import XCTest
@testable import LChatCore

// 🤖 Pins the notification monogram to the Avatar view's rules (initial +
// djb2 palette pick) so a person's banner face can't drift from their in-app
// face, and smoke-tests the render.
final class MonogramImageTests: XCTestCase {
    func testInitialMirrorsAvatarView() {
        XCTAssertEqual(MonogramImage.initial(for: "paul"), "P")
        XCTAssertEqual(MonogramImage.initial(for: "  Éowyn  "), "É")
        XCTAssertEqual(MonogramImage.initial(for: "   "), "?")
        XCTAssertEqual(MonogramImage.initial(for: "🦊 Fox"), "🦊")
    }

    func testPaletteIndexIsDeterministicDjb2() {
        // djb2("Eleven") computed by the Avatar view's exact loop.
        var h = 5381
        for b in "Eleven".utf8 { h = (h &* 33) &+ Int(b) }
        XCTAssertEqual(MonogramImage.paletteIndex(for: "Eleven"), abs(h) % 8)
        XCTAssertEqual(MonogramImage.paletteIndex(for: "Eleven"),
                       MonogramImage.paletteIndex(for: "Eleven"))
        XCTAssertTrue((0..<8).contains(MonogramImage.paletteIndex(for: "任意の名前")))
    }

    func testRendersNonEmptyPNG() throws {
        let data = try XCTUnwrap(MonogramImage.pngData(name: "Paul"))
        // PNG magic — a real encode, not junk bytes.
        XCTAssertEqual(Array(data.prefix(4)), [0x89, 0x50, 0x4E, 0x47])
        XCTAssertGreaterThan(data.count, 500)
    }
}