using System.Globalization;
using System.Security.Cryptography;
using System.Text;
using SQLInsight.Repository;

namespace SQLInsight.Web.Api;

/// <summary>Body of POST /api/v1/support-cases.</summary>
public sealed record SupportCaseCreateBody(string? Title, string? Description, string? ContactName, string? ContactEmail, string? ContactPhone, long? FindingId);

/// <summary>Body of POST /api/v1/support-cases/{id}/close.</summary>
public sealed record SupportCaseCloseBody(string? Comment);

/// <summary>
/// Support cases through the API, e.g. from an ITSM system: create, list, read and close. The same logic as the
/// /support page; the agent sends them to SQLInsight Hub. Writing needs the scope support:write for tokens.
/// </summary>
public static class SupportApiEndpoints
{
    public static void Map(IEndpointRouteBuilder app)
    {
        ArgumentNullException.ThrowIfNull(app);
        var api = app.MapGroup("/api/v1/support-cases").DisableAntiforgery().WithTags("SQLInsight Pro API v1").RequireRead();
        api.MapPost("", CreateAsync)
            .WithSummary("Opret en supportsag / Create a support case")
            .WithDescription("202 Accepted with the local id and status Pending; the case number (SUP-…) follows when the agent has heard from SQLInsight Hub. "
                             + "Idempotency-Key header: the same key returns the same case. Needs scope support:write for tokens.");
        api.MapGet("", ListAsync).WithSummary("Kundens supportsager / Support cases (status, from, to, limit, continuation)");
        api.MapGet("/{id:long}", GetAsync).WithSummary("Én supportsag med status og sagsnummer / One support case");
        api.MapPost("/{id:long}/close", CloseAsync)
            .WithSummary("Luk en supportsag / Close a support case")
            .WithDescription("Status CloseRequested until the hub has confirmed it, then Closed. Closing a closed case returns 200. Needs scope support:write for tokens.");
    }

    private static IResult Forbidden(string detail) =>
        Results.Problem(statusCode: StatusCodes.Status403Forbidden, title: "Ikke tilladt", detail: detail);

    private static async Task<IResult> CreateAsync(SupportCaseCreateBody body, HttpContext http, InsightRepository repository, CancellationToken ct)
    {
        if (!ApiTokenHandler.HasScope(http.User, ApiToken.SupportWrite))
        {
            return Forbidden("API-tokenet mangler scope \"support:write\".");
        }

        var key = http.Request.Headers["Idempotency-Key"].ToString();
        var clientRequestId = key.Length == 0 ? Guid.NewGuid() : RequestId(key);
        var result = await Support.FileAsync(repository, clientRequestId, body.Title, body.Description, body.ContactName, body.ContactEmail, body.ContactPhone,
            body.FindingId, http.User.Identity?.Name, ct).ConfigureAwait(false);
        if (result.NotAllowed)
        {
            return Forbidden(Support.NotAllowedText);
        }

        if (result.Error is { } error)
        {
            return Results.Problem(statusCode: StatusCodes.Status422UnprocessableEntity, title: "Ugyldig sag", detail: error);
        }

        var row = (await repository.GetSupportCaseAsync(result.CaseId!.Value, ct).ConfigureAwait(false))!;
        return Results.Accepted($"/api/v1/support-cases/{row.CaseId}", Json(row));
    }

    /// <summary>An Idempotency-Key as the request id: a GUID as it is, anything else hashed to one.</summary>
    public static Guid RequestId(string key)
    {
        ArgumentNullException.ThrowIfNull(key);
        return Guid.TryParse(key, out var guid) ? guid : new Guid(SHA256.HashData(Encoding.UTF8.GetBytes(key)).AsSpan(0, 16));
    }

    private static async Task<IResult> ListAsync(InsightRepository repository, HttpContext http, CancellationToken ct,
        string? status = null, DateTimeOffset? from = null, DateTimeOffset? to = null, int? limit = null, string? continuation = null)
    {
        var offset = 0;
        if (continuation is { Length: > 0 } && !int.TryParse(continuation, NumberStyles.None, CultureInfo.InvariantCulture, out offset))
        {
            return Results.BadRequest("Ugyldig continuation.");
        }

        var size = Math.Clamp(limit ?? 100, 1, 1000);
        var (cases, more) = await repository.SearchSupportCasesAsync(status, from, to, offset, size, ct).ConfigureAwait(false);
        if (more)
        {
            http.Response.Headers["X-Continuation"] = (offset + size).ToString(CultureInfo.InvariantCulture);
        }

        return Results.Ok(cases.Select(Json));
    }

    private static async Task<IResult> GetAsync(long id, InsightRepository repository, CancellationToken ct) =>
        await repository.GetSupportCaseAsync(id, ct).ConfigureAwait(false) is { } row ? Results.Ok(Json(row)) : Results.NotFound();

    private static async Task<IResult> CloseAsync(long id, HttpContext http, InsightRepository repository, CancellationToken ct, SupportCaseCloseBody? body = null)
    {
        if (!ApiTokenHandler.HasScope(http.User, ApiToken.SupportWrite))
        {
            return Forbidden("API-tokenet mangler scope \"support:write\".");
        }

        if (body?.Comment?.Length > Contracts.SupportCaseCloseRequest.MaxComment)
        {
            return Results.Problem(statusCode: StatusCodes.Status422UnprocessableEntity, title: "Ugyldig lukning", detail: $"Kommentaren må højst være {Contracts.SupportCaseCloseRequest.MaxComment} tegn.");
        }

        var outcome = await repository.RequestSupportCloseAsync(id, http.User.Identity?.Name, body?.Comment, DateTimeOffset.UtcNow, ct).ConfigureAwait(false);
        if (outcome == SupportCloseOutcome.NotFound)
        {
            return Results.NotFound();
        }

        if (outcome == SupportCloseOutcome.Failed)
        {
            return Results.Problem(statusCode: StatusCodes.Status409Conflict, title: "Sagen kan ikke lukkes", detail: "SQLInsight Hub afviste sagen, så den findes ikke hos SEOSoft.");
        }

        var row = (await repository.GetSupportCaseAsync(id, ct).ConfigureAwait(false))!;
        return outcome == SupportCloseOutcome.AlreadyClosed ? Results.Ok(Json(row)) : Results.Accepted($"/api/v1/support-cases/{id}", Json(row));
    }

    private static object Json(SupportCaseRow c) => new
    {
        Id = c.CaseId,
        c.Reference,
        c.Title,
        c.Status,
        c.Source,
        c.FindingId,
        c.InstanceName,
        c.RuleId,
        c.RequestedBy,
        c.CreatedAt,
        c.SentAt,
        c.CloseRequestedAt,
        c.ClosedAt,
        c.ClosedBy,
        Error = c.Status == SupportCaseStatus.Failed ? c.LastError : null,
    };
}