package model

import (
	"fmt"
	"strings"

	"modelRT/constants"
	"modelRT/orm"
)

var allowedMeasurementTypes = map[string]struct{}{
	"TM": {},
	"TS": {},
	"TC": {},
	"TA": {},
	"SP": {},
}

// MeasurementTypeFromDataSource returns the two-character measurement type
// encoded in a CL3611 channel. Only TM, TS, TC, TA, and SP are valid.
func MeasurementTypeFromDataSource(dataSource orm.JSONMap) (string, error) {
	dataSourceType, err := integerJSONValue(dataSource["type"])
	if err != nil {
		return "", fmt.Errorf("invalid measurement data_source type: %w", err)
	}
	if dataSourceType != constants.DataSourceTypeCL3611 {
		return "", fmt.Errorf("measurement type requires data_source type %d, got %d", constants.DataSourceTypeCL3611, dataSourceType)
	}

	ioAddress, ok := dataSource["io_address"].(map[string]any)
	if !ok {
		if value, jsonMapOK := dataSource["io_address"].(orm.JSONMap); jsonMapOK {
			ioAddress = map[string]any(value)
		} else {
			return "", fmt.Errorf("measurement data_source io_address is not an object")
		}
	}

	channel, ok := ioAddress["channel"].(string)
	if !ok || len(channel) < 2 {
		return "", fmt.Errorf("measurement data_source channel must contain at least two characters")
	}

	measurementType := strings.ToUpper(channel[:2])
	if _, ok := allowedMeasurementTypes[measurementType]; !ok {
		return "", fmt.Errorf("unsupported measurement type %q", measurementType)
	}
	return measurementType, nil
}

func integerJSONValue(value any) (int, error) {
	switch typed := value.(type) {
	case int:
		return typed, nil
	case int8:
		return int(typed), nil
	case int16:
		return int(typed), nil
	case int32:
		return int(typed), nil
	case int64:
		return int(typed), nil
	case float32:
		converted := int(typed)
		if typed != float32(converted) {
			return 0, fmt.Errorf("expected integer, got %v", typed)
		}
		return converted, nil
	case float64:
		converted := int(typed)
		if typed != float64(converted) {
			return 0, fmt.Errorf("expected integer, got %v", typed)
		}
		return converted, nil
	default:
		return 0, fmt.Errorf("expected integer, got %T", value)
	}
}