;;; haskell-cabal.el --- Support for Cabal packages

;; Copyright (C) 2007, 2008  Stefan Monnier

;; Author: Stefan Monnier <monnier@iro.umontreal.ca>

;; This file is not part of GNU Emacs.

;; This file is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 3, or (at your option)
;; any later version.

;; This file is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to
;; the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; Todo:

;; - distinguish continued lines from indented lines.
;; - indent-line-function.
;; - outline-minor-mode.

;;; Code:

;; (defun haskell-cabal-extract-fields-from-doc ()
;;   (require 'xml)
;;   (with-no-warnings (require 'cl))
;;   (let ((section (completing-read
;;                   "Section: "
;;                   '("general-fields" "library" "executable" "buildinfo"))))
;;     (goto-char (point-min))
;;     (search-forward (concat "<sect3 id=\"" section "\">")))
;;   (let* ((xml (xml-parse-region
;;                (progn (search-forward "<variablelist>") (match-beginning 0))
;;                (progn (search-forward "</variablelist>") (point))))
;;          (varlist (remove-if-not 'consp (cddar xml)))
;;          (syms (mapcar (lambda (entry) (caddr (assq 'literal (assq 'term entry))))
;;                        varlist))
;;          (fields (mapcar (lambda (sym) (substring-no-properties sym 0 -1)) syms)))
;;     fields))

(require 'cl-lib)
(require 'haskell-utils)

(defconst haskell-cabal-general-fields
  ;; Extracted with (haskell-cabal-extract-fields-from-doc "general-fields")
  '("name" "version" "cabal-version" "license" "license-file" "copyright"
    "author" "maintainer" "stability" "homepage" "package-url" "synopsis"
    "description" "category" "tested-with" "build-depends" "data-files"
    "extra-source-files" "extra-tmp-files"))

(defconst haskell-cabal-library-fields
  ;; Extracted with (haskell-cabal-extract-fields-from-doc "library")
  '("exposed-modules"))

(defconst haskell-cabal-executable-fields
  ;; Extracted with (haskell-cabal-extract-fields-from-doc "executable")
  '("executable" "main-is"))

(defconst haskell-cabal-buildinfo-fields
  ;; Extracted with (haskell-cabal-extract-fields-from-doc "buildinfo")
  '("buildable" "other-modules" "hs-source-dirs" "extensions" "ghc-options"
    "ghc-prof-options" "hugs-options" "nhc-options" "includes"
    "install-includes" "include-dirs" "c-sources" "extra-libraries"
    "extra-lib-dirs" "cc-options" "ld-options" "frameworks"))

(defvar haskell-cabal-mode-syntax-table
  (let ((st (make-syntax-table)))
    ;; The comment syntax can't be described simply in syntax-table.
    ;; We could use font-lock-syntactic-keywords, but is it worth it?
    ;; (modify-syntax-entry ?-  ". 12" st)
    (modify-syntax-entry ?\n ">" st)
    (modify-syntax-entry ?. "w"  st)
    (modify-syntax-entry ?- "w"  st)
    st))

(defvar haskell-cabal-font-lock-keywords
  ;; The comment syntax can't be described simply in syntax-table.
  ;; We could use font-lock-syntactic-keywords, but is it worth it?
  '(("^[ \t]*--.*" . font-lock-comment-face)
    ("^ *\\([^ \t:]+\\):" (1 font-lock-keyword-face))
    ("^\\(Library\\)[ \t]*\\({\\|$\\)" (1 font-lock-keyword-face))
    ("^\\(Executable\\|Test-Suite\\|Benchmark\\)[ \t]+\\([^\n \t]*\\)"
     (1 font-lock-keyword-face) (2 font-lock-function-name-face))
    ("^\\(Flag\\)[ \t]+\\([^\n \t]*\\)"
     (1 font-lock-keyword-face) (2 font-lock-constant-face))
    ("^\\(Source-Repository\\)[ \t]+\\(head\\|this\\)"
     (1 font-lock-keyword-face) (2 font-lock-constant-face))
    ("^ *\\(if\\)[ \t]+.*\\({\\|$\\)" (1 font-lock-keyword-face))
    ("^ *\\(}[ \t]*\\)?\\(else\\)[ \t]*\\({\\|$\\)"
     (2 font-lock-keyword-face))))

(defvar haskell-cabal-buffers nil
  "List of Cabal buffers.")

(defun haskell-cabal-buffers-clean (&optional buffer)
  (let ((bufs ()))
    (dolist (buf haskell-cabal-buffers)
      (if (and (buffer-live-p buf) (not (eq buf buffer))
               (with-current-buffer buf (derived-mode-p 'haskell-cabal-mode)))
          (push buf bufs)))
    (setq haskell-cabal-buffers bufs)))

(defun haskell-cabal-unregister-buffer ()
  (haskell-cabal-buffers-clean (current-buffer)))

;;;###autoload
(add-to-list 'auto-mode-alist '("\\.cabal\\'" . haskell-cabal-mode))

(defvar haskell-cabal-mode-map
  (let ((map (make-sparse-keymap)))
    (define-key map (kbd "C-c C-s") 'haskell-cabal-subsection-arrange-lines)
    (define-key map (kbd "C-M-n") 'haskell-cabal-next-section)
    (define-key map (kbd "C-M-p") 'haskell-cabal-previous-section)
    (define-key map (kbd "M-n") 'haskell-cabal-next-subsection)
    (define-key map (kbd "M-p") 'haskell-cabal-previous-subsection)
    (define-key map (kbd "C-<down>") 'haskell-cabal-next-subsection)
    (define-key map (kbd "C-<up>") 'haskell-cabal-previous-subsection)
    (define-key map (kbd "C-c C-f") 'haskell-cabal-find-or-create-source-file)
    (define-key map (kbd "M-g l") 'haskell-cabal-goto-library-section)
    (define-key map (kbd "M-g e") 'haskell-cabal-goto-executable-section)
    (define-key map (kbd "M-g b") 'haskell-cabal-goto-benchmark-section)
    (define-key map (kbd "M-g t") 'haskell-cabal-goto-test-suite-section)
    map))

;;;###autoload
(define-derived-mode haskell-cabal-mode fundamental-mode "Haskell-Cabal"
  "Major mode for Cabal package description files."
  (set (make-local-variable 'font-lock-defaults)
       '(haskell-cabal-font-lock-keywords t t nil nil))
  (add-to-list 'haskell-cabal-buffers (current-buffer))
  (add-hook 'change-major-mode-hook 'haskell-cabal-unregister-buffer nil 'local)
  (add-hook 'kill-buffer-hook 'haskell-cabal-unregister-buffer nil 'local)
  (set (make-local-variable 'comment-start) "-- ")
  (set (make-local-variable 'comment-start-skip) "\\(^[ \t]*\\)--[ \t]*")
  (set (make-local-variable 'comment-end) "")
  (set (make-local-variable 'comment-end-skip) "[ \t]*\\(\\s>\\|\n\\)")
  (set (make-local-variable 'indent-line-function) 'haskell-cabal-indent-line)
  (setq indent-tabs-mode nil)
  )

(defun haskell-cabal-get-setting (name)
  (save-excursion
    (let ((case-fold-search t))
      (goto-char (point-min))
      (when (re-search-forward
             (concat "^[ \t]*" (regexp-quote name)
                     ":[ \t]*\\(.*\\(\n[ \t]+[ \t\n].*\\)*\\)")
             nil t)
        (let ((val (match-string 1))
              (start 1))
          (when (match-end 2)             ;Multiple lines.
            ;; The documentation is not very precise about what to do about
            ;; the \n and the indentation: are they part of the value or
            ;; the encoding?  I take the point of view that \n is part of
            ;; the value (so that values can span multiple lines as well),
            ;; and that only the first char in the indentation is part of
            ;; the encoding, the rest is part of the value (otherwise, lines
            ;; in the value cannot start with spaces or tabs).
            (while (string-match "^[ \t]\\(?:\\.$\\)?" val start)
              (setq start (1+ (match-beginning 0)))
              (setq val (replace-match "" t t val))))
          val)))))

;;;###autoload
(defun haskell-cabal-guess-setting (name)
  "Guess the specified setting of this project.
If there is no valid .cabal file to get the setting from (or
there is no corresponding setting with that name in the .cabal
file), then this function returns nil."
  (interactive)
  (when (and name buffer-file-name)
    (let ((cabal-file (haskell-cabal-find-file)))
      (when (and cabal-file (file-readable-p cabal-file))
        (with-temp-buffer
          (insert-file-contents cabal-file)
          (haskell-cabal-get-setting name))))))

;;;###autoload
(defun haskell-cabal-get-dir ()
  "Get the Cabal dir for a new project. Various ways of figuring this out,
   and indeed just prompting the user. Do them all."
  (let* ((file (haskell-cabal-find-file))
         (dir (when file (file-name-directory file))))
    (haskell-utils-read-directory-name
     (format "Cabal dir%s: " (if file (format " (guessed from %s)" (file-relative-name file)) ""))
     dir)))

(defun haskell-cabal-compute-checksum (dir)
  "Compute MD5 checksum of package description file in DIR.
Return nil if no Cabal description file could be located via
`haskell-cabal-find-pkg-desc'."
  (let ((cabal-file (haskell-cabal-find-pkg-desc dir)))
    (when cabal-file
      (with-temp-buffer
        (insert-file-contents cabal-file)
        (md5 (buffer-string))))))

(defun haskell-cabal-find-file (&optional dir)
  "Search for package description file upwards starting from DIR.
If DIR is nil, `default-directory' is used as starting point for
directory traversal.  Upward traversal is aborted if file owner
changes.  Uses`haskell-cabal-find-pkg-desc' internally."
  (let ((use-dir (or dir default-directory)))
    (while (and use-dir (not (file-directory-p use-dir)))
      (setq use-dir (file-name-directory (directory-file-name use-dir))))
    (when use-dir
      (catch 'found
        (let ((user (nth 2 (file-attributes use-dir)))
              ;; Abbreviate, so as to stop when we cross ~/.
              (root (abbreviate-file-name use-dir)))
          ;; traverse current dir up to root as long as file owner doesn't change
          (while (and root (equal user (nth 2 (file-attributes root))))
            (let ((cabal-file (haskell-cabal-find-pkg-desc root)))
              (when cabal-file
                (throw 'found cabal-file)))

            (let ((proot (file-name-directory (directory-file-name root))))
              (if (equal proot root) ;; fix-point reached?
                  (throw 'found nil)
                (setq root proot))))
          nil)))))

(defun haskell-cabal-find-pkg-desc (dir &optional allow-multiple)
  "Find a package description file in the directory DIR.
Returns nil if none or multiple \".cabal\" files were found.  If
ALLOW-MULTIPLE is non nil, in case of multiple \".cabal\" files,
a list is returned instead of failing with a nil result."
  ;; This is basically a port of Cabal's
  ;; Distribution.Simple.Utils.findPackageDesc function
  ;;  http://hackage.haskell.org/packages/archive/Cabal/1.16.0.3/doc/html/Distribution-Simple-Utils.html
  ;; but without the exception throwing.
  (let* ((cabal-files
          (cl-remove-if 'file-directory-p
                        (cl-remove-if-not 'file-exists-p
                                          (directory-files dir t ".\\.cabal\\'")))))
    (cond
     ((= (length cabal-files) 1) (car cabal-files)) ;; exactly one candidate found
     (allow-multiple cabal-files) ;; pass-thru multiple candidates
     (t nil))))

(defun haskell-cabal-find-dir (&optional dir)
  "Like `haskell-cabal-find-file' but returns directory instead.
See `haskell-cabal-find-file' for meaning of DIR argument."
  (let ((cabal-file (haskell-cabal-find-file dir)))
    (when cabal-file
      (file-name-directory cabal-file))))

;;;###autoload
(defun haskell-cabal-visit-file (other-window)
  "Locate and visit package description file for file visited by current buffer.
This uses `haskell-cabal-find-file' to locate the closest
\".cabal\" file and open it.  This command assumes a common Cabal
project structure where the \".cabal\" file is in the top-folder
of the project, and all files related to the project are in or
below the top-folder.  If called with non-nil prefix argument
OTHER-WINDOW use `find-file-other-window'."
  (interactive "P")
  ;; Note: We aren't allowed to rely on haskell-session here (which,
  ;; in pathological cases, can have a different .cabal file
  ;; associated with the current buffer)
  (if buffer-file-name
      (let ((cabal-file (haskell-cabal-find-file (file-name-directory buffer-file-name))))
        (if cabal-file
            (if other-window
                (find-file-other-window cabal-file)
              (find-file cabal-file))
          (error "Could not locate \".cabal\" file for %S" buffer-file-name)))
    (error "Cannot locate \".cabal\" file for buffers not visiting any file")))

(defvar haskell-cabal-commands
  '("install"
    "update"
    "list"
    "info"
    "upgrade"
    "fetch"
    "unpack"
    "check"
    "sdist"
    "upload"
    "report"
    "init"
    "configure"
    "build"
    "copy"
    "haddock"
    "clean"
    "hscolour"
    "register"
    "test"
    "help"
    "run"))


(defgroup haskell-cabal nil
  "Haskell cabal files"
  :group 'haskell
)

(defcustom haskell-cabal-list-comma-position
  'before
  "Where to put the comma in lists"
  :safe t
  :group 'haskell-cabal
  :type '(choice (const before)
                 (const after)))

(defconst haskell-cabal-section-header-regexp "^[[:alnum:]]" )
(defconst haskell-cabal-subsection-header-regexp "^[ \t]*[[:alnum:]]\\w*:")
(defconst haskell-cabal-comment-regexp "^[ \t]*--")
(defconst haskell-cabal-empty-regexp "^[ \t]*$")
(defconst haskell-cabal-conditional-regexp "^[ \t]*\\(\\if\\|else\\|}\\)")

(defun haskell-cabal-classify-line ()
  "Classify the current line into 'section-header 'subsection-header 'section-data 'comment and 'empty '"
  (save-excursion
    (beginning-of-line)
    (cond
     ((looking-at haskell-cabal-subsection-header-regexp ) 'subsection-header)
     ((looking-at haskell-cabal-section-header-regexp) 'section-header)
     ((looking-at haskell-cabal-comment-regexp) 'comment)
     ((looking-at haskell-cabal-empty-regexp ) 'empty)
     ((looking-at haskell-cabal-conditional-regexp ) 'conditional)
     (t 'section-data))))

(defun haskell-cabal-header-p ()
  "Is the current line a section or subsection header?"
  (cl-case (haskell-cabal-classify-line)
    ((section-header subsection-header) t)))

(defun haskell-cabal-section-header-p ()
  "Is the current line a section or subsection header?"
  (cl-case (haskell-cabal-classify-line)
    ((section-header) t)))


(defun haskell-cabal-section-beginning ()
  "Find the beginning of the current section"
  (save-excursion
    (while (not (or (bobp) (haskell-cabal-section-header-p)))
      (forward-line -1))
    (point)))

(defun haskell-cabal-beginning-of-section ()
  "go to the beginning of the section"
  (interactive)
  (goto-char (haskell-cabal-section-beginning))
)

(defun haskell-cabal-section-end ()
  "Find the end of the current section"
  (interactive)
  (save-excursion
    (if  (re-search-forward "\n\\([ \t]*\n\\)*[[:alnum:]]" nil t)
         (match-beginning 0)
         (point-max))))

(defun haskell-cabal-end-of-section ()
  "go to the end of the section"
  (interactive)
  (goto-char (haskell-cabal-section-end)))

(defun haskell-cabal-next-section ()
  "Go to the next extion"
  (interactive)
  (when (haskell-cabal-section-header-p) (forward-line))
  (while (not (or (eobp) (haskell-cabal-section-header-p)))
    (forward-line)))

(defun haskell-cabal-previous-section ()
  "Go to the next extion"
  (interactive)
  (when (haskell-cabal-section-header-p) (forward-line -1))
  (while (not (or (bobp) (haskell-cabal-section-header-p)))
    (forward-line -1)))

(defun haskell-cabal-subsection-end ()
  "find the end of the current subsection"
  (save-excursion
    (haskell-cabal-beginning-of-subsection)
    (forward-line)
    (while (and (not (eobp))
                (member (haskell-cabal-classify-line) '(empty section-data)))
      (forward-line))
    (unless (eobp) (forward-line -1))
    (while (and (equal  (haskell-cabal-classify-line) 'empty)
                (not (bobp)))
      (forward-line -1))
    (end-of-line)
    (point)))

(defun haskell-cabal-end-of-subsection ()
  "go to the end of the current subsection"
  (interactive)
  (goto-char (haskell-cabal-subsection-end)))

(defun haskell-cabal-section ()
  "Get the name and data of the associated section"
  (save-excursion
    (haskell-cabal-beginning-of-section)
    (when (and (haskell-cabal-section-header-p)
               (looking-at "^\\(\\w+\\)[ \t]*\\(.*\\)$"))
      (list :name (match-string-no-properties 1)
            :value (match-string-no-properties 2)
            :beginning (match-beginning 0)
            :end (haskell-cabal-section-end)))))


(defun haskell-cabal-subsection ()
  "Get the name and bounds of of the current subsection"
  (save-excursion
    (haskell-cabal-beginning-of-subsection)
    (when  (looking-at "\\([ \t]*\\(\\w*\\):\\)[ \t]*")
      (list :name (match-string-no-properties 2)
            :beginning (match-end 0)
            :end (save-match-data (haskell-cabal-subsection-end))
            :data-start-column (save-excursion (goto-char (match-end 0))
                                               (current-column)
                                               )))))


(defun haskell-cabal-section-name (section)
  (plist-get section :name))

(defun haskell-cabal-section-value (section)
  (plist-get section :value))

(defun haskell-cabal-section-start (section)
  (plist-get section :beginning))

(defun haskell-cabal-section-data-start-column (section)
  (plist-get section :data-start-column))

(defmacro haskell-cabal-with-subsection (subsection replace &rest funs)
  "Copy subsection data into a temporary buffer, save indentation
and execute FORMS

If REPLACE is non-nil the subsection data is replaced with the
resultung buffer-content"
  (let ((section (make-symbol "section"))
        (beg (make-symbol "beg"))
        (end (make-symbol "end"))
        (start-col (make-symbol "start-col"))
        (section-data (make-symbol "section-data")))
    `(let* ((,section ,subsection)
            (,beg (plist-get ,section :beginning))
            (,end (plist-get  ,section :end))
            (,start-col (plist-get  ,section :data-start-column))
            (,section-data (buffer-substring ,beg ,end))
            (section-name (plist-get ,section :name )))
       (save-excursion
         (prog1
             (with-temp-buffer
               (setq indent-tabs-mode nil)
               (indent-to ,start-col)
               (insert ,section-data)
               (goto-char (point-min))
               (prog1
                   (progn (haskell-cabal-save-indentation ,@funs))
                 (goto-char (point-min))
                 (when (looking-at (format "[ ]\\{0,%d\\}" (1+ ,start-col)))
                     (replace-match ""))

                 (setq ,section-data (buffer-substring (point-min) (point-max)))))
           ,@(when replace
               `((delete-region ,beg ,end)
                 (goto-char ,beg)
                 (insert ,section-data))))))))

(defmacro haskell-cabal-each-line (&rest fun)
  "Execute FOMRS on each line"
  `(save-excursion
     (while (< (point) (point-max))
       ,@fun
       (forward-line))))

(defun haskell-cabal-chomp-line ()
  "Remove leading and trailing whitespaces from current line"
  (beginning-of-line)
  (when (looking-at "^[ \t]*\\([^ \t]\\|\\(?:[^ \t].*[^ \t]\\)\\)[ \t]*$")
    (replace-match (match-string 1) nil t)
    t))


(defun haskell-cabal-min-indentation (&optional beg end)
  "Compute largest common whitespace prefix of each line in between BEG and END"
  (save-excursion
    (goto-char (or beg (point-min)))
    (let ((min-indent nil))
      (while (< (point) (or end (point-max)))
        (let ((indent (current-indentation)))
          (if (and (not (haskell-cabal-ignore-line-p))
                   (or (not min-indent)
                       (< indent min-indent)))
              (setq min-indent indent)))
        (forward-line))
      min-indent)))

(defun haskell-cabal-ignore-line-p ()
  "Does line only contain whitespaces and comments?"
  (save-excursion
    (beginning-of-line)
    (looking-at "^[ \t]*\\(?:--.*\\)?$")))

(defun haskell-cabal-kill-indentation ()
  "Remove longest common whitespace prefix from each line"
  (goto-char (point-min))
  (let ((indent (haskell-cabal-min-indentation)))
    (haskell-cabal-each-line (unless (haskell-cabal-ignore-line-p)
                               (delete-char indent)) )
    indent))

(defun haskell-cabal-add-indentation (indent)
  (goto-char (point-min))
  (haskell-cabal-each-line
   (unless (haskell-cabal-ignore-line-p)
     (indent-to indent))))


(defmacro haskell-cabal-save-indentation (&rest funs)
  "Strip indentation from each line, execute FORMS and reinstate indentation
   so that the indentation of the FIRST LINE matches"
  (let ((old-l1-indent (make-symbol "new-l1-indent"))
        (new-l1-indent (make-symbol "old-l1-indent"))
        (res nil))
    `(let ( (,old-l1-indent (save-excursion
                              (goto-char (point-min))
                              (current-indentation))))
       (unwind-protect
           (progn
             (haskell-cabal-kill-indentation)
             ,@funs)
         (progn
           (goto-char (point-min))
           (let ((,new-l1-indent (current-indentation)))
             (haskell-cabal-add-indentation (- ,old-l1-indent
                                           ,new-l1-indent))))))))

(defun haskell-cabal-strip-list ()
  "strip commas from comma-seperated list"
  (goto-char (point-min))
;; split list items on single line
  (while (re-search-forward
          "\\([^ \t,\n]\\)[ \t]*,[ \t]*\\([^ \t,\n]\\)"  nil t)
    (replace-match "\\1\n\\2" nil nil))
  (goto-char (point-min))
  (while (re-search-forward "^\\([ \t]*\\),\\([ \t]*\\)" nil t)
    (replace-match "" nil nil))
  (goto-char (point-min))
  (while (re-search-forward ",[ \t]*$" nil t)
    (replace-match "" nil nil))
  (goto-char (point-min))
  (haskell-cabal-each-line (haskell-cabal-chomp-line)))

(defun haskell-cabal-listify ()
  "Add commas so that buffer contains a comma-seperated list"
  (cl-case haskell-cabal-list-comma-position
    ('before
     (goto-char (point-min))
     (while (haskell-cabal-ignore-line-p) (forward-line))
     (indent-to 2)
     (forward-line)
     (haskell-cabal-each-line
      (unless (haskell-cabal-ignore-line-p)
        (insert ", "))))
    ('after
     (goto-char (point-max))
     (while (not (bobp))
       (unless (haskell-cabal-ignore-line-p)
         (forward-line -1)
         (end-of-line)
         (insert ",")
         (beginning-of-line))))))



(defmacro haskell-cabal-with-cs-list (&rest funs)
  "format buffer so that each line contains a list element "
  `(progn
    (save-excursion (haskell-cabal-strip-list))
    (unwind-protect (progn ,@funs)
      (haskell-cabal-listify))))


(defun haskell-cabal-sort-lines-key-fun ()
  (when (looking-at "[ \t]*--[ \t,]*")
    (goto-char (match-end 0)))
  nil)

(defmacro haskell-cabal-save-position (&rest forms)
  "Save position as mark, execute FORMs and go back to mark"
  `(prog2
       (haskell-cabal-mark)
       (progn ,@forms)
     (haskell-cabal-goto-mark)
     (haskell-cabal-remove-mark)))

(defun haskell-cabal-subsection-arrange-lines ()
  "Sort lines of current subsection"
  (interactive)
  (haskell-cabal-save-position
   (haskell-cabal-with-subsection
    (haskell-cabal-subsection) t
    (haskell-cabal-with-cs-list
     (sort-subr nil 'forward-line 'end-of-line
                'haskell-cabal-sort-lines-key-fun)
     ))))

(defun haskell-cabal-subsection-beginning ()
  "find the beginning of the current subsection"
  (save-excursion
    (while (and (not (bobp))
                (not (haskell-cabal-header-p)))
      (forward-line -1))
    (back-to-indentation)
    (point)))

(defun haskell-cabal-beginning-of-subsection ()
  "go to the beginniing of the current subsection"
  (interactive)
  (goto-char (haskell-cabal-subsection-beginning)))

(defun haskell-cabal-next-subsection ()
  "go to the next subsection"
  (interactive)
  (if (haskell-cabal-header-p) (forward-line))
  (while (and (not (eobp))
              (not (haskell-cabal-header-p)))
    (forward-line))
  (haskell-cabal-forward-to-line-entry))

(defun haskell-cabal-previous-subsection ()
  "go to the next subsection"
  (interactive)
  (if (haskell-cabal-header-p) (forward-line -1))
  (while (and (not (bobp))
              (not (haskell-cabal-header-p)))
    (forward-line -1))
  (haskell-cabal-forward-to-line-entry)
  )


(defun haskell-cabal-find-subsection-by (section pred)
  "Find sunsection with name NAME"
  (save-excursion
    (when section (goto-char (haskell-cabal-section-start section)))
    (let* ((end (if section (haskell-cabal-section-end) (point-max)))
           (found nil))
      (while (and (< (point) end)
                  (not found))
        (let ((subsection (haskell-cabal-subsection)))
          (when (and subsection (funcall pred subsection))
            (setq found subsection)))
        (haskell-cabal-next-subsection))
      found)))

(defun haskell-cabal-find-subsection (section name)
  "Find sunsection with name NAME"
  (let ((downcase-name (downcase name)))
    (haskell-cabal-find-subsection-by
     section
     '(lambda (subsection)
        (string= (downcase (haskell-cabal-section-name subsection))
                 downcase-name)))))

(defun haskell-cabal-goto-subsection (name)
  (let ((subsection (haskell-cabal-find-subsection (haskell-cabal-section) name)))
    (when subsection
      (goto-char (haskell-cabal-section-start subsection)))))

(defun haskell-cabal-goto-exposed-modules ()
  (interactive)
  (haskell-cabal-goto-subsection "exposed-modules"))

(defun haskell-cabal-subsection-entry-list (section name)
  "Get the data of a subsection as a list"
  (let ((subsection (haskell-cabal-find-subsection section name)))
    (when subsection
      (haskell-cabal-with-subsection
       subsection nil
       (haskell-cabal-with-cs-list
        (delete-matching-lines
         (format "\\(?:%s\\)\\|\\(?:%s\\)"
                 haskell-cabal-comment-regexp
                 haskell-cabal-empty-regexp)
         (point-min) (point-max))
        (split-string (buffer-substring-no-properties (point-min) (point-max))
                      "\n" t))))))

(defun haskell-cabal-remove-mark ()
  (remove-list-of-text-properties (point-min) (point-max)
                                  '(haskell-cabal-marker)))


(defun haskell-cabal-mark ()
  "Mark the current position with the text property haskell-cabal-marker"
  (haskell-cabal-remove-mark)
  (put-text-property (line-beginning-position) (line-end-position)
                     'haskell-cabal-marker 'marked-line)
  (put-text-property (point) (1+ (point))
                     'haskell-cabal-marker 'marked))


(defun haskell-cabal-goto-mark ()
  "Go to marked line"
  (let ((marked-pos (text-property-any (point-min) (point-max)
                                       'haskell-cabal-marker
                                       'marked))
        (marked-line (text-property-any (point-min) (point-max)
                                       'haskell-cabal-marker
                                       'marked-line) )
        )
    (cond (marked-pos (goto-char marked-pos))
          (marked-line (goto-char marked-line)))))

(defmacro haskell-cabal-with-subsection-line (replace &rest forms)
  "Mark line and "
  `(progn
     (haskell-cabal-mark)
     (unwind-protect
         (haskell-cabal-with-subsection (haskell-cabal-subsection) ,replace
          (haskell-cabal-goto-mark)
          ,@forms)
       (haskell-cabal-remove-mark))))


(defun haskell-cabal-get-line-content ()
  (haskell-cabal-with-subsection-line
   nil
   (haskell-cabal-with-cs-list
    (haskell-cabal-goto-mark)
    (buffer-substring-no-properties (line-beginning-position)
                                    (line-end-position)))))

(defun haskell-cabal-module-to-filename (module)
  (concat  (replace-regexp-in-string "[.]" "/" module ) ".hs"))

(defconst haskell-cabal-module-sections '("exposed-modules" "other-modules")
  "List of sections that contain module names"
)

(defconst haskell-cabal-file-sections
  '("main-is" "c-sources" "data-files" "extra-source-files"
    "extra-doc-files" "extra-tmp-files" )
  "List of subsections that contain filenames"
  )

(defconst haskell-cabal-source-bearing-sections
  '("library" "executable" "test-suite" "benchmark"))

(defun haskell-cabal-source-section-p (section)
  (not (not  (member (downcase (haskell-cabal-section-name section))
                      haskell-cabal-source-bearing-sections))))

(defun haskell-cabal-line-filename ()
  "Expand filename in current line according to the subsection type

Module names in exposed-modules and other-modules are expanded by replacing each dot (.) in the module name with a foward slash (/) and appending \".hs\"

Example: Foo.Bar.Quux ==> Foo/Bar/Quux.hs

Source names from main-is and c-sources sections are left untouched

"
  (let ((entry (haskell-cabal-get-line-content))
        (subsection (downcase (haskell-cabal-section-name
                               (haskell-cabal-subsection)))))
    (cond ((member subsection haskell-cabal-module-sections)
           (haskell-cabal-module-to-filename entry))
          ((member subsection haskell-cabal-file-sections) entry))))

(defun haskell-cabal-join-paths (&rest args)
  "Crude hack to replace f-join"
  (mapconcat 'identity args "/")
)

(defun haskell-cabal-find-or-create-source-file ()
  "Open the source file this line refers to"
  (interactive)
  (let* ((src-dirs (append (haskell-cabal-subsection-entry-list
                            (haskell-cabal-section) "hs-source-dirs")
                           '("")))
         (base-dir (file-name-directory (buffer-file-name)))
         (filename (haskell-cabal-line-filename)))
    (when filename
      (let ((candidates
             (delq nil (mapcar
                        (lambda (dir)
                          (let ((file (haskell-cabal-join-paths base-dir dir filename)))
                            (when (and (file-readable-p file)
                                       (not (file-directory-p file)))
                              file)))
                        src-dirs))))
        (if (null candidates)
            (let* ((src-dir (haskell-cabal-join-paths base-dir (or (car src-dirs) "")))
                   (newfile (haskell-cabal-join-paths src-dir filename))
                   (subdir (file-name-directory newfile))
                   (do-create-p (y-or-n-p (format "Create file %s ?" newfile))))
              (when do-create-p
                (find-file-other-window newfile )))
          (find-file-other-window (car candidates)))))))


(defun haskell-cabal-find-section-type (type &optional wrap)
  (save-excursion
    (haskell-cabal-next-section)
    (while
        (not
         (or
          (eobp)
          (string=
           (downcase type)
           (downcase  (haskell-cabal-section-name (haskell-cabal-section))))))
      (haskell-cabal-next-section))
    (if (eobp)
      (if wrap (progn
                 (goto-char (point-min))
                 (haskell-cabal-find-section-type type nil) )
        nil)
      (point))))

(defun haskell-cabal-goto-section-type  (type)
  (let ((section (haskell-cabal-find-section-type type t)))
    (if section (goto-char section)
      (message "No %s section found" type))))

(defun haskell-cabal-goto-library-section ()
  (interactive)
  (haskell-cabal-goto-section-type "library"))

(defun haskell-cabal-goto-test-suite-section ()
  (interactive)
  (haskell-cabal-goto-section-type "test-suite"))

(defun haskell-cabal-goto-executable-section ()
  (interactive)
  (haskell-cabal-goto-section-type "executable"))

(defun haskell-cabal-goto-benchmark-section ()
  (interactive)
  (haskell-cabal-goto-section-type "benchmark"))



(defun haskell-cabal-line-entry-column ()
  "Column at which the line entry starts"
  (save-excursion
    (cl-case (haskell-cabal-classify-line)
      (section-data (beginning-of-line)
                    (when (looking-at "[ ]*\\(?:,[ ]*\\)?")
                      (goto-char  (match-end 0))
                      (current-column)))
      (subsection-header
       (haskell-cabal-section-data-start-column (haskell-cabal-subsection))))))

(defun haskell-cabal-forward-to-line-entry ()
  "go forward to the beginning of the line entry (but never move backwards)"
  (let ((col (haskell-cabal-line-entry-column)))
    (when (and col (< (current-column) col))
      (beginning-of-line)
      (forward-char col))))

(defun haskell-cabal-indent-line ()
  "Indent current line according to subsection"
  (interactive)
  (cl-case (haskell-cabal-classify-line)
    (section-data
     (save-excursion
       (let ((indent (haskell-cabal-section-data-start-column
                      (haskell-cabal-subsection))))
         (indent-line-to indent)
         (beginning-of-line)
         (when (looking-at "[ ]*\\([ ]\\{2\\},[ ]*\\)")
           (replace-match ", " t t nil 1)))))
    (empty
     (indent-relative)))
  (haskell-cabal-forward-to-line-entry))

(defun haskell-cabal-map-sections (fun)
  "Execute fun over each section, collecting the result"
  (save-excursion
    (goto-char (point-min))
    (let ((results nil))
        (while (not (eobp))
          (let* ((section (haskell-cabal-section))
                 (result (and section (funcall fun (haskell-cabal-section)))))
            (when section (setq results (cons result results))))
          (haskell-cabal-next-section))
        (nreverse  results))))

(defun haskell-cabal-section-add-build-dependency (dependency &optional sort sec)
  "Add a build dependency to the build-depends section"
  (let* ((section (or sec (haskell-cabal-section)))
         (subsection (and section
                          (haskell-cabal-find-subsection section "build-depends"))))
    (when subsection
      (haskell-cabal-with-subsection
       subsection t
       (haskell-cabal-with-cs-list
        (insert dependency)
        (insert "\n")
        (when sort
          (goto-char (point-min))
          (sort-subr nil 'forward-line 'end-of-line
                     'haskell-cabal-sort-lines-key-fun)))))))

(defun haskell-cabal-add-build-dependency (dependency &optional sort silent)
  "Add a build dependencies to sections"
  (haskell-cabal-map-sections
   (lambda (section)
     (when (haskell-cabal-source-section-p section)
       (when (or silent
                 (y-or-n-p (format  "Add dependency %s to %s section %s?"
                                    dependency
                                    (haskell-cabal-section-name section)
                                    (haskell-cabal-section-value section))))
         (haskell-cabal-section-add-build-dependency dependency sort section)
         nil)))))

(defun haskell-cabal-add-dependency (package &optional version no-prompt
                                                   sort silent)
  "Add PACKAGE (and optionally suffix -VERSION) to the cabal
file. Prompts the user before doing so.

If VERSION is non-nil it will be appended as a minimum version.
If NO-PROMPT is nil the minimum-version is read from the minibuffer
When SORT is non-nil the package entries are sorted afterwards
If SILENT ist nil the user is prompted for each source-section
"
  (interactive
   (list (read-from-minibuffer "Package entry: ")
         nil t t nil))
  (save-window-excursion
    (find-file-other-window (haskell-cabal-find-file))
    (let ((entry (if no-prompt package
                   (read-from-minibuffer
                    "Package entry: "
                    (concat package (if version (concat " >= " version) ""))))))
      (haskell-cabal-add-build-dependency entry sort silent)
      (when (or silent (y-or-n-p "Save cabal file?"))
        (save-buffer)))))

(provide 'haskell-cabal)

;;; haskell-cabal.el ends here
