mv /ana, /ledger to /src/

src/ledger/transaction.go

@@ -0,0 +1,223 @@
+package ledger
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"regexp"
+	"strconv"
+	"unicode"
+)
+
+type transaction struct {
+	date        string
+	description string
+	payee       string
+	recipients  []transactionRecipient
+}
+
+func (t transaction) empty() bool {
+	return fmt.Sprint(t) == fmt.Sprint(transaction{})
+}
+
+type transactionRecipient struct {
+	name     string
+	value    float64
+	currency string
+	isSet    bool
+}
+
+func (t transactionRecipient) empty() bool {
+	return t == (transactionRecipient{})
+}
+
+func (files Files) transactions() ([]transaction, error) {
+	result := make([]transaction, 0)
+	for i := range files {
+		some, err := files._transactions(files[i])
+		if err != nil {
+			return nil, err
+		}
+		result = append(result, some...)
+	}
+	return result, nil
+}
+
+func (files Files) _transactions(file string) ([]transaction, error) {
+	f, err := os.Open(string(file))
+	if os.IsNotExist(err) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	r := bufio.NewReaderSize(f, 2048)
+
+	result := make([]transaction, 0)
+	for {
+		one, err := readTransaction(r)
+		if !one.empty() {
+			result = append(result, one)
+		}
+		if err == io.EOF {
+			return result, nil
+		}
+		if err != nil {
+			return result, err
+		}
+	}
+}
+
+func readTransaction(r *bufio.Reader) (transaction, error) {
+	result, err := _readTransaction(r)
+	if err != nil {
+		return result, err
+	}
+	if result.empty() {
+		return result, nil
+	}
+	if result.payee == "" && len(result.recipients) < 2 {
+		return result, fmt.Errorf("found a transaction with no payee and less than 2 recipeints: %+v", result)
+	}
+	if result.payee != "" && len(result.recipients) < 1 {
+		return result, fmt.Errorf("found a transaction with payee but no recipeints: %+v", result)
+	}
+	return result, nil
+}
+
+func _readTransaction(r *bufio.Reader) (transaction, error) {
+	readTransactionLeadingWhitespace(r)
+
+	firstLine, err := readTransactionLine(r)
+	if len(bytes.TrimSpace(firstLine)) == 0 {
+		return transaction{}, err
+	}
+
+	dateDescriptionPattern := regexp.MustCompile(`^([0-9]+-[0-9]+-[0-9]+)\s+(.*)$`)
+	dateDescriptionMatches := dateDescriptionPattern.FindAllSubmatch(firstLine, 4)
+	if len(dateDescriptionMatches) != 1 {
+		return transaction{}, fmt.Errorf("bad first line: %v matches: %q", len(dateDescriptionMatches), firstLine)
+	} else if len(dateDescriptionMatches[0]) != 3 {
+		return transaction{}, fmt.Errorf("bad first line: %v submatches: %q", len(dateDescriptionMatches[0]), firstLine)
+	}
+	result := transaction{
+		date:        string(dateDescriptionMatches[0][1]),
+		description: string(dateDescriptionMatches[0][2]),
+	}
+
+	for {
+		name, value, currency, isSet, err := readTransactionName(r)
+		if name != "" {
+			if currency == "" {
+				result.payee = name
+			} else {
+				result.recipients = append(result.recipients, transactionRecipient{
+					name:     name,
+					value:    value,
+					currency: currency,
+					isSet:    isSet,
+				})
+			}
+		}
+		if name == "" || err != nil {
+			return result, err
+		}
+	}
+}
+
+func readTransactionLeadingWhitespace(r *bufio.Reader) {
+	b, err := r.Peek(2048)
+	if err != nil && err != io.EOF {
+		return
+	}
+
+	i := 0
+	for i < len(b) {
+		if len(bytes.TrimSpace(b[:i])) != 0 {
+			break
+		}
+		i++
+	}
+
+	if i > 0 {
+		r.Read(make([]byte, i-1))
+	}
+}
+
+func readTransactionLine(r *bufio.Reader) ([]byte, error) {
+	for {
+		b, err := _readTransactionLine(r)
+		if err != nil || (len(bytes.TrimSpace(b)) > 0 && bytes.TrimSpace(b)[0] != '#') {
+			return b, err
+		}
+	}
+}
+
+func _readTransactionLine(r *bufio.Reader) ([]byte, error) {
+	b, err := r.Peek(2048)
+	if len(b) == 0 {
+		return nil, err
+	}
+
+	endOfLine := len(b)
+	if idx := bytes.Index(b, []byte{'\n'}); idx > -1 {
+		endOfLine = idx
+	}
+
+	b2 := make([]byte, endOfLine)
+	n, err := r.Read(b2)
+	if err == io.EOF {
+		err = nil
+	}
+
+	if check, _ := r.Peek(1); len(check) == 1 && check[0] == '\n' {
+		r.Read(make([]byte, 1))
+	}
+
+	return b2[:n], err
+}
+
+func readTransactionName(r *bufio.Reader) (string, float64, string, bool, error) {
+	line, err := readTransactionLine(r)
+	if err != nil {
+		return "", 0, "", false, err
+	}
+
+	if len(line) > 0 && !unicode.IsSpace(rune(line[0])) {
+		r2 := *r
+		*r = *bufio.NewReader(io.MultiReader(bytes.NewReader(append(line, '\n')), &r2))
+		return "", 0, "", false, nil
+	}
+
+	fields := bytes.Fields(line)
+
+	isSet := false
+	if len(fields) > 2 && string(fields[1]) == "=" {
+		isSet = true
+		fields = append(fields[:1], fields[2:]...)
+	}
+
+	switch len(fields) {
+	case 1: // payee
+		return string(fields[0]), 0, "", false, nil
+	case 2: // payee $00.00
+		b := bytes.TrimLeft(fields[1], "$")
+		value, err := strconv.ParseFloat(string(b), 64)
+		if err != nil {
+			return "", 0, "", isSet, fmt.Errorf("failed to parse value from $XX.YY from %q (%q): %w", line, fields[1], err)
+		}
+		return string(fields[0]), value, string(USD), isSet, nil
+	case 3: // payee 00.00 XYZ
+		value, err := strconv.ParseFloat(string(fields[1]), 64)
+		if err != nil {
+			return "", 0, "", false, fmt.Errorf("failed to parse value from XX.YY XYZ from %q (%q): %w", line, fields[1], err)
+		}
+		return string(fields[0]), value, string(fields[2]), isSet, nil
+	default:
+		return "", 0, "", isSet, fmt.Errorf("cannot interpret %q", line)
+	}
+}