import Foundation
import Testing
import Vision

@testable import Photochk

@Suite("キャッシュ")
struct FingerprintCacheTests {
    private func makeFile(at directory: URL) throws -> ScannedFile {
        let url = directory.appendingPathComponent("cached.jpg")
        try TestImages.writeJPEG(TestImages.pattern(seed: 3), to: url, quality: 0.9)

        let values = try url.resourceValues(forKeys: [.fileSizeKey, .contentModificationDateKey])
        return ScannedFile(
            url: url,
            fileSize: Int64(values.fileSize ?? 0),
            modificationDate: values.contentModificationDate ?? Date(),
            creationDate: nil
        )
    }

    @Test("dHash と feature print がディスクを経由して復元できる")
    func roundTrip() async throws {
        let directory = try TestImages.makeTemporaryDirectory()
        defer { try? FileManager.default.removeItem(at: directory) }

        let file = try makeFile(at: directory)
        let cacheURL = directory.appendingPathComponent("cache.plist")

        let basics = try #require(DHash.compute(for: file.url))
        let print = try await FeaturePrinter.compute(for: file.url)

        let writer = FingerprintCache(fileURL: cacheURL)
        await writer.store(basics: [file.url: basics], for: [file])
        await writer.store(featurePrints: [file.url: print], for: [file])
        await writer.save()

        let reader = FingerprintCache(fileURL: cacheURL)
        let restoredBasics = await reader.basics(for: [file])
        let restoredPrints = await reader.featurePrints(for: [file])

        #expect(restoredBasics[file.url]?.dHash == basics.dHash)
        let restoredPrint = try #require(restoredPrints[file.url])
        // 同一の特徴量なので距離は 0
        #expect(try restoredPrint.distance(to: print) == 0)
    }

    @Test("ファイルが更新されていたらキャッシュは使われない")
    func invalidatesOnChange() async throws {
        let directory = try TestImages.makeTemporaryDirectory()
        defer { try? FileManager.default.removeItem(at: directory) }

        let file = try makeFile(at: directory)
        let cache = FingerprintCache(fileURL: nil)
        let basics = try #require(DHash.compute(for: file.url))
        await cache.store(basics: [file.url: basics], for: [file])

        let changed = ScannedFile(
            url: file.url,
            fileSize: file.fileSize + 100,
            modificationDate: file.modificationDate,
            creationDate: nil
        )
        #expect(await cache.basics(for: [changed]).isEmpty)
        #expect(await cache.basics(for: [file]).count == 1)
    }

    @Test("消えたファイルのエントリは prune で捨てられる")
    func prunesMissingFiles() async throws {
        let directory = try TestImages.makeTemporaryDirectory()
        defer { try? FileManager.default.removeItem(at: directory) }

        let file = try makeFile(at: directory)
        let cache = FingerprintCache(fileURL: nil)
        let basics = try #require(DHash.compute(for: file.url))
        await cache.store(basics: [file.url: basics], for: [file])

        await cache.prune(keeping: [])
        #expect(await cache.basics(for: [file]).isEmpty)
    }
}