package http

import (
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"math"
	"net/http"
	"regexp"
	"strconv"
	"strings"
	"time"
	"unicode/utf8"

	"primaya-api/cpone-middleware/internal/repository"
)

var integerValue = regexp.MustCompile(`^[+-]?\d+$`)

type LabRegistrationResponse struct {
	Success bool                            `json:"success"`
	Status  string                          `json:"status"`
	Message string                          `json:"message"`
	Data    *repository.LabRegistrationData `json:"data"`
}

type validatedLabRegistration struct {
	Params repository.LabRegistrationParams
}

func (h Handler) RegisterLab(w http.ResponseWriter, r *http.Request) {
	payload, err := decodeJSONObject(r)
	if err != nil {
		writeLabResponse(w, http.StatusUnprocessableEntity, false, "validation_error", err.Error(), nil)
		return
	}

	validated, validationMessage := validateLabRegistration(payload)
	if validationMessage != "" {
		writeLabResponse(w, http.StatusUnprocessableEntity, false, "validation_error", validationMessage, nil)
		return
	}

	outcome, err := h.labRepo.RegisterLab(r.Context(), validated.Params)
	if err != nil {
		var validationErr repository.ValidationError
		if errors.As(err, &validationErr) {
			writeLabResponse(w, http.StatusUnprocessableEntity, false, "validation_error", validationErr.Message, nil)
			return
		}

		writeLabResponse(w, http.StatusInternalServerError, false, "error", err.Error(), nil)
		return
	}

	writeLabResponse(w, outcome.HTTPStatus, outcome.Success, outcome.Status, outcome.Message, outcome.Data)
}

func decodeJSONObject(r *http.Request) (map[string]any, error) {
	decoder := json.NewDecoder(r.Body)
	decoder.UseNumber()

	payload := make(map[string]any)
	if err := decoder.Decode(&payload); err != nil {
		// Laravel treats an empty, malformed, or non-object JSON body as empty
		// request input; validation then reports the first required field.
		return payload, nil
	}

	var trailing any
	if err := decoder.Decode(&trailing); !errors.Is(err, io.EOF) {
		return make(map[string]any), nil
	}
	return payload, nil
}

func validateLabRegistration(payload map[string]any) (validatedLabRegistration, string) {
	medrecID, message := requiredString(payload, "medrec_id", 50, "Medrec ID wajib diisi")
	if message != "" {
		return validatedLabRegistration{}, message
	}

	jakarta, err := time.LoadLocation("Asia/Jakarta")
	if err != nil {
		return validatedLabRegistration{}, err.Error()
	}
	registrationDate := time.Now().In(jakarta)
	if value, present := nullableValue(payload, "tanggal"); present {
		dateText, ok := value.(string)
		if !ok || !validDateFormat(dateText, jakarta) {
			return validatedLabRegistration{}, "Tanggal registrasi harus format Y-m-d"
		}
		registrationDate, _ = time.ParseInLocation("2006-01-02", dateText, jakarta)
	}

	departmentID, message := requiredString(payload, "departemen_id", 50, "Departemen wajib diisi untuk membuat registrasi")
	if message != "" {
		return validatedLabRegistration{}, message
	}
	doctorID, message := requiredString(payload, "dokter_id", 50, "Dokter penanggung jawab wajib diisi")
	if message != "" {
		return validatedLabRegistration{}, message
	}

	senderDoctorID, senderPresent, message := optionalString(payload, "dokter_pengirim_id", 50)
	if message != "" {
		return validatedLabRegistration{}, message
	}
	referrer, referrerPresent, message := optionalString(payload, "perujuk", 255)
	if message != "" {
		return validatedLabRegistration{}, message
	}
	if !senderPresent && !referrerPresent {
		return validatedLabRegistration{}, "Dokter pengirim atau perujuk wajib diisi"
	}

	patientType, message := requiredString(payload, "jenis_pasien_id", 20, "Jenis pasien wajib diisi")
	if message != "" {
		return validatedLabRegistration{}, message
	}
	patientType = strings.TrimSpace(patientType)

	tariffPeriodID, message := requiredInteger(payload, "periode_tarif_id", "Periode tarif wajib diisi")
	if message != "" {
		return validatedLabRegistration{}, message
	}
	if tariffPeriodID < 1 {
		return validatedLabRegistration{}, "The periode tarif id must be at least 1."
	}

	companyID, companyPresent, message := optionalString(payload, "perusahaan_id", 50)
	if message != "" {
		return validatedLabRegistration{}, message
	}
	insuranceID, insurancePresent, message := optionalString(payload, "asuransi_id", 50)
	if message != "" {
		return validatedLabRegistration{}, message
	}
	providerID, _, message := optionalString(payload, "provider_id", 50)
	if message != "" {
		return validatedLabRegistration{}, message
	}
	policyNumber, _, message := optionalString(payload, "nomer_polis", 100)
	if message != "" {
		return validatedLabRegistration{}, message
	}
	employeeID, _, message := optionalString(payload, "nik_karyawan", 100)
	if message != "" {
		return validatedLabRegistration{}, message
	}
	employeeName, _, message := optionalString(payload, "nama_karyawan", 255)
	if message != "" {
		return validatedLabRegistration{}, message
	}

	var groupTariffID int64
	if value, present := nullableValue(payload, "group_tarif_id"); present {
		parsed, ok := parseInteger(value)
		if !ok {
			return validatedLabRegistration{}, "The group tarif id must be an integer."
		}
		if parsed < 1 && patientType != "0" {
			return validatedLabRegistration{}, "The group tarif id must be at least 1."
		}
		groupTariffID = parsed
	}

	if patientType != "0" {
		if !companyPresent || strings.TrimSpace(companyID) == "" {
			return validatedLabRegistration{}, "Perusahaan wajib diisi untuk pasien penjamin"
		}
		if !insurancePresent || strings.TrimSpace(insuranceID) == "" {
			return validatedLabRegistration{}, "Asuransi/penanggung wajib diisi untuk pasien penjamin"
		}
		if groupTariffID < 1 {
			return validatedLabRegistration{}, "Group tarif wajib diisi untuk pasien penjamin"
		}
	} else {
		companyID = ""
		insuranceID = ""
		providerID = ""
		groupTariffID = 0
	}

	classID, classPresent, message := optionalString(payload, "kelas_id", 50)
	if message != "" {
		return validatedLabRegistration{}, message
	}
	if !classPresent || strings.TrimSpace(classID) == "" {
		classID = "Default"
	} else {
		classID = strings.TrimSpace(classID)
	}

	var dailyShiftID *int64
	if value, present := nullableValue(payload, "shift_harian_id"); present {
		parsed, ok := parseInteger(value)
		if !ok {
			return validatedLabRegistration{}, "The shift harian id must be an integer."
		}
		if parsed < 1 {
			return validatedLabRegistration{}, "The shift harian id must be at least 1."
		}
		dailyShiftID = &parsed
	}

	workingDiagnosis, message := requiredString(payload, "diagnosa_kerja", 1000, "Diagnosa kerja wajib diisi")
	if message != "" {
		return validatedLabRegistration{}, message
	}
	if utf8.RuneCountInString(workingDiagnosis) < 3 {
		return validatedLabRegistration{}, "Diagnosa kerja minimal 3 karakter"
	}
	if consistsOfOneRepeatedRune(workingDiagnosis) {
		return validatedLabRegistration{}, "Diagnosa kerja tidak valid"
	}

	notes, _, message := optionalString(payload, "catatan", 1000)
	if message != "" {
		return validatedLabRegistration{}, message
	}
	channel, channelPresent, message := optionalString(payload, "channel", 50)
	if message != "" {
		return validatedLabRegistration{}, message
	}
	if !channelPresent {
		channel = "CPONE"
	}
	channel = strings.ToUpper(strings.TrimSpace(channel))

	return validatedLabRegistration{Params: repository.LabRegistrationParams{
		MedrecID:         medrecID,
		RegistrationDate: registrationDate,
		DepartmentID:     departmentID,
		DoctorID:         doctorID,
		SenderDoctorID:   senderDoctorID,
		Referrer:         referrer,
		PatientType:      patientType,
		TariffPeriodID:   tariffPeriodID,
		CompanyID:        strings.TrimSpace(companyID),
		InsuranceID:      strings.TrimSpace(insuranceID),
		ProviderID:       strings.TrimSpace(providerID),
		GroupTariffID:    groupTariffID,
		PolicyNumber:     strings.TrimSpace(policyNumber),
		EmployeeID:       strings.TrimSpace(employeeID),
		EmployeeName:     strings.TrimSpace(employeeName),
		ClassID:          classID,
		DailyShiftID:     dailyShiftID,
		WorkingDiagnosis: workingDiagnosis,
		Notes:            notes,
		Channel:          channel,
	}}, ""
}

func requiredString(payload map[string]any, key string, maxLength int, requiredMessage string) (string, string) {
	value, exists := payload[key]
	if !exists || isLaravelEmpty(value) {
		return "", requiredMessage
	}
	text, ok := value.(string)
	if !ok {
		return "", fmt.Sprintf("The %s must be a string.", validationAttribute(key))
	}
	if maxLength > 0 && utf8.RuneCountInString(text) > maxLength {
		return "", fmt.Sprintf("The %s must not be greater than %d characters.", validationAttribute(key), maxLength)
	}
	return text, ""
}

func optionalString(payload map[string]any, key string, maxLength int) (string, bool, string) {
	value, present := nullableValue(payload, key)
	if !present {
		return "", false, ""
	}
	text, ok := value.(string)
	if !ok {
		return "", false, fmt.Sprintf("The %s must be a string.", validationAttribute(key))
	}
	if maxLength > 0 && utf8.RuneCountInString(text) > maxLength {
		return "", false, fmt.Sprintf("The %s must not be greater than %d characters.", validationAttribute(key), maxLength)
	}
	return text, true, ""
}

func requiredInteger(payload map[string]any, key string, requiredMessage string) (int64, string) {
	value, exists := payload[key]
	if !exists || isLaravelEmpty(value) {
		return 0, requiredMessage
	}
	parsed, ok := parseInteger(value)
	if !ok {
		return 0, fmt.Sprintf("The %s must be an integer.", validationAttribute(key))
	}
	return parsed, ""
}

func nullableValue(payload map[string]any, key string) (any, bool) {
	value, exists := payload[key]
	if !exists || value == nil || value == "" {
		return nil, false
	}
	return value, true
}

func parseInteger(value any) (int64, bool) {
	switch typed := value.(type) {
	case json.Number:
		if integerValue.MatchString(typed.String()) {
			parsed, err := strconv.ParseInt(typed.String(), 10, 64)
			return parsed, err == nil
		}
		parsedFloat, err := strconv.ParseFloat(typed.String(), 64)
		if err != nil || math.Trunc(parsedFloat) != parsedFloat || parsedFloat > math.MaxInt64 || parsedFloat < math.MinInt64 {
			return 0, false
		}
		return int64(parsedFloat), true
	case string:
		typed = strings.TrimSpace(typed)
		if !integerValue.MatchString(typed) || hasInvalidIntegerLeadingZero(typed) {
			return 0, false
		}
		parsed, err := strconv.ParseInt(typed, 10, 64)
		return parsed, err == nil
	case bool:
		if typed {
			return 1, true
		}
		return 0, false
	default:
		return 0, false
	}
}

func hasInvalidIntegerLeadingZero(value string) bool {
	digits := strings.TrimPrefix(strings.TrimPrefix(value, "+"), "-")
	return len(digits) > 1 && strings.HasPrefix(digits, "0")
}

func isLaravelEmpty(value any) bool {
	if value == nil || value == "" {
		return true
	}
	switch typed := value.(type) {
	case []any:
		return len(typed) == 0
	case map[string]any:
		return len(typed) == 0
	default:
		return false
	}
}

func validDateFormat(value string, location *time.Location) bool {
	parsed, err := time.ParseInLocation("2006-01-02", value, location)
	return err == nil && parsed.Format("2006-01-02") == value
}

func consistsOfOneRepeatedRune(value string) bool {
	var first rune
	count := 0
	for _, current := range value {
		if count == 0 {
			first = current
		} else if current != first {
			return false
		}
		count++
	}
	return count > 0
}

func validationAttribute(key string) string {
	return strings.ReplaceAll(key, "_", " ")
}

func writeLabResponse(
	w http.ResponseWriter,
	statusCode int,
	success bool,
	status string,
	message string,
	data *repository.LabRegistrationData,
) {
	WriteJSON(w, statusCode, LabRegistrationResponse{
		Success: success,
		Status:  status,
		Message: message,
		Data:    data,
	})
}