import XCTest
import Foundation
import ForgeGrade
import ForgeColor
@testable import ForgeVideo

final class VideoTests: XCTestCase {

    // Solid-color test source produces frames of declared size.
    func testTestPatternSource() async throws {
        let source = TestPatternSource(width: 8, height: 4, color: SIMD3(0.5, 0.25, 0.75))
        let frame = try await source.nextFrame()
        XCTAssertEqual(frame.width, 8)
        XCTAssertEqual(frame.height, 4)
        XCTAssertEqual(frame.pixels.count, 8 * 4)
        XCTAssertEqual(frame.pixels[0].x, 0.5, accuracy: 1e-6)
    }

    // Grading a frame applies the stack per pixel.
    func testGradeFrame() async throws {
        let source = TestPatternSource(width: 4, height: 2, color: SIMD3(0.25, 0.25, 0.25))
        let stack = GradeStack(nodes: [GradeNode(kind: .cdl(CDL(
            slope: SIMD3(2, 2, 2), offset: .zero, power: .one, saturation: 1)))])
        let frame = try await source.nextFrame()
        let graded = FrameProcessor.apply(stack: stack, to: frame)
        XCTAssertEqual(graded.pixels[0].x, 0.5, accuracy: 1e-6)
        XCTAssertEqual(graded.width, 4)
        // Timecode preserved.
        XCTAssertEqual(graded.timecode, frame.timecode)
    }

    // Still grab writes PPM (portable, no image lib dep) and returns path.
    func testStillGrabWritesPPM() async throws {
        let source = TestPatternSource(width: 4, height: 4, color: SIMD3(1, 0, 0))
        let frame = try await source.nextFrame()
        let dir = NSTemporaryDirectory() + "forge-stills-\(UUID().uuidString)"
        let grabber = StillGrabber(directory: dir)
        let path = try grabber.grab(frame: frame, clipName: "A001C001")
        defer { try? FileManager.default.removeItem(atPath: dir) }

        XCTAssertTrue(FileManager.default.fileExists(atPath: path))
        XCTAssertTrue(path.hasSuffix(".ppm"))
        XCTAssertTrue(path.contains("A001C001"))
        let data = try Data(contentsOf: URL(fileURLWithPath: path))
        // Compare header bytes directly — string decoding of Data slices is
        // unreliable across Foundation implementations.
        let expectedHeader = [UInt8]("P6\n4 4\n255\n".utf8)
        XCTAssertEqual([UInt8](data.prefix(expectedHeader.count)), expectedHeader)
        // First pixel red: 255 0 0.
        let headerLen = "P6\n4 4\n255\n".utf8.count
        XCTAssertEqual(data[headerLen], 255)
        XCTAssertEqual(data[headerLen + 1], 0)
        XCTAssertEqual(data[headerLen + 2], 0)
    }

    // Values clamp to 0-255 on write.
    func testStillClampsRange() async throws {
        let source = TestPatternSource(width: 2, height: 2, color: SIMD3(2.0, -0.5, 0.5))
        let frame = try await source.nextFrame()
        let dir = NSTemporaryDirectory() + "forge-stills-\(UUID().uuidString)"
        defer { try? FileManager.default.removeItem(atPath: dir) }
        let path = try StillGrabber(directory: dir).grab(frame: frame, clipName: "clamp")
        let data = try Data(contentsOf: URL(fileURLWithPath: path))
        let headerLen = "P6\n2 2\n255\n".utf8.count
        XCTAssertEqual(data[headerLen], 255)     // 2.0 -> 255
        XCTAssertEqual(data[headerLen + 1], 0)   // -0.5 -> 0
        XCTAssertEqual(data[headerLen + 2], 128) // 0.5 -> 128 (rounded)
    }

    // Null sink accepts frames without error (SDI-out stand-in).
    func testNullSink() async throws {
        let sink = NullFrameSink()
        let source = TestPatternSource(width: 2, height: 2, color: .zero)
        try await sink.consume(frame: try await source.nextFrame())
        let count = await sink.consumedCount
        XCTAssertEqual(count, 1)
    }
}