;;; Consfigurator -- Lisp declarative configuration management system

;;; Copyright (C) 2020-2022  Sean Whitton <spwhitton@spwhitton.name>

;;; 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 this program.  If not, see <http://www.gnu.org/licenses/>.

(in-package :consfigurator.property.file)
(named-readtables:in-readtable :consfigurator)

(defun map-remote-file-lines (file function)
  "Apply FUNCTION to the lines of FILE.  Safe to use in a :POSIX property.

For efficiency, a :LISP property might want to use streams, but there's no
point in doing that here because WRITE-REMOTE-FILE is synchronous."
  (let* ((orig-lines (and (remote-exists-p file)
                          (lines (read-remote-file file))))
         (new-lines (funcall function orig-lines)))
    (if (equal orig-lines new-lines)
        :no-change
        (write-remote-file file (unlines new-lines)))))

(defprop has-content :posix (path content &key (mode nil mode-supplied-p))
  "Ensure there is a file at PATH whose content is CONTENT.
CONTENT can be a list of lines or a single string."
  (declare (indent 1))
  (:desc (declare (ignore content mode mode-supplied-p))
         #?"${path} has defined content")
  (:apply (unless mode-supplied-p (containing-directory-exists path))
          (apply #'maybe-write-remote-file-string
                 path
                 (etypecase content
                   (list
                    ;; Within a DEFPROPSPEC it is easy to accidentally pass a
                    ;; quoted list to this property.  Error rather than write
                    ;; the quoted list into the remote file.
                    (assert (every #'stringp content))
                    (unlines content))
                   (string (format nil "~A~&" content)))
                 (and mode-supplied-p `(:mode ,mode)))))

(defpropspec exists-with-content :posix
    (path content &key (mode nil mode-supplied-p))
  "Like FILE:HAS-CONTENT, but unapplicable, where unapplying means deleting
PATH, rather than restoring any old content it might have had.

The semantics of this property are that if it is applied, the file has content
CONTENT, and if it is not applied to a host, the file does not exist.  Thus,
it should be used to create new files on the host, not to replace the contents
of existing files, such as those installed by operating system packages.  For
replacing the contents of existing files, prefer FILE:HAS-CONTENT."
  (declare (indent 1))
  (:desc #?"${path} exists with defined content")
  `(with-unapply
     (has-content ,path ,content ,@(and mode-supplied-p `(:mode ,mode)))
     :unapply (does-not-exist ,path)))

(defprop contains-lines :posix (path &rest lines)
  "Ensure there is a file at PATH containing each of LINES once."
  (declare (indent 1))
  (:apply
   (containing-directory-exists path)
   (let ((new-lines (copy-list (ensure-cons lines)))
         (existing-lines (and (remote-exists-p path)
                              (lines (read-remote-file path)))))
     (dolist (existing-line existing-lines)
       (deletef new-lines existing-line :test #'string=))
     (if new-lines
         (write-remote-file path (unlines (nconc existing-lines new-lines)))
         :no-change))))

(defprop lacks-lines :posix (path &rest lines)
  "If there is a file at PATH, ensure it does not contain any of LINES."
  (:apply
   (map-remote-file-lines
    path
    (curry #'remove-if (lambda (l) (member l lines :test #'string=))))))

(defprop lacks-lines-matching :posix (path &rest patterns)
  "If there is a file a PATH, ensure it does not contain any lines matching
any of the regular expressions PATTERNS."
  (:apply
   (let ((scanners (mapcar #'re:create-scanner patterns)))
     (map-remote-file-lines
      path (lambda (lines)
             (loop for line in lines
                   unless (loop for s in scanners thereis (re:scan s line))
                     collect line))))))

(defprop has-mode :posix (path mode)
  "Ensure that a file has a particular numeric mode."
  (:desc (format nil "~A has mode ~O" path mode))
  (:apply
   (with-change-if-changes-file (path)
     (mrun (format nil "chmod ~O ~A" mode path)))))

(defprop has-ownership :posix (path &key user group)
  "Ensure that a file has particular ownership and group ownership."
  (:desc (format nil "~A has~:[~; owner ~:*~A~]~:[~;~2:*~:[~;,~] group ~A~]"
                 path user group))
  (:hostattrs
   (unless (or user group)
     (inapplicable-property "Not enough arguments.")))
  ;; We don't want to execute chown(1) unless we're sure it's needed because
  ;; in some circumstances doing so also changes the file mode.
  (:check (multiple-value-bind (mode size mtime owner gowner)
              (remote-file-stats path)
            (declare (ignore mode size mtime))
            (and (or (not user) (string= user owner))
                 (or (not group) (string= group gowner)))))
  (:apply
   (if user
       (mrun "chown" "-h" (format nil "~A~:[~;:~:*~A~]" user group) path)
       (mrun "chgrp" "-h" group path))))

(defprop does-not-exist :posix (&rest paths)
  "Ensure that files do not exist."
  (:desc (if (cdr paths)
             #?"@{paths} do not exist"
             #?"${(car paths)} does not exist"))
  (:check (not (apply #'remote-exists-some-p paths)))
  (:apply (mrun "rm" "-f" paths)))

(defprop directory-does-not-exist :posix
    (&rest directories
           ;; Ensure that there's a trailing slash at the end of each
           ;; namestring, such that if a regular file of the same name as the
           ;; directory exists, 'rm -rf' will not delete it.
           &aux (directories
                 (mapcar (compose #'ensure-trailing-slash #'unix-namestring)
                         directories)))
  "Recursively ensure that DIRECTORIES do not exist."
  (:desc (if (cdr directories)
             #?"@{directories} do not exist"
             #?"${(car directories)} does not exist"))
  (:check (not (apply #'remote-exists-p directories)))
  (:apply (mrun "rm" "-rf" directories)))

(defprop data-uploaded :posix (iden1 iden2 destination)
  (:desc #?"${destination} installed")
  (:hostattrs
   (declare (ignore destination))
   (require-data iden1 iden2))
  (:apply
   (containing-directory-exists destination)
   (maybe-write-remote-file-data destination iden1 iden2)))

(defproplist host-data-uploaded :posix
    (destination
     ;; Require an absolute path because we don't know the remote home
     ;; directory at hostattrs time, so can't resolve it ourselves.
     &aux (destination (unix-namestring
                        (ensure-pathname destination :want-absolute t))))
  (data-uploaded (get-hostname) destination destination))

(defprop secret-uploaded :posix (iden1 iden2 destination)
  (:desc #?"${destination} installed")
  (:hostattrs
   (declare (ignore destination))
   (require-data iden1 iden2))
  (:apply
   (maybe-write-remote-file-data destination iden1 iden2 :mode #o600)))

(defproplist host-secret-uploaded :posix
    (destination
     ;; Require an absolute path like with HOST-DATA-UPLOADED.
     &aux (destination (unix-namestring
                        (ensure-pathname destination :want-absolute t))))
  (secret-uploaded (get-hostname) destination destination))

(defprop data-cache-purged :posix ()
  "Ensure that any prerequisite data cached in the remote home directory is removed."
  (:desc "Consfigurator data cache cleaned")
  (:apply (directory-does-not-exist
           (merge-pathnames "data/" (get-connattr :consfigurator-cache)))))

(defprop regex-replaced-lines :posix (file regex replace)
  "Like s/REGEX/REPLACE/ on the lines of FILE.
Uses CL-PPCRE:REGEX-REPLACE, which see for the syntax of REPLACE."
  (:apply
   (map-remote-file-lines
    file
    (lambda (lines)
      (mapcar (lambda (line) (re:regex-replace regex line replace)) lines)))))

(defprop directory-exists :posix (dir)
  "Ensure that a directory and its parents exists."
  (:desc (strcat (unix-namestring dir) " exists"))
  (:apply
   (mrun "mkdir" "-p" dir)
   ;; assume it was already there
   :no-change))

(defprop containing-directory-exists :posix (file)
  "Ensure that a file's directory and the latter's parents exist."
  (:desc #?"Directory containing ${file} exists")
  (:apply
   (if (pathname-name file)
       (let ((parent (unix-namestring (pathname-directory-pathname file))))
         (when (plusp (length parent))
           (mrun "mkdir" "-p" parent)))
       (mrun "mkdir" "-p" (pathname-parent-directory-pathname file)))
   ;; likewise assume it was already there
   :no-change))

;; readlink(1) is not POSIX.  This is a safe parse of ls(1) output given its
;; POSIX specification.
(defun remote-link-target (symlink)
  (loop with s = (stripln (run :env '(:LC_ALL "C") "ls" "-ld" symlink))
        and found = 0 and just-found
        for i from 0 below (length s)

        if (char= (elt s i) #\Space)
          unless just-found do (incf found) (setq just-found t)
            end
        else do (setq just-found nil)

        when (>= found 8)
          return (subseq s (+ (length symlink) i 5))))

(defprop symlinked :posix (&key from to)
  "Ensure FROM is a symlink to TO.  Symbolic links are overwritten; it is an
error if FROM is another kind of file, except when unapplying.

The link target, TO, is literal: if it is a relative path, then it is not
relative to the remote home directory, but instead relative to the directory
that contains FROM.  To create a link with a target under the remote home
directory, you can use one or more '../', or an absolute path."
  (:desc #?"Symlinked ${from} -> ${to}")
  (:apply
   (unless (and from to)
     (simple-program-error
      "FILE:SYMLINKED: need both :FROM and :TO arguments."))
   (when (pathnamep to)
     (setq to (unix-namestring to)))
   (let* ((link (remote-test "-L" from))
          (exists (remote-exists-p from)))
     (when (and exists (not link))
       (failed-change "~A exists but is not a symbolic link." from))
     (if (and link (string= (remote-link-target from) to))
         :no-change
         (progn (containing-directory-exists from)
                ;; With at least GNU ln(1), passing -f, but not also -T, does
                ;; not replace an existing link in some cases.
                ;; -T is not POSIX, so we just remove any existing link first.
                (does-not-exist from)
                (mrun "ln" "-sf" to from)))))
  (:unapply
   (declare (ignore to))
   (if (remote-test "-L" from)
       (mrun "rm" from)
       :no-change)))

(defprop is-copy-of :posix (dest source)
  "Ensure that DEST is a copy of SOURCE.  SOURCE may be a regular file or a
symbolic link, in which case the target of the link will be copied."
  (:desc #?"${dest} is copy of ${source}")
  (:check
   (and (remote-test "-f" dest)
        (zerop (mrun :for-exit "cmp" "-s" dest source))))
  (:apply
   (with-remote-temporary-file
       (temp :directory (pathname-directory-pathname dest))
     (mrun "cp" "-L" "--preserve=all" source temp)
     (mrun "mv" temp dest))))


;;;; Config files

;; all our actual uses of this so far could avoid traversing the lines of the
;; file more than once if this function instead applied MAP to each line and
;; then just transformed it back right away, but in the future we might want
;; to write functions which operate on the whole set of lines at once
(defun config-file-map
    (&key (parse-comment "#") (new-comment "# ")
       (parse-section (constantly nil)) (new-section #'identity)
       parse-kv new-kv map)
  "Return a function suitable for passing to FILE:MAP-REMOTE-FILE-LINES, to
modify the lines of a config file using MAP.  MAP is a function from a list of
config file lines to a list of config file lines, except that lines which set
values in the original file will be replaced by lists of the form (COMMENTED
SECTION KEY VALUE), where

    - COMMENTED is a boolean indicating whether the line was commented
    - SECTION is the section of the config file in which the line appears

and KEY and VALUE are the key and value.  MAP may return lists of this form
and they will be converted back into strings.

Other arguments:

- PARSE-COMMENT is a CL-PPCRE regular expression which, when matched at the
  beginning of a line, indicates a comment.  It is assumed that it can be
  repeated and may be followed by whitespace.

- NEW-COMMENT is a string to be prepended to lines to comment them out.

- PARSE-SECTION is a function which returns the name of the section if passed
  a line which begins a section of the config file, or nil if the line does
  not start a section.  It can also be a CL-PPCRE regexp, which should extract
  the section name as the first capture group.  Lines will be passed to this
  function (or matched against this regexp) uncommented.

- NEW-SECTION is a function which takes a section name and returns a line
  (without trailing newline) beginning a new section with that name.

- PARSE-KV is a function which returns as a cons the key and value set by a
  line of the config file, or nil if the line is something else.  It can also
  be a CL-PPCRE regexp, which should extract the key and value as the first
  and second capture groups, respectively.  Lines will be passed to this
  function (or matched against this regexp) uncommented.

- NEW-KV is a function of two arguments, a key and a value, which returns an
  uncommented line setting the key and value."
  (unless (functionp parse-section)
    (let ((orig parse-section))
      (setq parse-section (lambda (line)
                            (multiple-value-bind (match groups)
                                (re:scan-to-strings orig line)
                              (when match (elt groups 0)))))))
  (unless (functionp parse-kv)
    (let ((orig parse-kv))
      (setq parse-kv (lambda (line)
                       (multiple-value-bind (match groups)
                           (re:scan-to-strings orig line)
                         (and match (cons (elt groups 0) (elt groups 1))))))))
  (flet ((uncomment (line)
           (multiple-value-list
            (re:regex-replace #?/^(?:${parse-comment})+\s*/ line ""))))
    (lambda (lines)
      (let* ((unmapped
               (loop with current-section
                     for line in lines
                     for (uncommented commentedp) = (uncomment line)
                     for (k . v) = (funcall parse-kv uncommented)
                     for new-section
                       = (and (not commentedp)
                              (funcall parse-section uncommented))
                     do (setq current-section
                              (or new-section current-section))
                     if (and k v)
                       collect (list commentedp current-section k v)
                     else collect line))
             (mapped (funcall map unmapped)))
        (loop with current-section and collectedp
              for line in mapped
              for line-section = (etypecase line
                                   (cons (cadr line))
                                   (string (funcall parse-section line)))

              if (and (listp line)
                      line-section
                      (not (string= line-section current-section)))
                when collectedp collect "" end
                and collect (funcall new-section line-section)
                and do (setq current-section line-section)
              else if (and (stringp line)
                           line-section
                           (not (string= line-section current-section)))
                     do (setq current-section line-section)

              if (listp line)
                collect (with-output-to-string (s)
                          (destructuring-bind (commentedp sec k v) line
                            (declare (ignore sec))
                            (when commentedp (princ new-comment s))
                            (princ (funcall new-kv k v) s)))
              else collect line
              do (setq collectedp t))))))

(defun simple-conf-update (file pairs &rest args)
  (let ((keys (make-hash-table :test #'equal)))
    (loop for (k v) on pairs by #'cddr
          unless (stringp v)
            do (simple-program-error
                "Values passed are not all strings, or list is not even")
          do (setf (gethash k keys) v))
    (containing-directory-exists file)
    (map-remote-file-lines
     file (apply
           #'config-file-map
           :map
           (lambda (lines)
             (let ((new-lines
                     (loop for line in lines
                           for key = (and (listp line) (caddr line))
                           for val = (and (listp line) (gethash key keys))
                           if (eql val :done)
                             collect (list* t nil (cddr line))
                           else if val
                                  collect (list nil nil key val)
                                  and do (setf (gethash key keys) :done)
                           else collect line)))
               (loop for k being the hash-keys in keys using (hash-value v)
                     unless (eql v :done)
                       collect (list nil nil k v) into accum
                     finally (return (nconc new-lines accum)))))
           args))))

(defprop contains-conf-space :posix (file &rest pairs)
  "Where FILE is a config file in which keys and values are separated by spaces
and there are no sections, and PAIRS is a list of even length of alternating
keys and values, set each of these keys and values in FILE.

If there are any other lines which set values for the same keys, they will be
commented out; the first commented or uncommented line for each key will be
uncommented and used to set the value, if it exists."
  (:desc (format nil "~A has ~{\"~A ~A\"~^, ~}" file pairs))
  (:apply (simple-conf-update file pairs
                              :parse-kv #?/^(\S+)\s+(.+)/
                              :new-kv (lambda (k v) #?"${k} ${v}"))))

(defprop contains-conf-tab :posix (file &rest pairs)
  "Like FILE:CONTAINS-CONF-SPACE, but separate keys and values with a tab rather
than a space when updating lines."
  (:desc (format nil "~A has ~{\"~A ~A\"~^, ~}" file pairs))
  (:apply (simple-conf-update file pairs
                              :parse-kv #?/^(\S+)\s+(.+)/
                              :new-kv (lambda (k v) #?"${k}	${v}"))))

(defprop contains-conf-equals :posix (file &rest pairs)
  "Where FILE is a config file in which keys and values are separated by \" = \"
and there are no sections, and PAIRS is a list of even length of alternating
keys and values, set each of these keys and values in FILE.

If there are any other lines which set values for the same keys, they will be
commented out; the first commented or uncommented line for each key will be
uncommented and used to set the value, if it exists."
  (:desc (format nil "~A has ~{~A = ~A~^, ~}" file pairs))
  (:apply (simple-conf-update file pairs
                              :parse-kv #?/^([^\s=]+)\s?=\s?(.*)/
                              :new-kv (lambda (k v) #?"${k} = ${v}"))))

(defprop contains-conf-unspaced :posix (file &rest pairs)
  "Where FILE is a config file in which keys and values are separated by \"=\",
without spaces, there are no sections, and PAIRS is a list of even length of
alternating keys and values, set each of these keys and values in FILE.

If there are any other lines which set values for the same keys, they will be
commented out; the first commented or uncommented line for each key will be
uncommented and used to set the value, if it exists."
  (:desc (format nil "~A has ~{~A=~A~^, ~}" file pairs))
  (:apply (simple-conf-update file pairs
                              :parse-kv #?/^([^\s=]+)=(.*)/
                              :new-kv (lambda (k v) #?"${k}=${v}"))))

(defprop contains-conf-shell :posix (file &rest pairs)
  "Where FILE is a shell config file, like those in /etc/default, and PAIRS is a
list of even length of alternating keys and values, set each of these keys and
values in FILE.

If there are any other lines which set values for the same keys, they will be
commented out; the first commented or uncommented line for each key will be
uncommented and used to set the value, if it exists."
  (:desc (format nil "~A has ~{~A=~S~^, ~}" file pairs))
  (:apply (simple-conf-update file (loop for (k v) on pairs by #'cddr
                                         collect k collect (sh-escape v))
                              ;; include quoting as part of the value so we
                              ;; don't end up substituting double quotation
                              ;; marks for single, or similar
                              :parse-kv #?/^([^\s=]+)\s?=\s?(.*)/
                              :new-kv (lambda (k v) #?"${k}=${v}"))))

(defprop contains-ini-settings :posix (file &rest triples)
  "Where FILE is an INI file, and each of TRIPLES is a list of three elements,
a section name, key and value, set those keys and values in FILE.  Keys
containing '=' are not supported.

If there are any other lines which set values for the same keys in the same
sections, they will be commented out.  The first commented or uncommented line
for each key in its section will be uncommented and used to set the value, if
it exists.

Some normalisation will be performed: whitespace around the '=' will be
removed, and semicolon comment chars will be replaced with '#'."
  (:desc (format nil "~A has ~{~{[~A] ~A = ~A~}~^, ~}" file triples))
  (:apply
   (let ((parse-section #?/^\[(.+)\]$/)
         (keys (make-hash-table :test #'equal)))
     (loop for (s k v) in triples
           do (setf (gethash (cons s k) keys) v))
     (map-remote-file-lines
      file
      (config-file-map
       :parse-comment "[#;]"
       :parse-section parse-section
       :new-section (lambda (s) #?"[${s}]")
       :parse-kv #?/^([^=\s]+)\s*=\s*(.*)/
       :new-kv (lambda (k v) #?"${k}=${v}")
       :map
       (lambda (lines)
         (let ((new-lines
                 (loop with current
                       for (line . rest) on lines
                       for upcoming
                         = (loop for line in rest until (listp line)
                                 finally
                                    (alet (cadr line)
                                      (return
                                        (and (not (string= it current))
                                             it))))
                       and key = (and (listp line) (caddr line))
                       for pair = (and key (cons (cadr line) key))
                       for val  = (and key (gethash pair keys))

                       if (eql val :done)
                         collect (cons t (cdr line))
                       else if val
                              collect (list nil (cadr line) key val)
                              and do (setf (gethash pair keys) :done)
                       else collect line

                       ;; If we're about to reach a new section insert any
                       ;; remaining pairs in this section, as that's better
                       ;; than inserting a new section with the same name at
                       ;; the end of the file.
                       if upcoming
                         nconc (loop for pair being the hash-keys in keys
                                       using (hash-value v)
                                     for (s . k) = pair
                                     when (and (string= current s)
                                               (not (eql v :done)))
                                       collect (list nil s k v)
                                       and do (setf (gethash pair keys) :done))
                         and do (setq current upcoming))))
           (loop for pair being the hash-keys in keys using (hash-value v)
                 for (s . k) = pair
                 unless (eql v :done)
                   collect (list nil s k v) into accum
                 finally (return
                           (nconc new-lines
                                  (sort accum #'string< :key #'cadr)))))))))))

(defun update-unix-table (file source target entries &key (no-source "none"))
  "Ensure that the UNIX table at FILE (e.g. /etc/fstab) contains each of
ENTRIES, using a simple merge procedure: existing lines of the file with the
same value for the TARGETth field are updated to match the corresponding
members of ENTRIES, except that if the SOURCEth field of the existing entry is
not NO-SOURCE and the corresponding member of ENTRIES is STRING= to either
NO-SOURCE or \"PLACEHOLDER\", use the existing field value.

Sort the lines to avoid certain possible failures.  For each pair of lines, if
the TARGETth or the SOURCEth field of the first line is a path and a subpath
of the TARGETth field of the second line, sort the second line earlier.
Otherwise, try to avoid disturbing line order.  This avoids failures to mount
because the filesystem containing the mount point is not mounted yet, and
ensures that partitions containing things like swap files are mounted before
an attempt is made to activate the swap, set up the bind mount, etc."
  (let ((unknown (list no-source "PLACEHOLDER"))
        (pending (make-hash-table :test #'equal)))
    (dolist (entry entries)
      (setf (gethash (nth target (words entry)) pending) entry))
    (containing-directory-exists file)
    (map-remote-file-lines
     file
     (lambda (lines)
       (stable-sort
        (loop for line in lines
              for line-fields = (words line)
              for line-source = (nth source line-fields)
              and line-target = (nth target line-fields)
              for entry = (when-let* ((entry (gethash line-target pending))
                                      (fields (words entry)))
                            (when (and (member (nth source fields)
                                               unknown :test #'string=)
                                       (not (string= line-source no-source)))
                              (setf (nth source fields) line-source))
                            (format nil "~{~A~^ ~}" fields))
              if entry
                collect it into accum and do (remhash line-target pending)
              else collect line into accum
              finally (return (nconc accum (hash-table-values pending))))
        (lambda (a b)
          (flet ((subpathp (x y)
                   (and (plusp (length x)) (plusp (length y))
                        (char= #\/ (first-char x) (first-char y))
                        (subpathp (ensure-pathname x)
                                  (ensure-directory-pathname y)))))
            (and
             ;; If either line is blank treat as equal.
             (plusp (length a)) (plusp (length b))
             ;; If either line is a comment treat as equal.
             (not (char= #\# (first-char a))) (not (char= #\# (first-char b)))
             ;; Now compare the TARGETth and SOURCEth fields of B to the
             ;; TARGETth field of A.
             (let ((a (words a)) (b (words b)))
               (let ((a-target (nth target a)))
                 (or (subpathp (nth target b) a-target)
                     (subpathp (nth source b) a-target))))))))))))
