enbas/internal/client/client.go

package client

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"
	"time"

	"codeflow.dananglin.me.uk/apollo/enbas/internal/config"
)

const (
	applicationJSON string = "application/json; charset=utf-8"
	redirectURI     string = "urn:ietf:wg:oauth:2.0:oob"
	userAgent       string = "Enbas/0.0.0"
)

type Client struct {
	Authentication config.Credentials
	HTTPClient     http.Client
	UserAgent      string
	Timeout        time.Duration
}

func NewClientFromFile(path string) (*Client, error) {
	config, err := config.NewCredentialsConfigFromFile(path)
	if err != nil {
		return nil, fmt.Errorf("unable to get the authentication configuration: %w", err)
	}

	currentAuthentication := config.Credentials[config.CurrentAccount]

	return NewClient(currentAuthentication), nil
}

func NewClient(authentication config.Credentials) *Client {
	httpClient := http.Client{}

	gtsClient := Client{
		Authentication: authentication,
		HTTPClient:     httpClient,
		UserAgent:      userAgent,
		Timeout:        5 * time.Second,
	}

	return &gtsClient
}

func (g *Client) AuthCodeURL() string {
	format := "%s/oauth/authorize?client_id=%s&redirect_uri=%s&response_type=code"
	escapedRedirectURI := url.QueryEscape(redirectURI)

	return fmt.Sprintf(
		format,
		g.Authentication.Instance,
		g.Authentication.ClientID,
		escapedRedirectURI,
	)
}

func (g *Client) DownloadMedia(url, path string) error {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()

	request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return fmt.Errorf("unable to create the HTTP request: %w", err)
	}

	request.Header.Set("User-Agent", g.UserAgent)

	response, err := g.HTTPClient.Do(request)
	if err != nil {
		return fmt.Errorf("received an error after attempting the download: %w", err)
	}
	defer response.Body.Close()

	if response.StatusCode != http.StatusOK {
		return BadStatusCodeError{
			statusCode: response.StatusCode,
		}
	}

	file, err := os.Create(path)
	if err != nil {
		return fmt.Errorf("unable to create %s: %w", path, err)
	}
	defer file.Close()

	if _, err = io.Copy(file, response.Body); err != nil {
		return fmt.Errorf("unable to save the download to %s: %w", path, err)
	}

	return nil
}

type requestParameters struct {
	httpMethod  string
	url         string
	contentType string
	requestBody io.Reader
	output      any
}

func (g *Client) sendRequest(params requestParameters) error {
	ctx, cancel := context.WithTimeout(context.Background(), g.Timeout)
	defer cancel()

	request, err := http.NewRequestWithContext(ctx, params.httpMethod, params.url, params.requestBody)
	if err != nil {
		return fmt.Errorf("unable to create the HTTP request: %w", err)
	}

	if params.contentType != "" {
		request.Header.Set("Content-Type", params.contentType)
	}

	request.Header.Set("Accept", applicationJSON)
	request.Header.Set("User-Agent", g.UserAgent)

	if len(g.Authentication.AccessToken) > 0 {
		request.Header.Set("Authorization", "Bearer "+g.Authentication.AccessToken)
	}

	response, err := g.HTTPClient.Do(request)
	if err != nil {
		return fmt.Errorf("received an error after sending the request: %w", err)
	}

	defer response.Body.Close()

	if response.StatusCode < http.StatusOK || response.StatusCode >= http.StatusBadRequest {
		message := struct {
			Error string `json:"error"`
		}{
			Error: "",
		}

		if err := json.NewDecoder(response.Body).Decode(&message); err != nil {
			return ResponseError{
				StatusCode:       response.StatusCode,
				Message:          "",
				MessageDecodeErr: err,
			}
		}

		return ResponseError{
			StatusCode:       response.StatusCode,
			Message:          message.Error,
			MessageDecodeErr: nil,
		}
	}

	if params.output == nil {
		return nil
	}

	if err := json.NewDecoder(response.Body).Decode(params.output); err != nil {
		return fmt.Errorf(
			"unable to decode the response from the GoToSocial server: %w",
			err,
		)
	}

	return nil
}