// Models/LocalNotification.swift
// ------------------------------
// SwiftData model backing the in-app notification inbox.
//
// WHY THIS IS A LOCAL STORE, unlike every other server-backed list in the app.
// `GET /api/v1/notifications` is a POLLER, not an inbox: it filters to
// `is_read = False` and never sends the flag at all
// (app/api/notifications.py :: list_notifications). So the instant a
// notification is marked read the server stops returning it — there is no
// response the iPad could render as "read", and before this every row in the
// list was unread by definition, which is why they all looked identical.
// Keeping our own copy is the only way to show read and unread side by side.
//
// The web already has a real inbox (routes/notifications.py :: index, with an
// all / unread / read filter and paging). If a mobile equivalent is ever added,
// this model should become a cache of it rather than the source of truth — see
// rule 92.
//
// Scope: notifications are per-user, so this is purged on an identity change
// like everything else (rule 88).

import Foundation
import SwiftData

@Model
final class LocalNotification {

    /// Server notification id — stable identity, and the value
    /// `PATCH /api/v1/notifications/mark-read` takes.
    /// No inline default: a `.unique` key must not carry one (rule 63).
    @Attribute(.unique) var serverId: Int

    var title: String
    var body: String

    /// e.g. `issue_assigned`, `sla_alert`, `scheduled_inspection`. Nil for rows
    /// created before the server's phase17 migration added the column.
    var eventType: String?

    /// Set when the notification refers to an issue — drives "View Issue".
    var issueId: Int?

    /// Server `created_at`, parsed. Falls back to receipt time when the string
    /// cannot be parsed so ordering never collapses to a single instant.
    var createdAt: Date

    /// When THIS device first saw it. Distinct from `createdAt`: a notification
    /// raised while the iPad was offline arrives late but keeps its real time.
    var receivedAt: Date

    // ── Read state ────────────────────────────────────────────────────────
    // Set optimistically on tap / Mark All so the UI responds offline, then
    // pushed to the server. Read state is shared with the web (rule 92).

    var isRead: Bool = false
    var readAt: Date?

    /// True while this row's read state has not yet reached the server.
    /// Drained by `SyncManager.pushNotificationReadState()`.
    ///
    /// Non-optional with an inline default so SwiftData migrates lightweight
    /// (rule 8).
    var readSyncPending: Bool = false

    init(from api: APINotification) {
        self.serverId        = api.id
        self.title           = api.title
        self.body            = api.body
        self.eventType       = api.eventType
        self.issueId         = api.issueId
        self.createdAt       = SyncManager.isoFormatter.date(from: api.createdAt) ?? Date()
        self.receivedAt      = Date()
        self.isRead          = false
        self.readAt          = nil
        self.readSyncPending = false
    }

    /// Refresh the mutable text from a later poll.
    ///
    /// Deliberately does NOT touch `isRead`. The endpoint only ever returns
    /// UNREAD rows, so being returned again carries no information about read
    /// state — it usually just means our mark-read has not been pushed yet.
    /// Clobbering it here would make a notification the inspector just opened
    /// pop straight back to unread.
    func update(from api: APINotification) {
        self.title     = api.title
        self.body      = api.body
        self.eventType = api.eventType
        self.issueId   = api.issueId
        if let parsed = SyncManager.isoFormatter.date(from: api.createdAt) {
            self.createdAt = parsed
        }
    }

    /// Mark read locally and queue the server push. Idempotent.
    func markRead() {
        guard !isRead else { return }
        isRead          = true
        readAt          = Date()
        readSyncPending = true
    }
}