[MM-20684] Slash Command Autocomplete (#14557)

* [MM-20684] Initial implementation of the Command Autocomplete (#13602)

* Implement Autocomplete Data

* Change CommandName to Trigger

* Fix Autocomplete test

* Make stylistic changes

* Rename a bunch of fields and methods

* Fix variable names, safer type assertions

* [MM-20684] plugin autocomplete implementation (#14259)

* Add an endpoint for command autocomplete suggestions

* Add full Suggestion to the AutocompleteSugestion struct

* Add Dynamic Argument support

* Tidy up things

* Fix missed test case

* Add support of the named arguments

* Update autocomplete API

Fix review issues

Implement dynamic args as a local request

* Fix ineffassign

* Add support of the uppercase letters in arguments

* Add support of the optional arguments

* Remove ineffectual assignment

* Add support for icons (#14489)

* Address couple of nits

* Add comment to IconData

* Add types to all consts

Co-authored-by: mattermod <mattermod@users.noreply.github.com>

model/command_autocomplete_test.go

@@ -0,0 +1,108 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"net/url"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAutocompleteData(t *testing.T) {
+	ad := NewAutocompleteData("jira", "", "Avaliable commands:")
+	assert.Nil(t, ad.IsValid())
+	ad.RoleID = "some_id"
+	assert.NotNil(t, ad.IsValid())
+	ad.RoleID = SYSTEM_ADMIN_ROLE_ID
+	assert.Nil(t, ad.IsValid())
+	ad.AddDynamicListArgument("help", "/some/url", true)
+	assert.Nil(t, ad.IsValid())
+	ad.AddNamedTextArgument("name", "help", "[text]", "", true)
+	assert.Nil(t, ad.IsValid())
+
+	ad = getAutocompleteData()
+	assert.Nil(t, ad.IsValid())
+	command := NewAutocompleteData("", "", "")
+	ad.AddCommand(command)
+	assert.NotNil(t, ad.IsValid())
+
+	ad = getAutocompleteData()
+	command = NewAutocompleteData("disconnect", "", "disconnect")
+	command.AddTextArgument("help", "[text]", "")
+	command.AddNamedTextArgument("some", "help", "[text]", "", true)
+	ad.AddCommand(command)
+	assert.Nil(t, ad.IsValid())
+
+	ad = getAutocompleteData()
+	command = NewAutocompleteData("disconnect", "", "disconnect")
+	command.AddDynamicListArgument("help", "valid_url", true)
+	ad.AddCommand(command)
+	assert.Nil(t, ad.IsValid())
+
+	ad = getAutocompleteData()
+	command = NewAutocompleteData("disconnect", "", "disconnect")
+	command.AddDynamicListArgument("help", "/valid/url", true)
+	items := []AutocompleteListItem{
+		{
+			Hint:     "help",
+			Item:     "",
+			HelpText: "text",
+		},
+	}
+	command.AddStaticListArgument("help", true, items)
+	ad.AddCommand(command)
+	assert.NotNil(t, ad.IsValid())
+
+	ad = getAutocompleteData()
+	ad.AddCommand(nil)
+	assert.NotNil(t, ad.IsValid())
+
+	ad = getAutocompleteData()
+	command = NewAutocompleteData("Disconnect", "", "")
+	ad.AddCommand(command)
+	assert.NotNil(t, ad.IsValid())
+}
+
+func TestAutocompleteDataJSON(t *testing.T) {
+	ad := getAutocompleteData()
+	b, err := ad.ToJSON()
+	assert.Nil(t, err)
+	ad2, err := AutocompleteDataFromJSON(b)
+	assert.Nil(t, err)
+	assert.True(t, ad2.Equals(ad))
+}
+
+func getAutocompleteData() *AutocompleteData {
+	ad := NewAutocompleteData("jira", "", "Avaliable commands:")
+	ad.RoleID = SYSTEM_USER_ROLE_ID
+	command := NewAutocompleteData("connect", "", "Connect to mattermost")
+	command.RoleID = SYSTEM_ADMIN_ROLE_ID
+	items := []AutocompleteListItem{
+		{
+			Hint:     "arg1",
+			Item:     "help1",
+			HelpText: "text1",
+		}, {
+			Hint:     "arg2",
+			Item:     "help2",
+			HelpText: "text2",
+		},
+	}
+	command.AddStaticListArgument("help", true, items)
+	command.AddNamedTextArgument("some", "help", "[text]", "", true)
+	command.AddNamedDynamicListArgument("other", "help", "/other/url", true)
+	ad.AddCommand(command)
+	return ad
+}
+
+func TestUpdateRelativeURLsForPluginCommands(t *testing.T) {
+	ad := getAutocompleteData()
+	baseURL, _ := url.Parse("http://localhost:8065/plugins/com.mattermost.demo-plugin")
+	err := ad.UpdateRelativeURLsForPluginCommands(baseURL)
+	assert.Nil(t, err)
+	arg, ok := ad.SubCommands[0].Arguments[2].Data.(*AutocompleteDynamicListArg)
+	assert.True(t, ok)
+	assert.Equal(t, "http://localhost:8065/plugins/com.mattermost.demo-plugin/other/url", arg.FetchURL)
+}