import XCTest
import Foundation
@testable import ForgeProxy

final class WatchFolderTests: XCTestCase {

    var dir: String!

    override func setUpWithError() throws {
        dir = NSTemporaryDirectory() + "forge-watch-\(UUID().uuidString)"
        try FileManager.default.createDirectory(atPath: dir, withIntermediateDirectories: true)
    }

    override func tearDown() {
        try? FileManager.default.removeItem(atPath: dir)
    }

    // New stable file enqueued exactly once.
    func testNewFileEnqueuedOnce() async throws {
        let watcher = WatchFolder(
            path: dir,
            extensions: ["mov"],
            pollInterval: .milliseconds(30),
            stabilityChecks: 2)
        var enqueued = [String]()
        let stream = await watcher.start()

        try Data("clip".utf8).write(to: URL(fileURLWithPath: dir + "/C001.mov"))

        let collector = Task {
            for await path in stream {
                enqueued.append(path)
            }
        }
        try await Task.sleep(for: .milliseconds(400))
        await watcher.stop()
        _ = await collector.result

        XCTAssertEqual(enqueued.count, 1)
        XCTAssertTrue(enqueued[0].hasSuffix("C001.mov"))
    }

    // Growing file (partial write) not enqueued until size stable.
    func testGrowingFileWaitsForStability() async throws {
        let watcher = WatchFolder(
            path: dir,
            extensions: ["mov"],
            pollInterval: .milliseconds(40),
            stabilityChecks: 2)
        let path = dir + "/GROW.mov"
        try Data("start".utf8).write(to: URL(fileURLWithPath: path))

        let stream = await watcher.start()
        actor Seen {
            var paths = [String]()
            var at: [ContinuousClock.Instant] = []
            func add(_ p: String) {
                paths.append(p)
                at.append(.now)
            }
        }
        let seen = Seen()
        let collector = Task {
            for await p in stream {
                await seen.add(p)
            }
        }

        // Keep growing for ~200ms.
        for i in 0..<5 {
            try await Task.sleep(for: .milliseconds(40))
            let h = FileHandle(forWritingAtPath: path)!
            h.seekToEndOfFile()
            h.write(Data("more\(i)".utf8))
            try h.close()
        }
        let growEnd = ContinuousClock.now
        try await Task.sleep(for: .milliseconds(400))
        await watcher.stop()
        _ = await collector.result

        let paths = await seen.paths
        let times = await seen.at
        XCTAssertEqual(paths.count, 1)
        // Enqueue happened after growth stopped.
        XCTAssertGreaterThan(times[0], growEnd)
    }

    // Extension filter.
    func testExtensionFilter() async throws {
        let watcher = WatchFolder(path: dir, extensions: ["mov"], pollInterval: .milliseconds(30), stabilityChecks: 1)
        try Data("x".utf8).write(to: URL(fileURLWithPath: dir + "/note.txt"))
        try Data("y".utf8).write(to: URL(fileURLWithPath: dir + "/C002.mov"))

        let stream = await watcher.start()
        var enqueued = [String]()
        let collector = Task {
            for await p in stream { enqueued.append(p) }
        }
        try await Task.sleep(for: .milliseconds(300))
        await watcher.stop()
        _ = await collector.result

        XCTAssertEqual(enqueued.count, 1)
        XCTAssertTrue(enqueued[0].hasSuffix(".mov"))
    }

    // Already-processed file skipped across watcher runs via skip list.
    func testSkipListPersistsAcrossRuns() async throws {
        try Data("x".utf8).write(to: URL(fileURLWithPath: dir + "/C003.mov"))

        let skipList = ProcessedSkipList()
        let w1 = WatchFolder(path: dir, extensions: ["mov"], pollInterval: .milliseconds(30), stabilityChecks: 1, skipList: skipList)
        let s1 = await w1.start()
        var first = [String]()
        let c1 = Task { for await p in s1 { first.append(p) } }
        try await Task.sleep(for: .milliseconds(250))
        await w1.stop()
        _ = await c1.result
        XCTAssertEqual(first.count, 1)

        // Second watcher with same skip list: nothing new.
        let w2 = WatchFolder(path: dir, extensions: ["mov"], pollInterval: .milliseconds(30), stabilityChecks: 1, skipList: skipList)
        let s2 = await w2.start()
        var second = [String]()
        let c2 = Task { for await p in s2 { second.append(p) } }
        try await Task.sleep(for: .milliseconds(250))
        await w2.stop()
        _ = await c2.result
        XCTAssertTrue(second.isEmpty)
    }
}