using System.Text.Json;
using System.Text.Json.Nodes;
using System.Text.RegularExpressions;

namespace Recordingtest.Normalizer;

public static class Rules
{
    // Matches ISO8601 (with optional fractional seconds and timezone) and common "yyyy-MM-dd HH:mm:ss"
    public static readonly Regex TimestampRegex = new(
        @"\d{4}-\d{2}-\d{2}[T ]\d{2}:\d{2}:\d{2}(?:\.\d+)?(?:Z|[+-]\d{2}:?\d{2})?",
        RegexOptions.Compiled);

    public static readonly Regex GuidRegex = new(
        @"\b[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\b",
        RegexOptions.Compiled);

    public static (string output, int count) StripTimestamps(string input)
    {
        int count = 0;
        var result = TimestampRegex.Replace(input, _ => { count++; return "<TS>"; });
        return (result, count);
    }

    public static (string output, int count) MaskGuids(string input)
    {
        int count = 0;
        var result = GuidRegex.Replace(input, _ => { count++; return "<GUID>"; });
        return (result, count);
    }

    public static (string output, int count) NormalizePaths(string input)
    {
        int count = 0;
        string result = input;

        var repo = Environment.GetEnvironmentVariable("RECORDINGTEST_REPO");
        if (string.IsNullOrEmpty(repo))
        {
            repo = Directory.GetCurrentDirectory();
        }

        // Try both raw and JSON-escaped (\\) forms
        foreach (var candidate in EnumerateForms(repo))
        {
            result = ReplaceCounting(result, candidate, "<REPO>", ref count);
        }

        var home = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
        if (!string.IsNullOrEmpty(home))
        {
            foreach (var candidate in EnumerateForms(home))
            {
                result = ReplaceCounting(result, candidate, "<USER>", ref count);
            }
        }

        return (result, count);
    }

    private static IEnumerable<string> EnumerateForms(string path)
    {
        yield return path;
        // JSON-escaped backslashes
        if (path.Contains('\\'))
            yield return path.Replace("\\", "\\\\");
        // forward slashes
        if (path.Contains('\\'))
            yield return path.Replace('\\', '/');
    }

    private static string ReplaceCounting(string input, string find, string replace, ref int count)
    {
        if (string.IsNullOrEmpty(find)) return input;
        int idx = 0;
        var sb = new System.Text.StringBuilder();
        while (true)
        {
            int next = input.IndexOf(find, idx, StringComparison.OrdinalIgnoreCase);
            if (next < 0)
            {
                sb.Append(input, idx, input.Length - idx);
                break;
            }
            sb.Append(input, idx, next - idx);
            sb.Append(replace);
            count++;
            idx = next + find.Length;
        }
        return sb.ToString();
    }

    /// <summary>
    /// JSON-aware: parse and round all double values to 6 decimals. Operates only when input is JSON.
    /// Returns (json-output, count) when input is JSON; otherwise returns input unchanged with count=0.
    /// </summary>
    public static (JsonNode? node, int count) RoundFloatsInNode(JsonNode? node)
    {
        int count = 0;
        if (node is null) return (null, 0);
        Walk(node);
        return (node, count);

        void Walk(JsonNode n)
        {
            if (n is JsonObject obj)
            {
                foreach (var kv in obj.ToList())
                {
                    if (kv.Value is JsonValue v && TryAsDouble(v, out var d, out var wasFloat) && wasFloat)
                    {
                        var rounded = Math.Round(d, 6, MidpointRounding.AwayFromZero);
                        obj[kv.Key] = JsonValue.Create(rounded);
                        count++;
                    }
                    else if (kv.Value is JsonObject || kv.Value is JsonArray)
                    {
                        Walk(kv.Value);
                    }
                }
            }
            else if (n is JsonArray arr)
            {
                for (int i = 0; i < arr.Count; i++)
                {
                    var item = arr[i];
                    if (item is JsonValue v && TryAsDouble(v, out var d, out var wasFloat) && wasFloat)
                    {
                        var rounded = Math.Round(d, 6, MidpointRounding.AwayFromZero);
                        arr[i] = JsonValue.Create(rounded);
                        count++;
                    }
                    else if (item is JsonObject || item is JsonArray)
                    {
                        Walk(item);
                    }
                }
            }
        }
    }

    private static bool TryAsDouble(JsonValue v, out double d, out bool wasFloat)
    {
        d = 0;
        wasFloat = false;
        var el = v.GetValue<object?>();
        // Use the underlying JsonElement when possible
        if (v.TryGetValue<JsonElement>(out var je))
        {
            if (je.ValueKind == JsonValueKind.Number)
            {
                var raw = je.GetRawText();
                if (raw.Contains('.') || raw.Contains('e') || raw.Contains('E'))
                {
                    if (je.TryGetDouble(out d))
                    {
                        wasFloat = true;
                        return true;
                    }
                }
            }
        }
        return false;
    }

    /// <summary>
    /// Allowlist of field names whose values are known to be volatile boolean/scalar
    /// settings (per docs/sut-catalog/json-configs.json). The values are replaced with
    /// a deterministic placeholder so golden-file comparisons stay stable while still
    /// preserving the field's presence and key order.
    /// </summary>
    public static readonly HashSet<string> VolatileSettingFieldNames = new(StringComparer.Ordinal)
    {
        "CanOverrideWireColorWithFace",
        "IsSidePanelVisible",
        "OverrideFaceColor",
        "Solar_IsLocalTime",
        "VisibleGrid",
        "GridSnap",
        "MidpointOsnap",
        "GridSpacing",
        "GridColor.ALPHA",
        "GridColor.BLUE",
        "GridColor.GREEN",
        "GridColor.RED",
        "MajorGridColor.ALPHA",
        "MajorGridColor.BLUE",
        "MajorGridColor.GREEN",
        "MajorGridColor.RED",
    };

    public static (JsonNode? node, int count) MaskVolatileSettings(JsonNode? node)
    {
        int count = 0;
        if (node is null) return (null, 0);
        Walk(node);
        return (node, count);

        void Walk(JsonNode n)
        {
            if (n is JsonObject obj)
            {
                foreach (var kv in obj.ToList())
                {
                    if (VolatileSettingFieldNames.Contains(kv.Key))
                    {
                        obj[kv.Key] = JsonValue.Create("<VOLATILE>");
                        count++;
                    }
                    else if (kv.Value is JsonObject || kv.Value is JsonArray)
                    {
                        Walk(kv.Value);
                    }
                }
            }
            else if (n is JsonArray arr)
            {
                foreach (var item in arr)
                {
                    if (item is JsonObject || item is JsonArray) Walk(item);
                }
            }
        }
    }

    /// <summary>
    /// Returns a new JsonNode with object keys sorted recursively. Counts the number of objects sorted.
    /// </summary>
    public static (JsonNode? node, int count) SortJsonKeys(JsonNode? node)
    {
        int count = 0;
        var result = SortInternal(node, ref count);
        return (result, count);
    }

    private static JsonNode? SortInternal(JsonNode? node, ref int count)
    {
        if (node is JsonObject obj)
        {
            count++;
            var sorted = new JsonObject();
            foreach (var kv in obj.OrderBy(k => k.Key, StringComparer.Ordinal))
            {
                sorted[kv.Key] = SortInternal(kv.Value, ref count);
            }
            return sorted;
        }
        if (node is JsonArray arr)
        {
            var newArr = new JsonArray();
            foreach (var item in arr)
            {
                newArr.Add(SortInternal(item, ref count));
            }
            return newArr;
        }
        if (node is JsonValue v)
        {
            // Clone scalar
            return JsonNode.Parse(v.ToJsonString());
        }
        return null;
    }
}