;; -*- lexical-binding: t; -*-
;; Copyright (c) 2014 Microsoft Corporation. All rights reserved.
;; Released under Apache 2.0 license as described in the file LICENSE.
;;
;; Author: Soonho Kong
;;
(require 'cl-lib)
(require 'dash)
(require 'dash-functional)
(require 'flycheck)
(require 's)
(require 'lean-debug)
(require 'lean-variable)
(require 'lean-cmd)
(require 'lean-info)
(require 'lean-util)

;; Parameters
;; ==========
(defvar lean-server-process-name      "lean-server")
(defvar lean-server-buffer-name       "*lean-server*")
(defvar lean-server-trace-buffer-name "*lean-server-trace*")
(defvar lean-server-option            "--server")

;; Log & Trace
;; ===========
(defun lean-server-log (format-string &rest args)
  "Display a message at the bottom of the *lean-server* buffer."
  (lean-output-to-buffer (lean-server-get-buffer)
                         (concat format-string)
                         args)
  (apply 'lean-debug (cons format-string args)))


(defun lean-server-trace (format-string &rest args)
  "Display a message at the bottom of the *lean-server* buffer."
  (when lean-debug-mode
    (when lean-global-server-last-time-sent
      (let ((time-diff (- (float-time) lean-global-server-last-time-sent)))
        (lean-output-to-buffer lean-server-trace-buffer-name
                                    "SLEEP %i\n"
                                    `(,(truncate (* 1000 time-diff))))))
    (setq lean-global-server-last-time-sent (float-time))
    (lean-output-to-buffer lean-server-trace-buffer-name
                                format-string args)))

;; How to read data from an async process
;; ======================================
(defconst lean-server-syntax-pattern
  `((INFO    ,(rx line-start "-- BEGININFO" (* not-newline) line-end)
             ,(rx line-start (group "-- ENDINFO") line-end))
    (SET     ,(rx line-start "-- BEGINSET"  line-end)
             ,(rx line-start (group "-- ENDSET")  line-end))
    (EVAL    ,(rx line-start "-- BEGINEVAL"  line-end)
             ,(rx line-start (group "-- ENDEVAL") line-end))
    (OPTIONS ,(rx line-start "-- BEGINOPTIONS" line-end)
             ,(rx line-start (group "-- ENDOPTIONS") line-end))
    (SHOW    ,(rx line-start "-- BEGINSHOW" line-end)
             ,(rx line-start (group "-- ENDSHOW") line-end))
    (FINDP   ,(rx line-start "-- BEGINFINDP" (* not-newline) line-end)
             ,(rx line-start (group "-- ENDFINDP") line-end))
    (FINDG   ,(rx line-start "-- BEGINFINDG" (* not-newline) line-end)
             ,(rx line-start (group "-- ENDFINDG") line-end))
    (WAIT    ,(rx line-start "-- BEGINWAIT" line-end)
             ,(rx line-start (group "-- ENDWAIT") line-end))
    (ERROR   ,(rx line-start "-- " (0+ not-newline) line-end)
             ,(rx line-start (group "-- ERROR" (0+ not-newline)) line-end)))
  "Regular expression pattern for lean-server message syntax")

(defun lean-server-split-buffer (buf-str beg-regex end-regex)
  ""
  (let ((beg (string-match beg-regex buf-str))
        (end (string-match end-regex buf-str))
        pre body post)
    (when (and beg end)
      (setq end (match-end 1))
      (setq pre  (substring-no-properties buf-str 0 beg))
      (setq body (substring-no-properties buf-str beg end))
      (setq post (substring-no-properties buf-str end))
      `(,pre ,body ,post))))

(defun lean-server-check-buffer-and-partition (buf-str)
  "Return the status of buffer."
  (when buf-str
    (let (matches partition-result)
      (setq matches
            (cl-loop for (type beg-regex end-regex) in lean-server-syntax-pattern
                     do (setq partition-result (lean-server-split-buffer buf-str beg-regex end-regex))
                     if partition-result
                     collect `(,type ,partition-result)))
      (when matches
        (-min-by (-on '< (lambda (type-partition-result) (length (car (cdr type-partition-result)))))
                 matches)))))

(defun lean-server-process-received-message (buf str)
  "Process received message from lean-server"
  (lean-server-log "%s:\n%s\n"
                   (propertize "Received Message" 'face 'font-lock-variable-name-face)
                   str)
  (setq lean-global-server-buffer (concat lean-global-server-buffer str)))

(defun lean-server-output-filter (process string)
  "Filter function attached to lean-server process"
  (lean-server-process-received-message (process-buffer process) string))

(defun lean-server-handle-signal (process event)
  "Handle signals for lean-server-process"
  (let ((event-string (s-trim event)))
    (lean-server-initialize-global-vars)
    (lean-debug "lean-server-handle-signal: %s"
                       (propertize event-string 'face '(:foreground "red")))
    (lean-server-trace "lean-server-handle-signal: %s\n"
                       (propertize event-string 'face '(:foreground "red")))))

;; How to create an async process
;; ==============================

(defun lean-server-cancel-retry-timer ()
  (when (timerp lean-global-retry-timer)
    (cancel-timer lean-global-retry-timer))
  (setq lean-global-retry-timer nil))

(defun lean-server-initialize-global-vars ()
  "Initialize lean-server related global variables"
  (setq lean-global-server-buffer nil)
  (setq lean-global-server-current-file-name nil)
  (setq lean-global-server-message-to-process nil)
  (setq lean-global-server-last-time-sent nil)
  (setq lean-global-async-task-queue nil)
  (setq lean-global-nay-retry-counter 0)
  (setq lean-global-option-alist nil)
  (lean-server-cancel-retry-timer))

(defun lean-server-create-process ()
  "Create lean-server process."
  (let ((process-connection-type nil)
        (lean-server-process
         (start-process lean-server-process-name
                        lean-server-buffer-name
                        (lean-get-executable lean-executable-name)
                        lean-server-option)))
    (set-process-coding-system lean-server-process 'utf-8 'utf-8)
    (set-process-filter lean-server-process 'lean-server-output-filter)
    (set-process-sentinel lean-server-process 'lean-server-handle-signal)
    (set-process-query-on-exit-flag lean-server-process nil)
    (lean-server-initialize-global-vars)
    (setq lean-global-server-process lean-server-process)
    (lean-debug "lean-server process %S is created" lean-server-process)
    lean-server-process))

(defun lean-server-kill-process ()
  "Kill lean-server process. Return t if killed, nil if nothing to kill"
  (interactive)
  (lean-server-initialize-global-vars)
  (cond
   ((and lean-global-server-process
         (not (= 0 (process-exit-status lean-global-server-process))))
    (setq lean-global-server-process nil) t)
   (lean-global-server-process
    (when (interactive-p)
      (message "lean-server-kill-process: %S killed" lean-global-server-process))
    (kill-process lean-global-server-process)
    (setq lean-global-server-process nil) t)
   (t
    (when (interactive-p)
      (message "lean-server-kill-process: no process to kill")) nil)))

(defun lean-server-restart-process ()
  "Restart lean-server process."
  (interactive)
  (and (lean-server-kill-process)
       (lean-server-create-process)))

(defun lean-server-process-exist-p ()
  "Return t if lean-server-process exists, otherwise return nil"
  (if lean-global-server-process
      t
    nil))

(defun lean-server-get-process ()
  "Get lean-server process. If needed, create a one."
  (cond ((not lean-global-server-process)
         (lean-server-create-process))
        ((not (process-live-p lean-global-server-process))
         (when (interactive-p)
           (message "lean-server-get-process: %S is not live, kill it"
                    lean-global-server-process))
         (lean-server-restart-process))
        (t lean-global-server-process)))

(defun lean-server-get-buffer ()
  "Get lean-server buffer."
  (process-buffer (lean-server-get-process)))

;; How to send data to an async process
;; ====================================
(defun lean-server-flush-changed-lines ()
  "Flush lean-changed-lines.

Send REPLACE commands to lean-server, reset lean-changed-lines to nil."
  (cl-loop for n in lean-changed-lines
           do (lean-server-send-cmd-async (lean-cmd-replace n (lean-grab-line n)))
           finally (setq lean-changed-lines nil)))

(defun lean-server-check-current-file (&optional file-name)
  "Check lean-global-server-current-file-name

If it's not the same with file-name (default: buffer-file-name), send VISIT cmd."
  (let ((current-file-name (or file-name (buffer-file-name))))
    (unless (string= lean-global-server-current-file-name
                     current-file-name)
      (lean-server-send-cmd-async (lean-cmd-visit)))))

(defun lean-server-before-send-cmd (cmd)
  "Operations to perform before sending a command."
  (cl-case (lean-cmd-type cmd)
    ('LOAD    (setq lean-global-server-current-file-name
                    (lean-cmd-load-get-file-name cmd)))
    ('VISIT   (setq lean-global-server-current-file-name
                    (lean-cmd-visit-get-file-name cmd)))
    ('REPLACE (lean-server-check-current-file))
    ('INSERT  (lean-server-check-current-file))
    ('REMOVE  (lean-server-check-current-file))
    ('INFO    (lean-server-flush-changed-lines))
    ('CHECK   ())
    ('SET     ())
    ('EVAL    (lean-server-check-current-file))
    ('OPTIONS ())
    ('SHOW    (lean-server-check-current-file))
    ('VALID   (lean-server-check-current-file))
    ('FINDP   (lean-server-flush-changed-lines)
              (lean-server-check-current-file))
    ('FINDG   (lean-server-flush-changed-lines)
              (lean-server-check-current-file))
    ('WAIT    (lean-server-check-current-file))
    ('SYNC    )))

(defun lean-server-delete-cache-file ()
  "Delete the .clean file for the current buffer (if any)"
  (let* ((file-name (buffer-file-name))
         (ext       (and file-name (f-ext file-name)))
         cache-file-name
         )
    (when (string= ext "lean")
      (setq cache-file-name
            (concat (f-no-ext file-name)
                    ".clean"))
      (when (f-file? cache-file-name)
        (lean-debug "Delete cache file %s" cache-file-name)
        (ignore-errors
          (delete-file cache-file-name))))))

(defun lean-server-after-send-cmd (cmd)
  "Operations to perform after sending a command."
  (cl-case (lean-cmd-type cmd)
    ('LOAD    (lean-server-delete-cache-file)
              (lean-server-handle-modified-buffer))
    ('VISIT   (lean-server-delete-cache-file)
              (lean-server-handle-modified-buffer))
    ('REPLACE ())
    ('INSERT  ())
    ('REMOVE  ())
    ('INFO    ())
    ('CHECK   ())
    ('SET     ())
    ('EVAL    ())
    ('OPTIONS ())
    ('SHOW    ())
    ('VALID   ())
    ('FINDP   ())
    ('FINDG   ())
    ('SYNC    ())))

(defun lean-server-send-cmd (cmd)
  "Send cmd to lean-server"
  (let ((proc (lean-server-get-process))
        (string-to-send (concat (lean-cmd-to-string cmd) "\n")))
    (lean-server-before-send-cmd cmd)
    ;; Logging
    (lean-server-log "%s:\n%s"
                     (propertize "Sent Message" 'face 'font-lock-variable-name-face)
                     string-to-send)
    ;; Trace
    (lean-server-trace
     (format "%s" string-to-send))
    (process-send-string proc string-to-send)
    (lean-server-after-send-cmd cmd)))

(defun lean-server-process-message-with-cont (body type cont cmd-type)
  "Process the message from lean-server and call continuation"
  (lean-debug "process-message-with-cont: type = %S, cmd-type = %S"
                     type cmd-type)
  (lean-debug "process-message-with-cont: body\n-----\n%s\n-----\n" body)
  (cl-case type
    (INFO
     (lean-debug "Process: INFO")
     (let ((info-record (lean-server-get-info-record-at-pos body)))
       (funcall cont info-record)))
    (SET
     (lean-debug "Process: SET")
     ;; Call cont with string
     (funcall cont (lean-set-parse-string body)))
    (EVAL
     (lean-debug "Process: EVAL")
     ;; Call cont with string
     (funcall cont (lean-eval-parse-string body)))
    (OPTIONS
     (lean-debug "Process: OPTIONS")
     ;; Call cont with alist of lean-option-records
     (funcall cont (lean-options-parse-string body)))
    (SHOW
     (lean-debug "Process: SHOW")
     ;; Call cont with string
     (funcall cont (lean-show-parse-string body)))
    (FINDP
     (lean-debug "Process: FINDP")
     ;; Call cont with (name * type) list
     (funcall cont (lean-findp-parse-string body)))
    (FINDG
     (lean-debug "Process: FINDG")
     ;; Call cont with (name * type) list
     (funcall cont (lean-findg-parse-string body)))
    (WAIT
     (lean-debug "Process: WAIT")
     ;; Call cont
     (funcall cont))
    (ERROR
     (lean-server-log "Error detected:\n%s" body))))

(defun lean-server-check-and-process-buffer-with-cont (cont cmd-type)
  "Check server-buffer and process the message with a continuation if it's ready."
  (let ((partition-result (lean-server-check-buffer-and-partition
                           lean-global-server-buffer))
        result)
    (condition-case err
        (pcase partition-result
          (`(,type (,pre ,body ,post))
           (lean-server-log "The following pre-message will be thrown away:")
           (lean-server-log "%s" pre)
           (setq lean-global-server-buffer post)
           (setq result (lean-server-process-message-with-cont body type cont cmd-type))
           `(PROCESSED ,result))
          (`nil '(NOTREADY)))
      (error `(ERROR ,err))
      (quit  `(QUIT  ,err)))))

(defun lean-server-async-task-queue-len ()
  (length lean-global-async-task-queue))

(defun lean-server-async-task-queue-push-back (cont cmd-type)
  (setq lean-global-async-task-queue (-snoc lean-global-async-task-queue
                                            `(,cont . ,cmd-type))))

(defun lean-server-async-task-queue-peek-front ()
  (car lean-global-async-task-queue))

(defun lean-server-async-task-queue-pop-front ()
  (!cdr lean-global-async-task-queue))

(defun lean-server-send-cmd-async (cmd &optional cont)
  "Send cmd to lean-server and attach continuation to the queue."
  (lean-debug "send-cmd-async: %S %S" (lean-cmd-type cmd) (cl-second cmd))
  (lean-debug "send-cmd-async: queue len = %d" (lean-server-async-task-queue-len))
  (lean-server-send-cmd cmd)
  (when cont
    (lean-server-async-task-queue-push-back cont (lean-cmd-type cmd))
    (lean-debug "send-cmd-async: added to %s the queue, queue size = %d"
                       (lean-cmd-type cmd)
                       (lean-server-async-task-queue-len))
    (lean-debug "send-cmd-async: call handler")
    (lean-server-set-timer-for-event-handler)))

(defun lean-server-consume-all-async-tasks ()
  (lean-debug "lean-server-consume-all-async-tasks: queue size = %d"
                     (lean-server-async-task-queue-len))
  (while lean-global-async-task-queue
    (accept-process-output (lean-server-get-process) 0 50 t)
    (let* ((front-item (lean-server-async-task-queue-peek-front))
           (cont       (car front-item))
           (cmd-type   (cdr front-item))
           (result (lean-server-check-and-process-buffer-with-cont cont
                                                                   cmd-type)))
      (pcase result
        (`(PROCESSED ,ret)
         (lean-server-async-task-queue-pop-front)
                  (lean-debug "lean-server-consume-all-sync-tasks: processed. queue size = %d"
                            (lean-server-async-task-queue-len)))
        (`(NOTREADY)
         (lean-debug "lean-server-consume-all-sync-tasks: not ready. queue size = %d"
                            (lean-server-async-task-queue-len)))
        (t
         (lean-server-async-task-queue-pop-front)
         (lean-debug "lean-server-consume-all-sync-tasks: either error or quit happend. queue size = %d"
                            (lean-server-async-task-queue-len))))))
  (lean-debug "lean-server-consume-all-async-tasks: over. queue size = %d"
                     (lean-server-async-task-queue-len)))

(defun lean-server-send-cmd-sync (cmd &optional cont)
  "Send cmd to lean-server (sync)."
  (lean-debug "send-cmd-sync: %S" (lean-cmd-type cmd))
  (lean-server-cancel-retry-timer)
  (lean-server-consume-all-async-tasks)
  (lean-server-send-cmd cmd)
  (let ((result (lean-server-check-and-process-buffer-with-cont cont (lean-cmd-type cmd))))
    (while (equal result '(NOTREADY))
      (accept-process-output (lean-server-get-process) 0 50 t)
      (setq result (lean-server-check-and-process-buffer-with-cont cont (lean-cmd-type cmd))))
    (pcase result
      (`(PROCESSED ,ret)
       (lean-debug "lean-server-send-cmd-sync: %S, processed result = %S"
                          cmd
                          result)
       ret)
      (`(ERROR ,err)
       (lean-debug "lean-server-send-cmd-sync: %S, error = %S"
                          cmd
                          err))
      (`(QUIT ,err)
       (lean-debug "lean-server-send-cmd-sync: %S, quit = %S"
                          cmd
                          err))
      (t
       (lean-debug "lean-server-send-cmd-sync: %S, ??? = %S"
                          cmd
                          result)))))

(defun lean-show-parse-string (str)
  "Parse the output of show command."
  (let ((str-list (split-string str "\n")))
    ;; Drop the first line "-- BEGINSHOW" and
    ;; the last line "-- ENDSHOW"
    (setq str-list
          (-take (- (length str-list) 2)
                 (-drop 1 str-list)))
    (string-join str-list "\n")))

(defun lean-findp-parse-string (str)
  "Parse the output of findp command."
  (let ((str-list (split-string str "\n")))
    ;; Drop the first line "-- BEGINFINDP" and
    ;; the last line "-- ENDFINDP"
    (setq str-list
          (-take (- (length str-list) 2)
                 (-drop 1 str-list)))
    (--map
     (let ((items (split-string it "|")))
       `(,(cl-first items) . ,(cl-second items))) str-list)))

(defun lean-findg-parse-string (str)
  "Parse the output of findg command."
  (let ((str-list (split-string str "\n")))
    ;; Drop the first line "-- BEGINFINDG" and
    ;; the last line "-- ENDFINDG"
    (setq str-list
          (-take (- (length str-list) 2)
                 (-drop 1 str-list)))
    (--map
     (let ((items (split-string it "|")))
       `(,(cl-first items) . ,(cl-second items))) str-list)))

(defun lean-server-show ()
  (interactive)
  (lean-server-send-cmd-async (lean-cmd-show) 'message))

(defun lean-server-valid ()
  (interactive)
  (lean-server-send-cmd-async (lean-cmd-valid) 'message))

(defun lean-server-set-timer-for-event-handler ()
  (lean-debug "set-timer-for-event-handler")
  (unless lean-global-retry-timer
    (setq lean-global-retry-timer
          (run-with-idle-timer
           (if (current-idle-time)
               (time-add (seconds-to-time lean-server-retry-time) (current-idle-time))
             lean-server-retry-time)
           nil
           'lean-server-event-handler)))
  nil)

(defun lean-server-get-info-record-at-pos (body)
  (let* ((file-name (buffer-file-name))
         (column (lean-line-offset)))
    (when (and (or (looking-at (rx (or white "," ")" "}" "]")))
                   (eolp))
               (> column 1))
      (setq column (1- column)))
    (lean-info-record-parse body file-name column)))

(defun lean-server-event-handler ()
  "Process an item from async-task-queue.

If it's successful, take it out from the queue.
Otherwise, set an idle-timer to call the handler again"
  (lean-server-cancel-retry-timer)
  (when (eq major-mode 'lean-mode)
    (let* ((front-item (lean-server-async-task-queue-peek-front))
           (cont       (car front-item))
           (cmd-type   (cdr front-item))
           (result     (lean-server-check-and-process-buffer-with-cont cont
                                                                       cmd-type)))
      (pcase result
        (`(PROCESSED ,ret)
         (lean-server-async-task-queue-pop-front)
         (lean-debug "event-handler: processed. now the queue size = %d\n"
                            (lean-server-async-task-queue-len))
         ret)
        (`(NOTREADY)
         (lean-debug "event-handler: not ready. queue size = %d"
                            (lean-server-async-task-queue-len)))
        (`(ERROR ,err)
         (lean-server-async-task-queue-pop-front)
         (lean-debug "event-handler: error %S. queue size = %d"
                            err
                            (lean-server-async-task-queue-len)))
        (`(QUIT ,err)
         (lean-server-async-task-queue-pop-front)
         (lean-debug "event-handler: quit %S. queue size = %d"
                            err
                            (lean-server-async-task-queue-len)))))
    (if lean-global-async-task-queue (lean-server-set-timer-for-event-handler))))

(defun lean-server-after-save ()
  (let ((current-file-name (buffer-file-name)))
    (when current-file-name
      (lean-debug "lean-server-handle-save: %s" current-file-name)
      (lean-server-send-cmd-async (lean-cmd-visit current-file-name)))))

(defun lean-server-save-buffer-to-temp-file (prefix)
  "Save the current buffer to a temp-file and return its path"
  (interactive)
  (let ((temp-file (make-temp-file prefix)))
    (with-current-buffer (flymake-copy-buffer-to-temp-buffer (current-buffer))
      (set-visited-file-name temp-file)
      (save-buffer 0)
      (kill-buffer))
    temp-file))

(defun lean-server-handle-modified-buffer ()
  "Handle modified buffer when lean-mode start"
  (when (buffer-modified-p)
    (lean-server-send-cmd-async (lean-cmd-sync))))

(provide 'lean-server)