using System.Globalization;
using System.Text;
using System.Text.Json;

namespace FinalFactory.Rendezvous.TestClient;

internal sealed class TestClientOutput(TextWriter standardOutput, TextWriter standardError, bool json)
{
    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web)
    {
        WriteIndented = false,
    };

    private readonly object _gate = new();
    private readonly TextWriter _standardOutput = standardOutput ?? throw new ArgumentNullException(nameof(standardOutput));
    private readonly TextWriter _standardError = standardError ?? throw new ArgumentNullException(nameof(standardError));
    private readonly bool _json = json;

    internal void Write(
        string eventName,
        string status,
        string? phase = null,
        string? listingId = null,
        string? displayName = null,
        string? outcome = null,
        string? endpointType = null,
        int? count = null,
        long? elapsedMilliseconds = null,
        string? message = null) => WriteCore(
            _standardOutput,
            new TestClientEvent
            {
                Event = SafeToken(eventName) ?? string.Empty,
                Status = SafeToken(status) ?? string.Empty,
                Phase = SafeToken(phase),
                ListingId = SafeToken(listingId),
                DisplayName = SafeText(displayName),
                Outcome = SafeToken(outcome),
                EndpointType = SafeToken(endpointType),
                Count = count,
                ElapsedMilliseconds = elapsedMilliseconds,
                Message = SafeText(message),
            });

    internal void WriteError(
        string eventName,
        string status,
        string message,
        string? phase = null,
        string? outcome = null) => WriteCore(
            _standardError,
            new TestClientEvent
            {
                Event = SafeToken(eventName) ?? string.Empty,
                Status = SafeToken(status) ?? string.Empty,
                Phase = SafeToken(phase),
                Outcome = SafeToken(outcome),
                Message = SafeText(message),
            });

    internal void WritePrompt(string prompt)
    {
        if (_json)
        {
            return;
        }
        lock (_gate)
        {
            _standardOutput.Write(SafeText(prompt));
            _standardOutput.Flush();
        }
    }

    private void WriteCore(TextWriter writer, TestClientEvent item)
    {
        string line = _json
            ? JsonSerializer.Serialize(item, JsonOptions)
            : HumanLine(item);
        lock (_gate)
        {
            writer.WriteLine(line);
            writer.Flush();
        }
    }

    private static string HumanLine(TestClientEvent item)
    {
        StringBuilder line = new();
        line.Append('[').Append(item.Status).Append("] ").Append(item.Event);
        Append(line, "phase", item.Phase);
        Append(line, "listing", item.ListingId);
        Append(line, "name", item.DisplayName, quote: true);
        Append(line, "outcome", item.Outcome);
        Append(line, "endpoint", item.EndpointType);
        if (item.Count.HasValue)
        {
            Append(line, "count", item.Count.Value.ToString(System.Globalization.CultureInfo.InvariantCulture));
        }
        if (item.ElapsedMilliseconds.HasValue)
        {
            Append(
                line,
                "elapsedMs",
                item.ElapsedMilliseconds.Value.ToString(System.Globalization.CultureInfo.InvariantCulture));
        }
        Append(line, "message", item.Message, quote: true);
        return line.ToString();
    }

    private static void Append(
        StringBuilder builder,
        string name,
        string? value,
        bool quote = false)
    {
        if (!string.IsNullOrEmpty(value))
        {
            builder.Append(' ').Append(name).Append('=');
            if (quote)
            {
                builder.Append('"').Append(value.Replace("\\", "\\\\", StringComparison.Ordinal)
                    .Replace("\"", "\\\"", StringComparison.Ordinal)).Append('"');
            }
            else
            {
                builder.Append(value);
            }
        }
    }

    private static string? SafeToken(string? value)
    {
        if (value is null)
        {
            return null;
        }
        return new string(value
            .Take(96)
            .Select(static character => char.IsAsciiLetterOrDigit(character)
                || character is '.' or '-' or '_' or ':'
                    ? char.ToLowerInvariant(character)
                    : '_')
            .ToArray());
    }

    private static string? SafeText(string? value)
    {
        if (value is null)
        {
            return null;
        }
        return new string(value
            .Take(160)
            .Select(static character => IsUnsafeHumanCharacter(character) ? '?' : character)
            .ToArray());
    }

    private static bool IsUnsafeHumanCharacter(char character) =>
        char.GetUnicodeCategory(character) is
            UnicodeCategory.Control
            or UnicodeCategory.Format
            or UnicodeCategory.LineSeparator
            or UnicodeCategory.ParagraphSeparator
            or UnicodeCategory.Surrogate
            or UnicodeCategory.PrivateUse;

    private sealed class TestClientEvent
    {
        public int Version { get; init; } = 1;
        public string Event { get; init; } = string.Empty;
        public string Status { get; init; } = string.Empty;
        public string? Phase { get; init; }
        public string? ListingId { get; init; }
        public string? DisplayName { get; init; }
        public string? Outcome { get; init; }
        public string? EndpointType { get; init; }
        public int? Count { get; init; }
        public long? ElapsedMilliseconds { get; init; }
        public string? Message { get; init; }
    }
}