(defvar ledger-path "/Users/johnw/bin/ledger")
(defvar ledger-sample-doc-path "/Users/johnw/src/ledger/doc/sample.dat")
(defvar ledger-normalization-args "--args-only --columns 80")

(defun ledger-texi-write-test (name command input output &optional category)
  (let ((buf (current-buffer)))
    (with-current-buffer (find-file-noselect
                          (expand-file-name (concat name ".test") category))
      (erase-buffer)
      (let ((case-fold-search nil))
        (if (string-match "\\$LEDGER\\s-+" command)
            (setq command (replace-match "" t t command)))
        (if (string-match " -f \\$\\([-a-z]+\\)" command)
            (setq command (replace-match "" t t command))))
      (insert command ?\n)
      (insert "<<<" ?\n)
      (insert input)
      (insert ">>>1" ?\n)
      (insert output)
      (insert ">>>2" ?\n)
      (insert "=== 0" ?\n)
      (save-buffer)
      (unless (eq buf (current-buffer))
        (kill-buffer (current-buffer))))))

(defun ledger-texi-update-test ()
  (interactive)
  (let ((details (ledger-texi-test-details))
        (name (file-name-sans-extension
               (file-name-nondirectory (buffer-file-name)))))
    (ledger-texi-write-test
     name (nth 0 details)
     (nth 1 details)
     (ledger-texi-invoke-command
      (ledger-texi-expand-command
       (nth 0 details)
       (ledger-texi-write-test-data name (nth 1 details)))))))

(defun ledger-texi-test-details ()
  (goto-char (point-min))
  (let ((command (buffer-substring (point) (line-end-position)))
        input output)
    (re-search-forward "^<<<")
    (let ((input-beg (1+ (match-end 0))))
      (re-search-forward "^>>>1")
      (let ((output-beg (1+ (match-end 0))))
        (setq input (buffer-substring input-beg (match-beginning 0)))
        (re-search-forward "^>>>2")
        (setq output (buffer-substring output-beg (match-beginning 0)))
        (list command input output)))))

(defun ledger-texi-expand-command (command data-file)
  (if (string-match "\\$LEDGER" command)
      (replace-match (format "%s -f \"%s\" %s" ledger-path
                             data-file ledger-normalization-args) t t command)
    (concat (format "%s -f \"%s\" %s " ledger-path
                    data-file ledger-normalization-args) command)))

(defun ledger-texi-invoke-command (command)
  (with-temp-buffer (shell-command command t (current-buffer))
    (if (= (point-min) (point-max))
        (progn
          (push-mark nil t)
          (message "Command '%s' yielded no result at %d" command (point))
          (ding))
      (buffer-string))))

(defun ledger-texi-write-test-data (name input)
  (let ((path (expand-file-name name temporary-file-directory)))
    (with-current-buffer (find-file-noselect path)
      (erase-buffer)
      (insert input)
      (save-buffer))
    path))

(defun ledger-texi-update-examples ()
  (interactive)
  (save-excursion
    (goto-char (point-min))
    (while (re-search-forward "^@c \\(\\(?:sm\\)?ex\\) \\(\\S-+\\): \\(.*\\)" nil t)
      (let ((section (match-string 1))
            (example-name (match-string 2))
            (command (match-string 3)) expanded-command
            (data-file ledger-sample-doc-path)
            input output)
        (goto-char (match-end 0))
        (forward-line)
        (when (looking-at "@\\(\\(?:small\\)?example\\)")
          (let ((beg (point)))
            (re-search-forward "^@end \\(\\(?:small\\)?example\\)")
            (delete-region beg (1+ (point)))))

        (when (let ((case-fold-search nil))
                (string-match " -f \\$\\([-a-z]+\\)" command))
          (let ((label (match-string 1 command)))
            (setq command (replace-match "" t t command))
            (save-excursion
              (goto-char (point-min))
              (search-forward (format "@c data: %s" label))
              (re-search-forward "@\\(\\(?:small\\)?example\\)")
              (forward-line)
              (let ((beg (point)))
                (re-search-forward "@end \\(\\(?:small\\)?example\\)")
                (setq data-file (ledger-texi-write-test-data
                                 (format "%s.dat" label)
                                 (buffer-substring-no-properties
                                  beg (match-beginning 0))))))))

        (let ((section-name (if (string= section "smex")
                                "smallexample"
                              "example"))
              (output (ledger-texi-invoke-command
                       (ledger-texi-expand-command command data-file))))
          (insert "@" section-name ?\n output
                  "@end " section-name ?\n))

        ;; Update the regression test associated with this example
        (ledger-texi-write-test example-name command input output
                                "../test/manual")))))

(provide 'ldg-texi)