86 lines
1.8 KiB
Go
86 lines
1.8 KiB
Go
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package pipe
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import (
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"encoding/json"
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"errors"
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"fmt"
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"strconv"
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"strings"
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)
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const fieldsLength = 4
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// Record stores fields of a log line.
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type Record struct {
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Domain string
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Page string
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Visits int
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Uniques int
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}
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// Sum the numeric fields with another record.
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func (r Record) Sum(other Record) Record {
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r.Visits += other.Visits
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r.Uniques += other.Uniques
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return r
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}
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// UnmarshalText to a *Record.
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func (r *Record) UnmarshalText(p []byte) (err error) {
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fields := strings.Fields(string(p))
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if len(fields) != fieldsLength {
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return fmt.Errorf("wrong number of fields %q", fields)
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}
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r.Domain, r.Page = fields[0], fields[1]
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if r.Visits, err = parseStr("visits", fields[2]); err != nil {
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return err
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}
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if r.Uniques, err = parseStr("uniques", fields[3]); err != nil {
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return err
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}
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return validate(*r)
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}
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// UnmarshalJSON to a *Record.
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func (r *Record) UnmarshalJSON(data []byte) error {
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// `methodless` doesn't have any methods including UnmarshalJSON.
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// This trick prevents the stack-overflow (infinite loop).
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type methodless Record
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var m methodless
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if err := json.Unmarshal(data, &m); err != nil {
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return err
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}
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// Cast back to the Record and save.
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*r = Record(m)
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return validate(*r)
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}
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// parseStr helps UnmarshalText for string to positive int parsing.
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func parseStr(name, v string) (int, error) {
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n, err := strconv.Atoi(v)
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if err != nil {
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return 0, fmt.Errorf("Record.UnmarshalText %q: %v", name, err)
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}
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return n, nil
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}
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// validate whether a parsed record is valid or not.
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func validate(r Record) (err error) {
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switch {
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case r.Domain == "":
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err = errors.New("record.domain cannot be empty")
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case r.Page == "":
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err = errors.New("record.page cannot be empty")
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case r.Visits < 0:
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err = errors.New("record.visits cannot be negative")
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case r.Uniques < 0:
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err = errors.New("record.uniques cannot be negative")
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}
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return
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}
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