using Microsoft.Playwright;

const string defaultSelector = "button:has-text('Click to')";

var targetUrl = PromptForTargetUrl();
var options = StressOptions.Parse(args, defaultSelector, targetUrl);

Console.WriteLine($"URL: {options.TargetUrl}");
Console.WriteLine($"Instances: {options.InstanceCount}");
Console.WriteLine($"Interval: {options.IntervalMs}ms");
Console.WriteLine($"Selector: {options.ButtonSelector}");
Console.WriteLine($"Headless: {options.Headless}");
Console.WriteLine("Press Ctrl+C to stop.");

using var cts = new CancellationTokenSource();
Console.CancelKeyPress += (_, eventArgs) =>
{
    eventArgs.Cancel = true;
    cts.Cancel();
};

var workers = Enumerable.Range(1, options.InstanceCount)
    .Select(instanceId => RunWorkerAsync(instanceId, options, cts.Token))
    .ToArray();

await Task.WhenAll(workers);

static string PromptForTargetUrl()
{
    while (true)
    {
        Console.Write("Enter target URL: ");
        var input = Console.ReadLine();

        if (!string.IsNullOrWhiteSpace(input)
            && Uri.TryCreate(input, UriKind.Absolute, out var uri)
            && (uri.Scheme == Uri.UriSchemeHttp || uri.Scheme == Uri.UriSchemeHttps))
        {
            return uri.ToString();
        }

        Console.WriteLine("Invalid URL. Please enter a full http/https URL.");
    }
}

static async Task RunWorkerAsync(int instanceId, StressOptions options, CancellationToken cancellationToken)
{
    try
    {
        using var playwright = await Playwright.CreateAsync();
        await using var browser = await playwright.Chromium.LaunchAsync(new BrowserTypeLaunchOptions
        {
            Headless = options.Headless
        });

        var page = await browser.NewPageAsync();
        await page.GotoAsync(options.TargetUrl, new PageGotoOptions
        {
            WaitUntil = WaitUntilState.DOMContentLoaded,
            Timeout = 30000
        });

        Console.WriteLine($"[{instanceId}] connected");
        var clickCount = 0;

        while (!cancellationToken.IsCancellationRequested)
        {
            try
            {
                // HTMX can replace the button after each request, so resolve it fresh every loop.
                var button = page.Locator(options.ButtonSelector).First;
                await button.WaitForAsync(new LocatorWaitForOptions
                {
                    State = WaitForSelectorState.Visible,
                    Timeout = 5000
                });
                await button.ClickAsync(new LocatorClickOptions
                {
                    Timeout = 5000,
                    Force = true
                });

                clickCount += 1;
                if (clickCount % 25 == 0)
                {
                    Console.WriteLine($"[{instanceId}] clicks sent: {clickCount}");
                }
            }
            catch (TimeoutException)
            {
                Console.WriteLine($"[{instanceId}] click timeout");
            }
            catch (PlaywrightException ex)
            {
                Console.WriteLine($"[{instanceId}] click error: {ex.Message}");
            }

            try
            {
                await Task.Delay(options.IntervalMs, cancellationToken);
            }
            catch (OperationCanceledException)
            {
                break;
            }
        }

        await page.CloseAsync();
        Console.WriteLine($"[{instanceId}] stopped");
    }
    catch (OperationCanceledException)
    {
        Console.WriteLine($"[{instanceId}] canceled");
    }
    catch (Exception ex)
    {
        Console.WriteLine($"[{instanceId}] fatal: {ex.Message}");
        if (ex.Message.Contains("Executable doesn't exist", StringComparison.OrdinalIgnoreCase))
        {
            Console.WriteLine("Install browser binaries first:");
            Console.WriteLine("./bin/Debug/net10.0/.playwright/node/linux-x64/node ./bin/Debug/net10.0/.playwright/package/cli.js install chromium");
        }
    }
}

internal sealed record StressOptions(
    string TargetUrl,
    int InstanceCount,
    int IntervalMs,
    string ButtonSelector,
    bool Headless)
{
    public static StressOptions Parse(string[] args, string defaultSelector, string targetUrl)
    {
        var instanceCount = ParsePositiveInt(Environment.GetEnvironmentVariable("INSTANCE_COUNT"), 20);
        var intervalMs = ParsePositiveInt(Environment.GetEnvironmentVariable("CLICK_INTERVAL_MS"), 200);
        var buttonSelector = Environment.GetEnvironmentVariable("BUTTON_SELECTOR") ?? defaultSelector;
        var headless = ParseBool(Environment.GetEnvironmentVariable("HEADLESS"), true);

        foreach (var arg in args)
        {
            var split = arg.Split('=', 2, StringSplitOptions.TrimEntries);
            if (split.Length != 2)
            {
                continue;
            }

            var key = split[0].TrimStart('-', '/').ToLowerInvariant();
            var value = split[1];

            switch (key)
            {
                case "instances":
                case "instancecount":
                    instanceCount = ParsePositiveInt(value, instanceCount);
                    break;
                case "interval":
                case "intervalms":
                    intervalMs = ParsePositiveInt(value, intervalMs);
                    break;
                case "selector":
                case "buttonselector":
                    buttonSelector = value;
                    break;
                case "headless":
                    headless = ParseBool(value, headless);
                    break;
            }
        }

        return new StressOptions(targetUrl, instanceCount, intervalMs, buttonSelector, headless);
    }

    private static int ParsePositiveInt(string? rawValue, int fallback)
    {
        if (!string.IsNullOrWhiteSpace(rawValue) && int.TryParse(rawValue, out var parsed) && parsed > 0)
        {
            return parsed;
        }

        return fallback;
    }

    private static bool ParseBool(string? rawValue, bool fallback)
    {
        if (!string.IsNullOrWhiteSpace(rawValue) && bool.TryParse(rawValue, out var parsed))
        {
            return parsed;
        }

        return fallback;
    }
}