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txt.go
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txt.go
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// Copyright © 2011-12 Qtrac Ltd.
//
// This program or package and any associated files are licensed under the
// Apache License, Version 2.0 (the "License"); you may not use these files
// except in compliance with the License. You can get a copy of the License
// at: http://www.apache.org/licenses/LICENSE-2.0.
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"bufio"
"errors"
"fmt"
"io"
"strings"
"time"
)
const noteSep = ":"
type TxtMarshaler struct{}
func (TxtMarshaler) MarshalInvoices(writer io.Writer,
invoices []*Invoice) error {
bufferedWriter := bufio.NewWriter(writer)
defer bufferedWriter.Flush()
var write writerFunc = func(format string,
args ...interface{}) error {
_, err := fmt.Fprintf(bufferedWriter, format, args...)
return err
}
if err := write("%s %d\n", fileType, fileVersion); err != nil {
return err
}
for _, invoice := range invoices {
if err := write.writeInvoice(invoice); err != nil {
return err
}
}
return nil
}
type writerFunc func(string, ...interface{}) error
func (write writerFunc) writeInvoice(invoice *Invoice) error {
note := ""
if invoice.Note != "" {
note = noteSep + " " + invoice.Note
}
if err := write("INVOICE ID=%d CUSTOMER=%d DEPARTMENT=%s RAISED=%s "+
"DUE=%s PAID=%t%s\n", invoice.Id, invoice.CustomerId,
invoice.DepartmentId, invoice.Raised.Format(dateFormat),
invoice.Due.Format(dateFormat), invoice.Paid, note); err != nil {
return err
}
if err := write.writeItems(invoice.Items); err != nil {
return err
}
return write("\f\n")
}
func (write writerFunc) writeItems(items []*Item) error {
for _, item := range items {
note := ""
if item.Note != "" {
note = noteSep + " " + item.Note
}
if err := write("ITEM ID=%s PRICE=%.2f QUANTITY=%d TAXBAND=%d%s\n",
item.Id, item.Price, item.Quantity, item.TaxBand, note);
err != nil {
return err
}
}
return nil
}
func (TxtMarshaler) UnmarshalInvoices(reader io.Reader) (
invoices []*Invoice, err error) {
bufferedReader := bufio.NewReader(reader)
var version int
if version, err = checkTxtVersion(bufferedReader); err != nil {
return nil, err
}
var line string
eof := false
for lino := 2; !eof; lino++ {
line, err = bufferedReader.ReadString('\n')
if err == io.EOF {
err = nil
eof = true
} else if err != nil {
return nil, err
}
if invoices, err = parseTxtLine(version, lino, line, invoices);
err != nil {
return nil, err
}
}
return invoices, nil
}
func checkTxtVersion(bufferedReader *bufio.Reader) (version int,
err error) {
if _, err = fmt.Fscanf(bufferedReader, "INVOICES %d\n", &version);
err != nil {
err = errors.New("cannot read non-invoices text file")
} else if version > fileVersion {
err = fmt.Errorf("version %d is too new to read", version)
}
return version, err
}
func parseTxtLine(version, lino int, line string, invoices []*Invoice) (
[]*Invoice, error) {
var err error
if strings.HasPrefix(line, "INVOICE") {
var invoice *Invoice
invoice, err = parseTxtInvoice(version, lino, line)
invoices = append(invoices, invoice)
} else if strings.HasPrefix(line, "ITEM") {
if len(invoices) == 0 {
err = fmt.Errorf("item outside of an invoice line %d", lino)
} else {
var item *Item
item, err = parseTxtItem(version, lino, line)
items := &invoices[len(invoices)-1].Items
*items = append(*items, item)
}
}
return invoices, err
}
func parseTxtInvoice(version, lino int, line string) (invoice *Invoice,
err error) {
invoice = &Invoice{}
var raised, due string
if version == fileVersion {
if _, err = fmt.Sscanf(line, "INVOICE ID=%d CUSTOMER=%d "+
"DEPARTMENT=%s RAISED=%s DUE=%s PAID=%t", &invoice.Id,
&invoice.CustomerId, &invoice.DepartmentId, &raised, &due,
&invoice.Paid); err != nil {
return nil, fmt.Errorf("invalid invoice %v line %d", err, lino)
}
} else {
if _, err = fmt.Sscanf(line, "INVOICE ID=%d CUSTOMER=%d "+
"RAISED=%s DUE=%s PAID=%t", &invoice.Id,
&invoice.CustomerId, &raised, &due, &invoice.Paid);
err != nil {
return nil, fmt.Errorf("invalid invoice %v line %d", err, lino)
}
}
if invoice.Raised, err = time.Parse(dateFormat, raised); err != nil {
return nil, fmt.Errorf("invalid raised %v line %d", err, lino)
}
if invoice.Due, err = time.Parse(dateFormat, due); err != nil {
return nil, fmt.Errorf("invalid due %v line %d", err, lino)
}
if i := strings.Index(line, noteSep); i > -1 {
invoice.Note = strings.TrimSpace(line[i+len(noteSep):])
}
if version < fileVersion {
updateInvoice(invoice)
}
return invoice, nil
}
func parseTxtItem(version, lino int, line string) (item *Item,
err error) {
item = &Item{}
if version == fileVersion {
if _, err = fmt.Sscanf(line, "ITEM ID=%s PRICE=%f "+
"QUANTITY=%d TAXBAND=%d", &item.Id, &item.Price,
&item.Quantity, &item.TaxBand); err != nil {
return nil, fmt.Errorf("invalid item %v line %d", err, lino)
}
} else {
if _, err = fmt.Sscanf(line, "ITEM ID=%s PRICE=%f QUANTITY=%d",
&item.Id, &item.Price, &item.Quantity); err != nil {
return nil, fmt.Errorf("invalid item %v line %d", err, lino)
}
}
if i := strings.Index(line, noteSep); i > -1 {
item.Note = strings.TrimSpace(line[i+len(noteSep):])
}
if version < fileVersion {
updateItem(item)
}
return item, nil
}