package ntfy

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
)

// Event is one NDJSON object from GET /topic/json.
type Event struct {
	ID         string          `json:"id"`
	Time       int64           `json:"time"`
	Expires    int64           `json:"expires,omitempty"`
	Event      string          `json:"event"`
	Topic      string          `json:"topic"`
	Message    string          `json:"message"`
	Title      string          `json:"title"`
	Tags       []string        `json:"tags"`
	Priority   int             `json:"priority"`
	Click      string          `json:"click"`
	SequenceID string          `json:"sequence_id,omitempty"`
	Attachment *Attachment     `json:"attachment,omitempty"`
	Actions    json.RawMessage `json:"actions,omitempty"`
}

// Attachment describes a file linked from a message.
type Attachment struct {
	Name    string `json:"name"`
	URL     string `json:"url"`
	Type    string `json:"type,omitempty"`
	Size    int64  `json:"size,omitempty"`
	Expires int64  `json:"expires,omitempty"`
}

// ParseLine decodes one NDJSON line. ok is false for blank lines.
func ParseLine(line []byte) (Event, bool, error) {
	line = bytes.TrimSpace(line)
	if len(line) == 0 {
		return Event{}, false, nil
	}
	var ev Event
	if err := json.Unmarshal(line, &ev); err != nil {
		return Event{}, false, err
	}
	if ev.Event == "" {
		return Event{}, false, fmt.Errorf("missing event")
	}
	return ev, true, nil
}

// ReadLines yields each decoded event until EOF or a read error.
// Malformed JSON is reported and skipped so one bad line does not kill the stream.
func ReadLines(r io.Reader, yield func(Event) error, onBad func(error)) error {
	sc := newScanner(r)
	for sc.Scan() {
		ev, ok, err := ParseLine(sc.Bytes())
		if err != nil {
			if onBad != nil {
				onBad(err)
			}
			continue
		}
		if !ok {
			continue
		}
		if err := yield(ev); err != nil {
			return err
		}
	}
	return sc.Err()
}