using ClawdDotNet.App;
using ClawdDotNet.Core.Mcp;
using ClawdDotNet.Web.Contracts;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.Logging;

namespace ClawdDotNet.Web.Endpoints;

/// <summary>
/// #713: The MCP server over HTTP (streamable HTTP, answered as JSON — no event stream) and
/// the administration of personal tokens.
///
/// <para><c>/mcp</c> lies outside <c>/api</c> on purpose: it does not take the WebUI's token
/// and does not get the socket's token-free access. The one thing that opens it is an MCP
/// token — a run's, or a personal one — and that token says which agent is asking.</para>
/// </summary>
internal static class McpEndpoints
{
    /// <summary>One JSON-RPC message is small; anything this large is not one.</summary>
    private const int MaxMessageBytes = 1024 * 1024;

    public static void MapMcp(this WebApplication app, ILoggerFactory loggerFactory)
    {
        var logger = loggerFactory.CreateLogger("ClawdDotNet.Web.Mcp");

        app.MapPost("/mcp", async (HttpContext context, AppHost host, CancellationToken ct) =>
        {
            // Browsers send an Origin; MCP clients do not. A page must not be able to talk to
            // the server through the visitor's browser (DNS rebinding, MCP transport spec).
            if (context.Request.Headers.Origin.Count > 0)
                return Results.StatusCode(StatusCodes.Status403Forbidden);

            if (host.Mcp is not { } grants || host.McpToolHost is not { } engine)
                return ApiEndpoints.Unavailable("No MCP server: agents are not active in this instance.");

            var grant = await grants.ResolveAsync(BearerToken(context.Request), ct);
            if (grant is null)
            {
                context.Response.Headers.WWWAuthenticate = "Bearer";
                return Results.Json(new { error = "No valid MCP token." }, statusCode: StatusCodes.Status401Unauthorized);
            }

            if (context.Request.ContentLength is > MaxMessageBytes)
                return Results.StatusCode(StatusCodes.Status413PayloadTooLarge);

            string message;
            using (var reader = new StreamReader(context.Request.Body))
            {
                var buffer = new char[MaxMessageBytes + 1];
                var read = await reader.ReadBlockAsync(buffer.AsMemory(), ct);
                if (read > MaxMessageBytes)
                    return Results.StatusCode(StatusCodes.Status413PayloadTooLarge);
                message = new string(buffer, 0, read);
            }

            var answer = await new McpServer(engine, logger).HandleAsync(message, grant, ct);
            return answer is null
                ? Results.StatusCode(StatusCodes.Status202Accepted)
                : Results.Text(answer, "application/json");
        });

        // #725: An inbound trigger — n8n or any system that sends a request. Outside /api: its
        // own token is the key, and it can do one thing — hand its agent a task.
        app.MapPost(Security.McpTransport.TriggerPath, async (HttpContext context, AppHost host, CancellationToken ct) =>
        {
            if (context.Request.Headers.Origin.Count > 0)
                return Results.StatusCode(StatusCodes.Status403Forbidden);
            if (host.Triggers is not { } triggers)
                return ApiEndpoints.Unavailable("No inbound triggers in this instance.");
            if (context.Request.ContentLength is > Core.Triggers.InboundTriggers.MaxPayloadBytes)
                return Results.StatusCode(StatusCodes.Status413PayloadTooLarge);

            string payload;
            using (var reader = new StreamReader(context.Request.Body))
            {
                var buffer = new char[Core.Triggers.InboundTriggers.MaxPayloadBytes + 1];
                var read = await reader.ReadBlockAsync(buffer.AsMemory(), ct);
                if (read > Core.Triggers.InboundTriggers.MaxPayloadBytes)
                    return Results.StatusCode(StatusCodes.Status413PayloadTooLarge);
                payload = new string(buffer, 0, read);
            }

            var result = await triggers.ReceiveAsync(BearerToken(context.Request), payload, ct);
            return result.Outcome switch
            {
                Core.Triggers.TriggerOutcome.Accepted => Results.Json(new { ok = true, taskId = result.TaskId }, statusCode: StatusCodes.Status202Accepted),
                Core.Triggers.TriggerOutcome.Unauthorized => Results.Json(new { ok = false, error = result.Message }, statusCode: StatusCodes.Status401Unauthorized),
                Core.Triggers.TriggerOutcome.Limited => Results.Json(new { ok = false, error = result.Message }, statusCode: StatusCodes.Status429TooManyRequests),
                Core.Triggers.TriggerOutcome.TooLarge => Results.StatusCode(StatusCodes.Status413PayloadTooLarge),
                _ => Results.Json(new { ok = false, error = result.Message }, statusCode: StatusCodes.Status503ServiceUnavailable)
            };
        });

        var triggerAdmin = app.MapGroup("/api/triggers");

        triggerAdmin.MapGet("/", async (AppHost host, CancellationToken ct) =>
            host.Triggers is { } triggers
                ? Results.Ok((await triggers.ListAsync(ct)).Select(t => new TriggerDto(t.Id, t.Label, t.AgentId, t.PerHour, t.CreatedAtUtc, t.RevokedAtUtc, t.LastUsedAtUtc, t.Received, t.Active)).ToList())
                : Results.Ok(Array.Empty<TriggerDto>()));

        triggerAdmin.MapPost("/", async (AppHost host, TriggerInputDto input, CancellationToken ct) =>
        {
            if (host.Triggers is not { } triggers)
                return ApiEndpoints.Unavailable("No inbound triggers in this instance.");
            if (!host.Instance.Agents.Any(a => string.Equals(a.AgentId, input.AgentId, StringComparison.OrdinalIgnoreCase)))
                return Results.BadRequest(new OutcomeDto(false, $"There is no agent '{input.AgentId}'."));
            var (t, token) = await triggers.IssueAsync(input.Label ?? "", input.AgentId, input.PerHour ?? 30, ct);
            return Results.Ok(new TriggerIssuedDto(new TriggerDto(t.Id, t.Label, t.AgentId, t.PerHour, t.CreatedAtUtc, null, null, 0, true), token));
        });

        triggerAdmin.MapDelete("/{id}", async (AppHost host, string id, CancellationToken ct) =>
            host.Triggers is { } triggers && await triggers.RevokeAsync(id, ct)
                ? Results.Ok(new OutcomeDto(true, "Revoked."))
                : Results.NotFound(new OutcomeDto(false, $"No active trigger '{id}'.")));

        // #197: External MCP servers — the human adds them, the agents use them as tools.
        var servers = app.MapGroup("/api/mcp-servers");

        servers.MapGet("/", (AppHost host) => Results.Ok(host.Instance.McpServers.Select(s => ServerDto(host, s)).ToList()));

        servers.MapPost("/", async (AppHost host, McpServerInputDto input, CancellationToken ct) =>
        {
            var id = (input.Id ?? "").Trim().ToLowerInvariant();
            if (!Core.Mcp.McpConnections.IdPattern().IsMatch(id))
                return Results.BadRequest(new OutcomeDto(false, "An id is 1–31 lower-case letters, digits, '-' or '_'."));
            if (host.Instance.McpServers.Any(s => string.Equals(s.Id, id, StringComparison.OrdinalIgnoreCase)))
                return Results.BadRequest(new OutcomeDto(false, $"There is already a server '{id}'."));
            var server = new Core.Mcp.McpServerConfig { Id = id };
            if (Apply(server, input) is { } problem)
                return Results.BadRequest(new OutcomeDto(false, problem));
            host.Instance.McpServers.Add(server);
            return await SaveAndSyncAsync(host, $"MCP server '{server.Name}' added as tool {Core.Mcp.McpServerTool.NameFor(id)}.", ct);
        });

        servers.MapPut("/{id}", async (AppHost host, string id, McpServerInputDto input, CancellationToken ct) =>
        {
            if (host.Instance.McpServers.FirstOrDefault(s => string.Equals(s.Id, id, StringComparison.OrdinalIgnoreCase)) is not { } server)
                return Results.NotFound(new OutcomeDto(false, $"No server '{id}'."));
            if (Apply(server, input) is { } problem)
                return Results.BadRequest(new OutcomeDto(false, problem));
            return await SaveAndSyncAsync(host, $"MCP server '{server.Name}' saved.", ct);
        });

        servers.MapDelete("/{id}", async (AppHost host, string id, CancellationToken ct) =>
        {
            var removed = host.Instance.McpServers.RemoveAll(s => string.Equals(s.Id, id, StringComparison.OrdinalIgnoreCase));
            return removed == 0
                ? Results.NotFound(new OutcomeDto(false, $"No server '{id}'."))
                : await SaveAndSyncAsync(host, $"MCP server '{id}' removed. Agents that had its tool keep the entry until it is taken away.", ct);
        });

        servers.MapPost("/{id}/refresh", async (AppHost host, string id, CancellationToken ct) =>
        {
            if (host.McpServers?.Find(id) is not { } tool)
                return Results.NotFound(new OutcomeDto(false, $"No server '{id}'."));
            var ok = await tool.RefreshAsync(ct);
            return Results.Ok(new OutcomeDto(ok, ok ? $"{tool.RemoteTools.Count} tool(s) found." : $"Not reachable: {tool.Problem}"));
        });

        // Streamable HTTP lets a server refuse the event stream; this one keeps no sessions.
        app.MapMethods("/mcp", ["GET", "DELETE"], () => Results.StatusCode(StatusCodes.Status405MethodNotAllowed));

        var tokens = app.MapGroup("/api/mcp/tokens");

        tokens.MapGet("/", async (AppHost host, CancellationToken ct) =>
        {
            if (host.Mcp is not { } grants)
                return Results.Ok(Array.Empty<McpTokenDto>());
            var now = DateTime.UtcNow;
            return Results.Ok((await grants.ListPersonalAsync(ct))
                .Select(t => new McpTokenDto(t.Id, t.AgentId, t.Label, t.CreatedAtUtc, t.ExpiresAtUtc, t.RevokedAtUtc, t.IsActive(now)))
                .ToList());
        });

        tokens.MapPost("/", async (AppHost host, McpTokenInputDto input, CancellationToken ct) =>
        {
            if (host.Mcp is not { } grants)
                return ApiEndpoints.Unavailable("No MCP server in this instance.");
            if (!host.Instance.Agents.Any(a => string.Equals(a.AgentId, input.AgentId, StringComparison.OrdinalIgnoreCase)))
                return Results.BadRequest(new OutcomeDto(false, $"There is no agent '{input.AgentId}'."));

            var (info, token) = await grants.IssuePersonalAsync(
                input.AgentId, input.Label ?? "", input.Days ?? 30, ct);
            return Results.Ok(new McpTokenIssuedDto(
                new McpTokenDto(info.Id, info.AgentId, info.Label, info.CreatedAtUtc, info.ExpiresAtUtc, null, true),
                token));
        });

        tokens.MapDelete("/{id}", async (AppHost host, string id, CancellationToken ct) =>
            host.Mcp is { } grants && await grants.RevokeAsync(id, ct)
                ? Results.Ok(new OutcomeDto(true, "Revoked."))
                : Results.NotFound(new OutcomeDto(false, $"No active token '{id}'.")));
    }

    // ─── external MCP servers (#197) ───

    private static McpServerDto ServerDto(AppHost host, Core.Mcp.McpServerConfig s)
    {
        var tool = host.McpServers?.Find(s.Id);
        return new McpServerDto(s.Id, s.Name, s.Url, Core.Mcp.McpServerTool.NameFor(s.Id), s.Enabled, s.TimeoutSeconds,
            s.Headers.Keys.Order(StringComparer.OrdinalIgnoreCase).ToList(), s.WithoutApproval,
            tool?.RemoteTools.Select(t => new McpRemoteToolDto(t.Name, t.Description)).ToList() ?? [],
            tool?.RefreshedAtUtc, tool?.Problem);
    }

    /// <summary>Writes the input into the server; headers only where a value was given — an empty value removes one.</summary>
    private static string? Apply(Core.Mcp.McpServerConfig server, McpServerInputDto input)
    {
        if (input.Name is not null)
            server.Name = input.Name.Trim();
        if (string.IsNullOrWhiteSpace(server.Name))
            server.Name = server.Id;
        if (input.Url is not null)
        {
            if (!Uri.TryCreate(input.Url.Trim(), UriKind.Absolute, out var uri) || uri.Scheme is not ("http" or "https"))
                return "The address must be an http(s) URL.";
            server.Url = uri.ToString();
        }
        if (string.IsNullOrWhiteSpace(server.Url))
            return "The server needs an address.";
        if (input.Enabled is { } enabled)
            server.Enabled = enabled;
        if (input.TimeoutSeconds is { } timeout)
            server.TimeoutSeconds = Math.Clamp(timeout, 5, 600);
        if (input.WithoutApproval is not null)
            server.WithoutApproval = input.WithoutApproval.Select(o => o.Trim()).Where(o => o.Length > 0).Distinct().ToList();
        foreach (var (name, value) in input.Headers ?? [])
        {
            if (string.IsNullOrWhiteSpace(name) || name.Any(c => c <= ' ' || c == ':'))
                return $"'{name}' is no header name.";
            if (string.IsNullOrEmpty(value))
                server.Headers.Remove(name);
            else
                server.Headers[name.Trim()] = value;
        }
        return null;
    }

    private static async Task<IResult> SaveAndSyncAsync(AppHost host, string message, CancellationToken ct)
    {
        host.SaveInstance(new App.InstanceChange(App.InstanceChangeKind.Settings));
        if (host.McpServers is { } connections)
            await connections.SyncAsync(ct);
        return Results.Ok(new OutcomeDto(true, message));
    }

    /// <summary>Only the header — never the query string: an address ends up in logs.</summary>
    private static string? BearerToken(HttpRequest request)
    {
        var header = request.Headers.Authorization.ToString();
        return header.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase) ? header[7..].Trim() : null;
    }
}