feat: impl requests handllers for contacts and healthcheck

internal/handler/errors.go

@@ -0,0 +1,88 @@
+package handler
+
+import (
+	"fmt"
+	"net/http"
+)
+
+/*
+	Domain (First Digit)
+
+		1xxx - Request/Input Errors
+
+		2xxx - Authentication/Authorization
+
+		3xxx - Business Logic/Validation
+
+		4xxx - Data/Resource Errors
+
+		5xxx - System/External Service Errors
+
+	Category (Second Digit)
+
+		x0xx - General/Generic errors in that domain
+
+		x1xx - Format/Structure errors
+
+		x2xx - Validation/Constraint errors
+
+		x3xx - State/Workflow errors
+
+		x4xx - Permission/Access errors
+
+	Specific Error (Last Two Digits)
+
+		xx00-xx99 - Specific error instances
+*/
+
+// Domains
+const (
+	DomainRequest = 1000
+	DomainAuth    = 2000
+	DomainData    = 4000
+	DomainSystem  = 5000
+)
+
+const (
+	CategoryGeneral    = 0
+	CategoryFormat     = 100
+	CategoryValidation = 200
+	CategoryState      = 300
+	CategoryPermission = 400
+)
+
+// Err code Domain + Category + Specific
+const (
+	CodeInvalidJSON      = DomainRequest + CategoryFormat + 1
+	InvalidParamFormat   = DomainRequest + CategoryFormat + 0
+	CodeValidationFailed = DomainRequest + CategoryValidation + 0
+	CodeMissingRequired  = DomainRequest + CategoryValidation + 1
+	CodeNotFound         = DomainData + CategoryPermission + 0
+	CodeInternalError    = DomainSystem + CategoryGeneral + 0
+)
+
+var (
+	ErrInvalidJSON     = APIError{Code: CodeInvalidJSON, Message: "Invalid JSON in request body"}
+	ErrValidation      = APIError{Code: CodeValidationFailed, Message: "Validation failed"}
+	ErrMissingRequired = APIError{Code: CodeMissingRequired, Message: "Required field is missing"}
+	ErrNotFound        = APIError{Code: CodeNotFound, Message: "Resource not found"}
+	ErrInternalServer  = APIError{Code: CodeInternalError, Message: "Internal server error"}
+	ErrInvalidFormat   = APIError{Code: InvalidParamFormat, Message: "The given param doesn't match the format expectations"}
+)
+
+// Helper functions for common errors
+func BadRequest(w http.ResponseWriter, err APIError, details string) {
+	JSONError(w, err.Message, details, err.Code, http.StatusBadRequest)
+}
+
+func NotFound(w http.ResponseWriter, err APIError, details string) {
+	JSONError(w, err.Message, details, err.Code, http.StatusNotFound)
+}
+
+func InternalError(w http.ResponseWriter, err error) {
+	JSONError(w, ErrInternalServer.Message, err.Error(), ErrInternalServer.Code, http.StatusInternalServerError)
+}
+
+func RequiredFieldErr(field string) string {
+	return (fmt.Sprintf("%s %s", field, required_field))
+}