package apple

import (
	"encoding/base64"
	"encoding/json"
	"strings"
	"time"
)

func ParseTransactionJWS(jws string) (*TransactionPayload, error) {
	parts := strings.Split(jws, ".")
	if len(parts) != 3 {
		return nil, ErrInvalidJWS
	}
	payloadB64 := parts[1]
	// add padding if required
	switch len(payloadB64) % 4 {
	case 2:
		payloadB64 += "=="
	case 3:
		payloadB64 += "="
	}
	data, err := base64.RawURLEncoding.DecodeString(payloadB64)
	if err != nil {
		return nil, err
	}
	var raw map[string]interface{}
	if err = json.Unmarshal(data, &raw); err != nil {
		return nil, err
	}
	var resp TransactionPayload
	if v, ok := raw["bundleId"].(string); ok {
		resp.BundleId = v
	}
	if v, ok := raw["productId"].(string); ok {
		resp.ProductId = v
	}
	if v, ok := raw["transactionId"].(string); ok {
		resp.TransactionId = v
	}
	if v, ok := raw["originalTransactionId"].(string); ok {
		resp.OriginalTransactionId = v
	}
	if v, ok := raw["purchaseDate"].(float64); ok {
		resp.PurchaseDate = time.UnixMilli(int64(v))
	} else if v, ok := raw["purchaseDate"].(int64); ok {
		resp.PurchaseDate = time.UnixMilli(v)
	}
	if v, ok := raw["revocationDate"].(float64); ok {
		t := time.UnixMilli(int64(v))
		resp.RevocationDate = &t
	}
	return &resp, nil
}