using System.Text.Json;
using Microsoft.Extensions.Logging;

namespace Registration.Data;

/// <summary>
/// Real data service backed by dbRegistration.
/// Calls dbo.spRegistration with the standard @action/@rqst/@resp pattern.
///
/// Activate by swapping DI registration in Program.cs:
///   services.AddSingleton&lt;IRegistrationDataService, SqlDataService&gt;();
/// </summary>
public class SqlDataService : IRegistrationDataService
{
    private readonly SqlService _sql;
    private readonly ILogger<SqlDataService> _log;

    private const string Proc = "dbo.spRegistration";

    public SqlDataService(SqlService sql, ILogger<SqlDataService> log)
    {
        _sql = sql;
        _log = log;
    }

    public async Task<RegistrationListResult> GetPendingAsync(CancellationToken ct)
    {
        var resp = await _sql.ExecProcAsync(Proc, "pending", "{}", ct: ct);
        return JsonSerializer.Deserialize<RegistrationListResult>(resp, JsonOpts)
            ?? new() { Ok = false };
    }

    public async Task<Applicant?> GetByIdAsync(string registrationId, CancellationToken ct)
    {
        var rqst = JsonSerializer.Serialize(new { registrationId });
        var resp = await _sql.ExecProcAsync(Proc, "get", rqst, ct: ct);

        using var doc = JsonDocument.Parse(resp);
        if (doc.RootElement.TryGetProperty("applicant", out var app))
            return JsonSerializer.Deserialize<Applicant>(app.GetRawText(), JsonOpts);

        return null;
    }

    public async Task<RegistrationResult> RegisterAsync(RegisterRequest request, CancellationToken ct)
    {
        var rqst = JsonSerializer.Serialize(request, JsonOpts);
        var resp = await _sql.ExecProcAsync(Proc, "register", rqst, ct: ct);
        return JsonSerializer.Deserialize<RegistrationResult>(resp, JsonOpts)
            ?? new() { Ok = false, Error = "Deserialization failed" };
    }

    public async Task<RegistrationResult> RejectAsync(string registrationId, string? reason, string? rejectedBy, CancellationToken ct)
    {
        var rqst = JsonSerializer.Serialize(new { registrationId, reason, rejectedBy });
        var resp = await _sql.ExecProcAsync(Proc, "reject", rqst, ct: ct);
        return JsonSerializer.Deserialize<RegistrationResult>(resp, JsonOpts)
            ?? new() { Ok = false, Error = "Deserialization failed" };
    }

    public async Task<RegistrationResult> CompleteAsync(string registrationId, string? platformClientId, CancellationToken ct)
    {
        var rqst = JsonSerializer.Serialize(new { registrationId, platformClientId });
        var resp = await _sql.ExecProcAsync(Proc, "complete", rqst, ct: ct);
        return JsonSerializer.Deserialize<RegistrationResult>(resp, JsonOpts)
            ?? new() { Ok = false, Error = "Deserialization failed" };
    }

    private static readonly JsonSerializerOptions JsonOpts = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        PropertyNameCaseInsensitive = true
    };
}