;;; stash.scm --- A Guile script for moving directories and creating symlinks with conflict resolution
;;;
;;; Author: Glenn Thompson <glenn@kirstol.org>
;;; Version: 0.1.0-alpha.1
;;; Created: 2024-12-03
;;; Compatibility: Guile 3.0.9
;;; Keywords: symlink, file management, conflict resolution, backup
;;;
;;; Commentary:
;;;
;;; Stash is a command-line utility written in Guile Scheme designed to facilitate the movement of directories and
;;; creation of symbolic links (symlinks) for files and directories. It allows users to specify a source directory
;;; and a target directory where the symlink should be created. The utility handles potential conflicts with existing
;;; files or directories at the target location, offering users the choice to overwrite, back up, or skip the creation of new symlinks.
;;;
;;; Main Features:
;;; - Command-line argument parsing for specifying source and target paths.
;;; - Conflict detection with interactive user resolution options (overwrite, backup, skip, or cancel).
;;; - Moving directories and creating symlinks.
;;; - Simple and interactive user interface for easy use.
;;;
;;; Usage:
;;;
;;; guile -L . stash.scm --target=<target-dir> --source=<source-dir>
;;;
;;; Replace <target-dir> with the directory where you want the symlink to be created,
;;; and <source-dir> with the path to the source directory.
;;;
;;; License:
;;;
;;; This project is licensed under the GNU General Public License v3.
;;;
;;; Code:

;; Import necessary modules
(use-modules (ice-9 getopt-long)
             (ice-9 popen)
             (ice-9 rdelim)
             (ice-9 format)
             (srfi srfi-1)
             (srfi srfi-19))  ;; Use for list handling and date-time formatting

;;; ANSI Color Codes for terminal output
(define red-text "\x1b[31m")
(define yellow-text "\x1b[33m")
(define green-text "\x1b[32m")
(define reset-text "\x1b[0m")

;;; Function to wrap messages in color
(define (color-message message color)
  (string-append color message reset-text))

;;; Helper function to get a formatted current time string
(define (current-timestamp)
  "Return the current date and time as a formatted string."
  (let* ((time (current-time))
         (seconds (time-second time)))
    (strftime "%Y-%m-%d-%H-%M-%S" (localtime seconds))))

;;; Improved logging function with timestamp
(define (log-action message)
  "Log an action with a timestamp to the stash.log file."
  (let ((log-port (open-file "stash.log" "a")))  ;; Open file in append mode
    (display (string-append "[" (current-timestamp) "] " message) log-port)
    (newline log-port)
    (close-port log-port)))  ;; Close the port after writing

;;; Expand ~ in paths to the full home directory path
(define (expand-home path)
  "Expand ~ to the user's home directory."
  (if (string-prefix? "~" path)
      (string-append (getenv "HOME") (substring path 1))
      path))

;;; Helper function to back up a directory or symlink
(define (backup-path path)
  "Back up a directory or symlink by renaming it with a timestamp."
  (let ((backup-path (string-append path ".backup." (current-timestamp))))
    (rename-file path backup-path)
    (display (color-message (format #f "Backed up ~a to ~a\n" path backup-path) green-text))
    (log-action (format #f "Backed up ~a to ~a" path backup-path))))

;;; Function to handle command-line arguments
(define (parse-arguments args)
  "Parse command-line arguments."
  (let* ((opts (getopt-long args
                            '((target (value #t) (required? #t))
                              (source (value #t) (required? #t))))))
    opts))

;;; Helper function to quote shell arguments
(define (shell-quote-argument arg)
  "Quote shell argument to handle spaces or special characters."
  (if (string-contains arg " ")
      (string-append "\"" (string-replace arg "\"" "\\\"") "\"")
      arg))

;;; Helper function to delete a directory recursively
(define (delete-directory path)
  "Delete a directory recursively."
  (if (file-is-directory? path)
      (begin
        (system (string-append "rm -rf " (shell-quote-argument path)))  ;; Use rm -rf to delete recursively
        (log-action (format #f "Deleted directory: ~a" path)))  ;; Log the deletion
      (display (color-message "Error: Path is not a directory.\n" red-text))))

;;; Helper function to move source to target
(define (move-source-to-target source-dir target-dir)
  "Move the entire source directory to the target directory."
  (let* ((source-dir (expand-home source-dir))
         (target-dir (expand-home target-dir))
         (source-name (basename source-dir))
         (target-source-dir (string-append target-dir "/" source-name)))
    ;; Check if the target directory already exists
    (if (file-exists? target-source-dir)
        (begin
          (display (color-message (format #f "Directory ~a already exists.\n" target-source-dir) yellow-text))
          ;; Handle the conflict: overwrite, backup, or skip
          (let ((choice (prompt-user-for-backup-action)))
            (cond
              ((eq? choice 'overwrite)
               (delete-directory target-source-dir)
               (rename-file source-dir target-source-dir)
               (display (color-message (format #f "Overwriting directory ~a.\n" target-source-dir) green-text))
               (log-action (format #f "Overwritten directory: ~a" target-source-dir)))
              ((eq? choice 'backup)
               (backup-path target-source-dir)
               (rename-file source-dir target-source-dir)
               (display (color-message (format #f "Moved ~a to ~a\n" source-dir target-source-dir) green-text))
               (log-action (format #f "Moved ~a to ~a after backup" source-dir target-source-dir)))
              ((eq? choice 'skip)
               (display (color-message "Skipping move operation.\n" green-text))
               (log-action (format #f "Skipped moving directory: ~a" target-source-dir)))
              ((eq? choice 'cancel)
               (display (color-message "Operation cancelled by user.\n" yellow-text))
               (log-action "Operation cancelled by user.")
               (exit 0)))))
        ;; If the target directory doesn't exist, proceed with the move
        (begin
          (rename-file source-dir target-source-dir)
          (display (color-message (format #f "Moved ~a to ~a\n" source-dir target-source-dir) green-text))
          (log-action (format #f "Moved ~a to ~a" source-dir target-source-dir))))
    target-source-dir))  ;; Return the path of the moved source directory

;;; Helper function to create a symlink in the parent directory of the original source
(define (create-symlink-in-parent source-dir target-dir)
  "Create a symlink in the parent directory of source-dir."
  (let* ((parent-dir (expand-home (dirname source-dir)))  ;; Ensure the parent path is expanded
         (symlink-target (string-append parent-dir "/" (basename source-dir)))
         (target-dir (expand-home target-dir)))  ;; Ensure the target path is expanded
    ;; Check if symlink already exists
    (if (file-exists? symlink-target)
        (handle-conflicts source-dir symlink-target)  ;; Handle conflict if symlink or file exists
        (begin
          ;; Create the symlink if no conflict
          (symlink target-dir symlink-target)
          (display (color-message (format #f "Symlink created at ~a pointing to ~a\n" symlink-target target-dir) green-text))
          (log-action (format #f "Symlink created at ~a pointing to ~a" symlink-target target-dir))))))

;;; Conflict resolution handler with backup option
(define (prompt-user-for-backup-action)
  "Prompt the user to decide how to handle a conflict: overwrite (o), backup (b), skip (s), or cancel (c)."
  (display (color-message "A conflict was detected. Choose action - Overwrite (o), Backup (b), Skip (s), or Cancel (c): " yellow-text))
  (let ((response (read-line)))
    (cond
      ((string-ci=? response "o") 'overwrite)
      ((string-ci=? response "b") 'backup)
      ((string-ci=? response "s") 'skip)
      ((string-ci=? response "c") 'cancel)
      (else
       (display (color-message "Invalid input. Please try again.\n" red-text))
       (prompt-user-for-backup-action)))))

;;; Function to handle conflicts with symlinks and directories
(define (handle-conflicts source target)
  "Handle conflicts when a symlink or file already exists at the target location."
  (display (color-message (format #f "Conflict detected! A file or symlink already exists at ~a.\n" target) yellow-text))
  (let ((choice (prompt-user-for-backup-action)))  ;; Prompt for backup or overwrite
    (cond
      ((eq? choice 'overwrite)
       (if (file-is-symlink? target)
           (begin
             (delete-file target)
             (display (color-message "Removed the existing symbolic link.\n" green-text))
             (log-action (format #f "Removed the existing symbolic link at ~a" target))
             (create-symlink-in-parent source target))
           (display (color-message "Error: Target is not a symbolic link.\n" red-text))))
      ((eq? choice 'backup)
       (backup-path target)  ;; Backup the existing directory or symlink
       (create-symlink-in-parent source target))  ;; After backup, create the new symlink
      ((eq? choice 'skip)
       (log-action (format #f "Skipped creating symlink at ~a" target))
       (display (color-message "Keeping existing symbolic link.\n" green-text)))
      ((eq? choice 'cancel)
       (log-action "Operation cancelled by user.")
       (display (color-message "Operation cancelled.\n" yellow-text))
       (exit 0))
      (else
       (display (color-message "Invalid choice. Please try again.\n" red-text))
       (handle-conflicts source target)))))

;;; Main function to handle source and target operations
(define (handle-source-and-target source-dir target-dir)
  "Move the source directory to the target and create a symlink in the parent directory."
  (let ((target-source-dir (move-source-to-target source-dir target-dir)))  ;; Move the directory
    (create-symlink-in-parent source-dir target-source-dir)))  ;; Create the symlink if no conflict

;;; Main entry point
(define (main args)
  "Main function to parse arguments and execute the program."
  (setenv "GUILE_AUTO_COMPILE" "0")  ;; Disable auto-compilation to improve performance
  (let* ((options (parse-arguments args))
         (target-dir (assoc-ref options 'target))
         (source-dir (assoc-ref options 'source)))
    (if (and target-dir source-dir)
        (handle-source-and-target source-dir target-dir)  ;; Handle the source move and symlink creation
        (begin
          (display (color-message "Error: Missing required arguments.\n" red-text))
          (display (color-message "Usage: stash.scm --target=<target-dir> --source=<source-dir>\n" yellow-text))
          (exit 1)))))

;; Entry point for stash
(main (command-line))