import Foundation
import Testing

@testable import Infrastructure

@Suite(
    "FingerprintAssets method",
    .tags(.asset)
)
struct FingerprintAssetsTests {

    // MARK: Properties

    private let fingerprint = FingerprintAssets()

    // MARK: Functional tests

    @Test
    func `fingerprints the files under a directory`() throws {
        let directory = try makeDirectory(files: [
            "css/site.css": "body { margin: 0; }",
            "robots.txt": "User-agent: *"
        ])

        defer {
            removeDirectory(directory)
        }

        let token = try #require(fingerprint(directory.path))

        #expect(token.count == 16)
        #expect(token.allSatisfy { $0.isHexDigit })
    }

    @Test
    func `agrees across directories with identical contents`() throws {
        let files = [
            "css/site.css": "body { margin: 0; }",
            "js/site.js": "console.log(1);"
        ]
        let first = try makeDirectory(files: files)
        let second = try makeDirectory(files: files)

        defer {
            removeDirectory(first)
            removeDirectory(second)
        }

        #expect(fingerprint(first.path) == fingerprint(second.path))
    }

    @Test
    func `changes the token when a file's contents change`() throws {
        let directory = try makeDirectory(files: [
            "css/site.css": "body { margin: 0; }"
        ])

        defer {
            removeDirectory(directory)
        }

        let before = fingerprint(directory.path)

        try "body { margin: 1px; }".write(
            to: directory.appendingPathComponent("css/site.css"),
            atomically: true,
            encoding: .utf8
        )

        #expect(fingerprint(directory.path) != before)
    }

    @Test
    func `changes the token when a file is renamed`() throws {
        let contents = "body { margin: 0; }"
        let first = try makeDirectory(files: ["css/site.css": contents])
        let second = try makeDirectory(files: ["css/main.css": contents])

        defer {
            removeDirectory(first)
            removeDirectory(second)
        }

        #expect(fingerprint(first.path) != fingerprint(second.path))
    }

    @Test
    func `changes the token when a file is added`() throws {
        let directory = try makeDirectory(files: [
            "css/site.css": "body { margin: 0; }"
        ])

        defer {
            removeDirectory(directory)
        }

        let before = fingerprint(directory.path)

        try "console.log(1);".write(
            to: directory.appendingPathComponent("site.js"),
            atomically: true,
            encoding: .utf8
        )

        #expect(fingerprint(directory.path) != before)
    }

    @Test
    func `returns nil for a directory without files`() throws {
        let directory = try makeDirectory(files: [:])

        defer {
            removeDirectory(directory)
        }

        #expect(fingerprint(directory.path) == nil)
    }

    @Test
    func `returns nil for a missing directory`() {
        let missing = FileManager.default.temporaryDirectory
            .appendingPathComponent("FingerprintAssetsTests-missing-\(UUID().uuidString)")

        #expect(fingerprint(missing.path) == nil)
    }

}

// MARK: - Helpers

private extension FingerprintAssetsTests {

    // MARK: Methods

    /// Creates a unique temporary directory holding the given files, keyed by relative path.
    /// - Parameter files: the files to create, keyed by their path relative to the directory.
    /// - Returns: the URL of the created directory.
    func makeDirectory(
        files: [String: String]
    ) throws -> URL {
        let directory = FileManager.default.temporaryDirectory
            .appendingPathComponent("FingerprintAssetsTests-\(UUID().uuidString)")

        try FileManager.default.createDirectory(
            at: directory,
            withIntermediateDirectories: true
        )

        for (relativePath, contents) in files {
            let file = directory.appendingPathComponent(relativePath)

            try FileManager.default.createDirectory(
                at: file.deletingLastPathComponent(),
                withIntermediateDirectories: true
            )
            try contents.write(
                to: file,
                atomically: true,
                encoding: .utf8
            )
        }

        return directory
    }

    /// Removes a temporary directory created by ``makeDirectory(files:)``.
    /// - Parameter directory: the URL of the directory to remove.
    func removeDirectory(
        _ directory: URL
    ) {
        try? FileManager.default.removeItem(at: directory)
    }

}