using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using ScadaLink.AuditLog.Configuration;
using ScadaLink.AuditLog.Payload;
using ScadaLink.Commons.Entities.Audit;
using ScadaLink.Commons.Types.Enums;

namespace ScadaLink.AuditLog.Tests.Payload;

/// <summary>
/// Bundle B (M5-T5) tests for SQL parameter redaction in
/// <see cref="DefaultAuditPayloadFilter"/>. M4 Bundle A's
/// <c>AuditingDbCommand</c> emits <c>RequestSummary</c> as
/// <c>{"sql":"...","parameters":{"@name":"value", ...}}</c>; the SQL-parameter
/// redactor parses this shape on
/// <see cref="AuditChannel.DbOutbound"/> rows, replaces values whose key
/// matches the configured case-insensitive regex with <c>&lt;redacted&gt;</c>,
/// and re-serialises. Default behaviour with no opt-in: parameter values are
/// captured verbatim. Connection lookup uses the connection-name prefix of
/// <see cref="AuditEvent.Target"/> (everything before the first <c>.</c>) so
/// the same per-connection regex applies regardless of the SQL-snippet suffix
/// that <c>AuditingDbCommand</c> appends to disambiguate rows.
/// </summary>
public class SqlParamRedactionTests
{
    private static IOptionsMonitor<AuditLogOptions> Monitor(AuditLogOptions? opts = null) =>
        new StaticMonitor(opts ?? new AuditLogOptions());

    private static DefaultAuditPayloadFilter Filter(AuditLogOptions? opts = null) =>
        new(Monitor(opts), NullLogger<DefaultAuditPayloadFilter>.Instance);

    private static AuditEvent NewDbEvent(string target, string requestSummary) => new()
    {
        EventId = Guid.NewGuid(),
        OccurredAtUtc = DateTime.UtcNow,
        Channel = AuditChannel.DbOutbound,
        Kind = AuditKind.DbWrite,
        Status = AuditStatus.Delivered,
        Target = target,
        RequestSummary = requestSummary,
    };

    /// <summary>
    /// Build a RequestSummary in the exact shape M4's <c>AuditingDbCommand</c>
    /// emits — hand-rolled JSON with <c>"sql"</c> + <c>"parameters"</c> keys.
    /// Tests depend on this format; if AuditingDbCommand ever changes, this
    /// helper updates in lockstep.
    /// </summary>
    private static string DbRequestSummary(string sql, params (string name, string value)[] parameters)
    {
        var sb = new System.Text.StringBuilder();
        sb.Append("{\"sql\":\"").Append(sql).Append('"');
        if (parameters.Length > 0)
        {
            sb.Append(",\"parameters\":{");
            for (var i = 0; i < parameters.Length; i++)
            {
                if (i > 0) sb.Append(',');
                sb.Append('"').Append(parameters[i].name).Append("\":\"")
                    .Append(parameters[i].value).Append('"');
            }
            sb.Append('}');
        }
        sb.Append('}');
        return sb.ToString();
    }

    [Fact]
    public void NoOptIn_ParamsVerbatim_Unchanged()
    {
        var input = DbRequestSummary(
            "INSERT INTO Users (Name, Token) VALUES (@name, @token)",
            ("@name", "Alice"),
            ("@token", "secret-xyz"));
        var evt = NewDbEvent("PrimaryDb.INSERT INTO Users", input);

        var result = Filter().Apply(evt);

        Assert.Equal(input, result.RequestSummary);
    }

    [Fact]
    public void OptInRegex_AtToken_OrAtApikey_RedactsThoseValues_KeepsOthers()
    {
        var opts = new AuditLogOptions
        {
            PerTargetOverrides = new Dictionary<string, PerTargetRedactionOverride>
            {
                ["PrimaryDb"] = new PerTargetRedactionOverride
                {
                    RedactSqlParamsMatching = "^@(token|apikey)$",
                },
            },
        };
        var input = DbRequestSummary(
            "INSERT INTO Users (Name, Token, ApiKey) VALUES (@name, @token, @apikey)",
            ("@name", "Alice"),
            ("@token", "secret-xyz"),
            ("@apikey", "k-987"));
        var evt = NewDbEvent("PrimaryDb.INSERT INTO Users", input);

        var result = Filter(opts).Apply(evt);

        Assert.NotNull(result.RequestSummary);
        Assert.Contains("\"@name\":\"Alice\"", result.RequestSummary);
        Assert.Contains("\"@token\":\"<redacted>\"", result.RequestSummary);
        Assert.Contains("\"@apikey\":\"<redacted>\"", result.RequestSummary);
        Assert.DoesNotContain("secret-xyz", result.RequestSummary);
        Assert.DoesNotContain("k-987", result.RequestSummary);
    }

    [Fact]
    public void RegexCaseInsensitive_MatchesParamNames()
    {
        var opts = new AuditLogOptions
        {
            PerTargetOverrides = new Dictionary<string, PerTargetRedactionOverride>
            {
                ["PrimaryDb"] = new PerTargetRedactionOverride
                {
                    RedactSqlParamsMatching = "token",
                },
            },
        };
        var input = DbRequestSummary(
            "UPDATE x SET Token = @TOKEN",
            ("@TOKEN", "uppercased-secret"));
        var evt = NewDbEvent("PrimaryDb.UPDATE x SET Token", input);

        var result = Filter(opts).Apply(evt);

        Assert.NotNull(result.RequestSummary);
        Assert.Contains("\"@TOKEN\":\"<redacted>\"", result.RequestSummary);
        Assert.DoesNotContain("uppercased-secret", result.RequestSummary);
    }

    [Fact]
    public void NonDbOutboundChannel_NotAffected()
    {
        // ApiOutbound row whose RequestSummary happens to look like the
        // DbOutbound JSON shape (worst-case false positive). The SQL
        // redactor must NOT touch it — channel guards the stage.
        var opts = new AuditLogOptions
        {
            PerTargetOverrides = new Dictionary<string, PerTargetRedactionOverride>
            {
                ["PrimaryDb"] = new PerTargetRedactionOverride
                {
                    RedactSqlParamsMatching = "^@token$",
                },
            },
        };
        var input = DbRequestSummary(
            "SELECT @token",
            ("@token", "should-survive"));
        var evt = new AuditEvent
        {
            EventId = Guid.NewGuid(),
            OccurredAtUtc = DateTime.UtcNow,
            Channel = AuditChannel.ApiOutbound,
            Kind = AuditKind.ApiCall,
            Status = AuditStatus.Delivered,
            Target = "PrimaryDb.SELECT", // doesn't matter — channel guards
            RequestSummary = input,
        };

        var result = Filter(opts).Apply(evt);

        Assert.Equal(input, result.RequestSummary);
    }

    [Fact]
    public void PerTargetSetting_MatchesByTarget()
    {
        // Two connections — A is configured to redact tokens, B is not. Same
        // payload through each must yield different results.
        var opts = new AuditLogOptions
        {
            PerTargetOverrides = new Dictionary<string, PerTargetRedactionOverride>
            {
                ["ConnA"] = new PerTargetRedactionOverride
                {
                    RedactSqlParamsMatching = "^@token$",
                },
            },
        };
        var input = DbRequestSummary(
            "SELECT @token",
            ("@token", "the-secret"));

        var aEvt = NewDbEvent("ConnA.SELECT @token", input);
        var bEvt = NewDbEvent("ConnB.SELECT @token", input);

        var aResult = Filter(opts).Apply(aEvt);
        var bResult = Filter(opts).Apply(bEvt);

        Assert.Contains("<redacted>", aResult.RequestSummary!);
        Assert.DoesNotContain("the-secret", aResult.RequestSummary!);

        Assert.Equal(input, bResult.RequestSummary);
    }

    /// <summary>IOptionsMonitor test double.</summary>
    private sealed class StaticMonitor : IOptionsMonitor<AuditLogOptions>
    {
        private readonly AuditLogOptions _value;
        public StaticMonitor(AuditLogOptions value) => _value = value;
        public AuditLogOptions CurrentValue => _value;
        public AuditLogOptions Get(string? name) => _value;
        public IDisposable? OnChange(Action<AuditLogOptions, string?> listener) => null;
    }
}