//
//  MetadataStreamProcessorTests.swift
//  AudioStreamingTests
//
//  Created by Dimitrios Chatzieleftheriou on 22/10/2020.
//  Copyright © 2020 Decimal. All rights reserved.
//

@testable import AudioStreaming

import XCTest

class MetadataStreamProcessorTests: XCTestCase {
    var metadataDelegateSpy = MetadataDelegateSpy()

    func test_Processor_SendsCorrectValues_IfItCanProcessMetadata() throws {
        let parser = MetadataParser()
        let processor = MetadataStreamProcessor(parser: parser.eraseToAnyParser())

        // without calling `metadataAvailable(step:)` it should be false
        XCTAssertFalse(processor.canProcessMetadata)

        // calling `metadataAvailable(step:)` with zero
        processor.metadataAvailable(step: 0)

        // it should be false
        XCTAssertFalse(processor.canProcessMetadata)

        // calling `metadataAvailable(step:)` with greater zero
        processor.metadataAvailable(step: 1)

        // it should be true
        XCTAssertTrue(processor.canProcessMetadata)
    }

    func test_Processor_Outputs_Correct_Metadata_ForStep_WithEmptyMetadata() throws {
        let bundle = Bundle(for: MetadataStreamProcessorTests.self)
        let url = bundle.url(forResource: "raw-stream-audio-empty-metadata", withExtension: nil)!

        let data = try Data(contentsOf: url)

        let parser = MetadataParser()
        let processor = MetadataStreamProcessor(parser: parser.eraseToAnyParser())
        processor.delegate = metadataDelegateSpy
        // this is the step value as received from the http headers
        processor.metadataAvailable(step: 16000)

        let audio = processor.processMetadata(data: data)
        XCTAssertFalse(audio.isEmpty)

        XCTAssertTrue(metadataDelegateSpy.receivedMetadata.called)
        XCTAssertEqual(metadataDelegateSpy.receivedMetadata.result, .success(["StreamTitle": ""]))
    }

    func test_Processor_Outputs_Correct_Metadata_ForStep_WithMetadata() throws {
        let bundle = Bundle(for: MetadataStreamProcessorTests.self)
        let url = bundle.url(forResource: "raw-stream-audio-normal-metadata", withExtension: nil)!

        let data = try Data(contentsOf: url)

        let parser = MetadataParser()
        let processor = MetadataStreamProcessor(parser: parser.eraseToAnyParser())
        processor.delegate = metadataDelegateSpy
        // this is the step value as received from the http headers
        processor.metadataAvailable(step: 16000)

        let audio = processor.processMetadata(data: data)
        XCTAssertFalse(audio.isEmpty)

        XCTAssertTrue(metadataDelegateSpy.receivedMetadata.called)
        XCTAssertEqual(metadataDelegateSpy.receivedMetadata.result, .success(["StreamTitle": "Anomalie - Notre"]))
    }

    func test_Processor_Outputs_Correct_Metadata_ForStep_WithMetadata_Alt() throws {
        let bundle = Bundle(for: MetadataStreamProcessorTests.self)
        let url = bundle.url(forResource: "raw-stream-audio-normal-metadata-alt", withExtension: nil)!

        let data = try Data(contentsOf: url)

        let parser = MetadataParser()
        let processor = MetadataStreamProcessor(parser: parser.eraseToAnyParser())
        processor.delegate = metadataDelegateSpy
        // this is the step value as received from the http headers
        processor.metadataAvailable(step: 8000)

        let audio = processor.processMetadata(data: data)
        XCTAssertFalse(audio.isEmpty)

        XCTAssertTrue(metadataDelegateSpy.receivedMetadata.called)
        guard case .success = metadataDelegateSpy.receivedMetadata.result else {
            XCTFail()
            return
        }
        XCTAssertNotNil(metadataDelegateSpy.receivedMetadata.result)
    }

    func test_Processor_Outputs_Correct_Metadata_ForStep_NoMetadata() throws {
        let bundle = Bundle(for: MetadataStreamProcessorTests.self)
        let url = bundle.url(forResource: "raw-stream-audio-no-metadata", withExtension: nil)!

        let data = try Data(contentsOf: url)

        let parser = MetadataParser()
        let processor = MetadataStreamProcessor(parser: parser.eraseToAnyParser())
        processor.delegate = metadataDelegateSpy
        // this is the step value as received from the http headers
        processor.metadataAvailable(step: 16000)

        let audio = processor.processMetadata(data: data)
        XCTAssertFalse(audio.isEmpty)

        XCTAssertFalse(metadataDelegateSpy.receivedMetadata.called)
        XCTAssertNil(metadataDelegateSpy.receivedMetadata.result)
    }

    func test_Processor_Outputs_SameDataAsInput_ForEmptyData() throws {
        let data = Data()

        let parser = MetadataParser()
        let processor = MetadataStreamProcessor(parser: parser.eraseToAnyParser())
        processor.delegate = metadataDelegateSpy
        // this is the step value as received from the http headers
        processor.metadataAvailable(step: 16000)

        let audio = processor.processMetadata(data: data)
        XCTAssertTrue(audio.isEmpty)

        XCTAssertFalse(metadataDelegateSpy.receivedMetadata.called)
        XCTAssertNil(metadataDelegateSpy.receivedMetadata.result)
    }
}

class MetadataDelegateSpy: MetadataStreamSourceDelegate {
    var receivedMetadata: (called: Bool, result: Result<[String: String], MetadataParsingError>?) = (false, nil)
    func didReceiveMetadata(metadata: Result<[String: String], MetadataParsingError>) {
        receivedMetadata = (true, metadata)
    }
}