Add Bash and Zsh completion scripts (#22646)

This PR adds contrib scripts for bash and zsh completion.

Simply call:

```bash
source contrib/autocompletion/bash_autocomplete
```

or for Zsh:

```bash
source contrib/autocompletion/zsh_autocomplete
```

Signed-off-by: Andrew Thornton <art27@cantab.net>

---------

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: a101211279 <1012112796@qq.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

Dockerfile

 COPY docker/root /
 COPY --from=build-env /go/src/code.gitea.io/gitea/gitea /app/gitea/gitea
 COPY --from=build-env /go/src/code.gitea.io/gitea/environment-to-ini /usr/local/bin/environment-to-ini
+COPY --from=build-env /go/src/code.gitea.io/gitea/contrib/autocompletion/bash_autocomplete /etc/profile.d/gitea_bash_autocomplete.sh
 RUN chmod 755 /usr/bin/entrypoint /app/gitea/gitea /usr/local/bin/gitea /usr/local/bin/environment-to-ini
 RUN chmod 755 /etc/s6/gitea/* /etc/s6/openssh/* /etc/s6/.s6-svscan/*
+RUN chmod 644 /etc/profile.d/gitea_bash_autocomplete.sh

Dockerfile.rootless

 COPY docker/rootless /
 COPY --from=build-env --chown=root:root /go/src/code.gitea.io/gitea/gitea /app/gitea/gitea
 COPY --from=build-env --chown=root:root /go/src/code.gitea.io/gitea/environment-to-ini /usr/local/bin/environment-to-ini
+COPY --from=build-env /go/src/code.gitea.io/gitea/contrib/autocompletion/bash_autocomplete /etc/profile.d/gitea_bash_autocomplete.sh
 RUN chmod 755 /usr/local/bin/docker-entrypoint.sh /usr/local/bin/docker-setup.sh /app/gitea/gitea /usr/local/bin/gitea /usr/local/bin/environment-to-ini
+RUN chmod 644 /etc/profile.d/gitea_bash_autocomplete.sh
 
 #git:git
 USER 1000:1000

contrib/autocompletion/README

+Bash and Zsh completion
+=======================
+
+From within the gitea root run:
+
+```bash
+source contrib/autocompletion/bash_autocomplete
+```
+
+or for zsh run:
+
+```bash
+source contrib/autocompletion/zsh_autocomplete
+```
+
+These scripts will check if gitea is on the path and if so add autocompletion for `gitea`. Or if not autocompletion will work for `./gitea`.
+If gitea has been installed as a different program pass in the `PROG` environment variable to set the correct program name.

contrib/autocompletion/bash_autocomplete

+#! /bin/bash
+# Heavily inspired by https://github.com/urfave/cli
+
+_cli_bash_autocomplete() {
+  if [[ "${COMP_WORDS[0]}" != "source" ]]; then
+    local cur opts base
+    COMPREPLY=()
+    cur="${COMP_WORDS[COMP_CWORD]}"
+    if [[ "$cur" == "-"* ]]; then
+      opts=$( ${COMP_WORDS[@]:0:$COMP_CWORD} ${cur} --generate-bash-completion )
+    else
+      opts=$( ${COMP_WORDS[@]:0:$COMP_CWORD} --generate-bash-completion )
+    fi
+    COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
+    return 0
+  fi
+}
+
+if [ -z "$PROG" ] && [ ! "$(command -v gitea &> /dev/null)" ] ; then
+  complete -o bashdefault -o default -o nospace -F _cli_bash_autocomplete gitea
+elif [ -z "$PROG" ]; then
+  complete -o bashdefault -o default -o nospace -F _cli_bash_autocomplete ./gitea
+  complete -o bashdefault -o default -o nospace -F _cli_bash_autocomplete "$PWD/gitea"
+else
+  complete -o bashdefault -o default -o nospace -F _cli_bash_autocomplete "$PROG"
+  unset PROG
+fi
+
+
+

contrib/autocompletion/zsh_autocomplete

+#compdef ${PROG:=gitea}
+
+
+# Heavily inspired by https://github.com/urfave/cli
+
+_cli_zsh_autocomplete() {
+
+  local -a opts
+  local cur
+  cur=${words[-1]}
+  if [[ "$cur" == "-"* ]]; then
+    opts=("${(@f)$(_CLI_ZSH_AUTOCOMPLETE_HACK=1 ${words[@]:0:#words[@]-1} ${cur} --generate-bash-completion)}")
+  else
+    opts=("${(@f)$(_CLI_ZSH_AUTOCOMPLETE_HACK=1 ${words[@]:0:#words[@]-1} --generate-bash-completion)}")
+  fi
+
+  if [[ "${opts[1]}" != "" ]]; then
+    _describe 'values' opts
+  else
+    _files
+  fi
+
+  return
+}
+
+if [ -z $PROG ] ; then
+  compdef _cli_zsh_autocomplete gitea
+else
+  compdef _cli_zsh_autocomplete $(basename $PROG)
+fi

docs/content/doc/installation/from-binary.en-us.md

 cp gitea /usr/local/bin/gitea
 ```
 
+### Adding bash/zsh autocompletion (from 1.19)
+
+A script to enable bash-completion can be found at [`contrib/autocompletion/bash_autocomplete`](https://raw.githubusercontent.com/go-gitea/gitea/main/contrib/autocompletion/bash_autocomplete). This can be copied to `/usr/share/bash-completion/completions/gitea`
+or sourced within your `.bashrc`.
+
+Similarly a script for zsh-completion can be found at [`contrib/autocompletion/zsh_autocomplete`](https://raw.githubusercontent.com/go-gitea/gitea/main/contrib/autocompletion/zsh_autocomplete). This can be copied to `/usr/share/zsh/_gitea` or sourced within your
+`.zshrc`.
+
+YMMV and these scripts may need further improvement.
+
 ## Running Gitea
 
 After you complete the above steps, you can run Gitea two ways:

docs/content/doc/installation/from-source.en-us.md

 ```
 
 This can be combined with `CC`, `GOOS`, and `GOARCH` as above.
+
+### Adding bash/zsh autocompletion (from 1.19)
+
+A script to enable bash-completion can be found at [`contrib/autocompletion/bash_autocomplete`](https://raw.githubusercontent.com/go-gitea/gitea/main/contrib/autocompletion/bash_autocomplete). This should be altered as appropriate and can be `source` in your `.bashrc`
+or copied as `/usr/share/bash-completion/completions/gitea`.
+
+Similary a script for zsh-completion can be found at [`contrib/autocompletion/zsh_autocomplete`](https://raw.githubusercontent.com/go-gitea/gitea/main/contrib/autocompletion/zsh_autocomplete). This can be copied to `/usr/share/zsh/_gitea` or sourced within your
+`.zshrc`.
+
+YMMV and these scripts may need further improvement.

main.go

 		setFlagsAndBeforeOnSubcommands(&app.Commands[i], defaultFlags, establishCustomPath)
 	}
 
+	app.EnableBashCompletion = true
+
 	err := app.Run(os.Args)
 	if err != nil {
 		log.Fatal("Failed to run app with %s: %v", os.Args, err)