using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Text.Json;
using System.Threading.Tasks;
using Svrnty.MCP.Core;

namespace CodexMcpServer.Tools;

/// <summary>
/// MCP tool for listing CODEX documents with pagination support.
/// Calls CODEX API GET /api/documents endpoint.
/// </summary>
public class ListDocumentsTool : IMcpTool
{
    private readonly HttpClient _httpClient;
    private static readonly JsonDocument _schema = JsonDocument.Parse("""
    {
        "type": "object",
        "properties": {
            "page": {
                "type": "integer",
                "description": "Page number for pagination (1-based)"
            },
            "pageSize": {
                "type": "integer",
                "description": "Number of items per page"
            },
            "limit": {
                "type": "integer",
                "description": "Maximum number of items to return"
            },
            "offset": {
                "type": "integer",
                "description": "Number of items to skip"
            }
        }
    }
    """);

    public ListDocumentsTool(HttpClient httpClient)
    {
        _httpClient = httpClient ?? throw new ArgumentNullException(nameof(httpClient));

        // Set base address if not already set
        if (_httpClient.BaseAddress == null)
        {
            _httpClient.BaseAddress = new Uri("http://localhost:5050");
        }
    }

    /// <inheritdoc/>
    public string Name => "list_documents";

    /// <inheritdoc/>
    public string Description => "List all CODEX documents with optional pagination. Returns document summaries with metadata.";

    /// <inheritdoc/>
    public JsonDocument Schema => _schema;

    /// <inheritdoc/>
    public async Task<JsonDocument> ExecuteAsync(JsonDocument? arguments)
    {
        try
        {
            // Build query string from optional pagination parameters
            var queryParams = new List<string>();

            if (arguments != null)
            {
                var root = arguments.RootElement;

                if (root.TryGetProperty("page", out var pageElement) && pageElement.ValueKind == JsonValueKind.Number)
                {
                    queryParams.Add($"page={pageElement.GetInt32()}");
                }

                if (root.TryGetProperty("pageSize", out var pageSizeElement) && pageSizeElement.ValueKind == JsonValueKind.Number)
                {
                    queryParams.Add($"pageSize={pageSizeElement.GetInt32()}");
                }

                if (root.TryGetProperty("limit", out var limitElement) && limitElement.ValueKind == JsonValueKind.Number)
                {
                    queryParams.Add($"limit={limitElement.GetInt32()}");
                }

                if (root.TryGetProperty("offset", out var offsetElement) && offsetElement.ValueKind == JsonValueKind.Number)
                {
                    queryParams.Add($"offset={offsetElement.GetInt32()}");
                }
            }

            // Build final URL with query string
            var url = "/api/documents";
            if (queryParams.Any())
            {
                url += "?" + string.Join("&", queryParams);
            }

            // Call CODEX API
            var response = await _httpClient.GetAsync(url);

            if (!response.IsSuccessStatusCode)
            {
                var errorContent = await response.Content.ReadAsStringAsync();
                return CreateErrorResponse(
                    $"CODEX API returned error: {response.StatusCode}. {errorContent}"
                );
            }

            // Parse and return response
            var responseContent = await response.Content.ReadAsStringAsync();
            try
            {
                return JsonDocument.Parse(responseContent);
            }
            catch (JsonException ex)
            {
                return CreateErrorResponse($"Failed to parse CODEX API response: {ex.Message}");
            }
        }
        catch (HttpRequestException ex)
        {
            return CreateErrorResponse($"HTTP request failed: {ex.Message}");
        }
        catch (Exception ex)
        {
            return CreateErrorResponse($"Unexpected error: {ex.Message}");
        }
    }

    private static JsonDocument CreateErrorResponse(string message)
    {
        var error = new
        {
            error = message
        };
        return JsonDocument.Parse(JsonSerializer.Serialize(error));
    }
}