Move internal packages to an internal folder

For reference: https://go.dev/doc/go1.4#internalpackages

internal/integration/pocket/connector.go

@@ -0,0 +1,102 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package pocket // import "miniflux.app/v2/internal/integration/pocket"
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/url"
+
+	"miniflux.app/v2/internal/http/client"
+)
+
+// Connector manages the authorization flow with Pocket to get a personal access token.
+type Connector struct {
+	consumerKey string
+}
+
+// NewConnector returns a new Pocket Connector.
+func NewConnector(consumerKey string) *Connector {
+	return &Connector{consumerKey}
+}
+
+// RequestToken fetches a new request token from Pocket API.
+func (c *Connector) RequestToken(redirectURL string) (string, error) {
+	type req struct {
+		ConsumerKey string `json:"consumer_key"`
+		RedirectURI string `json:"redirect_uri"`
+	}
+
+	clt := client.New("https://getpocket.com/v3/oauth/request")
+	response, err := clt.PostJSON(&req{ConsumerKey: c.consumerKey, RedirectURI: redirectURL})
+	if err != nil {
+		return "", fmt.Errorf("pocket: unable to fetch request token: %v", err)
+	}
+
+	if response.HasServerFailure() {
+		return "", fmt.Errorf("pocket: unable to fetch request token, status=%d", response.StatusCode)
+	}
+
+	body, err := io.ReadAll(response.Body)
+	if err != nil {
+		return "", fmt.Errorf("pocket: unable to read response body: %v", err)
+	}
+
+	values, err := url.ParseQuery(string(body))
+	if err != nil {
+		return "", fmt.Errorf("pocket: unable to parse response: %v", err)
+	}
+
+	code := values.Get("code")
+	if code == "" {
+		return "", errors.New("pocket: code is empty")
+	}
+
+	return code, nil
+}
+
+// AccessToken fetches a new access token once the end-user authorized the application.
+func (c *Connector) AccessToken(requestToken string) (string, error) {
+	type req struct {
+		ConsumerKey string `json:"consumer_key"`
+		Code        string `json:"code"`
+	}
+
+	clt := client.New("https://getpocket.com/v3/oauth/authorize")
+	response, err := clt.PostJSON(&req{ConsumerKey: c.consumerKey, Code: requestToken})
+	if err != nil {
+		return "", fmt.Errorf("pocket: unable to fetch access token: %v", err)
+	}
+
+	if response.HasServerFailure() {
+		return "", fmt.Errorf("pocket: unable to fetch access token, status=%d", response.StatusCode)
+	}
+
+	body, err := io.ReadAll(response.Body)
+	if err != nil {
+		return "", fmt.Errorf("pocket: unable to read response body: %v", err)
+	}
+
+	values, err := url.ParseQuery(string(body))
+	if err != nil {
+		return "", fmt.Errorf("pocket: unable to parse response: %v", err)
+	}
+
+	token := values.Get("access_token")
+	if token == "" {
+		return "", errors.New("pocket: access_token is empty")
+	}
+
+	return token, nil
+}
+
+// AuthorizationURL returns the authorization URL for the end-user.
+func (c *Connector) AuthorizationURL(requestToken, redirectURL string) string {
+	return fmt.Sprintf(
+		"https://getpocket.com/auth/authorize?request_token=%s&redirect_uri=%s",
+		requestToken,
+		redirectURL,
+	)
+}