using System.Text.Json;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;
using SQLInsight.Contracts;
using SQLInsight.Hub.Data;
using SQLInsight.Hub.Support;

namespace SQLInsight.Hub.Api;

/// <summary>
/// Support cases for paying customers, through their agent:
/// POST /api/v1/cases creates a case (idempotent on ClientRequestId) and returns its number;
/// GET /api/v1/cases lists the customer's cases, also those SEOSoft created, so SQLInsight Web can show their status.
/// POST /api/v1/cases/{reference}/close closes one of the customer's own cases (idempotent).
/// </summary>
public static class CasesEndpoint
{
    private const int MaxListed = 200;

    public static void Map(IEndpointRouteBuilder app)
    {
        app.MapPost("/api/v1/cases", CreateAsync).DisableAntiforgery().AllowAnonymous();
        app.MapGet("/api/v1/cases", ListAsync).AllowAnonymous();
        app.MapPost("/api/v1/cases/{reference}/close", CloseAsync).DisableAntiforgery().AllowAnonymous();
    }

    internal static async Task<IResult> CreateAsync(
        HttpRequest request, HubDbContext db, IOptions<HubServerOptions> options, SupportNotifier notifier, TimeProvider time, CancellationToken cancellationToken)
    {
        var (license, rejected) = await FindingsEndpoint.AuthorizeAsync(request, db, options.Value, time, cancellationToken).ConfigureAwait(false);
        if (license is null)
        {
            return rejected!;
        }

        if (!license.IncludesPrioritySupport)
        {
            return FindingsEndpoint.Problem(403, "Licensen giver ikke support", "Supportsager kræver Professional eller Enterprise.");
        }

        if (request.ContentLength > 64 * 1024)
        {
            return FindingsEndpoint.Problem(413, "For stor", "Højst 64 KB.");
        }

        SupportCaseRequest? body;
        try
        {
            body = await JsonSerializer.DeserializeAsync<SupportCaseRequest>(request.Body, JsonSerializerOptions.Web, cancellationToken).ConfigureAwait(false);
        }
        catch (JsonException ex)
        {
            return FindingsEndpoint.Problem(400, "Ugyldig JSON", ex.Message);
        }

        if (body is null)
        {
            return FindingsEndpoint.Problem(400, "Ugyldig sag", "Body mangler.");
        }

        if (body.Validate() is { } invalid)
        {
            return FindingsEndpoint.Problem(422, "Ugyldig sag", invalid);
        }

        var now = time.GetUtcNow().UtcDateTime;
        await using var transaction = await db.Database.BeginTransactionAsync(cancellationToken).ConfigureAwait(false);
        await CustomerRegistration.LockAsync(db, license.Customer, cancellationToken).ConfigureAwait(false);
        var record = await db.Licenses.SingleOrDefaultAsync(l => l.LicenseId == license.LicenseId, cancellationToken).ConfigureAwait(false);
        if (record?.RevokedAt is not null)
        {
            return FindingsEndpoint.Problem(403, "Licensen er spærret", record.RevokedReason ?? "Kontakt SQLInsight-support.");
        }

        var (customer, _) = await CustomerRegistration.EnsureAsync(db, license, record, now, cancellationToken).ConfigureAwait(false);
        var existing = await db.SupportCases.SingleOrDefaultAsync(c => c.CustomerId == customer.Id && c.ClientRequestId == body.ClientRequestId, cancellationToken).ConfigureAwait(false);
        if (existing is not null)
        {
            await db.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
            await transaction.CommitAsync(cancellationToken).ConfigureAwait(false);
            return Results.Ok(SupportCaseStore.ToDto(existing));
        }

        var (created, error) = await SupportCaseStore.AddAsync(db, new SupportCase
        {
            CustomerId = customer.Id,
            Reference = string.Empty,
            Title = body.Title.Trim(),
            Description = Trimmed(body.Description),
            ContactName = body.ContactName.Trim(),
            ContactEmail = body.ContactEmail.Trim(),
            ContactPhone = Trimmed(body.ContactPhone),
            RequestedBy = Trimmed(body.RequestedBy),
            ClientRequestId = body.ClientRequestId,
            Source = SupportCaseSources.Customer,
            CreatedAt = now,
        }, cancellationToken).ConfigureAwait(false);
        if (created is null)
        {
            return FindingsEndpoint.Problem(409, "Sagen kunne ikke oprettes", error!);
        }

        // The finding the customer created the case from, if the hub has it as active and not yet in a case.
        if (body.InstanceName is { Length: > 0 } instance && body.RuleId is { Length: > 0 } rule && body.Subject is { } subject)
        {
            var finding = await db.Findings.SingleOrDefaultAsync(f => f.Instance!.CustomerId == customer.Id && f.Instance.InstanceKey == instance
                && f.RuleId == rule && f.Subject == subject && f.ResolvedAt == null && f.SupportCaseId == null, cancellationToken).ConfigureAwait(false);
            if (finding is not null)
            {
                finding.SupportCaseId = created.Id;
            }
        }

        await db.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
        await transaction.CommitAsync(cancellationToken).ConfigureAwait(false);

        await notifier.NotifyAsync(created, customer.Name, cancellationToken).ConfigureAwait(false);
        return Results.Created($"/api/v1/cases/{Uri.EscapeDataString(created.Reference)}", SupportCaseStore.ToDto(created));
    }

    internal static async Task<IResult> ListAsync(
        HttpRequest request, HubDbContext db, IOptions<HubServerOptions> options, TimeProvider time, CancellationToken cancellationToken)
    {
        var (license, rejected) = await FindingsEndpoint.AuthorizeAsync(request, db, options.Value, time, cancellationToken).ConfigureAwait(false);
        if (license is null)
        {
            return rejected!;
        }

        if (!license.IncludesPrioritySupport)
        {
            return FindingsEndpoint.Problem(403, "Licensen giver ikke support", "Supportsager kræver Professional eller Enterprise.");
        }

        var cases = await db.SupportCases.AsNoTracking()
            .Where(c => c.Customer!.Name == license.Customer)
            .OrderByDescending(c => c.CreatedAt)
            .Take(MaxListed)
            .ToListAsync(cancellationToken).ConfigureAwait(false);
        return Results.Ok(cases.Select(SupportCaseStore.ToDto).ToList());
    }

    internal static async Task<IResult> CloseAsync(
        string reference, HttpRequest request, HubDbContext db, IOptions<HubServerOptions> options, TimeProvider time, CancellationToken cancellationToken)
    {
        var (license, rejected) = await FindingsEndpoint.AuthorizeAsync(request, db, options.Value, time, cancellationToken).ConfigureAwait(false);
        if (license is null)
        {
            return rejected!;
        }

        if (!license.IncludesPrioritySupport)
        {
            return FindingsEndpoint.Problem(403, "Licensen giver ikke support", "Supportsager kræver Professional eller Enterprise.");
        }

        SupportCaseCloseRequest body;
        try
        {
            body = request.ContentLength is null or 0
                ? new SupportCaseCloseRequest(null, null)
                : await JsonSerializer.DeserializeAsync<SupportCaseCloseRequest>(request.Body, JsonSerializerOptions.Web, cancellationToken).ConfigureAwait(false)
                  ?? new SupportCaseCloseRequest(null, null);
        }
        catch (JsonException ex)
        {
            return FindingsEndpoint.Problem(400, "Ugyldig JSON", ex.Message);
        }

        if (body.Validate() is { } invalid)
        {
            return FindingsEndpoint.Problem(422, "Ugyldig lukning", invalid);
        }

        // Only the license's own customer's cases: anyone else's is simply not found.
        var supportCase = await db.SupportCases
            .SingleOrDefaultAsync(c => c.Customer!.Name == license.Customer && c.Reference == reference, cancellationToken).ConfigureAwait(false);
        if (supportCase is null)
        {
            return FindingsEndpoint.Problem(404, "Ukendt sag", $"Sagen {reference} findes ikke.");
        }

        if (supportCase.IsOpen)
        {
            supportCase.IsOpen = false;
            supportCase.ClosedAt = time.GetUtcNow().UtcDateTime;
            supportCase.ClosedBy = "Kunde: " + (string.IsNullOrWhiteSpace(body.RequestedBy) ? "ukendt" : body.RequestedBy.Trim());
            supportCase.ClosedComment = Trimmed(body.Comment);
            await db.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
        }

        return Results.Ok(SupportCaseStore.ToDto(supportCase));
    }

    private static string? Trimmed(string? value) => string.IsNullOrWhiteSpace(value) ? null : value.Trim();
}