;;; prog-python-conf.el --- Python development configuration -*- lexical-binding: t; -*-
;;; Commentary:
;;; Configuration for Python development including LSP support, formatting,
;;; testing, virtual environments, and debugging.
;;; Code:

;; Python mode settings
;; (use-package python
;;   :ensure nil
;;   :mode ("\\.py\\'" . python-mode)
;;   :interpreter ("python" "python3")
;;   :custom
;;   (python-indent-offset 4)
;;   (python-indent-guess-indent-offset nil)
;;   (python-shell-interpreter "python3")
;;   (python-shell-completion-native-enable nil)  ; Avoid readline issues
;;   :config
;;   ;; Remove trailing whitespace on save
;;   (add-hook 'python-mode-hook
;;             (lambda ()
;;               (add-hook 'before-save-hook #'delete-trailing-whitespace nil t))))

;; Python Tree-Sitter mode configuration
;; Emacs 29+ includes built-in tree-sitter support
(use-package python
  :ensure nil
  :mode ("\\.py\\'" . python-ts-mode)
  :interpreter ("python" . python-ts-mode)
  :custom
  (python-indent-offset 4)
  (python-indent-guess-indent-offset nil)
  (python-shell-interpreter "python3")
  (python-shell-completion-native-enable nil)  ; Avoid readline issues
  :init
  ;; Remap python-mode to python-ts-mode when tree-sitter is available
  (when (and (fboundp 'treesit-available-p)
             (treesit-available-p))
    (add-to-list 'major-mode-remap-alist '(python-mode . python-ts-mode)))

  :config
  ;; Ensure tree-sitter grammar is installed
  (defun fu-python-ensure-treesit-grammar ()
    "Ensure Python tree-sitter grammar is installed."
    (when (and (fboundp 'treesit-available-p)
               (treesit-available-p)
               (not (treesit-language-available-p 'python)))
      (message "Python tree-sitter grammar not found. Install with M-x treesit-install-language-grammar RET python RET")))

  (add-hook 'after-init-hook #'fu-python-ensure-treesit-grammar)

  ;; Common settings for both python-mode and python-ts-mode
  (defun fu-python-common-setup ()
    "Common setup for Python modes."
    (setq-local tab-width 4)
    (setq-local indent-tabs-mode nil)
    ;; Remove trailing whitespace on save
    (add-hook 'before-save-hook #'delete-trailing-whitespace nil t))

  (add-hook 'python-mode-hook #'fu-python-common-setup)
  (add-hook 'python-ts-mode-hook #'fu-python-common-setup))

;; Virtual environment management
(use-package pyvenv
  :defer t
  :config
  (setq pyvenv-mode-line-indicator '(pyvenv-virtual-env-name ("[venv:" pyvenv-virtual-env-name "] ")))

  ;; Automatically activate virtual environment
  (defun fu-python-auto-activate-venv ()
    "Automatically activate Python virtual environment if found.
Looks for .venv, venv, env directories or .python-version file."
    (interactive)
    (let* ((project-root (or (locate-dominating-file default-directory ".venv")
                             (locate-dominating-file default-directory "venv")
                             (locate-dominating-file default-directory "env")
                             (locate-dominating-file default-directory ".python-version")))
           (venv-path (when project-root
                        (or (expand-file-name ".venv" project-root)
                            (expand-file-name "venv" project-root)
                            (expand-file-name "env" project-root)))))
      (when (and venv-path (file-directory-p venv-path))
        (pyvenv-activate venv-path)
        (message "Activated virtual environment: %s" venv-path))))

  (add-hook 'python-mode-hook #'fu-python-auto-activate-venv)
  (add-hook 'python-ts-mode-hook #'fu-python-auto-activate-venv))

;; Python formatting with Black
(use-package python-black
  :defer t
  :commands (python-black-buffer python-black-region python-black-on-save-mode)
  :hook ((python-mode python-ts-mode) . python-black-on-save-mode-enable-dwim)
  :config
  (defun python-black-on-save-mode-enable-dwim ()
    "Enable python-black-on-save-mode if black is available."
    (when (executable-find "black")
      (python-black-on-save-mode 1))))

;; Import sorting with isort
(use-package py-isort
  :defer t
  :commands (py-isort-buffer py-isort-region)
  :hook (before-save . fu-python-isort-before-save)
  :config
  (defun fu-python-isort-before-save ()
    "Run isort before saving if in python-mode or python-ts-mode and isort is available."
    (when (and (derived-mode-p 'python-mode 'python-ts-mode)
               (executable-find "isort"))
      (py-isort-buffer))))

;; Python REPL enhancements
(use-package python
  :ensure nil
  :config
  ;; Send region/buffer to Python REPL
  (defun fu-python-shell-send-region-or-buffer ()
    "Send the current region to Python REPL, or whole buffer if no region is active."
    (interactive)
    (if (use-region-p)
        (python-shell-send-region (region-beginning) (region-end))
      (python-shell-send-buffer)))

  (defun fu-python-shell-send-defun-and-step ()
    "Send the current function to Python REPL and move to next function."
    (interactive)
    (python-shell-send-defun nil)
    (python-nav-forward-defun))

  :bind ((:map python-mode-map
               ("C-c C-c" . fu-python-shell-send-region-or-buffer)
               ("C-c C-n" . fu-python-shell-send-defun-and-step)
               ("C-c C-r" . python-shell-send-region)
               ("C-c C-b" . python-shell-send-buffer)
               ("C-c C-z" . python-shell-switch-to-shell))
         (:map python-ts-mode-map
               ("C-c C-c" . fu-python-shell-send-region-or-buffer)
               ("C-c C-n" . fu-python-shell-send-defun-and-step)
               ("C-c C-r" . python-shell-send-region)
               ("C-c C-b" . python-shell-send-buffer)
               ("C-c C-z" . python-shell-switch-to-shell))))

;; Python debugger (pdb) integration
(use-package realgud
  :defer t
  :commands (realgud:pdb))

;; Optional: IPython integration
;; Uncomment if you prefer IPython over standard Python REPL
;; (use-package python
;;   :config
;;   (when (executable-find "ipython")
;;     (setq python-shell-interpreter "ipython"
;;           python-shell-interpreter-args "-i --simple-prompt --no-color-info"
;;           python-shell-prompt-regexp "In \\[[0-9]+\\]: "
;;           python-shell-prompt-output-regexp "Out\\[[0-9]+\\]: "
;;           python-shell-completion-setup-code
;;           "from IPython.core.completerlib import module_completion"
;;           python-shell-completion-module-string-code
;;           "';'.join(module_completion('''%s'''))\n"
;;           python-shell-completion-string-code
;;           "';'.join(get_ipython().Completer.all_completions('''%s'''))\n")))

;; LSP configuration with Eglot
(with-eval-after-load 'eglot
  ;; Prefer pyright over pylsp if available
  (when (executable-find "pyright-langserver")
    (add-to-list 'eglot-server-programs
                 '(python-mode . ("pyright-langserver" "--stdio"))))

  ;; Enable eglot for Python
  (add-hook 'python-mode-hook #'eglot-ensure)
  (add-hook 'python-ts-mode-hook #'eglot-ensure))

;; Flycheck for additional linting (optional, alongside Flymake)
;; (use-package flycheck
;;   :hook (python-mode . flycheck-mode)
;;   :config
;;   (setq flycheck-python-flake8-executable "python3"
;;         flycheck-python-pycompile-executable "python3"
;;         flycheck-python-pylint-executable "python3"))

;; Jupyter notebook support (optional)
;; (use-package ein
;;   :defer t
;;   :commands (ein:run ein:login))

(provide 'prog-python-conf)
;;; prog-python-conf.el ends here