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@@ -0,0 +1,160 @@
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+package module
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+
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+import (
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+ "encoding/json"
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+ "errors"
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+ "fmt"
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+ "log"
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+ "net/http"
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+ "runtime"
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+)
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+
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+// Err... are errors used globally
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+var (
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+ ErrUnknown = errors.New("Unknown error")
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+ // ErrRetrievingImage = errors.New("Error retrieving image")
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+ // ErrInvalidURL = errors.New("Passed URL is not valid")
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+ // ErrDecodingImage = errors.New("Error decoding image")
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+ // ErrWidthNoInteger = errors.New("Error parsing width parameter as integer")
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+ // ErrHeightNoInteger = errors.New("Error parsing height parameter as integer")
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+ // ErrAspectRatioWidthNoInteger = errors.New("Error parsing aspect ratio width parameter as integer")
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+ // ErrAspectRatioHeightNoInteger = errors.New("Error parsing aspect ratio height parameter as integer")
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+ ErrReadingRequestBody = errors.New("Error reading request body")
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+ ErrDecodingJSON = errors.New("Error decoding JSON")
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+ // ErrDecodingBase64 = errors.New("Error decoding base64 encoded image")
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+ // ErrReadingCroppedImage = errors.New("Error reading cropped image")
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+ // ErrCreatingThumbnail = errors.New("Error creating thumbnail")
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+ // ErrDecodingImageInternal = errors.New("Error decoding image")
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+ // ErrEncodingImage = errors.New("Error encoding image")
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+ ErrSendingResponse = errors.New("Error sending response")
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+ ErrEncodingJSON = errors.New("Error encoding JSON")
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+ ErrDatabase = errors.New("Database error")
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+ ErrRetrievingTestData = errors.New("Error receiving Testdata")
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+ ErrParsingInt = errors.New("Error parsing string to int")
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+)
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+
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+// StatusCodeMapper maps errors to HTTP Status codes
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+var StatusCodeMapper = map[error]int{
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+ ErrUnknown: http.StatusInternalServerError,
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+ // ErrRetrievingImage: http.StatusBadRequest,
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+ // ErrInvalidURL: http.StatusBadRequest,
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+ // ErrDecodingImage: http.StatusBadRequest,
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+ // ErrWidthNoInteger: http.StatusBadRequest,
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+ // ErrHeightNoInteger: http.StatusBadRequest,
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+ // ErrAspectRatioWidthNoInteger: http.StatusBadRequest,
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+ // ErrAspectRatioHeightNoInteger: http.StatusBadRequest,
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+ ErrReadingRequestBody: http.StatusBadRequest,
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+ ErrDecodingJSON: http.StatusBadRequest,
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+ // ErrDecodingBase64: http.StatusBadRequest,
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+ // ErrReadingCroppedImage: http.StatusInternalServerError,
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+ // ErrCreatingThumbnail: http.StatusInternalServerError,
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+ // ErrDecodingImageInternal: http.StatusInternalServerError,
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+ // ErrEncodingImage: http.StatusInternalServerError,
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+ ErrSendingResponse: http.StatusInternalServerError,
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+ ErrEncodingJSON: http.StatusInternalServerError,
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+ ErrDatabase: http.StatusInternalServerError,
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+ ErrRetrievingTestData: http.StatusBadGateway,
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+ ErrParsingInt: http.StatusInternalServerError,
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+}
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+
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+// MetaError is two errors in one
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+type MetaError struct {
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+ outerError error
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+ innerError error
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+ httpStatus int
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+}
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+
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+// NewMetaError returns a new MetaError and automatically selects the suited HTTP Status Code
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+func NewMetaError(outerError error, innerError error) MetaError {
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+ return MetaError{outerError, innerError, StatusCodeMapper[outerError]}
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+}
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+
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+// NewMetaErrorWithStatus returns a new MetaError with manually selected HTTP Status Code
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+func NewMetaErrorWithStatus(outerError error, innerError error, httpStatus int) MetaError {
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+ return MetaError{outerError, innerError, httpStatus}
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+}
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+
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+func (err MetaError) Error() string {
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+ return err.outerError.Error() + ": " + err.innerError.Error()
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+}
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+
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+type StatusError struct {
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+ error
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+ httpStatus int
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+}
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+
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+func NewStatusError(err error, status int) StatusError {
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+ return StatusError{err, status}
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+}
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+
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+// HandleError will handle errors
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+func HandleError(outerErr error, innerErr error) {
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+ if innerErr != nil {
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+
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+ switch outerErr {
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+ case ErrDatabase:
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+ switch innerErr.Error() {
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+ case "record not found":
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+ panic(NewStatusError(innerErr, http.StatusNotFound))
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+ }
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+ }
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+
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+ panic(NewMetaError(outerErr, innerErr))
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+ }
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+}
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+
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+// HTTPStatusHandler ...
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+type HTTPStatusHandler struct {
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+ Debug bool // TODO implement
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+}
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+
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+// NewHTTPStatusHandler ...
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+func NewHTTPStatusHandler() *HTTPStatusHandler {
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+ return &HTTPStatusHandler{
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+ Debug: false,
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+ }
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+}
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+
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+// HTTPStatusRecovery catches errors and serves http statuses
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+func (rec *HTTPStatusHandler) ServeHTTP(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
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+ defer func() {
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+ if err := recover(); err != nil {
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+ // get the stack traces and print it out
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+ // stack := stack(0)
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+ // log.Printf("PANIC: %s\n%s", err, stack)
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+
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+ // convert err to a string
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+ var errMsg string
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+ if e, ok := err.(error); ok {
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+ errMsg = e.Error()
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+ } else {
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+ errMsg = fmt.Sprint(err)
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+ }
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+
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+ // Logging
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+ _, file, line, _ := runtime.Caller(4)
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+ log.Printf("%s:%d: %s", file, line, errMsg)
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+
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+ errText, jErr := json.Marshal(map[string]string{"status": errMsg})
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+ if jErr != nil {
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+ log.Println(jErr)
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+ // TODO handle error
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+ }
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+
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+ if _, ok := err.(MetaError); ok {
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+ http.Error(w, string(errText), err.(MetaError).httpStatus)
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+ } else if _, ok = err.(StatusError); ok {
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+ http.Error(w, string(errText), err.(StatusError).httpStatus)
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+ } else {
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+ http.Error(w, string(errText), http.StatusInternalServerError)
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+ }
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+ }
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+ }()
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+
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+ next(w, r)
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+}
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+
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+// Log logs
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+func Log(text string) {
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+ log.Println(text)
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+}
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Moritz Schmidt
7 years ago