feat: restructure province COVID-19 endpoints with nested JSON format

- Add new ProvinceCaseResponse DTOs with nested daily/cumulative/statistics structure
- Transform Indonesian field names to English equivalents (hari_ke->day, kasus_baru->daily, etc.)
- Update province endpoints to use new transformation logic
- Include province-specific fields (PersonUnderObservation, PersonUnderSupervision)
- Add comprehensive unit tests for transformation functions
- Maintain backward compatibility by preserving province information in response
- Follow same pattern as national endpoints for consistency

Author: ryanaidilp

internal/handler/covid_handler.go

@@ -90,7 +90,9 @@ func (h *CovidHandler) GetProvinceCases(w http.ResponseWriter, r *http.Request)
 				writeErrorResponse(w, http.StatusInternalServerError, err.Error())
 				return
 			}
-			writeSuccessResponse(w, cases)
+			// Transform to new response structure
+			responseData := models.TransformProvinceCaseSliceToResponse(cases)
+			writeSuccessResponse(w, responseData)
 			return
 		}
 
@@ -99,7 +101,9 @@ func (h *CovidHandler) GetProvinceCases(w http.ResponseWriter, r *http.Request)
 			writeErrorResponse(w, http.StatusInternalServerError, err.Error())
 			return
 		}
-		writeSuccessResponse(w, cases)
+		// Transform to new response structure
+		responseData := models.TransformProvinceCaseSliceToResponse(cases)
+		writeSuccessResponse(w, responseData)
 		return
 	}
 
@@ -112,7 +116,9 @@ func (h *CovidHandler) GetProvinceCases(w http.ResponseWriter, r *http.Request)
 			writeErrorResponse(w, http.StatusInternalServerError, err.Error())
 			return
 		}
-		writeSuccessResponse(w, cases)
+		// Transform to new response structure
+		responseData := models.TransformProvinceCaseSliceToResponse(cases)
+		writeSuccessResponse(w, responseData)
 		return
 	}
 
@@ -122,7 +128,9 @@ func (h *CovidHandler) GetProvinceCases(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	writeSuccessResponse(w, cases)
+	// Transform to new response structure
+	responseData := models.TransformProvinceCaseSliceToResponse(cases)
+	writeSuccessResponse(w, responseData)
 }
 
 func (h *CovidHandler) HealthCheck(w http.ResponseWriter, r *http.Request) {

internal/models/province_case_response.go

@@ -0,0 +1,113 @@
+package models
+
+import "time"
+
+// ProvinceCaseResponse represents the structured response for province COVID-19 case data
+type ProvinceCaseResponse struct {
+	Day        int64                     `json:"day"`
+	Date       time.Time                 `json:"date"`
+	Daily      ProvinceDailyCases        `json:"daily"`
+	Cumulative ProvinceCumulativeCases   `json:"cumulative"`
+	Statistics ProvinceCaseStatistics    `json:"statistics"`
+	Province   *Province                 `json:"province,omitempty"`
+}
+
+// ProvinceDailyCases represents new cases for a single day in a province
+type ProvinceDailyCases struct {
+	Positive                         int64 `json:"positive"`
+	Recovered                        int64 `json:"recovered"`
+	Deceased                         int64 `json:"deceased"`
+	Active                           int64 `json:"active"`
+	PersonUnderObservation           int64 `json:"person_under_observation"`
+	FinishedPersonUnderObservation   int64 `json:"finished_person_under_observation"`
+	PersonUnderSupervision           int64 `json:"person_under_supervision"`
+	FinishedPersonUnderSupervision   int64 `json:"finished_person_under_supervision"`
+}
+
+// ProvinceCumulativeCases represents total cases accumulated over time in a province
+type ProvinceCumulativeCases struct {
+	Positive                         int64 `json:"positive"`
+	Recovered                        int64 `json:"recovered"`
+	Deceased                         int64 `json:"deceased"`
+	Active                           int64 `json:"active"`
+	PersonUnderObservation           int64 `json:"person_under_observation"`
+	ActivePersonUnderObservation     int64 `json:"active_person_under_observation"`
+	FinishedPersonUnderObservation   int64 `json:"finished_person_under_observation"`
+	PersonUnderSupervision           int64 `json:"person_under_supervision"`
+	ActivePersonUnderSupervision     int64 `json:"active_person_under_supervision"`
+	FinishedPersonUnderSupervision   int64 `json:"finished_person_under_supervision"`
+}
+
+// ProvinceCaseStatistics contains calculated statistics and metrics for province data
+type ProvinceCaseStatistics struct {
+	Percentages      CasePercentages   `json:"percentages"`
+	ReproductionRate *ReproductionRate `json:"reproduction_rate,omitempty"`
+}
+
+// TransformToResponse converts a ProvinceCase model to the response format
+func (pc *ProvinceCase) TransformToResponse(date time.Time) ProvinceCaseResponse {
+	// Calculate active cases
+	dailyActive := pc.Positive - pc.Recovered - pc.Deceased
+	cumulativeActive := pc.CumulativePositive - pc.CumulativeRecovered - pc.CumulativeDeceased
+
+	// Calculate active under observation and supervision
+	activePersonUnderObservation := pc.CumulativePersonUnderObservation - pc.CumulativeFinishedPersonUnderObservation
+	activePersonUnderSupervision := pc.CumulativePersonUnderSupervision - pc.CumulativeFinishedPersonUnderSupervision
+
+	// Build response
+	response := ProvinceCaseResponse{
+		Day:  pc.Day,
+		Date: date,
+		Daily: ProvinceDailyCases{
+			Positive:                         pc.Positive,
+			Recovered:                        pc.Recovered,
+			Deceased:                         pc.Deceased,
+			Active:                           dailyActive,
+			PersonUnderObservation:           pc.PersonUnderObservation,
+			FinishedPersonUnderObservation:   pc.FinishedPersonUnderObservation,
+			PersonUnderSupervision:           pc.PersonUnderSupervision,
+			FinishedPersonUnderSupervision:   pc.FinishedPersonUnderSupervision,
+		},
+		Cumulative: ProvinceCumulativeCases{
+			Positive:                         pc.CumulativePositive,
+			Recovered:                        pc.CumulativeRecovered,
+			Deceased:                         pc.CumulativeDeceased,
+			Active:                           cumulativeActive,
+			PersonUnderObservation:           pc.CumulativePersonUnderObservation,
+			ActivePersonUnderObservation:     activePersonUnderObservation,
+			FinishedPersonUnderObservation:   pc.CumulativeFinishedPersonUnderObservation,
+			PersonUnderSupervision:           pc.CumulativePersonUnderSupervision,
+			ActivePersonUnderSupervision:     activePersonUnderSupervision,
+			FinishedPersonUnderSupervision:   pc.CumulativeFinishedPersonUnderSupervision,
+		},
+		Statistics: ProvinceCaseStatistics{
+			Percentages: calculatePercentages(pc.CumulativePositive, pc.CumulativeRecovered, pc.CumulativeDeceased, cumulativeActive),
+		},
+		Province: pc.Province,
+	}
+
+	// Add reproduction rate if available
+	if pc.Rt != nil && pc.RtUpper != nil && pc.RtLower != nil {
+		response.Statistics.ReproductionRate = &ReproductionRate{
+			Value:      *pc.Rt,
+			UpperBound: *pc.RtUpper,
+			LowerBound: *pc.RtLower,
+		}
+	}
+
+	return response
+}
+
+// TransformProvinceCaseWithDateToResponse converts a ProvinceCaseWithDate model to the response format
+func (pcd *ProvinceCaseWithDate) TransformToResponse() ProvinceCaseResponse {
+	return pcd.ProvinceCase.TransformToResponse(pcd.Date)
+}
+
+// TransformProvinceCaseSliceToResponse converts a slice of ProvinceCaseWithDate models to response format
+func TransformProvinceCaseSliceToResponse(cases []ProvinceCaseWithDate) []ProvinceCaseResponse {
+	responses := make([]ProvinceCaseResponse, len(cases))
+	for i, c := range cases {
+		responses[i] = c.TransformToResponse()
+	}
+	return responses
+}