namespace Harness {
    const fs: typeof import("fs") = require("fs");
    const path: typeof import("path") = require("path");
    const del: typeof import("del") = require("del");

    interface ExecResult {
        stdout: Buffer;
        stderr: Buffer;
        status: number | null;
    }

    interface UserConfig {
        types: string[];
        cloneUrl: string;
        path?: string;
    }

    abstract class ExternalCompileRunnerBase extends RunnerBase {
        abstract testDir: string;
        abstract report(result: ExecResult, cwd: string): string | null;
        enumerateTestFiles() {
            return IO.getDirectories(this.testDir);
        }
        /** Setup the runner's tests so that they are ready to be executed by the harness
         *  The first test should be a describe/it block that sets up the harness's compiler instance appropriately
         */
        initializeTests(): void {
            // Read in and evaluate the test list
            const testList = this.tests && this.tests.length ? this.tests : this.getTestFiles();

            // eslint-disable-next-line @typescript-eslint/no-this-alias
            const cls = this;
            describe(`${this.kind()} code samples`, function(this: Mocha.ISuiteCallbackContext) {
                this.timeout(600_000); // 10 minutes
                for (const test of testList) {
                    cls.runTest(typeof test === "string" ? test : test.file);
                }
            });
        }
        private runTest(directoryName: string) {
            // eslint-disable-next-line @typescript-eslint/no-this-alias
            const cls = this;
            const timeout = 600_000; // 10 minutes
            describe(directoryName, function(this: Mocha.ISuiteCallbackContext) {
                this.timeout(timeout);
                const cp: typeof import("child_process") = require("child_process");

                it("should build successfully", () => {
                    let cwd = path.join(IO.getWorkspaceRoot(), cls.testDir, directoryName);
                    const originalCwd = cwd;
                    const stdio = isWorker ? "pipe" : "inherit";
                    let types: string[] | undefined;
                    if (fs.existsSync(path.join(cwd, "test.json"))) {
                        const config = JSON.parse(fs.readFileSync(path.join(cwd, "test.json"), { encoding: "utf8" })) as UserConfig;
                        ts.Debug.assert(!!config.types, "Bad format from test.json: Types field must be present.");
                        ts.Debug.assert(!!config.cloneUrl, "Bad format from test.json: cloneUrl field must be present.");
                        const submoduleDir = path.join(cwd, directoryName);
                        if (!fs.existsSync(submoduleDir)) {
                            exec("git", ["clone", config.cloneUrl, directoryName], { cwd });
                        }
                        exec("git", ["reset", "HEAD", "--hard"], { cwd: submoduleDir });
                        exec("git", ["clean", "-f"], { cwd: submoduleDir });
                        exec("git", ["pull", "-f"], { cwd: submoduleDir });

                        types = config.types;

                        cwd = config.path ? path.join(cwd, config.path) : submoduleDir;
                    }
                    if (fs.existsSync(path.join(cwd, "package.json"))) {
                        if (fs.existsSync(path.join(cwd, "package-lock.json"))) {
                            fs.unlinkSync(path.join(cwd, "package-lock.json"));
                        }
                        if (fs.existsSync(path.join(cwd, "node_modules"))) {
                            del.sync(path.join(cwd, "node_modules"), { force: true });
                        }
                        exec("npm", ["i", "--ignore-scripts"], { cwd, timeout: timeout / 2 }); // NPM shouldn't take the entire timeout - if it takes a long time, it should be terminated and we should log the failure
                    }
                    const args = [path.join(IO.getWorkspaceRoot(), "built/local/tsc.js")];
                    if (types) {
                        args.push("--types", types.join(","));
                        // Also actually install those types (for, eg, the js projects which need node)
                        exec("npm", ["i", ...types.map(t => `@types/${t}`), "--no-save", "--ignore-scripts"], { cwd: originalCwd, timeout: timeout / 2 }); // NPM shouldn't take the entire timeout - if it takes a long time, it should be terminated and we should log the failure
                    }
                    args.push("--noEmit");
                    Baseline.runBaseline(`${cls.kind()}/${directoryName}.log`, cls.report(cp.spawnSync(`node`, args, { cwd, timeout, shell: true }), cwd));

                    function exec(command: string, args: string[], options: { cwd: string, timeout?: number }): void {
                        const res = cp.spawnSync(command, args, { timeout, shell: true, stdio, ...options });
                        if (res.status !== 0) {
                            throw new Error(`${command} ${args.join(" ")} for ${directoryName} failed: ${res.stderr && res.stderr.toString()}`);
                        }
                    }
                });
            });
        }
    }

    export class UserCodeRunner extends ExternalCompileRunnerBase {
        readonly testDir = "tests/cases/user/";
        kind(): TestRunnerKind {
            return "user";
        }
        report(result: ExecResult) {
            // eslint-disable-next-line no-null/no-null
            return result.status === 0 && !result.stdout.length && !result.stderr.length ? null : `Exit Code: ${result.status}
Standard output:
${sortErrors(stripAbsoluteImportPaths(result.stdout.toString().replace(/\r\n/g, "\n")))}


Standard error:
${stripAbsoluteImportPaths(result.stderr.toString().replace(/\r\n/g, "\n"))}`;
        }
    }

    export class DockerfileRunner extends ExternalCompileRunnerBase {
        readonly testDir = "tests/cases/docker/";
        kind(): TestRunnerKind {
            return "docker";
        }
        initializeTests(): void {
            // Read in and evaluate the test list
            const testList = this.tests && this.tests.length ? this.tests : this.getTestFiles();

            // eslint-disable-next-line @typescript-eslint/no-this-alias
            const cls = this;
            describe(`${this.kind()} code samples`, function(this: Mocha.ISuiteCallbackContext) {
                this.timeout(cls.timeout); // 20 minutes
                before(() => {
                    cls.exec("docker", ["build", ".", "-t", "typescript/typescript"], { cwd: IO.getWorkspaceRoot() }); // cached because workspace is hashed to determine cacheability
                });
                for (const test of testList) {
                    const directory = typeof test === "string" ? test : test.file;
                    const cwd = path.join(IO.getWorkspaceRoot(), cls.testDir, directory);
                    it(`should build ${directory} successfully`, () => {
                        const imageName = `tstest/${directory}`;
                        cls.exec("docker", ["build", "--no-cache", ".", "-t", imageName], { cwd }); // --no-cache so the latest version of the repos referenced is always fetched
                        const cp: typeof import("child_process") = require("child_process");
                        Baseline.runBaseline(`${cls.kind()}/${directory}.log`, cls.report(cp.spawnSync(`docker`, ["run", imageName], { cwd, timeout: cls.timeout, shell: true })));
                    });
                }
            });
        }

        private timeout = 1_200_000; // 20 minutes;
        private exec(command: string, args: string[], options: { cwd: string, timeout?: number }): void {
            const cp: typeof import("child_process") = require("child_process");
            const stdio = isWorker ? "pipe" : "inherit";
            const res = cp.spawnSync(command, args, { timeout: this.timeout, shell: true, stdio, ...options });
            if (res.status !== 0) {
                throw new Error(`${command} ${args.join(" ")} for ${options.cwd} failed: ${res.stderr && res.stderr.toString()}`);
            }
        }
        report(result: ExecResult) {
            // eslint-disable-next-line no-null/no-null
            return result.status === 0 && !result.stdout.length && !result.stderr.length ? null : `Exit Code: ${result.status}
Standard output:
${sanitizeDockerfileOutput(result.stdout.toString())}


Standard error:
${sanitizeDockerfileOutput(result.stderr.toString())}`;
        }
    }

    function sanitizeDockerfileOutput(result: string): string {
        return [
            normalizeNewlines,
            stripANSIEscapes,
            stripRushStageNumbers,
            stripWebpackHash,
            sanitizeVersionSpecifiers,
            sanitizeTimestamps,
            sanitizeSizes,
            sanitizeUnimportantGulpOutput,
            stripAbsoluteImportPaths,
        ].reduce((result, f) => f(result), result);
    }

    function normalizeNewlines(result: string): string {
        return result.replace(/\r\n/g, "\n");
    }

    function stripANSIEscapes(result: string): string {
        return result.replace(/\x1b\[[0-9;]*[a-zA-Z]/g, "");
    }

    function stripRushStageNumbers(result: string): string {
        return result.replace(/\d+ of \d+:/g, "XX of XX:");
    }

    function stripWebpackHash(result: string): string {
        return result.replace(/Hash: \w+/g, "Hash: [redacted]");
    }

    function sanitizeSizes(result: string): string {
        return result.replace(/\d+(\.\d+)? ((Ki|M)B|bytes)/g, "X KiB");
    }

    /**
     * Gulp's output order within a `parallel` block is nondeterministic (and there's no way to configure it to execute in series),
     * so we purge as much of the gulp output as we can
     */
    function sanitizeUnimportantGulpOutput(result: string): string {
        return result.replace(/^.*(\] (Starting)|(Finished)).*$/gm, "") // "gulp" task start/end messages (nondeterministic order)
            .replace(/^.*(\] . (finished)|(started)).*$/gm, "") // "just" task start/end messages (nondeterministic order)
            .replace(/^.*\] Respawned to PID: \d+.*$/gm, "") // PID of child is OS and system-load dependent (likely stableish in a container but still dangerous)
            .replace(/\n+/g, "\n");
    }

    function sanitizeTimestamps(result: string): string {
        return result.replace(/\[\d?\d:\d\d:\d\d (A|P)M\]/g, "[XX:XX:XX XM]")
            .replace(/\[\d?\d:\d\d:\d\d\]/g, "[XX:XX:XX]")
            .replace(/\/\d+-\d+-[\d_TZ]+-debug.log/g, "\/XXXX-XX-XXXXXXXXX-debug.log")
            .replace(/\d+\/\d+\/\d+ \d+:\d+:\d+ (AM|PM)/g, "XX/XX/XX XX:XX:XX XM")
            .replace(/\d+(\.\d+)? sec(onds?)?/g, "? seconds")
            .replace(/\d+(\.\d+)? min(utes?)?/g, "")
            .replace(/\d+(\.\d+)? ?m?s/g, "?s")
            .replace(/ \(\?s\)/g, "");
    }

    function sanitizeVersionSpecifiers(result: string): string {
        return result
            .replace(/\d+.\d+.\d+-insiders.\d\d\d\d\d\d\d\d/g, "X.X.X-insiders.xxxxxxxx")
            .replace(/Rush Multi-Project Build Tool (\d+)\.\d+\.\d+/g, "Rush Multi-Project Build Tool $1.X.X")
            .replace(/([@v\()])\d+\.\d+\.\d+/g, "$1X.X.X")
            .replace(/webpack (\d+)\.\d+\.\d+/g, "webpack $1.X.X")
            .replace(/Webpack version: (\d+)\.\d+\.\d+/g, "Webpack version: $1.X.X");
    }

    /**
     * Import types and some other error messages use absolute paths in errors as they have no context to be written relative to;
     * This is problematic for error baselines, so we grep for them and strip them out.
     */
    function stripAbsoluteImportPaths(result: string) {
        const workspaceRegexp = new RegExp(IO.getWorkspaceRoot().replace(/\\/g, "\\\\"), "g");
        return result
            .replace(/import\(".*?\/tests\/cases\/user\//g, `import("/`)
            .replace(/Module '".*?\/tests\/cases\/user\//g, `Module '"/`)
            .replace(workspaceRegexp, "../../..");
    }

    function sortErrors(result: string) {
        return ts.flatten(splitBy(result.split("\n"), s => /^\S+/.test(s)).sort(compareErrorStrings)).join("\n");
    }

    const errorRegexp = /^(.+\.[tj]sx?)\((\d+),(\d+)\)(: error TS.*)/;
    function compareErrorStrings(a: string[], b: string[]) {
        ts.Debug.assertGreaterThanOrEqual(a.length, 1);
        ts.Debug.assertGreaterThanOrEqual(b.length, 1);
        const matchA = a[0].match(errorRegexp);
        if (!matchA) {
            return -1;
        }
        const matchB = b[0].match(errorRegexp);
        if (!matchB) {
            return 1;
        }
        const [, errorFileA, lineNumberStringA, columnNumberStringA, remainderA] = matchA;
        const [, errorFileB, lineNumberStringB, columnNumberStringB, remainderB] = matchB;
        return ts.comparePathsCaseSensitive(errorFileA, errorFileB) ||
            ts.compareValues(parseInt(lineNumberStringA), parseInt(lineNumberStringB)) ||
            ts.compareValues(parseInt(columnNumberStringA), parseInt(columnNumberStringB)) ||
            ts.compareStringsCaseSensitive(remainderA, remainderB) ||
            ts.compareStringsCaseSensitive(a.slice(1).join("\n"), b.slice(1).join("\n"));
    }

    export class DefinitelyTypedRunner extends ExternalCompileRunnerBase {
        readonly testDir = "../DefinitelyTyped/types/";
        workingDirectory = this.testDir;
        kind(): TestRunnerKind {
            return "dt";
        }
        report(result: ExecResult, cwd: string) {
            const stdout = removeExpectedErrors(result.stdout.toString(), cwd);
            const stderr = result.stderr.toString();

            // eslint-disable-next-line no-null/no-null
            return !stdout.length && !stderr.length ? null : `Exit Code: ${result.status}
Standard output:
${stdout.replace(/\r\n/g, "\n")}


Standard error:
${stderr.replace(/\r\n/g, "\n")}`;
        }
    }

    function removeExpectedErrors(errors: string, cwd: string): string {
        return ts.flatten(splitBy(errors.split("\n"), s => /^\S+/.test(s)).filter(isUnexpectedError(cwd))).join("\n");
    }
    /**
     * Returns true if the line that caused the error contains '$ExpectError',
     * or if the line before that one contains '$ExpectError'.
     * '$ExpectError' is a marker used in Definitely Typed tests,
     * meaning that the error should not contribute toward our error baslines.
     */
    function isUnexpectedError(cwd: string) {
        return (error: string[]) => {
            ts.Debug.assertGreaterThanOrEqual(error.length, 1);
            const match = error[0].match(/(.+\.tsx?)\((\d+),\d+\): error TS/);
            if (!match) {
                return true;
            }
            const [, errorFile, lineNumberString] = match;
            const lines = fs.readFileSync(path.join(cwd, errorFile), { encoding: "utf8" }).split("\n");
            const lineNumber = parseInt(lineNumberString) - 1;
            ts.Debug.assertGreaterThanOrEqual(lineNumber, 0);
            ts.Debug.assertLessThan(lineNumber, lines.length);
            const previousLine = lineNumber - 1 > 0 ? lines[lineNumber - 1] : "";
            return !ts.stringContains(lines[lineNumber], "$ExpectError") && !ts.stringContains(previousLine, "$ExpectError");
        };
    }
    /**
     * Split an array into multiple arrays whenever `isStart` returns true.
     * @example
     * splitBy([1,2,3,4,5,6], isOdd)
     * ==> [[1, 2], [3, 4], [5, 6]]
     * where
     * const isOdd = n => !!(n % 2)
     */
    function splitBy<T>(xs: T[], isStart: (x: T) => boolean): T[][] {
        const result = [];
        let group: T[] = [];
        for (const x of xs) {
            if (isStart(x)) {
                if (group.length) {
                    result.push(group);
                }
                group = [x];
            }
            else {
                group.push(x);
            }
        }
        if (group.length) {
            result.push(group);
        }
        return result;
    }
}