import XCTest
@testable import LChatCore

// The unread rule shared by refresh() and applyReadFrame(), and the ReadState
// storage behind it. The watermark half must match the web's seeding in
// shell.js loadThreads (same server field, same comparison); the manual-unread
// flag is native-only, deliberately device-local (the server mark is
// forward-only, so "unread again" can't ride the watermark itself).
final class ReadSyncTests: XCTestCase {
    func testIsUnread() {
        // Someone else's message past the watermark lights the dot…
        XCTAssertTrue(ThreadStore.isUnread(lastAt: 100, lastMine: false, seen: 50, manualUnreadAt: 0))
        // …a watermark covering it (read on ANY device) clears it…
        XCTAssertFalse(ThreadStore.isUnread(lastAt: 100, lastMine: false, seen: 100, manualUnreadAt: 0))
        XCTAssertFalse(ThreadStore.isUnread(lastAt: 100, lastMine: false, seen: 150, manualUnreadAt: 0))
        // …and your own last message never counts as unread, watermark or not.
        XCTAssertFalse(ThreadStore.isUnread(lastAt: 100, lastMine: true, seen: 0, manualUnreadAt: 0))

        // Mark-as-unread: the flag on exactly the newest message wins over a
        // covering watermark…
        XCTAssertTrue(ThreadStore.isUnread(lastAt: 100, lastMine: false, seen: 100, manualUnreadAt: 100))
        // …retires itself once a newer message arrives (the watermark rule
        // takes over)…
        XCTAssertTrue(ThreadStore.isUnread(lastAt: 120, lastMine: false, seen: 100, manualUnreadAt: 100))
        XCTAssertFalse(ThreadStore.isUnread(lastAt: 120, lastMine: false, seen: 120, manualUnreadAt: 100))
        // …and never overrides the own-message rule.
        XCTAssertFalse(ThreadStore.isUnread(lastAt: 100, lastMine: true, seen: 100, manualUnreadAt: 100))

        // An EMPTY thread (no messages, so lastAt 0) is never unread: 0 also
        // means "no manual flag", and the bare `manualUnreadAt == lastAt`
        // matched 0 == 0 — every empty thread relit its dot on every refresh
        // (the App Studio phantom dot, caught by the debug event window).
        XCTAssertFalse(ThreadStore.isUnread(lastAt: 0, lastMine: false, seen: 0, manualUnreadAt: 0))
    }

    func testManualUnreadStorage() {
        let inst = "test-\(UUID().uuidString)"
        XCTAssertEqual(ReadState.manualUnreadAt(instance: inst, thread: "t"), 0, "unset reads as 0")
        ReadState.setManualUnread(instance: inst, thread: "t", at: 42)
        XCTAssertEqual(ReadState.manualUnreadAt(instance: inst, thread: "t"), 42)
        ReadState.setManualUnread(instance: inst, thread: "t", at: 0)
        XCTAssertEqual(ReadState.manualUnreadAt(instance: inst, thread: "t"), 0, "0 clears the flag")
        UserDefaults.standard.removeObject(forKey: "lchat.unread|\(inst)|t")
    }
}