transform.go

package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"strings"

	"github.com/gobuffalo/packr"
	jsoniter "github.com/json-iterator/go"
	"github.com/pkg/errors"
	"github.com/urfave/cli"
)

func getByPath(tr map[string]interface{}, path []interface{}) map[string]interface{} {
	res := tr

	for _, k := range path {
		key := k.(string)
		res = res[key].(map[string]interface{})

		if res == nil {
			log.Printf("cannot get trNode by path: %v", path)
			return nil
		}
	}

	return res
}

func transform(node interface{}, trNode map[string]interface{}, tr map[string]interface{}) (interface{}, error) {
	// log.Printf("=> %v %v", node, trNode)

	_, isSlice := node.([]interface{})

	if trNode["tr/act"] != nil && !isSlice {
		var res interface{}
		trAct := trNode["tr/act"].(string)

		if trAct == "union" {
			args := trNode["tr/arg"].(map[string]interface{})
			ttype := args["type"].(string)
			transformed := make(map[string]interface{})

			if tr[ttype] != nil {
				if ttype == "Reference" {
					r, _ := transform(node, map[string]interface{}{"tr/act": "reference"}, tr)
					transformed[ttype] = r
				} else {
					r, _ := transform(node, tr[ttype].(map[string]interface{}), tr)
					transformed[ttype] = r
				}
			} else {
				transformed[ttype] = node
			}

			res = transformed
		} else if trAct == "reference" {
			v := node.(map[string]interface{})

			newref := make(map[string]interface{})

			if v["reference"] != nil {
				refstr, _ := v["reference"].(string)
				refcomps := strings.Split(refstr, "/")

				if len(refcomps) == 2 {
					newref["id"] = refcomps[1]
					newref["resourceType"] = refcomps[0]
				} else {
					newref["id"] = refstr
				}
			}

			if v["display"] != nil {
				newref["display"] = v["display"].(string)
			}

			res = newref
		}

		return res, nil
	}

	switch node.(type) {
	case map[string]interface{}:
		res := make(map[string]interface{})

		for k, v := range node.(map[string]interface{}) {
			if (trNode != nil) && (trNode[k] != nil) {
				nextTrNode := trNode[k].(map[string]interface{})
				args := nextTrNode["tr/arg"]
				key := k

				if args != nil {
					argsMap := args.(map[string]interface{})

					if argsMap != nil {
						key = argsMap["key"].(string)
					}
				}

				if nextTrNode["tr/move"] != nil {
					nextTrNode = getByPath(tr, nextTrNode["tr/move"].([]interface{}))
				}

				r, _ := transform(v, nextTrNode, tr)
				res[key] = r
			} else {
				r, _ := transform(v, nil, tr)
				res[k] = r
			}
		}

		return res, nil

	case []interface{}:
		res := make([]interface{}, 0, 8)

		for _, v := range node.([]interface{}) {
			r, _ := transform(v, trNode, tr)
			res = append(res, r)
		}

		return res, nil
	default:
		return node, nil
	}
}

var transformDatas = make(map[string]interface{})

func getTransformData(fhirVersion string) (map[string]interface{}, error) {
	if transformDatas[fhirVersion] != nil {
		return transformDatas[fhirVersion].(map[string]interface{}), nil
	}

	box := packr.NewBox("./transform")
	trData, err := box.Find(fmt.Sprintf("fhirbase-import-%s.json", fhirVersion))

	if err != nil {
		return nil, errors.Wrapf(err, "failed to find transformations data for FHIR version %s", fhirVersion)
	}

	iter := jsoniter.ConfigFastest.BorrowIterator(trData)
	defer jsoniter.ConfigFastest.ReturnIterator(iter)

	tr := iter.Read().(map[string]interface{})

	if tr == nil {
		return nil, fmt.Errorf("cannot parse transformations data for FHIR version %s", fhirVersion)
	}

	transformDatas[fhirVersion] = tr

	return tr, nil
}

func doTransform(res map[string]interface{}, fhirVersion string) (map[string]interface{}, error) {
	tr, err := getTransformData(fhirVersion)

	if err != nil {
		return nil, errors.Wrap(err, "cannot get transform data")
	}

	rt, ok := res["resourceType"].(string)

	if !ok {
		return nil, fmt.Errorf("cannot determine resourceType for resource %v", res)
	}

	trNode := tr[rt]

	if trNode == nil {
		// TODO: some warning output here?
		return res, nil
	}

	trNodeMap := trNode.(map[string]interface{})

	out, err := transform(res, trNodeMap, tr)

	if err != nil {
		return nil, errors.Wrapf(err, "cannot perform transformation for resource %v", res)
	}

	outMap, ok := out.(map[string]interface{})

	if !ok {
		return nil, fmt.Errorf("incorrect format after transformation: %v", out)
	}

	return outMap, nil
}

// TransformCommand transforms FHIR resource to internal JSON representation
func TransformCommand(c *cli.Context) error {
	if c.NArg() != 1 {
		cli.ShowCommandHelp(c, "transform")

		return fmt.Errorf("Missing required argument FILE")
	}

	fhirVersion := c.GlobalString("fhir")
	filename := c.Args().Get(0)

	fileContent, err := ioutil.ReadFile(filename)

	if err != nil {
		return errors.Wrapf(err, "Error reading file %s", filename)
	}

	iter := jsoniter.ConfigFastest.BorrowIterator(fileContent)
	defer jsoniter.ConfigFastest.ReturnIterator(iter)

	res := iter.Read()

	if res == nil {
		return errors.Wrapf(err, "Error parsing file %s as JSON", filename)
	}

	out, err := doTransform(res.(map[string]interface{}), fhirVersion)

	if err != nil {
		return errors.Wrap(err, "Error performing transformation")
	}

	outJson, err := jsoniter.ConfigFastest.MarshalIndent(out, "", "  ")

	os.Stdout.Write(outJson)
	os.Stdout.Write([]byte("\n"))

	return nil
}