package main

// Hearing mesh-mail's added events (novox/hq ADR 0459 §3, §12, issue 1518): mesh-mail-reader consumes
// mesh-mail.mail.*.message.added under its own runs-as account, exactly as mesh-mail-notifier does (main.go
// AddedPattern, watchWith), but records each one as a waiting mail (store.go, pgstore.go) BEFORE the handler
// returns success — so a mail heard is never lost, even across a restart: the controller composes a durable
// consumer (MaxDeliver 5, AckWait 30s) that redelivers an event five times before it is dead-lettered, and a
// store failure here must make that redelivery happen, never swallow the event.

import (
	"context"
	"encoding/json"
	"time"
)

// EventBody is what mesh-mail's added event says of a message (metadata only; mailevent.go names where it is
// said). Unknown fields are ignored: the reader reads only what it needs, never a body.
type EventBody struct {
	Account     string   `json:"account"`
	Folder      string   `json:"folder"`
	UID         uint32   `json:"uid"`
	UIDValidity uint32   `json:"uidvalidity"`
	MessageID   string   `json:"message-id"`
	Date        string   `json:"date"`
	From        []Person `json:"from"`
	Subject     string   `json:"subject"`
	Size        int64    `json:"size"`
	Flags       []string `json:"flags"`
}

// Hear records one added event as a waiting mail (1518/AC2): the store is written to before this returns
// nil, so the caller (the bus subscription's handler) only then acknowledges the event. A store failure is
// returned unchanged, so the event is redelivered rather than lost (1518/AC2). The same event heard twice
// (1518/AC3) is recorded once: AddWaiting itself is idempotent on the mail's own identity.
func Hear(ctx context.Context, store Store, raw json.RawMessage, now func() time.Time) error {
	var body EventBody
	if err := json.Unmarshal(raw, &body); err != nil {
		// An event this reader cannot even read is taken and dropped, exactly as mesh-mail-notifier does
		// (main.go watchWith): a malformed event would otherwise be redelivered forever, never succeeding.
		return nil
	}
	date, err := time.Parse(time.RFC3339, body.Date)
	if err != nil {
		date = now()
	}
	w := WaitingMail{
		Account:     body.Account,
		Folder:      body.Folder,
		MessageID:   body.MessageID,
		UIDValidity: body.UIDValidity,
		UID:         body.UID,
		Date:        date,
		From:        body.From,
		Subject:     body.Subject,
		Flags:       body.Flags,
		Size:        body.Size,
		Heard:       now(),
	}
	return store.AddWaiting(ctx, w)
}

// AddedPattern is the mesh-mail stream's event this module consumes (its own `consumes` entry, novox/hq ADR
// 0459 §3): a new message's `added` only.
const AddedPattern = "mesh-mail.mail.*.message.added"