;;; llm-common.scm - Shared utilities for LLM providers
;;;
;;; BSD-3-Clause License
;;; Copyright (c) 2025, Rolando Abarca

(module llm-common

(detect-mime-type
 image-mime-type?
 pdf-mime-type?
 vision-mime-type?
 read-file-base64
 read-text-file
 kebab->snake)

(import
 scheme
 chicken.base
 chicken.string
 chicken.pathname
 chicken.io
 srfi-13  ;; strings
 base64)  ;; base64 encoding

;;; ================================================================
;;; File Handling Helpers
;;; ================================================================

;; Detect MIME type from file path extension
(define (detect-mime-type path)
  (let* ((pn (make-pathname #f path))
         (ext (pathname-extension pn)))
    (cond
     ((not ext) "application/octet-stream")
     ((member ext '("jpg" "jpeg")) "image/jpeg")
     ((equal? ext "png") "image/png")
     ((equal? ext "gif") "image/gif")
     ((equal? ext "webp") "image/webp")
     ((equal? ext "pdf") "application/pdf")
     ((member ext '("txt" "md" "scm" "lisp" "c" "h" "js" "py" "rb")) "text/plain")
     (else "application/octet-stream"))))

;; Check if MIME type is an image
(define (image-mime-type? mime)
  (string-prefix? "image/" mime))

;; Check if MIME type is PDF
(define (pdf-mime-type? mime)
  (equal? mime "application/pdf"))

;; Check if MIME type is vision-compatible (images + PDFs)
;; Vision-capable models can read both via image_url content type
(define (vision-mime-type? mime)
  (or (image-mime-type? mime)
      (pdf-mime-type? mime)))

;; Read file as binary and encode to base64
(define (read-file-base64 path)
  (call-with-input-file path
    (lambda (port)
      (let* ((contents (read-string #f port))
             (encoded (base64-encode contents)))
        encoded))
    #:binary))

;; Read text file content
(define (read-text-file path)
  (call-with-input-file path
    (lambda (port)
      (read-string #f port))))

;;; ================================================================
;;; String Utilities
;;; ================================================================

;; Helper: Convert kebab-case symbol to snake_case symbol
;; 'get-current-time -> 'get_current_time
(define (kebab->snake sym)
  (string->symbol
   (string-translate (symbol->string sym) #\- #\_)))

) ;; end module