import CompressNIO
import Configuration
import Foundation
import Hummingbird
import HummingbirdTesting
import Infrastructure
import NIOCore
import Testing

@testable import Website
@testable import WebsiteLibrary

@Suite("App executable")
struct AppTests {

    // MARK: Constants

    // Referenced through fingerprinted URLs, or an immutable subset file in the case of a font, so all of these are served immutable.
    private let immutableExtensions: [AssetExtension] = [
        .css,
        .jpg,
        .js,
        .mp4,
        .webp,
        .woff2
    ]

    // Absolute path to the copy of the package's "Resources/Static" folder made into the test bundle
    // at build time — the repository tree itself is off limits to Xcode's test runner.
    private let staticFilesPath: String = {
        guard let url = Bundle.module.url(
            forResource: "Static",
            withExtension: nil
        ) else {
            preconditionFailure("The static files are missing from the test bundle.")
        }

        return url.path
    }()

    // MARK: Functional tests

    @Test
    func `landing page to be served at root`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/",
                method: .get
            ) { response in
                let body = String(buffer: response.body)

                #expect(response.status == .ok)
                #expect(response.headers[.contentType] == "text/html; charset=utf-8")
                #expect(body.contains("Hello world!"))
            }
        }
    }

    @Test
    func `landing page to answer a head request`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/",
                method: .head
            ) { response in
                #expect(response.status == .ok)
                #expect(response.headers[.contentType] == "text/html; charset=utf-8")
                #expect(response.body.readableBytes == 0)
            }
        }
    }

    @Test
    func `health check to be served at the health path`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/health",
                method: .get
            ) { response in
                let body = String(buffer: response.body)

                #expect(response.status == .ok)
                #expect(response.headers[.contentType] == "application/json")
                #expect(body == #"{"status":"ok"}"#)
            }
        }
    }

    @Test
    func `readiness check to be served at the readiness path`() async throws {
        // Live mode runs the application's service group, so the `Fluent` service starts before the
        // request and shuts its connection pool down after — the router-only mode never would.
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.live) { client in
            try await client.execute(
                uri: "/health/ready",
                method: .get
            ) { response in
                let body = String(buffer: response.body)

                #expect(response.status == .ok)
                #expect(response.headers[.contentType] == "application/json")
                #expect(body == #"{"status":"ready"}"#)
            }
        }
    }

    @Test(arguments: StaticFile.all)
    func `static files to be served`(
        staticFile file: StaticFile
    ) async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            for fileExtension in file.fileExtensions {
                try await client.execute(
                    uri: "/\(file.relativePath(for: fileExtension))",
                    method: .get
                ) { response in
                    #expect(response.status == .ok)
                    #expect(response.headers[.contentType] == fileExtension.contentType)

                    let cacheControl = try #require(response.headers[.cacheControl])

                    #expect(cacheControl.contains("public") == true)
                    #expect(cacheControl.contains("max-age=") == true)

                    if immutableExtensions.contains(fileExtension) {
                        #expect(cacheControl.contains("immutable") == true)
                    } else if fileExtension == .txt {
                        #expect(cacheControl.contains("must-revalidate") == true)
                    }
                }
            }
        }
    }

    @Test
    func `versioned asset URL to be served`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/css/shared.css?v=0123456789abcdef",
                method: .get
            ) { response in
                #expect(response.status == .ok)
                #expect(response.headers[.contentType] == "text/css")
            }
        }
    }

    @Test
    func `landing page to reference fingerprinted assets`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/",
                method: .get
            ) { response in
                let body = String(buffer: response.body)

                #expect(body.contains("/css/shared.css?v="))
                #expect(body.contains("/js/shared.js?v="))
            }
        }
    }

    @Test
    func `landing page to revalidate with an entity tag`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            let eTag = try await client.execute(
                uri: "/",
                method: .get
            ) { response in
                #expect(response.headers[.cacheControl] == "public, no-cache")

                return try #require(response.headers[.eTag])
            }

            try await client.execute(
                uri: "/",
                method: .get,
                headers: [.ifNoneMatch: eTag]
            ) { response in
                #expect(response.status == .notModified)
                #expect(response.body.readableBytes == 0)
                #expect(response.headers[.eTag] == eTag)
            }
        }
    }

    @Test
    func `responses to vary on language and encoding`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/",
                method: .get
            ) { response in
                let vary = try #require(response.headers[.vary])

                #expect(vary.contains("Accept-Language"))
                #expect(vary.contains("Accept-Encoding"))
            }
        }
    }

    @Test
    func `response to be compressed when the client supports it`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/",
                method: .get,
                headers: [.acceptEncoding: "gzip"]
            ) { response in
                #expect(response.status == .ok)
                #expect(response.headers[.contentEncoding] == "gzip")
            }
        }
    }

    @Test
    func `response to not be compressed when the client does not support it`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/",
                method: .get
            ) { response in
                #expect(response.status == .ok)
                #expect(response.headers[.contentEncoding] == nil)
            }
        }
    }

    /// `CompressionMiddleware` stands in for Hummingbird's `ResponseCompressionMiddleware`, which appends to `Content-Encoding` without
    /// checking for one: a pre-compressed page would ship as `gzip, gzip`. Decoding makes it visible — a doubly compressed page decodes once,
    /// into bytes that are not HTML.
    @Test
    func `page to be served pre-compressed, and only once`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/",
                method: .get,
                headers: [.acceptEncoding: "gzip, deflate, br"]
            ) { response in
                #expect(response.status == .ok)
                #expect(response.headers[values: .contentEncoding] == ["gzip"])

                var body = response.body
                let decoded = try body.decompress(with: .gzip())

                #expect(String(buffer: decoded).hasPrefix("<!DOCTYPE html>"))
                // Complete before the first byte is written, so it is sized rather than chunked.
                #expect(response.headers[.contentLength] == String(response.body.readableBytes))
                #expect(response.body.readableBytes < decoded.readableBytes)
            }
        }
    }

    /// The compressed copy is only handed to a client that asked for it; everyone else gets the rendered bytes.
    @Test
    func `page to be served uncompressed when gzip is not accepted`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/",
                method: .get,
                headers: [.acceptEncoding: "identity"]
            ) { response in
                #expect(response.status == .ok)
                #expect(response.headers[.contentEncoding] == nil)
                #expect(String(buffer: response.body).hasPrefix("<!DOCTYPE html>"))
            }
        }
    }

    @Test
    func `error page to be served when not found`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/this-path-does-not-exist",
                method: .get
            ) { response in
                let body = String(buffer: response.body)

                #expect(response.status == .notFound)
                #expect(response.headers[.contentType] == "text/html; charset=utf-8")
                #expect(body.contains("Page Not Found"))
            }
        }
    }

    @Test
    func `error page to reference fingerprinted assets`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/this-path-does-not-exist",
                method: .get
            ) { response in
                let body = String(buffer: response.body)

                #expect(body.contains("/css/not-found.css?v="))
                #expect(body.contains("/js/shared.js?v="))
            }
        }
    }

    @Test
    func `error page to be served without revalidation headers`() async throws {
        // A `304 Not Modified` only ever stands in for a success, so the error page must not
        // invite revalidation with an entity tag or a cache policy.
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/this-path-does-not-exist",
                method: .get
            ) { response in
                #expect(response.status == .notFound)
                #expect(response.headers[.eTag] == nil)
                #expect(response.headers[.cacheControl] == nil)
            }
        }
    }

    @Test
    func `error page to vary on language and encoding`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/this-path-does-not-exist",
                method: .get
            ) { response in
                let vary = try #require(response.headers[.vary])

                #expect(vary.contains("Accept-Language"))
                #expect(vary.contains("Accept-Encoding"))
            }
        }
    }

    @Test
    func `landing page to revalidate a conditional head request`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            let eTag = try await client.execute(
                uri: "/",
                method: .get
            ) { response in
                try #require(response.headers[.eTag])
            }

            try await client.execute(
                uri: "/",
                method: .head,
                headers: [.ifNoneMatch: eTag]
            ) { response in
                #expect(response.status == .notModified)
                #expect(response.body.readableBytes == 0)
            }
        }
    }

    @Test
    func `security headers to be applied to the landing page`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/",
                method: .get
            ) { response in
                #expect(response.status == .ok)
                #expect(response.headers[.contentSecurityPolicy] == String.Security.contentSecurityPolicy)
                #expect(response.headers[.xContentTypeOptions] == String.Security.contentTypeOptions)
                #expect(response.headers[.frameOptions] == String.Security.frameOptions)
                #expect(response.headers[.referrerPolicy] == String.Security.referrerPolicy)
                #expect(response.headers[.permissionsPolicy] == String.Security.permissionsPolicy)
                #expect(response.headers[.strictTransportSecurity] == nil)
            }
        }
    }

    @Test
    func `security headers to be applied to the error page`() async throws {
        try await app(
            staticFilesPath: staticFilesPath
        ).test(.router) { client in
            try await client.execute(
                uri: "/this-path-does-not-exist",
                method: .get
            ) { response in
                #expect(response.status == .notFound)
                #expect(response.headers[.contentSecurityPolicy] == String.Security.contentSecurityPolicy)
                #expect(response.headers[.xContentTypeOptions] == String.Security.contentTypeOptions)
            }
        }
    }

    @Test
    func `strict-transport-security to be applied when configured`() async throws {
        try await app(
            staticFilesPath: staticFilesPath,
            strictTransportSecurity: "max-age=31536000; includeSubDomains"
        ).test(.router) { client in
            try await client.execute(
                uri: "/",
                method: .get
            ) { response in
                #expect(response.status == .ok)
                #expect(response.headers[.strictTransportSecurity] == "max-age=31536000; includeSubDomains")
            }
        }
    }

}

// MARK: - Helpers

private extension AppTests {
    
    // MARK: Methods
    
    func app(
        staticFilesPath: String,
        strictTransportSecurity: String? = nil
    ) async throws -> some ApplicationProtocol {
        try await application(
            reader: reader(
                staticFilesPath: staticFilesPath,
                strictTransportSecurity: strictTransportSecurity
            )
        )
    }
    
    func reader(
        staticFilesPath: String,
        strictTransportSecurity: String? = nil
    ) -> ConfigReader {
        ConfigReader(providers: [{
            if let strictTransportSecurity {
                InMemoryProvider(values: [
                    .HTTP.host: "127.0.0.1",
                    .HTTP.port: "0",
                    .Log.level: "trace",
                    .Path.staticFiles: .init(stringLiteral: staticFilesPath),
                    .Security.strictTransportSecurity: .init(stringLiteral: strictTransportSecurity)
                ])
            } else {
                InMemoryProvider(values: [
                    .HTTP.host: "127.0.0.1",
                    .HTTP.port: "0",
                    .Log.level: "trace",
                    .Path.staticFiles: .init(stringLiteral: staticFilesPath),
                ])
            }
        }()])
    }

}