much better errors

internal/data/errors.go

@@ -0,0 +1,100 @@
+package data
+
+import (
+	"fmt"
+)
+
+type ErrorCode int
+
+const (
+	// 401 variants
+	ErrCodeInvalidCredentials ErrorCode = 4011
+	ErrCodeInvalidAuthToken   ErrorCode = 4012
+	ErrCodeAuthRequired       ErrorCode = 4013
+
+	// 403 variants
+	ErrCodeInactiveAccount ErrorCode = 4031
+	ErrCodeNotPermitted    ErrorCode = 4032
+
+	// 409 variants
+	ErrCodeEditConflict       ErrorCode = 4091
+	ErrCodeAlreadyVoted       ErrorCode = 4092
+	ErrCodeAlreadyBlindSigned ErrorCode = 4093
+	ErrCodeVoteAlreadyCast    ErrorCode = 4094
+
+	// 422 variants
+	ErrCodeValidationFailed ErrorCode = 4221
+	ErrCodeBlindedVoteRange ErrorCode = 4222
+	ErrCodeInvalidSignature ErrorCode = 4223
+	ErrCodeHasNotStarted    ErrorCode = 4224
+)
+
+type Error struct {
+	HttpCode int               `json:"http_code,omitempty"`
+	Code     ErrorCode         `json:"code,omitempty"`
+	Message  string            `json:"message"`
+	Details  map[string]string `json:"details,omitempty"`
+}
+
+func (e *Error) Error() string {
+	return e.Message
+}
+
+func (e *Error) WithDetails(details map[string]string) error {
+	e.Details = details
+	return e
+}
+
+
+func (e *Error) DetailMessages() []string {
+    msgs := make([]string, 0, len(e.Details))
+    for key, msg := range e.Details {
+        msgs = append(msgs, fmt.Sprintf("%s: %s", key, msg))
+    }
+    return msgs
+}
+
+func New(httpCode int, code ErrorCode, text string) error {
+	return &Error{HttpCode: httpCode, Code: code, Message: text}
+}
+
+var (
+    // 400 Bad Request
+    ErrFailedPEM       = New(400, 0, "failed to decode PEM block")
+    ErrBadlyFormedJSON = New(400, 0, "body contains badly-formed JSON")
+    ErrBodyEmpty       = New(400, 0, "body must not be empty")
+    ErrSingleValue     = New(400, 0, "body must only contain a single JSON value")
+    ErrInvalidID       = New(400, 0, "invalid id parameter")
+	ErrBadRequest      = New(400, 0, "the server cannot process the request due to a client error")
+
+    // 401 Unauthorized
+    ErrInvalidCredentials = New(401, 4011, "invalid credentials")
+    ErrInvalidAuthToken   = New(401, 4012, "invalid or missing authentication token")
+    ErrNoToken            = New(401, 4012, "token must be provided")
+    ErrAuthRequired       = New(401, 4013, "you must be authenticated to access this resource")
+    ErrHasNotStarted      = New(401, 4224, "the vote has not yet started")
+
+    // 403 Forbidden
+    ErrInactiveAccount = New(403, 4031, "your user account must be activated to access this resource")
+    ErrNotPermitted    = New(403, 4032, "your user account doesn't have the necessary permissions to access this resource")
+
+    // 404 Not Found
+    ErrRecordNotFound = New(404, 0, "record not found")
+    ErrNoPath         = New(404, 0, "path is required")
+
+    // 409 Conflict
+    ErrEditConflict       = New(409, 4091, "edit conflict")
+    ErrDuplicateVote      = New(409, 4092, "this signature has already been used to cast a vote")
+    ErrDuplicateBlindSign = New(409, 4093, "user has already requested a blind signature for this issue")
+    ErrDuplicateSignature = New(409, 4094, "this signature has already been used to cast a vote")
+    ErrDuplicateEmail     = New(409, 0, "duplicate email")
+    ErrDuplicateUser      = New(409, 0, "duplicate username")
+
+    // 422 Unprocessable Entity
+    ErrValidationFailed   = New(422, 4221, "validation failed")
+    ErrInvalidBlindedVote = New(422, 4222, "blinded_vote is out of valid range [1, n-1]")
+    ErrInvalidSignature   = New(422, 4223, "signature verification failed")
+
+    // 429 Too Many Requests
+    ErrRateLimitExceeded = New(429, 0, "rate limit exceeded")
+)

internal/data/helpers.go

@@ -3,14 +3,13 @@ package data
 import(
 	"crypto/rsa"
 	"encoding/pem"
-	"errors"
 	"crypto/x509"
 )
 
 func parsePrivateKey(pemBytes []byte) (*rsa.PrivateKey, error) {
 	block, _ := pem.Decode(pemBytes)
 	if block == nil {
-		return nil, errors.New("failed to decode PEM block")
+		return nil, ErrFailedPEM
 	}
 	return x509.ParsePKCS1PrivateKey(block.Bytes)
 }

internal/data/models.go

@@ -2,12 +2,6 @@ package data
 
 import (
 	"database/sql"
-	"errors"
-)
-
-var (
-	ErrRecordNotFound     = errors.New("record not found")
-	ErrEditConflict       = errors.New("edit conflict")
 )
 
 type Models struct {

internal/data/users.go

@@ -12,12 +12,6 @@ import (
 	"party.at/party/internal/validator"
 )
 
-var (
-	ErrDuplicateEmail     = errors.New("duplicate email")
-	ErrDuplicateUser      = errors.New("duplicate username")
-	ErrInvalidCredentials = errors.New("invalid credentials")
-)
-
 var AnonymousUser = &User{}
 
 type User struct {

internal/data/votes.go

@@ -1,7 +1,6 @@
 package data
 
 import (
-	"errors"
 	"time"
 	"database/sql"
 	"math/big"
@@ -12,14 +11,6 @@ import (
 	"github.com/lib/pq"
 )
 
-var (
-	ErrDuplicateBlindSign = errors.New("user has already requested a blind signature for this issue")
-	ErrInvalidBlindedVote = errors.New("blinded_vote is out of valid range [1, n-1]")
-	ErrInvalidSignature   = errors.New("signature verification failed")
-	ErrDuplicateVote      = errors.New("this signature has already been used to cast a vote")
-)
-
-
 type Vote struct {
 	ID        int64     `json:"id"`
 	OptionID  int64     `json:"option_id"`