121 lines
2.6 KiB
Go
121 lines
2.6 KiB
Go
package main
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import (
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"bufio"
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"bytes"
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"fmt"
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"io"
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"strconv"
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"strings"
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)
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type Transaction struct {
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Date string
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Description string
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Payer string
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Payee string
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Amount float32
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}
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func readTransaction(r io.Reader) (Transaction, error) {
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lines := make([][]byte, 3)
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for i := range lines {
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line, err := nextLine(r)
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if err != nil {
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return Transaction{}, err
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}
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lines[i] = line
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}
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for i := range lines {
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if len(lines[i]) == 0 {
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return Transaction{}, fmt.Errorf("stub transaction: line %d empty: %q, %q, %q", i, lines[0], lines[1], lines[2])
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}
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}
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var transaction Transaction
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for _, foo := range []func([][]byte) error{
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transaction.readDate,
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transaction.readDescription,
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transaction.readAmount,
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transaction.readPayerPayee,
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} {
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if err := foo(lines); err != nil {
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return Transaction{}, err
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}
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}
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return transaction, nil
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}
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func nextLine(r io.Reader) ([]byte, error) {
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line, err := readLine(r)
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for err == nil && len(bytes.TrimSpace(line)) == 0 {
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line, err = readLine(r)
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}
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return line, err
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}
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func readLine(r io.Reader) ([]byte, error) {
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w := bytes.NewBuffer(make([]byte, 0, 128))
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buff := make([]byte, 1)
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n, err := r.Read(buff)
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for err == nil && n > 0 && buff[0] != '\n' {
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w.Write(buff)
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n, err = r.Read(buff)
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}
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return w.Bytes(), err
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}
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func words(b []byte) [][]byte {
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scanner := bufio.NewScanner(bytes.NewReader(b))
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scanner.Split(bufio.ScanWords)
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words := make([][]byte, 0)
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for scanner.Scan() {
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words = append(words, []byte(scanner.Text()))
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}
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return words
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}
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func (transaction *Transaction) readDate(lines [][]byte) error {
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transaction.Date = string(words(lines[0])[0])
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return nil
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}
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func (transaction *Transaction) readDescription(lines [][]byte) error {
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transaction.Description = string(bytes.Join(words(lines[0])[1:], []byte(" ")))
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return nil
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}
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func (transaction *Transaction) readAmount(lines [][]byte) error {
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amount := string(words(lines[1])[1])
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f, err := strconv.ParseFloat(strings.Trim(amount, "$"), 32)
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transaction.Amount = float32(f)
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return err
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}
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func (transaction *Transaction) readPayerPayee(lines [][]byte) error {
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payer := string(words(lines[1])[0])
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payee := string(words(lines[2])[0])
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if transaction.Amount >= 0 {
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tmp := payer
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payer = payee
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payee = tmp
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} else {
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transaction.Amount *= -1
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}
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transaction.Payer = payer
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transaction.Payee = payee
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return nil
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}
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func (transaction Transaction) Marshal() string {
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return fmt.Sprintf(
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"%-25s%s\n%25s%-50s$%.2f\n%25s%s",
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transaction.Date,
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transaction.Description,
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"",
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transaction.Payee,
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transaction.Amount,
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"",
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transaction.Payer,
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)
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}
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