(define-module (web view markdown)
  #:use-module (json)
  #:use-module (ice-9 match)
  #:use-module (ice-9 format)
  #:use-module (ice-9 iconv)
  #:use-module (ice-9 receive)
  #:use-module (ice-9 string-fun)
  #:use-module (ice-9 textual-ports)
  #:use-module (ice-9 exceptions)
  #:use-module (ice-9 popen)
  #:use-module (ice-9 rdelim)
  #:use-module (sxml simple)
  #:use-module (web client)
  #:use-module (web uri)
  #:use-module (web request)
  #:use-module (web sxml)
  #:use-module (commonmark)

  #:export (markdown-file->sxml
            markdown-github->sxml
            fetch-file
            fetch-raw-file
            commit-file
            is-repo?))

(define (markdown-file->sxml fn)
  "Parse a local file"
  (commonmark->sxml
   (call-with-input-file fn
     get-string-all)))

(define (fetch-raw-file url)
  (receive (response-status response-body)
      (http-request url)
    response-body))

;; https://github.com/genenetwork/gn-docs/master/general/brand/aging/home.md
;; https://raw.githubusercontent.com/genenetwork/gn-docs/master/general/brand/aging/home.md
;; https://github.com/genenetwork/gn-docs/edit/master/general/brand/aging/home.md

(define (form-github-raw-url project repo page)
  (string-append "https://raw.githubusercontent.com/" project "/" repo "/master/" (string-join page "/")))

(define (form-github-edit-url project repo page)
  (string-append "https://github.com/" project "/" repo "/edit/master/" (string-join page "/")))

(define (markdown-github->sxml path)
  "Parse a github markdown file that is formed like genenetwork/gn-docs/general/brand/aging/home.md"
  (match-let (((project repo page ...) (string-split path #\/)))
    `(div (@ (class "markdown"))
          ,(commonmark->sxml
            (fetch-raw-file (pk (form-github-raw-url project repo (pk page)))))
          (p
           (div (@ (class "button-align-right"))
                (a (@ (href ,(form-github-edit-url project repo page)) (role "button")) "edit")))
          (br)
          (br))))

(define (fetch-file repo query_path)
  (let* ( (abs_path (string-append repo "/" query_path)))
    (if (file-exists? abs_path)  (let* ((full_path (canonicalize-path abs_path))
                                        (content (call-with-input-file full_path get-string-all))
                                        (commit-sha (get-latest-commit-sha1 repo)))
                                   `(("file_path" . ,query_path)
                                     ("content" . ,content)
                                     ("hash" . ,commit-sha))
                                   ) (throw 'file-error  (string-append "the file path " abs_path " does not exists")))))

(define (git-invoke repo-path . args)
  (apply system* "git" "-C" repo-path args))

(define (is-repo? repo-path)
  (let ((data (git-invoke repo-path  "rev-parse")))
    (zero? data)))

(define (get-latest-commit-sha1 repo-path)
  (let* ((output-port (open-input-pipe (string-append "git -C " repo-path " log -n 1 --pretty=format:%H HEAD")))
         (commit-sha (read-line output-port)))
    (close-port output-port)
    commit-sha))

(define* (commit-file repo file-path content commit-message username email #:optional (prev-commit ""))
  (if (string=? prev-commit (get-latest-commit-sha1 repo))
      #t
      (throw 'system-error (format #f "Commits do no match.Please pull in latest  changes for current * ~a * and prev * ~a * "
                                   (get-latest-commit-sha1 repo) prev-commit)))
  (if (is-repo? repo)
      (match (file-exists? (string-append repo "/" file-path))
        (#t
         (with-output-to-file (string-append repo "/" file-path)
           (lambda ()
             (display content)))
         (let* ((git-add-file (git-invoke repo "add" file-path))
                (git-commit-file
                 (git-invoke repo "commit"
                             "-m" commit-message
                             "-m" " * Commit made via the GN Markdown Editor"
                             "--author" (format  #f "~a <~a>" username  email)))
                (git-commit-sha (get-latest-commit-sha1 repo)))
           (if (zero? git-commit-file)
               `(("status" . "201") ("message" . "committed file successfully") ("content" . ,content) ("commit_sha" . ,git-commit-sha) ("commit_message" . ,commit-message) )
               `(("status" . "200") ("message" . "Nothing to commit, working tree clean") ("commit_sha" . ,git-commit-sha)))))
        (#f
         (throw 'system-error (string-append file-path  " File does not exist Error"))))
      (throw 'system-error (string-append repo " Is not a git repo."))))