisting (apply append funss)
                    (apply append varss)
                    (apply append let-funss)
                    (apply append let-varss))]))

;; cons-function-hoisting : FunctionDeclaration/hoisted * hoisting -> hoisting
(define (cons-function-hoisting fun h)
  (struct-copy hoisting h [functions (cons fun (hoisting-functions h))]))

;; cons-var-hoisting : Identifier * hoisting -> hoisting
(define (cons-var-hoisting var h)
  (struct-copy hoisting h [vars (cons var (hoisting-vars h))]))

;; cons-let-function-hoisting : FunctionDeclaration/hoisted * hoisting -> hoisting
(define (cons-let-function-hoisting fun h)
  (struct-copy hoisting h [let-functions (cons fun (hoisting-let-functions h))]))

;; cons-let-var-hoisting : Identifier * hoisting -> hoisting
(define (cons-let-var-hoisting var h)
  (struct-copy hoisting h [let-vars (cons var (hoisting-let-vars h))]))

;; a (continuation a -> b) is:
;;
;;   - (hoisting a -> b)

(define (continuation/c c)
  (hoisting? c . -> . any))

;; an (a ->k b) is:
;;
;;   - (a (continuation b -> c) -> c)

(define-syntax provide/contract/k
  (syntax-rules (->k)
    [(_ [name (domain . ->k . range)] ...)
     (provide/contract
      [name (domain (continuation/c range) . -> . any)]
      ...)]))

;; unique-vars : (listof FunctionDeclaration/hoisted) * (listof Identifier) -> (listof Identifier)
(define (unique-vars funs vars)
  (lset-difference Identifier=?
                   (delete-duplicates vars Identifier=?)
                   (map FunctionDeclaration-name funs)))

;; ===========================================================================
;; TOP-LEVEL HOISTING FUNCTIONS
;; ===========================================================================

;; wrap-in-implicit-block : region * (listof Statement) * (listof FunctionDeclaration/hoisted) * (listof Identifier) -> (listof Statement)
(define (wrap-in-implicit-block loc stmts let-funs let-vars)
  (list (make-BlockStatement/hoisted loc stmts let-funs let-vars)))

;; hoist-function-declaration : FunctionDeclaration -> FunctionDeclaration/hoisted
(define (hoist-function-declaration decl)
  (match decl
    [(struct FunctionDeclaration (location name args body))
     (hoist-source-elements body
                            (lambda (h stmts)
                              (match h
                                [(struct hoisting (funs vars let-funs let-vars))
                                 (make-FunctionDeclaration/hoisted location
                                                                   name
                                                                   args
                                                                   (wrap-in-implicit-block location stmts let-funs let-vars)
                                                                   funs
                                                                   (unique-vars funs vars))])))]))

;; hoist-script : (listof SourceElement) -> (listof FunctionDeclaration/hoisted)
;;                                          (listof Identifier)
;;                                          (listof Statement)
(define (hoist-script elts)
  (hoist-source-elements elts
                         (lambda (h stmts)
                           (match h
                             [(struct hoisting (funs vars let-funs let-vars))
                              (values funs
                                      (unique-vars funs vars)
                                      (wrap-in-implicit-block (@ (first elts) (last elts)) stmts let-funs let-vars))]))))

;; ===========================================================================
;; COMPOUND HOISTING FUNCTIONS
;; ===========================================================================

;; map-k : (a ->k b) (listof a) ->k (listof b)
(define (map-k hoist1 elts k)
  (if (null? elts)
      (k null-hoisting null)
      (hoist1 (car elts)
              (lambda (hoisting1 result)
                (map-k hoist1 (cdr elts)
                       (lambda (hoisting2 results)
                         (k (append-hoisting hoisting1 hoisting2)
                            (cons result results))))))))

;; filter-map-k : (a ->k (optional b)) (listof a) ->k (listof b)
(define (filter-map-k hoist1 elts k)
  (if (null? elts)
      (k null-hoisting null)
      (hoist1 (car elts)
              (lambda (hoisting1 result)
                (filter-map-k hoist1 (cdr elts)
                              (lambda (hoisting2 results)
                                (k (append-hoisting hoisting1 hoisting2)
                                   (if result (cons result results) results))))))))

;; append-map-k : (a ->k (listof b)) (listof a) ->k (listof b)
(define (append-map-k hoist1 elts k)
  (if (null? elts)
      (k null-hoisting null)
      (hoist1 (car elts)
              (lambda (hoisting1 results1)
                (append-map-k hoist1 (cdr elts)
                              (lambda (hoisting2 results2)
                                (k (append-hoisting hoisting1 hoisting2)
                                   (append results1 results2))))))))

;; hoist-source-elements : (listof SourceElement) ->k (listof Statement)
(define (hoist-source-elements elts k)
  (map-k hoist-source-element elts k))

;; hoist-optional-expression : (optional Expression) -> (optional Expression)
(define (hoist-optional-expression expr)
  (and expr (hoist-expression expr)))

;; hoist-substatements : (listof SourceElement) ->k (listof Statement)
(define (hoist-substatements stmts k)
  (hoist-source-elements stmts k))
;(filter-map-k hoist-substatement stmts k))

;; hoist-var-initializers : (listof VariableInitializer) (optional region) ->k Expression
(define (hoist-var-initializers decls loc k)
  (filter-map-k hoist-var-initializer decls
                (lambda (h exprs)
                  (k h (if (and (pair? exprs)
                                (null? (cdr exprs)))
                           (car exprs)
                           (make-ListExpression loc exprs))))))

;; hoist-let-var-initializers : (listof VariableInitializer) (optional region) ->k Expression
(define (hoist-let-var-initializers decls loc k)
  (filter-map-k hoist-let-var-initializer decls
                (lambda (h exprs)
                  (k h (if (and (pair? exprs)
                                (null? (cdr exprs)))
                           (car exprs)
                           (make-ListExpression loc exprs))))))

;; hoist-case-clauses : (listof CaseClause) ->k (listof CaseClause)
(define (hoist-case-clauses cases k)
  (map-k hoist-case-clause cases k))

;; hoist-catch-clauses : (listof CatchClause) ->k (listof CatchClause)
(define (hoist-catch-clauses catches k)
  (map-k hoist-catch-clause catches k))

;; ===========================================================================
;; CORE HOISTING FUNCTIONS
;; ===========================================================================

;; hoist-source-element : SourceElement ->k Statement
(define (hoist-source-element src k)
  (if (Declaration? src)
      (hoist-declaration src k)
      (hoist-statement src k)))

;; hoist-declaration : Declaration ->k Statement
(define (hoist-declaration decl0 k)
  (cond
    [(FunctionDeclaration? decl0)
     (k (cons-function-hoisting (hoist-function-declaration decl0) null-hoisting)
        (make-EmptyStatement (Term-location decl0)))]
    [(VariableDeclaration? decl0)
     (hoist-variable-declaration decl0
                                 (lambda (h expr)
                                   (k h (make-ExpressionStatement (Term-location decl0) expr))))]
    [(LetDeclaration? decl0)
     (hoist-let-declaration decl0
                            (lambda (h expr)
                              (k h (make-ExpressionStatement (Term-location decl0) expr))))]
    [else (error 'hoist-declaration (format "unrecognized declaration: ~v" decl0))]))

;; hoist-variable-declaration : VariableDeclaration ->k Expression
(define (hoist-variable-declaration decl0 k)
  (match decl0
    [(struct VariableDeclaration (loc bindings))
     (hoist-var-initializers bindings loc k)]))

;; hoist-let-declaration : LetDeclaration ->k Expression
(define (hoist-let-declaration decl0 k)
  (match decl0
    [(struct LetDeclaration (loc bindings))
     (hoist-let-var-initializers bindings loc k)]))

;; hoist-substatement : SourceElement ->k (optional Statement)
(define (hoist-substatement src0 k)
  (hoist-source-element src0 k))

;    (if (FunctionDeclaration? src0)
;        (k (cons-function-hoisting (hoist-function-declaration src0) null-hoisting) #f)
;        (hoist-statement src0 k)))

;; hoist-var-initializer : VariableInitializer ->k (optional Expression)
(define (hoist-var-initializer decl k)
  (match decl
    [(struct VariableInitializer (loc id #f))
     (k (cons-var-hoisting id null-hoisting) #f)]
    [(struct VariableInitializer (loc id init))
     (k (cons-var-hoisting id null-hoisting)
        (make-AssignmentExpression loc (make-VarReference (Term-location id) id) '= (hoist-expression init)))]))

;; hoist-let-var-initializer : VariableInitializer ->k (optional Expression)
(define (hoist-let-var-initializer decl k)
  (match decl
    [(struct VariableInitializer (loc id #f))
     (k (cons-let-var-hoisting id null-hoisting) #f)]
    [(struct VariableInitializer (loc id init))
     (k (cons-let-var-hoisting id null-hoisting)
        (make-AssignmentExpression loc (make-VarReference (Term-location id) id) '= (hoist-expression init)))]))

;; hoist-case-clause : CaseClause ->k CaseClause
(define (hoist-case-clause case k)
  (match case
    [(struct CaseClause (loc #f answer))
     (hoist-substatements answer
                          (lambda (h answer)
                            (k h (make-CaseClause loc #f answer))))]
    [(struct CaseClause (loc question answer))
     (hoist-substatements answer
                          (lambda (h answer)
                            (k h (make-CaseClause loc (hoist-expression question) answer))))]))

;; hoist-catch-clause : CatchClause ->k CatchClause
(define (hoist-catch-clause catch k)
  (match catch
    [(struct CatchClause (loc id body0))
     (hoist-statement body0
                      (lambda (h body)
                        (k h (make-CatchClause loc id body))))]))

(define (to-location x)
  (cond
    [(not x) #f]
    [(position? x) x]
    [else (ast-location x)]))

;; optional-statement->statement : (optional Statement) (optional has-location) -> Statement
(define (optional-statement->statement stmt loc)
  (or stmt (make-EmptyStatement (to-location loc))))

;; hoist-statement : Statement ->k Statement
(define (hoist-statement stmt k)
  (match stmt
    [(struct BlockStatement (loc stmts))
     (hoist-substatements stmts
                          (lambda (h stmts)
                            (match h
                              [(struct hoisting (funs vars let-funs let-vars))
                               (k (make-hoisting funs vars null null)
                                  (make-BlockStatement/hoisted loc stmts let-funs let-vars))])))]
    [(struct ExpressionStatement (loc expr))
     (k null-hoisting (make-ExpressionStatement loc (hoist-expression expr)))]
    [(struct IfStatement (loc test consequent0 alternate0))
     (hoist-substatement consequent0
                         (lambda (h1 consequent)
                           (if alternate0
                               (hoist-substatement alternate0
                                                   (lambda (h2 alternate)
                                                     (k (append-hoisting h1 h2)
                                                        (make-IfStatement loc
                                                                          (hoist-expression test)
                                                                          (optional-statement->statement consequent consequent0)
                                                                          alternate))))
                               (k h1 (make-IfStatement loc (hoist-expression test) (optional-statement->statement consequent consequent0) #f)))))]
    [(struct DoWhileStatement (loc body0 test))
     (hoist-substatement body0
                         (lambda (h body)
                           (k h (make-DoWhileStatement loc (optional-statement->statement body body0) (hoist-expression test)))))]
    [(struct WhileStatement (loc test body0))
     (hoist-substatement body0
                         (lambda (h body)
                           (k h (make-WhileStatement loc (hoist-expression test) (optional-statement->statement body body0)))))]
    [(struct ForStatement (loc (? VariableDeclaration? init) test incr body0))
     (hoist-variable-declaration init
                                 (lambda (h1 init)
                                   (hoist-substatement body0
                                                       (lambda (h2 body)
                                                         (k (append-hoisting h1 h2)
                                                            (make-ForStatement loc
                                                                               init
                                                                               (hoist-optional-expression test)
                                                                               (hoist-optional-expression incr)
                                                                               (optional-statement->statement body body0)))))))]
    ;; NOTE: this is a macro-expansion
    [(struct ForStatement (loc (struct LetDeclaration (loc* bindings)) test incr body0))
     (let ([bindings* (for/list ([binding bindings])
                        (struct-copy VariableInitializer binding [init #f]))]
           [inits* (make-ListExpression loc*
                                        (for/list ([binding bindings])
                                          (match binding
                                            [(struct VariableInitializer (loc id init))
                                             (let ([var (make-VarReference (Term-location id) id)])
                                               (make-AssignmentExpression loc var '= init))])))])
       ;; TODO: is it a problem that this indiscriminately makes a for-let into a substatement?
       (hoist-statement (make-LetStatement loc bindings* (make-ForStatement loc inits* test incr body0)) k))]
    [(struct ForStatement (loc init test incr body0))
     (hoist-substatement body0
                         (lambda (h body)
                           (k h (make-ForStatement loc
                                                   (hoist-optional-expression init)
                                                   (hoist-optional-expression test)
                                                   (hoist-optional-expression incr)
                                                   (optional-statement->statement body body0)))))]
    [(struct ForInStatement (loc (? Expression? lhs) container body0))
     (hoist-substatement body0
                         (lambda (h body)
                           (k h (make-ForInStatement loc
                                                     (hoist-expression lhs)
                                                     (hoist-expression container)
                                                     (optional-statement->statement body body0)))))]
    [(struct ForInStatement (loc (struct VariableDeclaration (_ (list (struct VariableInitializer (v-loc id #f))))) container body0))
     (hoist-substatement body0
                         (lambda (h body)
                           (k (cons-var-hoisting id h)
                              (make-ForInStatement loc
                                                   (make-VarReference v-loc id)
                                                   (hoist-expression container)
                                                   (optional-statement->statement body body0)))))]
    ;; NOTE: this is a macro expansion
    [(struct ForInStatement (loc (struct LetDeclaration (_ (list (struct VariableInitializer (v-loc id #f))))) container body0))
     (hoist-statement
      (make-LetStatement loc
                         (list (make-VariableInitializer v-loc id #f))
                         (make-ForInStatement loc
                                              (make-VarReference (Term-location id) id)
                                              container
                                              body0))
      k)]
    [(struct ReturnStatement (loc expr))
     (k null-hoisting (make-ReturnStatement loc (hoist-optional-expression expr)))]
    [(struct LetStatement (loc (list (struct VariableInitializer (binding-locs binding-names binding-inits)) ...) body0))
     (hoist-substatement body0
                         (lambda (h body)
                           (k h (make-LetStatement loc
                                                   (map make-VariableInitializer binding-locs binding-names (map hoist-optional-expression binding-inits))
                                                   (optional-statement->statement body body0)))))]
    [(struct WithStatement (loc test body0))
     (hoist-substatement body0
                         (lambda (h body)
                           (k h (make-WithStatement loc (hoist-expression test) (optional-statement->statement body body0)))))]
    [(struct SwitchStatement (loc expr cases))
     (hoist-case-clauses cases
                         (lambda (h cases)
                           (k h (make-SwitchStatement loc (hoist-expression expr) cases))))]
    [(struct LabelledStatement (loc label stmt0))
     (hoist-substatement stmt0
                         (lambda (h stmt)
                           (k h (make-LabelledStatement loc label (optional-statement->statement stmt stmt0)))))]
    [(struct ThrowStatement (loc expr))
     (k null-hoisting (make-ThrowStatement loc (hoist-expression expr)))]
    [(struct TryStatement (loc body0 catch0 finally0))
     (hoist-statement body0
                      (lambda (h1 body)
                        (hoist-catch-clauses catch0
                                             (lambda (h2 catch)
                                               (if finally0
                                                   (hoist-statement finally0
                                                                    (lambda (h3 finally)
                                                                      (k (append-hoisting h1 h2 h3)
                                                                         (make-TryStatement loc body catch finally))))
                                                   (k (append-hoisting h1 h2)
                                                      (make-TryStatement loc body catch #f)))))))]
    [_ (k null-hoisting stmt)]))

;; hoist-expression : Expression -> Expression
(define (hoist-expression expr)
  (match expr
    [(struct ArrayLiteral (loc elts))
     (make-ArrayLiteral loc (map hoist-optional-expression elts))]
    [(struct ObjectLiteral (loc (list (cons props vals) ...)))
     (make-ObjectLiteral loc (map cons props (map hoist-expression vals)))]
    [(struct BracketReference (loc container key))
     (make-BracketReference loc (hoist-expression container) (hoist-expression key))]
    [(struct DotReference (loc container id))
     (make-DotReference loc (hoist-expression container) id)]
    [(struct NewExpression (loc ctor args))
     (make-NewExpression loc (hoist-expression ctor) (map hoist-expression args))]
    [(struct PostfixExpression (loc expr op))
     (make-PostfixExpression loc (hoist-expression expr) op)]
    [(struct PrefixExpression (loc op expr))
     (make-PrefixExpression loc op (hoist-expression expr))]
    [(struct InfixExpression (loc left op right))
     (make-InfixExpression loc (hoist-expression left) op (hoist-expression right))]
    [(struct ConditionalExpression (loc test consequent alternate))
     (make-ConditionalExpression loc
                                 (hoist-expression test)
                                 (hoist-expression consequent)
                                 (hoist-expression alternate))]
    [(struct AssignmentExpression (loc left op right))
     (make-AssignmentExpression loc
                                (hoist-expression left)
                                op
                                (hoist-expression right))]
    [(struct FunctionExpression (loc name args body))
     (hoist-source-elements body
                            (lambda (h body)
                              (match h
                                [(struct hoisting (funs vars let-funs let-vars))
                                 (make-FunctionExpression/hoisted loc
                                                                  name
                                                                  args
                                                                  ;; TODO: should FunctionExpressions contain a block instead of a list?
                                                                  (wrap-in-implicit-block loc body let-funs let-vars)
                                                                  funs
                                                                  (unique-vars funs vars))])))]
    [(struct LetExpression (loc (list (struct VariableInitializer (binding-locs binding-names binding-inits)) ...) body))
     (make-LetExpression loc
                         (map make-VariableInitializer binding-locs binding-names (map hoist-optional-expression binding-inits))
                         (hoist-expression body))]
    [(struct CallExpression (loc method args))
     (make-CallExpression loc (hoist-expression method) (map hoist-expression args))]
    [(struct ParenExpression (loc expr))
     (make-ParenExpression loc (hoist-expression expr))]
    [(struct ListExpression (loc exprs))
     (make-ListExpression loc (map hoist-expression exprs))]
    [_ expr]))

(provide/contract
 [continuation/c ((or/c flat-contract? predicate/c) . -> . contract?)])

(provide/contract/k
 [hoist-source-elements ((listof SourceElement?) . ->k . (listof Statement?))]
 [hoist-declaration (Declaration? . ->k . Statement?)]
 [hoist-variable-declaration (VariableDeclaration? . ->k . Expression?)]
 [hoist-let-declaration (LetDeclaration? . ->k . Expression?)]
 [hoist-source-element (SourceElement? . ->k . Statement?)]
 [hoist-statement (Statement? . ->k . Statement?)]
 [hoist-substatement (SubStatement? . ->k . (optional/c Statement?))]
 [hoist-substatements ((listof SubStatement?) . ->k . (listof Statement?))]
 [hoist-var-initializer (VariableInitializer? . ->k . (optional/c Expression?))]
 ;[hoist-var-initializers ((listof VariableInitializer?) (optional/c region?) . ->k . Expression?)]
 [hoist-case-clause (CaseClause? . ->k . CaseClause?)]
 [hoist-case-clauses ((listof CaseClause?) . ->k . (listof CaseClause?))]
 [hoist-catch-clause (CatchClause? . ->k . CatchClause?)]
 [hoist-catch-clauses ((listof CatchClause?) . ->k . (listof CatchClause?))])

(provide/contract
 [hoist-expression (Expression? . -> . Expression?)]
 ;[hoist-expressions ((listof Expression?) . -> . (listof Expression?))]
 [hoist-function-declaration (FunctionDeclaration? . -> . FunctionDeclaration/hoisted?)]
 [hoist-script ((listof SourceElement?) . -> . (values (listof FunctionDeclaration/hoisted?)
                                                       (listof Identifier?)
                                                       (listof Statement?)))])

(provide/contract
 (struct (FunctionDeclaration/hoisted FunctionDeclaration) ([location (optional/c region?)]
                                                            [name Identifier?]
                                                            [args (listof Identifier?)]
                                                            [body (listof Statement?)]
                                                            [functions (listof FunctionDeclaration/hoisted?)]
                                                            [variables (listof Identifier?)]))
 (struct (FunctionExpression/hoisted FunctionExpression) ([location (optional/c region?)]
                                                          [name (optional/c Identifier?)]
                                                          [args (listof Identifier?)]
                                                          [body (listof Statement?)]
                                                          [functions (listof FunctionDeclaration/hoisted?)]
                                                          [variables (listof Identifier?)]))
 (struct (BlockStatement/hoisted BlockStatement) ([location (optional/c region?)]
                                                  [statements (listof Statement?)]
                                                  [functions (listof FunctionDeclaration/hoisted?)]
                                                  [variables (listof Identifier?)])))