feat: multiple oauth providers (#355)

* feat: add flag decoder (candidate)

* refactor: finalize flags decoder

* feat: add env decoder

* feat: add oauth config parsing logic

* feat: implement backend logic for multiple oauth providers

* feat: implement multiple oauth providers in the frontend

* feat: add some default icons

* chore: add credits for parser

* feat: style oauth auto redirect screen

* fix: bot suggestions

* refactor: rework decoders using simpler and more efficient pattern

* refactor: rework oauth name database migration

internal/utils/decoders/env_decoder_test.go

@@ -0,0 +1,60 @@
+package decoders_test
+
+import (
+	"testing"
+	"tinyauth/internal/config"
+	"tinyauth/internal/utils/decoders"
+
+	"gotest.tools/v3/assert"
+)
+
+func TestDecodeEnv(t *testing.T) {
+	// Variables
+	expected := config.Providers{
+		Providers: map[string]config.OAuthServiceConfig{
+			"client1": {
+				ClientID:           "client1-id",
+				ClientSecret:       "client1-secret",
+				Scopes:             []string{"client1-scope1", "client1-scope2"},
+				RedirectURL:        "client1-redirect-url",
+				AuthURL:            "client1-auth-url",
+				UserinfoURL:        "client1-user-info-url",
+				Name:               "Client1",
+				InsecureSkipVerify: false,
+			},
+			"client2": {
+				ClientID:           "client2-id",
+				ClientSecret:       "client2-secret",
+				Scopes:             []string{"client2-scope1", "client2-scope2"},
+				RedirectURL:        "client2-redirect-url",
+				AuthURL:            "client2-auth-url",
+				UserinfoURL:        "client2-user-info-url",
+				Name:               "My Awesome Client2",
+				InsecureSkipVerify: false,
+			},
+		},
+	}
+	test := map[string]string{
+		"PROVIDERS_CLIENT1_CLIENT_ID":            "client1-id",
+		"PROVIDERS_CLIENT1_CLIENT_SECRET":        "client1-secret",
+		"PROVIDERS_CLIENT1_SCOPES":               "client1-scope1,client1-scope2",
+		"PROVIDERS_CLIENT1_REDIRECT_URL":         "client1-redirect-url",
+		"PROVIDERS_CLIENT1_AUTH_URL":             "client1-auth-url",
+		"PROVIDERS_CLIENT1_USER_INFO_URL":        "client1-user-info-url",
+		"PROVIDERS_CLIENT1_NAME":                 "Client1",
+		"PROVIDERS_CLIENT1_INSECURE_SKIP_VERIFY": "false",
+		"PROVIDERS_CLIENT2_CLIENT_ID":            "client2-id",
+		"PROVIDERS_CLIENT2_CLIENT_SECRET":        "client2-secret",
+		"PROVIDERS_CLIENT2_SCOPES":               "client2-scope1,client2-scope2",
+		"PROVIDERS_CLIENT2_REDIRECT_URL":         "client2-redirect-url",
+		"PROVIDERS_CLIENT2_AUTH_URL":             "client2-auth-url",
+		"PROVIDERS_CLIENT2_USER_INFO_URL":        "client2-user-info-url",
+		"PROVIDERS_CLIENT2_NAME":                 "My Awesome Client2",
+		"PROVIDERS_CLIENT2_INSECURE_SKIP_VERIFY": "false",
+	}
+
+	// Test
+	res, err := decoders.DecodeEnv(test)
+	assert.NilError(t, err)
+	assert.DeepEqual(t, expected, res)
+}