;;; llm-chat-gemini.el --- Implements gemini llm intergration -*- lexical-binding: t; -*-

;; This file is not part of GNU Emacs.

;;; License:

;; llm-chat-gemini.el 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 3 of the License, or
;; (at your option) any later version.

;; llm-chat-gemini.el 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 this program.  If not, see <https://www.gnu.org/licenses/>.

;;; Code:

(require 'llm-chat-api)

(defvar llm-chat-gemini-models '("gemini-2.5-flash-preview-04-17" "gemini-2.5-pro-preview-03-25" "gemini-2.0-flash-lite" "gemini-1.5-flash" "gemini-1.5-flash-8b" "gemini-1.5-pro"))

(cl-defgeneric llm-chat-resolve-model-backend ((backend (eql 'gemini))
					       model)
  (if (member model llm-chat-gemini-models)
      t))

(defun llm-chat-gemini-get-model ()
  (if (member (llm-chat-get-model) llm-chat-gemini-models)
      (llm-chat-get-model)
    "gemini-2.0-flash-lite"))

(defun llm-chat-gemini-convert-history-contents ()
  (let ((contents '()))
	(dolist (history (llm-chat-get-history))
	  (let ((role (cdr (car history)))
		(text (cdr (car (cdr history)))))

	    (cond ((or (string= role "user") (string= role "system"))
		  (setq contents (append contents `((role . "user")
				      (parts . (((text . ,text))))))))
		  ((string= role "assistant")
		   (setq contents (append contents `((role . "model")
				      (parts . (((text . ,text)))))))))))
	contents))

(defun llm-chat-gemini-json ()
  (let ((json-object `((contents . (,(llm-chat-gemini-convert-history-contents)))
		       (generation_config . ((temperature . ,(llm-chat-get-temperature)))))))
    (json-encode json-object)))

(defun llm-chat-gemini-headers (backend)
  ())

(defun llm-chat-make-gemini-backend ()
  (make-llm-chat-backend
   :api-endpoint (concat "https://generativelanguage.googleapis.com/v1beta/models/"
			 (llm-chat-gemini-get-model)
			 ":streamGenerateContent?key="
			 (auth-source-pick-first-password :host "api.gemini.com"))
   :api-key (auth-source-pick-first-password :host "api.gemini.com")
   :headers-fn #'llm-chat-gemini-headers
   :json-fn #'llm-chat-gemini-json
   :filter-fn #'llm-chat-gemini-filter))

(defun llm-chat-gemini-filter (proc string)
  "Buffer incomplete JSON until a complete object is received, then parse."
  (setq llm-chat--incomplete (concat llm-chat--incomplete string))
  ;; Try to find a complete JSON object (simple heuristic: first { to last })
  (write-region string nil "/tmp/stream.txt" t)
  (when (and (string-match "{" llm-chat--incomplete)
	     (string-match "}[[:space:]]*\\'" llm-chat--incomplete))
    (let ((json-str (substring llm-chat--incomplete
			       (string-match "{" llm-chat--incomplete))))
      (condition-case err
	  (let* ((json-object (json-read-from-string json-str))
		 (candidates (alist-get 'candidates json-object))
		 (first-candidate (if (vectorp candidates) (aref candidates 0) nil))
		 (content (when first-candidate
			    (alist-get 'content first-candidate)))
		 (parts (when content (alist-get 'parts content)))
		 (text-part (when (and parts (vectorp parts) (> (length parts) 0))
			      (alist-get 'text (aref parts 0))))
		 (finish-reason (when first-candidate
				  (alist-get 'finishReason first-candidate))))
	    (with-current-buffer (get-buffer-create "*LLM Chat*")
	      (save-excursion
		(goto-char (point-max))
		(when text-part
		  (if (not (llm-chat-get-buffer))
		      (progn
			(if (not (bolp)) (insert "\n"))
			(insert "(AI): ")))
		  (insert text-part)
		  (llm-chat-set-buffer (concat (or (llm-chat-get-buffer) "") text-part)))
		(when (and finish-reason (string= finish-reason "STOP"))
		  (if (not (bolp)) (insert "\n"))
		  (insert "(USR):")
		  (llm-chat-add-assistant-history (llm-chat-get-buffer))
		  (llm-chat-set-buffer nil)))))
	(error
	 (message "Gemini filter: JSON parsing error: %s" (error-message-string err)))))
    (setq llm-chat--incomplete "")))

;; (defun llm-chat-gemini-filter (proc string)
;;   "Filter function to handle Gemini API JSON responses."
;;   (with-current-buffer (get-buffer-create "*LLM Chat*")
;;     (save-excursion
;;       (goto-char (point-max))
;;       (write-region (concat "start-----" string "-----end\n") nil "/tmp/stream.txt" t 'append)
;;       ;; Try to extract JSON from the received string
;;       (when-let* ((start-pos (string-match "{" string))
;;		  (json-string (substring string start-pos)))
;;	(condition-case err
;;	    (let* ((json-object (json-read-from-string json-string))
;;		   (candidates (alist-get 'candidates json-object))
;;		   (first-candidate (if (vectorp candidates) (aref candidates 0) nil))
;;		   (content (when first-candidate
;;			      (alist-get 'content first-candidate)))
;;		   (parts (when content (alist-get 'parts content)))
;;		   (text-part (when (and parts (vectorp parts))
;;				(alist-get 'text (aref parts 0))))
;;		   (finish-reason (when first-candidate
;;				    (alist-get 'finishReason first-candidate))))

;;	      (when text-part
;;		(if (not (llm-chat-get-buffer))
;;		    (progn
;;		      (if (not (bolp))
;;			  (insert "\n"))
;;		      (insert "(AI): ")))
;;		(insert text-part)
;;		(llm-chat-set-buffer (concat (or (llm-chat-get-buffer) "") text-part)))

;;	      (when (and finish-reason (string= finish-reason "STOP"))
;;		(if (not (bolp))
;;		    (insert "\n"))
;;		(insert "(USR):")
;;		(llm-chat-add-assistant-history (llm-chat-get-buffer))
;;		(llm-chat-set-buffer nil))))))))

(defun llm-chat-gemini-print-content (string)
  (let* ((json-object (json-read-from-string string))
	 (candidates (alist-get 'candidates json-object))
	 (first-candidate (aref candidates 0)))
    (when-let* ((content (alist-get 'content first-candidate))
		(parts (alist-get 'parts content))
		(first-part (aref parts 0))
		(text (alist-get 'text first-part)))
      text)))

(provide 'llm-chat-gemini)

;;; llm-chat-gemini.el ends here