;;; elogt.el --- Portage Emerge log browser -*- lexical-binding: t -*-



;; Copyright 2023 Gentoo Authors


;; 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 2 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.


;; Authors: Maciej Barć <xgqt@gentoo.org>
;; Maintainer: Gentoo Emacs project <emacs@gentoo.org>
;; Created: 03 Feb 2023
;; Version: 0.0.0
;; Keywords: convenience
;; Homepage: https://gitweb.gentoo.org/proj/emacs-elogt.git
;; Package-Requires: ((emacs "27.1"))
;; SPDX-License-Identifier: GPL-2.0-or-later



;;; Commentary:

;; Portage Emerge log browser for GNU Emacs.

;; ElogT displays the Portage logs in a convenient table and allows log file
;; browsing and deletion.



;;; Code:


(require 'ansi-color)


(defconst elogt-version "0.0.0"
  "ElogT version.")

(defconst elogt--portage-log-stars
  '((" \e[31;01m*\e[0m" . error)
    (" \e[32m*\e[0m"    . info)
    (" \e[33;01m*\e[0m" . warn)))

(defconst elogt--priority-level-indicators
  `((error . ,(propertize "Error" 'font-lock-face '(:foreground "red")))
    (info  . ,(propertize "Info"  'font-lock-face '(:foreground "green")))
    (warn  . ,(propertize "Warn"  'font-lock-face '(:foreground "orange")))
    (none  . ,(propertize "None"  'font-lock-face '(:foreground "purple")))))


;; Customization

(defgroup elogt nil
  "Customization for ElogT, Portage Emerge log browser."
  :group 'ebuild)

(defcustom elogt-portage-log-dir "/var/log/portage"
  "Portage log directory location."
  :safe 'stringp
  :type 'file
  :group 'elogt)

(defcustom elogt-check-priority t
  "Check priority of each logfile.

If set to nil entries will have a phony Info level."
  :type 'boolean
  :group 'elogt)


;; Log file processing

(defun elogt--gather-portage-logs ()
  "Gather logs from ‘elogt-log-dir’."
  (directory-files elogt-portage-log-dir t "\\.log"))

(defun elogt--logfile-find-stars (file-name)
  "Find special info indicators in FILE-NAME."
  (let ((buffer (find-file-noselect file-name 'nowarn 'rawfile))
        (found-stars nil))
    (with-current-buffer buffer
      (dolist (star elogt--portage-log-stars)
        (save-excursion
          (goto-char (point-min))
          (let ((found (search-forward (car star) nil 'noerror)))
            (when found
              (push (cdr star) found-stars))))))
    (kill-buffer buffer)
    found-stars))

(defun elogt--priority-level-property (key)
  "Rerun a value referenced by KEY of ‘elogt--priority-level-indicators’."
  (cdr (assoc key elogt--priority-level-indicators)))

(defun elogt--logfile-priority-level (file-name)
  "Return a FILE-NAME priority level.

A logfile priority level is one of: None, Info, Warn, Error."
  (let ((found-stars (elogt--logfile-find-stars file-name)))
    (cond
     ((not elogt-check-priority)  (elogt--priority-level-property 'info))
     ((null          found-stars) (elogt--priority-level-property 'none))
     ((member 'error found-stars) (elogt--priority-level-property 'error))
     ((member 'warn  found-stars) (elogt--priority-level-property 'warn))
     (t                           (elogt--priority-level-property 'info)))))

(defun elogt--file-size (file-path)
  "Return size of a given file at FILE-PATH."
  (file-size-human-readable-iec
   (file-attribute-size (file-attributes file-path))))

(defun elogt--logfile-properties (file-name)
  "Extract the properties form given FILE-NAME."
  (let ((splitted-file-name (split-string (file-name-base file-name) ":")))
    (cond
     ((= (length splitted-file-name) 3)
      (let ((category (car   splitted-file-name))
            (package  (cadr  splitted-file-name))
            (time     (caddr splitted-file-name)))
        (vector (elogt--logfile-priority-level file-name)
                category
                (propertize package 'face 'bold)
                (propertize time    'face 'italic)
                (elogt--file-size file-name))))
     (t
      (make-vector 5 "")))))

(defun elogt--make-log-table-contents ()
  "Make ElogT table contents."
  (let ((index 0))
    (mapcar (lambda (log-file-path)
              (let ((entry (list index
                                 (elogt--logfile-properties log-file-path))))
                (setq index (+ index 1))
                entry))
            (elogt--gather-portage-logs))))


;; Table interaction

(defun elogt--entry-logfile-path (table-entry)
  "Return a logfile path of a given ElogT TABLE-ENTRY."
  (format "%s/%s:%s:%s.log"
          elogt-portage-log-dir
          (aref table-entry 1)
          (substring-no-properties (aref table-entry 2))
          (substring-no-properties (aref table-entry 3))))

(defun elogt--get-table-entry-logfile-path ()
  "Return a logfile path of current ElogT table entry."
  (elogt--entry-logfile-path (tabulated-list-get-entry)))

(defun elogt--open-entry-file ()
  "Open a ElogT table entry at point.

Return opened buffer (done via `find-file')."
  (find-file (elogt--get-table-entry-logfile-path)))

(defun elogt-open-entry ()
  "Open specified ElogT table entry and put it in a mode for viewing only."
  (interactive)
  (let ((buffer (elogt--open-entry-file)))
    (with-current-buffer buffer
      (fundamental-mode)
      (ansi-color-apply-on-region (point-min) (point-max) 'preserve-sequences)
      (read-only-mode)
      (view-mode))))

(defun elogt--delete-entry-file ()
  "Delete a logfile of a entry at point."
  (delete-file (elogt--get-table-entry-logfile-path)))

(defun elogt-delete-entry ()
  "Delete specified ElogT table entry."
  (interactive)
  (elogt--delete-entry-file)
  (tabulated-list-delete-entry))

(defun elogt-refresh-table ()
  "Refresh the ElogT table."
  (interactive)
  (message "Refreshing the ElogT table, please wait...")
  (setq tabulated-list-entries (elogt--make-log-table-contents))
  (tabulated-list-init-header)
  (tabulated-list-print t)
  (message "The ElogT table is ready."))


;; Major mode

(defvar elogt-mode-hook nil
  "Hook for `elogt' major mode.")

(defvar elogt-mode-map
  (let ((elogt-mode-map (make-keymap)))
    (define-key elogt-mode-map (kbd "/") #'isearch-forward)
    (define-key elogt-mode-map (kbd "o") #'elogt-open-entry)
    (define-key elogt-mode-map (kbd "d") #'elogt-delete-entry)
    (define-key elogt-mode-map (kbd "g") #'elogt-refresh-table)
    elogt-mode-map)
  "Key map for `elogt' major mode.")

(define-derived-mode elogt-mode tabulated-list-mode
  "ElogT"
  "Major mode for browsing Portage log files."
  (setq tabulated-list-format
        [("Priority"  10 t)
         ("Category"  20 t)
         ("Package"   30 t)
         ("Time"      20 t)
         ("Size"      10 t)])
  (setq tabulated-list-sort-key (cons "Time" t))
  (run-hooks 'elogt-mode-hook)
  (use-local-map elogt-mode-map))


;; Main provided features

;;;###autoload
(defun elogt ()
  "Browse Portage log files."
  (interactive)
  (let ((buffer (get-buffer-create "*ElogT*")))
    (with-current-buffer buffer
      (elogt-mode)
      (elogt-refresh-table))
    (display-buffer buffer)))


(provide 'elogt)



;;; elogt.el ends here