#+TITLE: Ghub User and Developer Manual
:PREAMBLE:
#+AUTHOR: Jonas Bernoulli
#+EMAIL: jonas@bernoul.li
#+DATE: 2017-2021
#+LANGUAGE: en

#+TEXINFO_DIR_CATEGORY: Emacs
#+TEXINFO_DIR_TITLE: Ghub: (ghub).
#+TEXINFO_DIR_DESC: Minuscule client library for the Github API.
#+SUBTITLE: for version 3.5.3 (v3.5.3-4-g39f9a5b+1)

#+TEXINFO_DEFFN: t
#+OPTIONS: H:4 num:4 toc:2
#+PROPERTY: header-args :eval never
#+BIND: ox-texinfo+-before-export-hook ox-texinfo+-update-copyright-years
#+BIND: ox-texinfo+-before-export-hook ox-texinfo+-update-version-strings

Ghub is an Emacs library that is used by various packages to access
the APIs of various instances of various Git forge implementations.

#+TEXINFO: @noindent
This manual is for Ghub version 3.5.3 (v3.5.3-4-g39f9a5b+1).

#+BEGIN_QUOTE
Copyright (C) 2017-2021 Jonas Bernoulli <jonas@bernoul.li>

You can redistribute this document 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.

This document 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.
#+END_QUOTE
:END:
* Introduction

Ghub is an Emacs library that is used by various packages to access
the APIs of various instances of various Git forge implementations.

A forge is a web-based collaborative software platform for developing
and distributing computer applications.  Examples include Github and
Gitlab.

* Getting Started
** _ :ignore:

This manual guides you through the steps that are necessary to use the
Forge package and/or to make a request using just Ghub itself, such as
this:

#+BEGIN_SRC emacs-lisp
 (ghub-request "GET" "/user")
#+END_SRC

To be able to do that, Ghub needs to know who you want to talk to, who
you are, and how you are going to prove the latter to the former.

Additionally Ghub wants to know on behalf of which Emacs package it is
making a request.  So the question of "who is making the request" has
to be rephrased as "which human (or bot) is using what (Emacs) package
to make the request".  If for example, the human known as "tarsius" is
using the ~forge~ package, then that is represented in some places using
the string "tarsius^forge".

This package used to attempt to get the answers to these questions
using a setup wizard.  Unfortunately that had to be removed because
(a) it only ever supported Github, (b) Github is about to remove
support for that on their end, (c) it did not always work, and (d)
when it couldn't be used, or failed, then it made things /more/
complicated.

So now it is necessary for users to read some documentation and
because many things can go wrong, those instructions have to be fairly
detailed.  You can of course skip over most of this, but if things go
wrong, then I would like to kindly request that you take another
look before asking me for help.

** Basic Concepts, Arguments and Variables

Originally Ghub supported only Github but now it also supports Gitlab,
Gitea, Gogs and Bitbucket.  For the historic reason just given, the
function ~ghub-request~ defaults to acting on a ~github~ forge, but can
be told to act on another forge using the FORGE argument.

The FORGE argument only specifies what kind of forge to act on, not
which instance.  The HOST argument can be used to select the instance.
For some forges a default instance is defined:

- Forge ~github~ defaults to host ~api.github.com~.
- Forge ~gitlab~ defaults to host ~gitlab.com/api/v4~.
- Forge ~bitbucket~ defaults to host ~api.bitbucket.org/2.0~.
- No canonical host exists for the ~gitea~ and ~gogs~ forges and
  ~localhost:3000/api/v1~ is used as the default host in both cases.

Together the FORGE and HOST arguments specify the forge type and
instance.  In addition to that, it is also necessary to specify on
whose behalf the request is being made, which can be done using the
USERNAME and AUTH arguments.  For example:

#+BEGIN_SRC emacs-lisp
  (ghub-request "GET" "/user" nil
                :forge 'github
                :host "api.github.com"
                :username "tarsius"
                :auth 'forge)
#+END_SRC

Having to specify these arguments for every request is inconvenient.
Additional variables and convenience functions can be used to make
that unnecessary in most cases.

(But for debugging purposes the above explicit form is very useful.
You will obviously have to change the value of USERNAME and you should
use ~ghub~ as AUTH when first trying this at home.)

These variables can be set globally and/or for a specific repository.

- For "api.github.com" (aka the API of https://github.com) the Git
  variable ~github.user~ specifies the user.
- For another ~github~ instance the Git variable ~github.HOST.user~
  specifies the user.  The HOST in that variable name is the same
  as the value of the HOST argument of the called function.
- Instead of specifying the HOST in every function call, the Git
  variable ~github.host~ can be used.  This should only be set locally.

These ~github~ specific variables are discussed in more detail in
[[*Github Configuration Variables]].

#+TEXINFO: @noindent
For ~gitlab~ and ~bitbucket~ forges similar variables are available:

- ~gitlab.user~ specifies the https://gitlab.com user.
- ~gitlab.HOST.user~ specifies the user for the HOST ~gitlab~ instance.
- ~gitlab.host~ specifies the ~gitlab~ host, unless the HOST argument
  is non-nil
- ~bitbucket.user~ specifies the https://bitbucket.org user.
- ~bitbucket.HOST.user~ specifies the user for the HOST ~bitbucket~
  instance.
- ~bitbucket.host~ specifies the ~bitbucket~ host, unless the HOST
  argument is non-nil.

For the ~gitea~ and ~gogs~ forges some similar variables are available,
however for some of the ~ghub.*~ variables no equivalent variable exist
for these two forges:

- ~gitea.user~ is *not* used because no canonical ~gitea~ instance exists.
- ~gitea.HOST.user~ specifies the user for the HOST ~gitea~ instance.
- ~gitea.host~ specifies the ~gitea~ host, unless the HOST argument is
  non-nil
- ~gogs.user~ is *not* used because no canonical ~gogs~ instance exists.
- ~gogs.HOST.user~ specifies the user for the HOST ~gogs~ instance.
- ~gogs.host~ specifies the ~gogs~ host, unless the HOST argument is
  non-nil

** Setting the Username
*** _ :ignore:

Ghub needs to know your username that you use on the host that you
want it to connect to.  For each host a different Git variable has to
be set to specify the username on that host.  More than one variable
is needed because you might use different usernames on different
hosts.

*** Setting your Github.com Username
:PROPERTIES:
:UNNUMBERED: notoc
:END:

To inform Ghub about your "github.com" username do this:

#+BEGIN_SRC shell
  git config --global github.user USERNAME
#+END_SRC

If you need to identify as another user in a particular repository,
then you have to set that variable locally:

#+BEGIN_SRC shell
  cd /path/to/repo
  git config --local github.user USERNAME
#+END_SRC

*** Setting your Gitlab.com Username
:PROPERTIES:
:UNNUMBERED: notoc
:END:

To inform Ghub about your "gitlab.com" username do this:

#+BEGIN_SRC shell
  git config --global gitlab.user USERNAME
#+END_SRC

If you need to identify as another user in a particular repository,
then you have to set that variable locally:

#+BEGIN_SRC shell
  cd /path/to/repo
  git config --local gitlab.user USERNAME
#+END_SRC

Make sure you use the correct USERNAME for this forge/host.  It might
not be the same as on "github.com"!

*** Setting your Github Enterprise Username
:PROPERTIES:
:UNNUMBERED: notoc
:END:

For Github Enterprise instances you have to specify where the API
can be accessed and a different variable has to be used to set the
username.

For example if the API is available at ~https://example.com/api/v3~,
then you should do this:

#+BEGIN_SRC shell
  git config --global github.example.com/api/v3.user USERNAME
#+END_SRC

Make sure you use the correct USERNAME for this instance.  It might
not be the same as on "github.com"!

Doing this only tells Ghub who you are on this host, additionally you
have to tell Ghub which repository are connected to that forge/host,
like so:

#+BEGIN_SRC shell
  cd /path/to/repo
  git config --local github.host example.com/api/v3
#+END_SRC

*** Setting your Username for Other Hosts and/or Forges
:PROPERTIES:
:UNNUMBERED: notoc
:END:

To inform Ghub about your username on HOST (a FORGE instance) do this:

#+BEGIN_SRC shell
  git config --global FORGE.HOST.user USERNAME
#+END_SRC

FORGE can be one of ~bitbucket~, ~gitea~ or ~gogs~.  It can also be ~github~ or
~gitlab~; but if that is the case, then you should look at the preceding
sections instead, which discuss these cases specifically.

HOST identifies the instance.  This actually points at the top-level
endpoint of the API and may contain path components, e.g.:
~example.com/api~.

If you need to identify as another user in a particular repository,
then you have to set that variable locally:

#+BEGIN_SRC shell
  cd /path/to/repo
  git config --local FORGE.HOST.user USERNAME
#+END_SRC

** Creating and Storing a Token
*** Creating a Token

To create a token, use the web interface of the forge/host you want to
connect to.  Here is a list of pages to do this for certain popular
hosts:

- https://github.com/settings/tokens
- https://gitlab.com/-/profile/personal_access_tokens

For other forges we cannot provide a functioning URL because they
contain unknown values such as your name.  Just go to the general
settings page of the respective host and then go from there.

Except on ~gitea~ and ~gogs~ each token can be limited to certain
"scopes", i.e., it is possible to limit for which purposes any given
token can be used.

Before you create a token to be used for a certain package, you should
consult the documentation of that package, which in turn should tell
you which scopes are needed and why.  The Forge package for example
does so in [[info:forge#Token Creation]].

*** Storing a Token

Please also see [[info:auth]] for all the gory details about Auth-Source.

The variable ~auth-sources~ controls how and where Auth-Source keeps its
secrets.  The default value is a list of three files: ~("~/.authinfo"
"~/.authinfo.gpg" "~/.netrc")~, but to avoid confusion you should make
sure that only one of these files exists and then you should also
adjust the value of the variable to only ever use that file, for
example:

#+BEGIN_SRC emacs-lisp
  (setq auth-sources '("~/.authinfo"))
#+END_SRC

In ~~/.authinfo~ secrets are stored in plain text.  If you don't want
that, then you should use the encrypted ~~/.authinfo.gpg~ instead:

#+BEGIN_SRC emacs-lisp
  (setq auth-sources '("~/.authinfo.gpg"))
#+END_SRC

Auth-Source also supports storing secrets in various external
key-chains.  See info:auth for more information.

The default Auth-Source backends only support storing three values per
entry; the "machine", the "login" and the "password".  Because Ghub
uses separate tokens for each package, it has to squeeze four values
into those three slots, and it does that by using "USERNAME^PACKAGE"
as the "login".

Assuming your *Github* username is "ziggy", the package is named
"forge", and you want to access *Github.com* with the *token*
"012345abcdef...", an entry in one of the three mentioned files
would then look like this:

#+BEGIN_SRC example
  machine api.github.com login ziggy^forge password 012345abcdef...
#+END_SRC

Assuming your *Gitlab* username is "ziggy", the package is named
"forge", and you want to access *Gitlab.com* with the *token*
"012345abcdef...", an entry in one of the three mentioned files
would then look like this:

#+BEGIN_SRC example
  machine gitlab.com/api/v4 login ziggy^forge password 012345abcdef...
#+END_SRC

** Github Configuration Variables

The username and, unless you only use Github.com itself, the Github
Enterprise instance have to be configured using Git variables.  In
rare cases it might also be necessary to specify the identity of the
local machine, which is done using a lisp variable.

- Variable: github.user

  The Github.com username.  This should be set globally and if you
  have multiple Github.com user accounts, then you should set this
  locally only for those repositories that you want to access using
  the secondary identity.

- Variable: github.HOST.user

  This variable serves the same purpose as ~github.user~ but for the
  Github Enterprise instance identified by ~HOST~.

  The reason why separate variables are used is that this makes it
  possible to set both values globally instead of having to set one of
  the values locally in each and every repository that is connected to
  the Github Enterprise instance, not Github.com.

- Variable: github.host

  This variable should only be set locally for a repository and
  specifies the Github Enterprise edition that that repository is
  connected to.  You should not set this globally because then each
  and every repository becomes connected to the specified Github
  Enterprise instance, including those that should actually be
  connected to Github.com.

  When this is undefined, then "api.github.com" is used (defined in
  the constant ~ghub-default-host~, which you should never attempt to
  change.)

* API
** Their APIs

Of course this manual does not cover the APIs of all forges that it
supports, but for your convenience, here are the links to their API
manuals:

- Github:
  - https://developer.github.com/v4 (GraphQl)
  - https://developer.github.com/v3 (REST)
- Gitlab:
  - https://docs.gitlab.com/ee/api/README.html
- Gitea:
  - https://docs.gitea.io/en-us/api-usage
  - https://try.gitea.io/api/swagger
- Gogs:
  - https://github.com/gogs/go-gogs-client/wiki
- Bitbucket:
  - https://developer.atlassian.com/bitbucket/api/2/reference

** Making REST Requests

- Function: ghub-request method resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback url value error extra method*

  This function makes a request for ~RESOURCE~ using ~METHOD~.
  ~PARAMS~, ~QUERY~, ~PAYLOAD~ and/or ~HEADERS~ are alists holding
  additional request data.  The response body is returned and the
  response headers are stored in the variable ~ghub-response-headers~.

  - ~METHOD~ is the HTTP method, given as a string.
  - ~RESOURCE~ is the resource to access, given as a string beginning
    with a slash.

  - ~PARAMS~, ~QUERY~, ~PAYLOAD~ and ~HEADERS~ are alists and are used
    to specify request data.  All these arguments are alists that
    resemble the JSON expected and returned by the Github API.  The
    keys are symbols and the values stored in the ~cdr~ (not the
    ~cadr~) can be strings, integers, or lists of strings and
    integers.

    The Github API documentation is vague on how data has to be
    transmitted and for a particular resource usually just talks about
    "parameters".  Generally speaking when the ~METHOD~ is "HEAD" or
    "GET", then they have to be transmitted as a query, otherwise as a
    payload.

    - Use ~PARAMS~ to automatically transmit like ~QUERY~ or ~PAYLOAD~
      would depending on ~METHOD~.
    - Use ~QUERY~ to explicitly transmit data as a query.
    - Use ~PAYLOAD~ to explicitly transmit data as a payload.  Instead
      of an alist, ~PAYLOAD~ may also be a string, in which case it
      gets encoded as UTF-8 but is otherwise transmitted as-is.
    - Use ~HEADERS~ for those rare resources that require that the
      data is transmitted as headers instead of as a query or payload.
      When that is the case, then the Github API documentation usually
      mentions it explicitly.

  - If ~SILENT~ is non-nil, then progress reports and the like are not
    messaged.

  - If ~UNPAGINATE~ is t, then this function makes as many requests as
    necessary to get all values.  If ~UNPAGINATE~ is a natural number,
    then it gets at most that many pages.  For any other non-nil value
    it raises an error.

  - If ~NOERROR~ is non-nil, then no error is raised if the request
    fails and ~nil~ is returned instead.  If ~NOERROR~ is ~return~,
    then the error payload is returned instead of ~nil~.

  - If ~READER~ is non-nil, then it is used to read and return from
    the response buffer.  The default is ~ghub--read-json-payload~.
    For the very few resources that do not return JSON, you might want
    to use ~ghub--decode-payload~.

  - If ~USERNAME~ is non-nil, then the request is made on behalf of
    that user.  It is better to specify the user using the Git
    variable ~github.user~ for "api.github.com", or ~github.HOST.user~
    if connecting to a Github Enterprise instance.

  - Each package that uses Ghub should use its own token.  If ~AUTH~
    is ~nil~ or unspecified, then the generic ~ghub~ token is used
    instead.  This is only acceptable for personal utilities.  A
    package that is distributed to other users should always use this
    argument to identify itself, using a symbol matching its name.

    Package authors who find this inconvenient should write a wrapper
    around this function and possibly for the method-specific
    functions as well.

    Beside ~nil~, some other symbols have a special meaning too.
    ~none~ means to make an unauthorized request.  ~basic~ means to
    make a password based request.  If the value is a string, then it
    is assumed to be a valid token.  ~basic~ and an explicit token
    string are only intended for internal and debugging uses.

    If ~AUTH~ is a package symbol, then the scopes are specified using
    the variable ~AUTH-github-token-scopes~.  It is an error if that
    is not specified.  See ~ghub-github-token-scopes~ for an example.

  - If ~HOST~ is non-nil, then connect to that Github instance.
    This defaults to "api.github.com".  When a repository is connected
    to a Github Enterprise instance, then it is better to specify that
    using the Git variable ~github.host~ instead of using this
    argument.

  - If ~FORGE~ is ~gitlab~, then connect to Gitlab.com or, depending
    on ~HOST~, to another Gitlab instance.  This is only intended for
    internal use.  Instead of using this argument you should use
    function ~glab-request~ and other ~glab-*~ functions.

  - If ~CALLBACK~ and/or ~ERRORBACK~ is non-nil, then this function makes
    one or more asynchronous requests and calls ~CALLBACK~ or ~ERRORBACK~
    when finished.  If no error occurred, then it calls ~CALLBACK~,
    unless that is ~nil~.

    If an error occurred, then it calls ~ERRORBACK~, or if that is nil,
    then ~CALLBACK~.  ~ERRORBACK~ can also be ~t~, in which case it signals
    instead.  ~NOERROR~ is ignored for all asynchronous requests.

    Both callbacks are called with four arguments.

    1. For ~CALLBACK~, the combined value of the retrieved pages.
       For ~ERRORBACK~, the error that occurred when retrieving the
       last page.
    2. The headers of the last page as an alist.
    3. Status information provided by ~url-retrieve~.  Its ~:error~
       property holds the same information as the first argument to
       ~ERRORBACK~.
    4. A ~ghub--req~ struct, which can be passed to ~ghub-continue~
       (which see) to retrieve the next page, if any.

- Function: ghub-continue args

  If there is a next page, then this function retrieves that.

  This function is only intended to be called from callbacks.  If
  there is a next page, then that is retrieved and the buffer that
  the result will be loaded into is returned, or t if the process
  has already completed.  If there is no next page, then return nil.

  Callbacks are called with four arguments (see ~ghub-request~).
  The forth argument is a ~ghub--req~ struct, intended to be passed
  to this function.  A callback may use the struct's ~extra~ slot
  to pass additional information to the callback that will be called
  after the next request.  Use the function ~ghub-req-extra~ to get
  and set the value of that slot.

  As an example, using ~ghub-continue~ in a callback like so:

  #+BEGIN_SRC emacs-lisp
    (ghub-get "/users/tarsius/repos" nil
              :callback (lambda (value _headers _status req)
                          (unless (ghub-continue req)
                            (setq my-value value))))
  #+END_SRC

  is equivalent to:

  #+BEGIN_SRC emacs-lisp
    (ghub-get "/users/tarsius/repos" nil
              :unpaginate t
              :callback (lambda (value _headers _status _req)
                          (setq my-value value)))
  #+END_SRC

  To demonstrate how to pass information from one callback to the
  next, here we record when we start fetching each page:

  #+BEGIN_SRC emacs-lisp
    (ghub-get "/users/tarsius/repos" nil
              :extra (list (current-time))
              :callback (lambda (value _headers _status req)
                          (push (current-time) (ghub-req-extra req))
                          (unless (ghub-continue req)
                            (setq my-times (ghub-req-extra req))
                            (setq my-value value))))
  #+END_SRC

- Variable: ghub-response-headers

  A select few Github API resources respond by transmitting data in
  the response header instead of in the response body.  Because there
  are so few of these inconsistencies, ~ghub-request~ always returns
  the response body.

  To access the response headers use this variable after ~ghub-request~
  has returned.

- Function: ghub-response-link-relations req headers payload

  This function returns an alist of the link relations in ~HEADERS~, or
  if optional ~HEADERS~ is nil, then those in ~ghub-response-headers~.

  When accessing a Bitbucket instance then the link relations are in
  ~PAYLOAD~ instead of ~HEADERS~, making their API merely RESTish and
  forcing this function to append those relations to the value of
  ~ghub-response-headers~, for later use when this function is called
  with ~nil~ for ~PAYLOAD~.

** Making GraphQL Requests

- Function: ghub-graphql graphql &optional variables &key username auth host callback silent callback errorback value extra

  This function makes a GraphQL request using ~GRAPHQL~ and
  ~VARIABLES~ as inputs.  ~GRAPHQL~ is a GraphQL string.  ~VARIABLES~
  is a JSON-like alist.  The other arguments behave as for
  ~ghub-request~ (which see).

  The response is returned as a JSON-like alist.  Even if the response
  contains ~errors~, this function does not raise an error.
  Cursor-handling is likewise left to the caller.

~ghub-graphql~ is a thin convenience wrapper around ~ghub-request~,
similar to ~ghub-post~ and friends.  While the latter only hard-code
the value of the ~METHOD~ argument, the former also hard-codes ~RESOURCE~
and constructs ~PAYLOAD~ from ~GRAPHQL~ and ~VARIABLES~.  It also drops
~UNPAGINATE~, ~NOERROR~, ~READER~ (internal functions expect alist-ified
JSON) and ~FORGE~ (only Github currently supports GraphQL).

~ghub-graphql~ does not account for the fact that pagination works
differently in GraphQL than it does in REST, so users of this function
have to deal with that themselves.  Likewise error handling works
differently and has to be done by the caller too.

An early attempt at implementing automatic unpaginating for GraphQL
can be found in the ~faithful-graphql~ branch, provided I haven't
deleted that by now.  On that branch I try to do things as intended by
the designers of GraphQL, using variables and fragments, and drowning
in a sea of boilerplate.

The problem with that approach is that it only works for applications
that fetch specific information on demand and actually want things to
be paginated.  I am convinced that GraphQL is very nice for web apps.

However the Forge package for which I have implemented all of this has
very different needs.  It wants to fetch "all the data" and "cache"
it locally, so that it is available even when there is no internet
connection.  GraphQL was designed around the idea that you should be
able to "ask for what you need and get exactly that".  But when that
boils down to "look, if I persist, then you are going to hand me over
all the data anyway, so just caught it up already", then things start
to fall apart.  If Github's GraphQL allowed pagination to be turned
off completely, then teaching ~ghub-graphql~ about error handling would
be enough.

But it doesn't and when doing things as intended, then that leads to
huge amounts of repetitive boilerplate, which is so boring to write
that doing it without introducing bugs left and right is near
impossible; so I decided to give up on GraphQL variables, fragments
and conditions, and instead implement something more powerful, though
also more opinionated.

- Function: ghub--graphql-vacuum query variables callback &optional until &key narrow username auth host forge

  This function is an opinionated alternative to ~ghub-graphql~.
  It relies on dark magic to get the job done.

  It makes an initial request using ~QUERY~.  It then looks for
  paginated edges in the returned data and makes more requests to
  resolve them.  In order to do so it automatically transforms the
  initial ~QUERY~ into another query suitable for that particular edge.
  The data retrieved by subsequent requests is then injected into the
  data of the original request before that is returned or passed to
  the callback.  If subsequently retrieved data features new paginated
  edges, then those are followed recursively.

  The end result is essentially the same as using ~ghub-graphql~, if
  only it were possible to say "do not paginate anything".  The
  implementation is much more complicated because it is not possible
  to do that.

  ~QUERY~ is a GraphQL query expressed as an s-expression.  The bundled
  ~gsexp~ library is used to turn that into a GraphQL query string.
  Only a subset of the GraphQL features are supported; fragments for
  example are not, and magical stuff happens to variables.  This is
  not documented yet, I am afraid.  Look at existing callers.

  ~VARIABLES~ is a JSON-like alist as for ~ghub-graphql~.

  ~UNTIL~ is an alist ~((EDGE-until . VALUE)...)~.  When unpaginating ~EDGE~
  try not to fetch beyond the element whose first field has the value
  ~VALUE~ and remove that element as well as all "lesser" elements from
  the retrieved data if necessary.  Look at ~forge--pull-repository~ for
  an example.  This is only useful if you "cache" the response locally
  and want to avoid fetching data again that you already have.

  Other arguments behave as for ~ghub-graphql~ and ~ghub-request~, more or
  less.

Using ~ghub--graphql-vacuum~, the following resource specific functions
are implemented.  These functions are not part of the public API yet
and are very much subject to change.

- Function: ghub-fetch-repository owner name callback &optional until &key username auth host forge

  This function asynchronously fetches forge data about the specified
  repository.  Once all data has been collected, ~CALLBACK~ is called
  with the data as the only argument.

- Function: ghub-fetch-issue owner name callback &optional until &key username auth host forge

  This function asynchronously fetches forge data about the specified
  issue.  Once all data has been collected, ~CALLBACK~ is called
  with the data as the only argument.

- Function: ghub-fetch-pullreq owner name callback &optional until &key username auth host forge

  This function asynchronously fetches forge data about the specified
  pull-request.  Once all data has been collected, ~CALLBACK~ is called
  with the data as the only argument.

Note that in order to avoid duplication all of these functions base
their initial query on the query stored in ~ghub-fetch-repository~.  The
latter two pass that query through ~ghub--graphql-prepare-query~, which
then uses ~ghub--graphql-narrow-query~ to remove parts the caller is not
interested in.  These two functions are also used internally, when
unpaginating, but as demonstrated here they can be useful even before
making an initial request.

** Github Convenience Wrappers

- Function: ghub-head resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: ghub-get resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback

  These functions are simple wrappers around ~ghub-request~.  Their
  signature is identical to that of the latter, except that they do
  not have an argument named ~METHOD~.  The HTTP method is instead
  given by the second word in the function name.

  As described in the documentation for ~ghub-request~, it depends on
  the used method whether the value of the ~PARAMS~ argument is used
  as the query or the payload.  For the "HEAD" and "GET" methods it
  is used as the query.

- Function: ghub-put resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: ghub-post resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: ghub-patch resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: ghub-delete resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback

  These functions are simple wrappers around ~ghub-request~.  Their
  signature is identical to that of the latter, except that they do
  not have an argument named ~METHOD~.  The HTTP method is instead
  given by the second word in the function name.

  As described in the documentation for ~ghub-request~, it depends on
  the used method whether the value of the ~PARAMS~ argument is used
  as the query or the payload.  For the "PUT", "POST", "PATCH" and
  "DELETE" methods it is used as the payload.

- Function: ghub-wait resource &optional duration &key username auth host

  Some API requests result in an immediate successful response even
  when the requested action has not actually been carried out yet.
  An example is the request for the creation of a new repository,
  which doesn't cause the repository to immediately become available.
  The Github API documentation usually mentions this when describing
  an affected resource.

  If you want to do something with some resource right after making
  a request for its creation, then you might have to wait for it to
  actually be created.  This function can be used to do so.  It
  repeatedly tries to access the resource until it becomes available
  or until a timeout is reached.  In the latter case it signals
  ~ghub-error~.

  ~RESOURCE~ specifies the resource that this function waits for.

  ~DURATION~ specifies the maximum number of seconds to wait for,
  defaulting to 64 seconds.  Emacs will block during that time, but
  the user can abort using ~C-g~.

  The first attempt is made immediately and will often succeed.  If
  not, then another attempt is made after two seconds, and each
  subsequent attempt is made after waiting as long as we already
  waited between all preceding attempts combined.

  See ~ghub-request~'s documentation above for information about the
  other arguments.
  
** Non-Github Convenience Wrappers

~ghub-request~ and ~ghub-METHOD~ can be used to make a request for any
of the supported forge types, but except when making a request for
a ~github~ instance, then that requires the use of the FORGE argument.

To avoid that, functions named ~FORGE-request~ and ~FORGE-METHOD~ are also
available.  The following forms are equivalent, for example:

#+BEGIN_SRC emacs-lisp
  (ghub-get ... :auth 'PACKAGE :forge 'gitlab)
  (glab-get ... :auth 'PACKAGE)
#+END_SRC

These forms would remain equivalent even if you did not specify a
value for the AUTH arguments — but you should not do that if you plan
to share your code with others (see [[*Using Ghub in Your Own Package]]).
If you do omit AUTH, then the request is made on behalf of the ~ghub~
package, *regardless* of the symbol prefix of the function you use to do
so.

All ~FORGE-request~ and ~FORGE-METHOD~ functions, including but not
limited to ~ghub-METHOD~, are very simple wrappers around ~ghub-request~.
They take fewer arguments than ~ghub-request~ and instead pass constant
values for the arguments METHOD and/or FORGE.

- Function: buck-request resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: glab-request resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gogs-request resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback

  Wrappers around ~ghub-request~ which hardcode the FORGE to either
  ~bitbucket~, ~gitlab~, ~gogs~ or ~gitea~.

- Function: buck-get resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: buck-put resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: buck-post resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: buck-delete resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: glab-head resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: glab-get resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: glab-put resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: glab-post resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: glab-patch resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: glab-delete resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gogs-get resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gogs-put resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gogs-post resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gogs-patch resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gogs-delete resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gtea-get resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gtea-put resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gtea-post resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gtea-patch resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback
- Function: gtea-delete resource &optional params &key query payload headers unpaginate noerror reader username auth host callback errorback

  Wrappers around ~FORGE-METHOD~ which hardcode the FORGE to either
  ~bitbucket~, ~gitlab~, ~gogs~ or ~gitea~, and the METHOD to the implied
  method.

  Note that ~buck-head~, ~buck-patch~, ~gogs-head~ and ~gtea-head~ do not exist
  because the respective APIs do not appear to support these methods.

* Notes
** Using Ghub in Personal Scripts

You can of course use ~ghub-request~ and its wrapper functions in your
personal scripts.  Unlike when you use Ghub in a package that you
distribute for others to use, you don't have to explicitly specify a
package in personal scripts.

#+BEGIN_SRC emacs-lisp
  ;; This is perfectly acceptable in personal scripts ...
  (ghub-get "/user")

  ;; ... and actually equals to
  (ghub-get "/user" nil :auth 'ghub)

  ;; In packages you have to specify the package using AUTH.
  (ghub-get "/user" nil :auth 'some-package)
#+END_SRC

When the ~AUTH~ argument is not specified, then a request is made on
behalf of the ~ghub~ package itself.  Like for any other package you
have to create a dedicated token of coures.

** Using Ghub in Your Own Package

Every package should use its own token.  This allows you as the author
of some package to only request access to API scopes that are actually
needed, which in turn might make it easier for users to trust your
package not to do unwanted things.

You have to tell ~ghub-request~ on behalf of which package a request is
being made by passing the symbol ~PACKAGE~ as the value of its ~AUTH~
argument.

#+BEGIN_SRC emacs-lisp
  (ghub-request "GET" "/user" nil :auth 'PACKAGE)
#+END_SRC

Keep in mind that the users of your package will have to manually
create a suitable token.  To make that easier, you should not only
link to this manual but also prominently mention the scopes the token
needs; and explain what they are needed for.

** Forge Limitations and Notes

- There are no default Gitea and Gogs instances so the variables
  ~gitea.host~ and ~gogs.host~ are not taken into account.

- Gitea and Gogs do not support limiting a token to certain scopes.

- The Bitbucket API is fairly broken and my willingness to deal with
  that is extremely limited unless someone pays me vast amounts of
  money.

- The Gitlab API documentation is not always accurate, though I don't
  have an example at hand.  It also isn't structured well, making it
  occasionally difficult to find the information one is looking for.

- Where one would use ~user/repo~ when accessing another forge, one has
  to use ~user%2Frepo~ when accessing Gitlab, e.g.:

  #+BEGIN_SRC emacs-lisp
    (glab-get "/projects/python-mode-devs%2Fpython-mode")
  #+END_SRC

* Function Index
:PROPERTIES:
:APPENDIX:   t
:INDEX:      fn
:END:
* Variable Index
:PROPERTIES:
:APPENDIX:   t
:INDEX:      vr
:END:
* _ Copying
:PROPERTIES:
:COPYING:    t
:END:

#+BEGIN_QUOTE
Copyright (C) 2017-2021 Jonas Bernoulli <jonas@bernoul.li>

You can redistribute this document 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.

This document 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.
#+END_QUOTE

* _ :ignore:

#  LocalWords:  ARGS AUTH Bitbucket DEFFN DESC ERRORBACK EVAL Auth Ghub Gitea Github
#  LocalWords:  Gitlab Glab Gogs GraphQL LocalWords MERCHANTABILITY
#  LocalWords:  Makefile NOERROR PARAMS
#  LocalWords:  SRC UNPAGINATE alist alists api auth authinfo
#  LocalWords:  backend backends config customizable emacs eval
#  LocalWords:  featurep fn ghub gitea github glab gitlab gogs graphql hostname HTTP JSON
#  LocalWords:  mis netrc noerror num params pullreq repo src texinfo toc
#  LocalWords:  unencrypted unpaginate unpaginating utils vr ziggy

# IMPORTANT: Also update ORG_ARGS and ORG_EVAL in the Makefile.
# Local Variables:
# eval: (require 'ox-extra    nil t)
# eval: (require 'ox-texinfo+ nil t)
# eval: (and (featurep 'ox-extra) (ox-extras-activate '(ignore-headlines)))
# fill-column: 70
# indent-tabs-mode: nil
# org-src-preserve-indentation: nil
# sentence-end-double-space: t
# End: