Move internal packages to an internal folder

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

internal/integration/wallabag/wallabag.go

@@ -0,0 +1,118 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package wallabag // import "miniflux.app/v2/internal/integration/wallabag"
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/url"
+
+	"miniflux.app/v2/internal/http/client"
+)
+
+// Client represents a Wallabag client.
+type Client struct {
+	baseURL      string
+	clientID     string
+	clientSecret string
+	username     string
+	password     string
+	onlyURL      bool
+}
+
+// NewClient returns a new Wallabag client.
+func NewClient(baseURL, clientID, clientSecret, username, password string, onlyURL bool) *Client {
+	return &Client{baseURL, clientID, clientSecret, username, password, onlyURL}
+}
+
+// AddEntry sends a link to Wallabag.
+// Pass an empty string in `content` to let Wallabag fetch the article content.
+func (c *Client) AddEntry(link, title, content string) error {
+	if c.baseURL == "" || c.clientID == "" || c.clientSecret == "" || c.username == "" || c.password == "" {
+		return fmt.Errorf("wallabag: missing credentials")
+	}
+
+	accessToken, err := c.getAccessToken()
+	if err != nil {
+		return err
+	}
+
+	return c.createEntry(accessToken, link, title, content)
+}
+
+func (c *Client) createEntry(accessToken, link, title, content string) error {
+	endpoint, err := url.JoinPath(c.baseURL, "/api/entries.json")
+	if err != nil {
+		return fmt.Errorf("wallbag: unable to generate entries endpoint using %q: %v", c.baseURL, err)
+	}
+
+	data := map[string]string{"url": link, "title": title}
+	if !c.onlyURL {
+		data["content"] = content
+	}
+
+	clt := client.New(endpoint)
+	clt.WithAuthorization("Bearer " + accessToken)
+	response, err := clt.PostJSON(data)
+	if err != nil {
+		return fmt.Errorf("wallabag: unable to post entry using %q endpoint: %v", endpoint, err)
+	}
+
+	if response.HasServerFailure() {
+		return fmt.Errorf("wallabag: request failed using %q, status=%d", endpoint, response.StatusCode)
+	}
+
+	return nil
+}
+
+func (c *Client) getAccessToken() (string, error) {
+	values := url.Values{}
+	values.Add("grant_type", "password")
+	values.Add("client_id", c.clientID)
+	values.Add("client_secret", c.clientSecret)
+	values.Add("username", c.username)
+	values.Add("password", c.password)
+
+	endpoint, err := url.JoinPath(c.baseURL, "/oauth/v2/token")
+	if err != nil {
+		return "", fmt.Errorf("wallbag: unable to generate token endpoint using %q: %v", c.baseURL, err)
+	}
+
+	clt := client.New(endpoint)
+	response, err := clt.PostForm(values)
+	if err != nil {
+		return "", fmt.Errorf("wallabag: unable to get access token using %q endpoint: %v", endpoint, err)
+	}
+
+	if response.HasServerFailure() {
+		return "", fmt.Errorf("wallabag: request failed using %q, status=%d", endpoint, response.StatusCode)
+	}
+
+	token, err := decodeTokenResponse(response.Body)
+	if err != nil {
+		return "", err
+	}
+
+	return token.AccessToken, nil
+}
+
+type tokenResponse struct {
+	AccessToken  string `json:"access_token"`
+	Expires      int    `json:"expires_in"`
+	RefreshToken string `json:"refresh_token"`
+	Scope        string `json:"scope"`
+	TokenType    string `json:"token_type"`
+}
+
+func decodeTokenResponse(body io.Reader) (*tokenResponse, error) {
+	var token tokenResponse
+
+	decoder := json.NewDecoder(body)
+	if err := decoder.Decode(&token); err != nil {
+		return nil, fmt.Errorf("wallabag: unable to decode token response: %v", err)
+	}
+
+	return &token, nil
+}