using System.Text.Json;
using Ory.Kratos.Client.Api;
using khmereid_backend.Dtos;
using Ory.Kratos.Client.Model;
using Ory.Kratos.Client.Client;

namespace khmereid_backend.Integrations;

public class KratosApi : IAuthnApi
{
    private readonly FrontendApi _frontendApi;
    private readonly IdentityApi _identityApi;
    private readonly ILogger<KratosApi> _logger;

    public KratosApi(IConfiguration config, ILogger<KratosApi> logger)
    {
        var publicCfg = new Configuration { BasePath = config["Ory:Kratos:PublicUrl"]! };
        var adminCfg = new Configuration { BasePath = config["Ory:Kratos:AdminUrl"]! };

        _frontendApi = new FrontendApi(publicCfg);
        _identityApi = new IdentityApi(adminCfg);
        _logger = logger;
    }

    // --------------------------- Registration Flows ---------------------------
    public async Task<FlowDto> CreateOtpRegistrationFlowAsync(string phone)
    {
        var flow = await _frontendApi.CreateNativeRegistrationFlowAsync(returnSessionTokenExchangeCode: true);
        _logger.LogInformation("Started registration flow: {FlowId}", flow.Id);

        phone = phone.Trim();
        var method = new KratosUpdateRegistrationFlowWithCodeMethod(method: "code", traits: new { phone });
        var body = new KratosUpdateRegistrationFlowBody(method);

        try
        {
            var updatedFlow = await _frontendApi.UpdateRegistrationFlowAsync(flow.Id, body);
            return new FlowDto{};
        }
        catch (ApiException ex)
        {
            return HandleFlowException(ex);
        }
    }

    public async Task<SignupResultDto> CompleteOtpRegistrationFlowAsync(string otp, string phone, string flowId)
    {
        phone = phone.Trim();
        var method = new KratosUpdateRegistrationFlowWithCodeMethod(code: otp, method: "code", traits: new { phone });
        var body = new KratosUpdateRegistrationFlowBody(method);

        try
        {
            var result = await _frontendApi.UpdateRegistrationFlowAsync(flowId, body);
            _logger.LogInformation("Completed OTP registration flow for flow {FlowId}", flowId);

            return new SignupResultDto
            {
                IdentityId = Guid.Parse(result.Identity.Id),
                AccessToken = result.SessionToken,
                ExpiredAt = result.Session?.ExpiresAt
            };
        }
        catch (ApiException ex)
        {
            return HandleRegistrationException(ex);
        }
    }

    // --------------------------- Login Flows ---------------------------
    public async Task<FlowDto> CreateOtpLoginFlowAsync(string phone)
    {
        var flow = await _frontendApi.CreateNativeLoginFlowAsync(returnSessionTokenExchangeCode: true);
        _logger.LogInformation("Started login flow: {FlowId}", flow.Id);

        phone = phone.Trim();
        var method = new KratosUpdateLoginFlowWithCodeMethod(method: "code", csrfToken: "dfdfdfde", identifier: phone);
        var body = new KratosUpdateLoginFlowBody(method);

        try
        {
            var updatedFlow = await _frontendApi.UpdateLoginFlowAsync(flow.Id, body);
            return new FlowDto{};
        }
        catch (ApiException ex)
        {
            return HandleFlowException(ex);
        }
    }

    public async Task<LoginResultDto> CompleteOtpLoginFlowAsync(string flowId, string phone, string otp)
    {
        phone = "+" + phone.Trim();
        var method = new KratosUpdateLoginFlowWithCodeMethod(code: otp, method: "code", csrfToken: "dfdfdfde", identifier: phone);
        var body = new KratosUpdateLoginFlowBody(method);

        try
        {
            var result = await _frontendApi.UpdateLoginFlowAsync(flowId, body);
            _logger.LogInformation("Completed OTP login flow for flow {FlowId}", flowId);

            return new LoginResultDto
            {
                AccessToken = result.SessionToken,
                ExpiredAt = result.Session?.ExpiresAt
            };
        }
        catch (ApiException ex)
        {
            return HandleLoginException(ex);
        }
    }

    // --------------------------- Session & Logout ---------------------------
    public async Task<SessionDto> GetMeAsync(string sessionToken)
    {
        try
        {
            var session = await _frontendApi.ToSessionAsync(xSessionToken: sessionToken);
            return new SessionDto
            {
                Id = session.Identity.Id,
                ExpiresAt = session.ExpiresAt
            };
        }
        catch (ApiException ex) when (ex.ErrorCode == 401 || ex.ErrorCode == 403)
        {
            throw new UnauthorizedAccessException("Invalid or expired Kratos session token", ex);
        }
        catch (ApiException ex)
        {
            throw new InvalidOperationException($"Failed to fetch session from Kratos: {ex.Message}", ex);
        }
    }

    public async Task<dynamic> Logout(string sessionToken)
    {
        var body = new KratosPerformNativeLogoutBody(sessionToken: sessionToken);
        await _frontendApi.PerformNativeLogoutAsync(body);
        _logger.LogInformation("Logged out session with token {SessionToken}", sessionToken);
        return new { Message = "Logged out successfully." };
    }

    // --------------------------- Password Flow ---------------------------
    public async Task<dynamic> PasswordRegistrationFlowAsync(string flowId, string phone)
    {
        var method = new KratosUpdateRegistrationFlowWithPasswordMethod(
            password: "add3ae4d8ae8",
            traits: new { phone, identifier = phone },
            method: "password"
        );

        var body = new KratosUpdateRegistrationFlowBody(method);
        var result = await _frontendApi.UpdateRegistrationFlowAsync(flowId, body);

        _logger.LogInformation("Completed password registration flow for {Phone}", phone);
        return result;
    }

    // --------------------------- Private Helpers ---------------------------
    private static FlowDto HandleFlowException(ApiException ex)
    {
        var res = JsonSerializer.Deserialize<JsonElement>(ex.ErrorContent?.ToString() ?? "{}");

        if (ex.ErrorCode == 400 && res.TryGetProperty("state", out var stateProp) && stateProp.GetString() == "sent_email")
        {
            return new FlowDto
            {
                FlowId = res.GetProperty("id").GetString() ?? "",
                State = "sent_otp",
                ExpiresAt = res.TryGetProperty("expires_at", out var expiresAtProp) ? expiresAtProp.GetDateTime() : (DateTimeOffset?)null
            };
        }

        if (ex.ErrorCode == 400)
            return new FlowDto
            {
                Error = "BadRequest",
                Code = ex.ErrorCode.ToString(),
                Message = GetKratosErrorMessage(res)
            };

        throw new InvalidOperationException($"Kratos API returned {ex.ErrorCode}: {ex.Message}", ex);
    }

    private SignupResultDto HandleRegistrationException(ApiException ex)
    {
        var res = JsonSerializer.Deserialize<JsonElement>(ex.ErrorContent?.ToString() ?? "{}");

        if (ex.ErrorCode == 410 && res.TryGetProperty("use_flow_id", out var useFlowProp))
        {
            _logger.LogWarning("Registration flow expired. Use new flow: {FlowId}", useFlowProp.GetString());
            return new SignupResultDto
            {
                Error = "FlowExpired",
                Code = ex.ErrorCode.ToString(),
                Message = "Registration flow expired. Please restart registration.",
                UseFlowId = useFlowProp.GetString()
            };
        }

        if (ex.ErrorCode == 400)
            return new SignupResultDto
            {
                Code = ex.ErrorCode.ToString(),
                Error = "BadRequest",
                Message = GetKratosErrorMessage(res)
            };

        if (ex.ErrorCode == 404)
            return new SignupResultDto
            {
                Code = ex.ErrorCode.ToString(),
                Error = "NotFound",
                Message = "Registration flow not found."
            };

        return new SignupResultDto
        {
            Code = ex.ErrorCode.ToString(),
            Error = "UnhandledException",
            Message = $"Unhandled Kratos API exception: {ex.Message}"
        };
    }

    private static LoginResultDto HandleLoginException(ApiException ex)
    {
        var res = JsonSerializer.Deserialize<JsonElement>(ex.ErrorContent?.ToString() ?? "{}");

        if (ex.ErrorCode == 404)
            return new LoginResultDto
            {
                Error = "NotFound",
                Code = ex.ErrorCode.ToString(),
                Message = "Login flow not found."
            };

        return new LoginResultDto
        {
            Error = "BadRequest",
            Code = ex.ErrorCode.ToString(),
            Message = GetKratosErrorMessage(res)
        };
    }

    private static string GetKratosErrorMessage(JsonElement res)
    {
        if (res.TryGetProperty("error", out var errProp) && errProp.TryGetProperty("reason", out var reasonProp))
            return reasonProp.GetString() ?? "Bad request";

        if (res.TryGetProperty("ui", out var uiProp) &&
            uiProp.TryGetProperty("messages", out var messagesProp) &&
            messagesProp.ValueKind == JsonValueKind.Array &&
            messagesProp.GetArrayLength() > 0 &&
            messagesProp[0].TryGetProperty("text", out var textProp))
            return textProp.GetString() ?? "Bad request";

        return "Bad request";
    }
}