import SwiftUI
import Testing
@testable import Kanban

/// **`BoardBackgroundFilters`** — the Background tab's generated picker: the default-tone rule and
/// the pure filters → `FacetsRecipe` assembly, pinned the way the popover's other pure seams are
/// (`BoardInfoMetrics`, `BoardDiskFootprint` in `BoardInfoTabTests`). Everything else about the
/// carousel — the strip's layout, the placeholder chip, the apply gesture — is SwiftUI and
/// deliberately untested; `FacetsGeneratorTests` and `GeneratedBackgroundTests` already cover the
/// generator and the write path this feeds.
@Suite("Board popover ▸ Background tab filters")
struct BoardBackgroundFiltersTests {

    @Test("Dark system appearance opens on Tone Dark, light opens on Tone Light")
    func defaultToneFollowsTheSystem() {
        #expect(BoardBackgroundFilters.defaultTone(colorScheme: .dark) == .dark)
        #expect(BoardBackgroundFilters.defaultTone(colorScheme: .light) == .light)
    }

    @Test("The opening state is mono, medium, mid — only tone varies with the system")
    func initialStateIsTheReviewedDefaults() {
        let light = BoardBackgroundFilters.initial(colorScheme: .light)
        #expect(light.tone == .light)
        #expect(light.colors == .mono)
        #expect(light.mesh == .medium)
        #expect(light.saturation == .mid)

        let dark = BoardBackgroundFilters.initial(colorScheme: .dark)
        #expect(dark.tone == .dark)
        #expect(dark.colors == .mono)
        #expect(dark.mesh == .medium)
        #expect(dark.saturation == .mid)
    }

    @Test("A hue and a seed assemble the exact recipe the filters describe")
    func recipeAssemblesEveryAxis() {
        let filters = BoardBackgroundFilters(tone: .dark, colors: .trio, mesh: .fine, saturation: .rich)
        let recipe = filters.recipe(hue: .iris, seed: 0x5EED)

        #expect(recipe.hue == .iris)
        #expect(recipe.strategy == .trio)
        #expect(recipe.density == .fine)
        #expect(recipe.tone == .dark)
        #expect(recipe.saturation == .rich)
        #expect(recipe.seed == 0x5EED)
    }

    @Test("Two hues under the same filters and seed differ only in hue")
    func onlyHueChangesAcrossTheWheel() {
        let filters = BoardBackgroundFilters.initial(colorScheme: .light)
        let sky = filters.recipe(hue: .sky, seed: 42)
        let rose = filters.recipe(hue: .rose, seed: 42)

        #expect(sky.hue == .sky)
        #expect(rose.hue == .rose)
        #expect(sky.strategy == rose.strategy)
        #expect(sky.density == rose.density)
        #expect(sky.tone == rose.tone)
        #expect(sky.saturation == rose.saturation)
        #expect(sky.seed == rose.seed)
    }

    @Test("The same filters and seed recipe identically — the preview/apply agreement the carousel depends on")
    func sameInputsRecipeIdentically() {
        let filters = BoardBackgroundFilters(tone: .light, colors: .duo, mesh: .coarse, saturation: .soft)
        #expect(filters.recipe(hue: .forest, seed: 7) == filters.recipe(hue: .forest, seed: 7))
    }
}