// ExtractionPluginTests.cs -- Tests for the extraction plugin's schema validation
// and external API tool methods.
//
// ValidateSchema is tested directly (no external APIs needed).
// LookupCounterparty, ValidateTrade, and ValidateCurrency are tested with
// mocked HttpClients using MockHttpMessageHandler to simulate API responses.

using System.Net;
using System.Net.Http.Json;
using System.Text.Json;
using ChatAgent.Api.Plugins;
using ChatAgent.Api.Services;
using ChatAgent.Shared.Models;
using Moq;
using Moq.Protected;

namespace ChatAgent.Api.Tests;

public class ExtractionPluginTests
{
    // Helper to create an ExtractionPlugin with mocked HttpClients
    private static ExtractionPlugin CreatePluginWithMocks(
        HttpMessageHandler? counterpartyHandler = null,
        HttpMessageHandler? tradeHandler = null,
        HttpMessageHandler? currencyHandler = null)
    {
        var counterpartyClient = new CounterpartyApiClient(
            new HttpClient(counterpartyHandler ?? CreateOkHandler("[]"))
            { BaseAddress = new Uri("http://test/") });

        var tradeClient = new TradeApiClient(
            new HttpClient(tradeHandler ?? CreateOkHandler("{\"isValid\":true}"))
            { BaseAddress = new Uri("http://test/") });

        var currencyClient = new CurrencyApiClient(
            new HttpClient(currencyHandler ?? CreateOkHandler("{\"isValid\":true}"))
            { BaseAddress = new Uri("http://test/") });

        return new ExtractionPlugin(counterpartyClient, tradeClient, currencyClient);
    }

    // Creates an HttpMessageHandler that returns a 200 OK with the given JSON body
    private static HttpMessageHandler CreateOkHandler(string jsonBody)
    {
        var mock = new Mock<HttpMessageHandler>();
        mock.Protected()
            .Setup<Task<HttpResponseMessage>>(
                "SendAsync",
                ItExpr.IsAny<HttpRequestMessage>(),
                ItExpr.IsAny<CancellationToken>())
            .ReturnsAsync(new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StringContent(jsonBody, System.Text.Encoding.UTF8, "application/json")
            });
        return mock.Object;
    }

    // Creates an HttpMessageHandler that throws HttpRequestException
    private static HttpMessageHandler CreateErrorHandler()
    {
        var mock = new Mock<HttpMessageHandler>();
        mock.Protected()
            .Setup<Task<HttpResponseMessage>>(
                "SendAsync",
                ItExpr.IsAny<HttpRequestMessage>(),
                ItExpr.IsAny<CancellationToken>())
            .ThrowsAsync(new HttpRequestException("Connection refused"));
        return mock.Object;
    }

    // --- ValidateSchema tests ---

    [Fact]
    public void ValidateSchema_ValidResult_ReturnsValid()
    {
        var plugin = CreatePluginWithMocks();
        var extraction = new ExtractionResult
        {
            Items = new List<TradeItem>
            {
                new()
                {
                    Valuedate = "27/11/2025",
                    Counterparty = "Assured Guaranty UK Limited",
                    TradeId = 79353083,
                    DisplayCcy = "GBP",
                    Pv = 4562456.0,
                    Breakclause = "N"
                }
            }
        };

        var resultJson = plugin.ValidateSchema(JsonSerializer.Serialize(extraction));
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.True(result.IsValid);
        Assert.Empty(result.Errors);
    }

    [Fact]
    public void ValidateSchema_MissingFields_ReturnsErrors()
    {
        var plugin = CreatePluginWithMocks();
        // Missing counterparty and display_ccy
        var extraction = new ExtractionResult
        {
            Items = new List<TradeItem>
            {
                new()
                {
                    Valuedate = "27/11/2025",
                    TradeId = 79353083,
                    Pv = 4562456.0,
                    Breakclause = "N"
                }
            }
        };

        var resultJson = plugin.ValidateSchema(JsonSerializer.Serialize(extraction));
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.False(result.IsValid);
        Assert.Contains(result.Errors, e => e.Contains("counterparty"));
        Assert.Contains(result.Errors, e => e.Contains("display_ccy"));
    }

    [Fact]
    public void ValidateSchema_InvalidBreakclause_ReturnsError()
    {
        var plugin = CreatePluginWithMocks();
        var extraction = new ExtractionResult
        {
            Items = new List<TradeItem>
            {
                new()
                {
                    Valuedate = "27/11/2025",
                    Counterparty = "Test Corp",
                    TradeId = 12345,
                    DisplayCcy = "GBP",
                    Pv = 100.0,
                    Breakclause = "Maybe"
                }
            }
        };

        var resultJson = plugin.ValidateSchema(JsonSerializer.Serialize(extraction));
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.False(result.IsValid);
        Assert.Contains(result.Errors, e => e.Contains("'Y' or 'N'"));
    }

    [Fact]
    public void ValidateSchema_InvalidJson_ReturnsError()
    {
        var plugin = CreatePluginWithMocks();
        var resultJson = plugin.ValidateSchema("not valid json");
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.False(result.IsValid);
        Assert.Contains(result.Errors, e => e.Contains("Invalid JSON"));
    }

    [Fact]
    public void ValidateSchema_EmptyItems_ReturnsError()
    {
        var plugin = CreatePluginWithMocks();
        var resultJson = plugin.ValidateSchema("{\"items\":[]}");
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.False(result.IsValid);
        Assert.Contains(result.Errors, e => e.Contains("no items"));
    }

    // --- LookupCounterparty tests ---

    [Fact]
    public async Task LookupCounterparty_SingleMatch_ReturnsValid()
    {
        var candidates = new List<CandidateMatch>
        {
            new() { Name = "Assured Guaranty UK Ltd", LegalEntity = "AG-UK-001" }
        };
        var handler = CreateOkHandler(JsonSerializer.Serialize(candidates));
        var plugin = CreatePluginWithMocks(counterpartyHandler: handler);

        var resultJson = await plugin.LookupCounterparty("Assured Guaranty");
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.True(result.IsValid);
        Assert.NotNull(result.Candidates);
        Assert.Single(result.Candidates);
    }

    [Fact]
    public async Task LookupCounterparty_MultipleMatches_ReturnsInvalidWithCandidates()
    {
        var candidates = new List<CandidateMatch>
        {
            new() { Name = "Assured Guaranty UK Ltd", LegalEntity = "AG-UK-001" },
            new() { Name = "Assured Guaranty EU Ltd", LegalEntity = "AG-EU-002" }
        };
        var handler = CreateOkHandler(JsonSerializer.Serialize(candidates));
        var plugin = CreatePluginWithMocks(counterpartyHandler: handler);

        var resultJson = await plugin.LookupCounterparty("Assured Guaranty");
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.False(result.IsValid);
        Assert.NotNull(result.Candidates);
        Assert.Equal(2, result.Candidates.Count);
    }

    [Fact]
    public async Task LookupCounterparty_ApiError_ReturnsErrorMessage()
    {
        var plugin = CreatePluginWithMocks(counterpartyHandler: CreateErrorHandler());

        var resultJson = await plugin.LookupCounterparty("Test");
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.False(result.IsValid);
        Assert.Contains(result.Errors, e => e.Contains("Counterparty API unavailable"));
    }

    // --- ValidateTrade tests ---

    [Fact]
    public async Task ValidateTrade_ValidId_ReturnsValid()
    {
        var handler = CreateOkHandler("{\"isValid\":true}");
        var plugin = CreatePluginWithMocks(tradeHandler: handler);

        var resultJson = await plugin.ValidateTrade(79353083);
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.True(result.IsValid);
    }

    [Fact]
    public async Task ValidateTrade_InvalidId_ReturnsError()
    {
        var handler = CreateOkHandler("{\"isValid\":false,\"message\":\"Trade not found\"}");
        var plugin = CreatePluginWithMocks(tradeHandler: handler);

        var resultJson = await plugin.ValidateTrade(99999);
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.False(result.IsValid);
        Assert.Contains(result.Errors, e => e.Contains("Trade not found"));
    }

    [Fact]
    public async Task ValidateTrade_ApiError_ReturnsErrorMessage()
    {
        var plugin = CreatePluginWithMocks(tradeHandler: CreateErrorHandler());

        var resultJson = await plugin.ValidateTrade(12345);
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.False(result.IsValid);
        Assert.Contains(result.Errors, e => e.Contains("Trade validation API unavailable"));
    }

    // --- ValidateCurrency tests ---

    [Fact]
    public async Task ValidateCurrency_ValidCode_ReturnsValid()
    {
        var handler = CreateOkHandler("{\"isValid\":true}");
        var plugin = CreatePluginWithMocks(currencyHandler: handler);

        var resultJson = await plugin.ValidateCurrency("GBP");
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.True(result.IsValid);
    }

    [Fact]
    public async Task ValidateCurrency_InvalidCode_ReturnsError()
    {
        var handler = CreateOkHandler("{\"isValid\":false,\"message\":\"Unknown currency\",\"suggestions\":[\"GBP\",\"GEL\"]}");
        var plugin = CreatePluginWithMocks(currencyHandler: handler);

        var resultJson = await plugin.ValidateCurrency("GBX");
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.False(result.IsValid);
        Assert.Contains(result.Errors, e => e.Contains("GBP"));
    }

    [Fact]
    public async Task ValidateCurrency_ApiError_ReturnsErrorMessage()
    {
        var plugin = CreatePluginWithMocks(currencyHandler: CreateErrorHandler());

        var resultJson = await plugin.ValidateCurrency("USD");
        var result = JsonSerializer.Deserialize<ValidationResult>(resultJson);

        Assert.NotNull(result);
        Assert.False(result.IsValid);
        Assert.Contains(result.Errors, e => e.Contains("Currency validation API unavailable"));
    }
}