brokeyourbike/clearbank-api-client-go

package clearbank

import (
    "bytes"
    "context"
    "encoding/json"
    "fmt"
    "io"
    "net/http"
    "slices"
    "strings"

    "github.com/brokeyourbike/clearbank-api-client-go/signature"
    "github.com/go-playground/validator/v10"
    "github.com/sirupsen/logrus"
)

const defaultBaseURL = "https://institution-api-sim.clearbank.co.uk"

// requestIdCtx is the context key for the request ID.
type requestIdCtx struct{}

type HttpClient interface {
    Do(req *http.Request) (*http.Response, error)
}

type Signer interface {
    signature.Signer
}

type RequestIdGen func() string

type Client interface {
    TestClient
    RateClient
    StatementClient
    AccountsClient
    TransactionsClient
    MCCYAccountsClient
    MCCYTransactionsClient
    FxClient
}

var _ Client = (*client)(nil)

type client struct {
    httpClient   HttpClient
    signer       Signer
    logger       *logrus.Logger
    validate     *validator.Validate
    requestIdGen RequestIdGen
    baseURL      string
    token        string
}

// ClientOption is a function that configures a Client.
type ClientOption func(*client)

// WithHTTPClient sets the HTTP client for the ClearBank API client.
func WithHTTPClient(c HttpClient) ClientOption {
    return func(target *client) {
        target.httpClient = c
    }
}

// WithLogger sets the *logrus.Logger for the ClearBank API client.
func WithLogger(l *logrus.Logger) ClientOption {
    return func(target *client) {
        target.logger = l
    }
}

// WithBaseURL sets the base URL for the ClearBank API client.
func WithBaseURL(baseURL string) ClientOption {
    return func(target *client) {
        target.baseURL = strings.TrimSuffix(baseURL, "/")
    }
}

// WithRequestIDGenerator generate requestId on demand.
func WithRequestIDGenerator(f RequestIdGen) ClientOption {
    return func(target *client) {
        target.requestIdGen = f
    }
}

func NewClient(token string, signer Signer, options ...ClientOption) *client {
    c := &client{
        httpClient: http.DefaultClient,
        signer:     signer,
        validate:   validator.New(validator.WithRequiredStructEnabled()),
        baseURL:    defaultBaseURL,
        token:      token,
    }

    for _, option := range options {
        option(c)
    }

    return c
}

func (c *client) newRequest(ctx context.Context, method, url string, body interface{}) (*request, error) {
    req, err := http.NewRequestWithContext(ctx, method, c.baseURL+url, nil)
    if err != nil {
        return nil, fmt.Errorf("failed to create request: %w", err)
    }

    var b []byte
    var requestID string

    switch req.Method {
    case http.MethodPut, http.MethodPost, http.MethodPatch, http.MethodDelete:
        b, err = json.Marshal(body)
        if err != nil {
            return nil, fmt.Errorf("failed to marshal payload: %w", err)
        }

        signature, err := c.signer.Sign(ctx, b)
        if err != nil {
            return nil, fmt.Errorf("failed to sign payload: %w", err)
        }

        req.Body = io.NopCloser(bytes.NewReader(b))
        req.Header.Set("DigitalSignature", string(signature))

        if c.requestIdGen != nil {
            requestID = c.requestIdGen()
        }
        if v := RequestIdFromContext(ctx); v != "" {
            requestID = v
        }
        req.Header.Set("X-Request-Id", requestID)
    }

    if c.logger != nil {
        c.logger.WithContext(ctx).WithFields(logrus.Fields{
            "http.request.method":             req.Method,
            "http.request.url":                req.URL.String(),
            "http.request.body.content":       string(b),
            "http.request.headers.request_id": requestID,
        }).Debug("clearbank.client -> request")
    }

    req.Header.Set("Content-Type", "application/json")
    req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", c.token))
    return NewRequest(req), nil
}

func (c *client) do(ctx context.Context, req *request) error {
    resp, err := c.httpClient.Do(req.req)
    if err != nil {
        return fmt.Errorf("failed to send request: %w", err)
    }
    defer resp.Body.Close()

    b, err := io.ReadAll(resp.Body)
    if err != nil {
        return fmt.Errorf("failed to read response body: %w", err)
    }

    resp.Body = io.NopCloser(bytes.NewBuffer(b))

    if c.logger != nil {
        c.logger.WithContext(ctx).WithFields(logrus.Fields{
            "http.response.status_code":  resp.StatusCode,
            "http.response.body.content": string(b),
            "http.response.headers":      resp.Header,
        }).Debug("clearbank.client -> response")
    }

    if !slices.Contains(req.expectedStatuses, resp.StatusCode) {
        unexpectedResponse := UnexpectedResponse{Status: resp.StatusCode, Body: string(b)}

        var errResponse ErrResponse
        if err := json.Unmarshal(b, &errResponse); err != nil {
            return unexpectedResponse
        }

        if err := c.validate.Struct(errResponse); err != nil {
            return unexpectedResponse
        }

        return errResponse
    }

    if req.decodeTo != nil {
        if err := json.NewDecoder(resp.Body).Decode(req.decodeTo); err != nil {
            return fmt.Errorf("failed to decode response: %w", err)
        }
    }

    return nil
}

// RequestIdContext adds a request ID to the given context.
func RequestIdContext(ctx context.Context, id string) context.Context {
    return context.WithValue(ctx, requestIdCtx{}, id)
}

// RequestIdFromContext returns the request ID from the given context.
func RequestIdFromContext(ctx context.Context) string {
    if ctx == nil {
        return ""
    }

    if id, ok := ctx.Value(requestIdCtx{}).(string); ok {
        return id
    }

    return ""
}