// -----------------------------------------------------------------------------
// CommandHandlers.Drift.cs
// Sprint: SPRINT_3600_0004_0001_ui_evidence_chain
// Tasks: UI-019, UI-020, UI-021
// Description: Command handlers for reachability drift CLI.
// -----------------------------------------------------------------------------

using System.Text.Json;
using Spectre.Console;

namespace StellaOps.Cli.Commands;

internal static partial class CommandHandlers
{
    private static readonly JsonSerializerOptions DriftJsonOptions = new()
    {
        WriteIndented = true,
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase
    };

    /// <summary>
    /// Handler for `drift compare` command.
    /// </summary>
    internal static async Task HandleDriftCompareAsync(
        IServiceProvider services,
        string baseId,
        string? headId,
        string? image,
        string? repo,
        string output,
        string minSeverity,
        bool onlyIncreases,
        bool verbose,
        CancellationToken cancellationToken)
    {
        // TODO: Replace with actual service call when drift API is available
        var console = AnsiConsole.Console;

        if (verbose)
        {
            console.MarkupLine($"[dim]Comparing drift: base={baseId}, head={headId ?? "(latest)"}[/]");
        }

        // Placeholder: In real implementation, call drift service
        var driftResult = new DriftResultDto
        {
            Id = Guid.NewGuid().ToString("N")[..8],
            ComparedAt = DateTimeOffset.UtcNow.ToString("O"),
            BaseGraphId = baseId,
            HeadGraphId = headId ?? "latest",
            Summary = new DriftSummaryDto
            {
                TotalSinks = 0,
                IncreasedReachability = 0,
                DecreasedReachability = 0,
                UnchangedReachability = 0,
                NewSinks = 0,
                RemovedSinks = 0,
                RiskTrend = "stable",
                NetRiskDelta = 0
            },
            DriftedSinks = Array.Empty<DriftedSinkDto>()
        };

        switch (output)
        {
            case "json":
                await WriteJsonOutputAsync(console, driftResult, cancellationToken);
                break;
            case "sarif":
                await WriteSarifOutputAsync(console, driftResult, cancellationToken);
                break;
            default:
                WriteTableOutput(console, driftResult, onlyIncreases, minSeverity);
                break;
        }
    }

    /// <summary>
    /// Handler for `drift show` command.
    /// </summary>
    internal static async Task HandleDriftShowAsync(
        IServiceProvider services,
        string id,
        string output,
        bool expandPaths,
        bool verbose,
        CancellationToken cancellationToken)
    {
        var console = AnsiConsole.Console;

        if (verbose)
        {
            console.MarkupLine($"[dim]Showing drift result: {id}[/]");
        }

        // Placeholder: In real implementation, call drift service
        var driftResult = new DriftResultDto
        {
            Id = id,
            ComparedAt = DateTimeOffset.UtcNow.ToString("O"),
            BaseGraphId = "base",
            HeadGraphId = "head",
            Summary = new DriftSummaryDto
            {
                TotalSinks = 0,
                IncreasedReachability = 0,
                DecreasedReachability = 0,
                UnchangedReachability = 0,
                NewSinks = 0,
                RemovedSinks = 0,
                RiskTrend = "stable",
                NetRiskDelta = 0
            },
            DriftedSinks = Array.Empty<DriftedSinkDto>()
        };

        switch (output)
        {
            case "json":
                await WriteJsonOutputAsync(console, driftResult, cancellationToken);
                break;
            case "sarif":
                await WriteSarifOutputAsync(console, driftResult, cancellationToken);
                break;
            default:
                WriteTableOutput(console, driftResult, false, "info");
                break;
        }
    }

    // Task: UI-020 - Table output using Spectre.Console
    private static void WriteTableOutput(
        IAnsiConsole console,
        DriftResultDto result,
        bool onlyIncreases,
        string minSeverity)
    {
        // Header panel
        var header = new Panel(new Markup($"[bold]Reachability Drift[/] [dim]({result.Id})[/]"))
            .Border(BoxBorder.Rounded)
            .Padding(1, 0);
        console.Write(header);

        // Summary table
        var summaryTable = new Table()
            .Border(TableBorder.Rounded)
            .AddColumn("Metric")
            .AddColumn("Value");

        summaryTable.AddRow("Trend", FormatTrend(result.Summary.RiskTrend));
        summaryTable.AddRow("Net Risk Delta", FormatDelta(result.Summary.NetRiskDelta));
        summaryTable.AddRow("Increased", result.Summary.IncreasedReachability.ToString());
        summaryTable.AddRow("Decreased", result.Summary.DecreasedReachability.ToString());
        summaryTable.AddRow("New Sinks", result.Summary.NewSinks.ToString());
        summaryTable.AddRow("Removed Sinks", result.Summary.RemovedSinks.ToString());

        console.Write(summaryTable);

        // Sinks table
        if (result.DriftedSinks.Length == 0)
        {
            console.MarkupLine("[green]No drifted sinks found.[/]");
            return;
        }

        var sinksTable = new Table()
            .Border(TableBorder.Rounded)
            .AddColumn("Severity")
            .AddColumn("Sink")
            .AddColumn("CVE")
            .AddColumn("Bucket Change")
            .AddColumn("Delta");

        var severityOrder = new Dictionary<string, int>
        {
            ["critical"] = 0,
            ["high"] = 1,
            ["medium"] = 2,
            ["low"] = 3,
            ["info"] = 4
        };

        var minSevOrder = severityOrder.GetValueOrDefault(minSeverity, 2);

        foreach (var sink in result.DriftedSinks)
        {
            var sevOrder = severityOrder.GetValueOrDefault(sink.Severity ?? "info", 4);
            if (sevOrder > minSevOrder) continue;
            if (onlyIncreases && !sink.IsRiskIncrease) continue;

            sinksTable.AddRow(
                FormatSeverity(sink.Severity),
                sink.SinkSymbol ?? "unknown",
                sink.CveId ?? "-",
                $"{sink.PreviousBucket ?? "N/A"} → {sink.CurrentBucket}",
                FormatDelta(sink.RiskDelta));
        }

        console.Write(sinksTable);
    }

    // Task: UI-021 - JSON output
    private static async Task WriteJsonOutputAsync(
        IAnsiConsole console,
        DriftResultDto result,
        CancellationToken cancellationToken)
    {
        var json = JsonSerializer.Serialize(result, DriftJsonOptions);
        console.WriteLine(json);
        await Task.CompletedTask;
    }

    // Task: UI-022, UI-023 - SARIF output (placeholder)
    private static async Task WriteSarifOutputAsync(
        IAnsiConsole console,
        DriftResultDto result,
        CancellationToken cancellationToken)
    {
        // TODO: Implement full SARIF 2.1.0 generation in DriftSarifGenerator
        var sarif = new
        {
            version = "2.1.0",
            schema = "https://raw.githubusercontent.com/oasis-tcs/sarif-spec/master/Schemata/sarif-schema-2.1.0.json",
            runs = new[]
            {
                new
                {
                    tool = new
                    {
                        driver = new
                        {
                            name = "StellaOps Drift",
                            version = "1.0.0",
                            informationUri = "https://stellaops.io/docs/drift"
                        }
                    },
                    results = result.DriftedSinks.Select(sink => new
                    {
                        ruleId = sink.CveId ?? $"drift-{sink.SinkSymbol}",
                        level = MapSeverityToSarif(sink.Severity),
                        message = new
                        {
                            text = $"Reachability changed: {sink.PreviousBucket ?? "N/A"} → {sink.CurrentBucket}"
                        },
                        locations = Array.Empty<object>()
                    }).ToArray()
                }
            }
        };

        var json = JsonSerializer.Serialize(sarif, DriftJsonOptions);
        console.WriteLine(json);
        await Task.CompletedTask;
    }

    private static string FormatTrend(string trend) => trend switch
    {
        "increasing" => "[red]↑ Increasing[/]",
        "decreasing" => "[green]↓ Decreasing[/]",
        _ => "[dim]→ Stable[/]"
    };

    private static string FormatDelta(int delta) => delta switch
    {
        > 0 => $"[red]+{delta}[/]",
        < 0 => $"[green]{delta}[/]",
        _ => "[dim]0[/]"
    };

    private static string FormatSeverity(string? severity) => severity switch
    {
        "critical" => "[white on red] CRITICAL [/]",
        "high" => "[black on darkorange] HIGH [/]",
        "medium" => "[black on yellow] MEDIUM [/]",
        "low" => "[black on olive] LOW [/]",
        _ => "[dim] INFO [/]"
    };

    private static string MapSeverityToSarif(string? severity) => severity switch
    {
        "critical" or "high" => "error",
        "medium" => "warning",
        _ => "note"
    };

    // DTOs for drift output
    private sealed record DriftResultDto
    {
        public string Id { get; init; } = string.Empty;
        public string ComparedAt { get; init; } = string.Empty;
        public string BaseGraphId { get; init; } = string.Empty;
        public string HeadGraphId { get; init; } = string.Empty;
        public DriftSummaryDto Summary { get; init; } = new();
        public DriftedSinkDto[] DriftedSinks { get; init; } = Array.Empty<DriftedSinkDto>();
    }

    private sealed record DriftSummaryDto
    {
        public int TotalSinks { get; init; }
        public int IncreasedReachability { get; init; }
        public int DecreasedReachability { get; init; }
        public int UnchangedReachability { get; init; }
        public int NewSinks { get; init; }
        public int RemovedSinks { get; init; }
        public string RiskTrend { get; init; } = "stable";
        public int NetRiskDelta { get; init; }
    }

    private sealed record DriftedSinkDto
    {
        public string? SinkSymbol { get; init; }
        public string? CveId { get; init; }
        public string? Severity { get; init; }
        public string? PreviousBucket { get; init; }
        public string CurrentBucket { get; init; } = string.Empty;
        public bool IsRiskIncrease { get; init; }
        public int RiskDelta { get; init; }
    }
}