using System;
using System.Collections.Generic;
using System.Text;
using System.Text.Json;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Net.Mime;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Console;
using Microsoft.AspNetCore.Http;
using CrupestApi.Config;

public class TodoItem
{
    public string Status { get; set; } = default!;
    public string Title { get; set; } = default!;
}

internal class Program
{
    private static void Main(string[] args)
    {
        using var httpClient = new HttpClient();

        var builder = WebApplication.CreateBuilder(args);

        string configFilePath = Environment.GetEnvironmentVariable("CRUPEST_API_CONFIG_FILE") ?? "/config.json";

        builder.Configuration.AddJsonFile(configFilePath, optional: false, reloadOnChange: true);

        string? logFilePath = Environment.GetEnvironmentVariable("CRUPEST_API_LOG_FILE");
        if (logFilePath is not null)
        {
            // TODO: Log to file.
            builder.Logging.AddSimpleConsole(logger =>
            {
                logger.ColorBehavior = LoggerColorBehavior.Disabled;
            });
        }

        var app = builder.Build();

        app.MapGet("/api/todos", async ([FromServices] IConfiguration configuration, [FromServices] ILoggerFactory loggerFactory) =>
        {
            var logger = loggerFactory.CreateLogger("CrupestApi.Todos");

            static string CreateGraphQLQuery(TodoConfiguration todoConfiguration)
            {
                return $$"""
{
    user(login: "{{todoConfiguration.Username}}") {
        projectV2(number: {{todoConfiguration.ProjectNumber}}) {
          items(last: {{todoConfiguration.Count ?? 20}}) {
            nodes {
              __typename
              content {
                __typename
                ... on Issue {
                  title
                  closed
                }
                ... on PullRequest {
                  title
                  closed
                }
                ... on DraftIssue {
                  title
                }
              }
            }
          }
        }
      }
    }
""";
            }

            var todoConfiguration = configuration.GetSection("Todos").Get<TodoConfiguration>();
            if (todoConfiguration is null)
            {
                throw new Exception("Fail to get todos configuration.");
            }

            using var requestContent = new StringContent(JsonSerializer.Serialize(new
            {
                query = CreateGraphQLQuery(todoConfiguration)
            }));
            requestContent.Headers.ContentType = new MediaTypeHeaderValue(MediaTypeNames.Application.Json, Encoding.UTF8.WebName);

            using var request = new HttpRequestMessage(HttpMethod.Post, "https://api.github.com/graphql");
            request.Content = requestContent;
            request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", todoConfiguration.Token);

            using var response = await httpClient.SendAsync(request);
            var responseBody = await response.Content.ReadAsStringAsync();
            logger.LogInformation(response.StatusCode.ToString());
            logger.LogInformation(responseBody);


            if (response.IsSuccessStatusCode)
            {
                using var responseJson = JsonSerializer.Deserialize<JsonDocument>(responseBody);
                if (responseJson is null)
                {
                    throw new Exception("Fail to deserialize response body.");
                }

                var nodes = responseJson.RootElement.GetProperty("data").GetProperty("user").GetProperty("projectV2").GetProperty("items").GetProperty("nodes").EnumerateArray();

                var result = new List<TodoItem>();

                foreach (var node in nodes)
                {
                    var content = node.GetProperty("content");
                    var title = content.GetProperty("title").GetString();
                    if (title is null)
                    {
                        throw new Exception("Fail to get title.");
                    }
                    JsonElement closedElement;
                    bool closed;
                    if (content.TryGetProperty("closed", out closedElement))
                    {
                        closed = closedElement.GetBoolean();
                    }
                    else
                    {
                        closed = false;
                    }

                    result.Add(new TodoItem
                    {
                        Title = title,
                        Status = closed ? "Done" : "Todo"
                    });
                }

                return Results.Json(result, new JsonSerializerOptions
                {
                    PropertyNamingPolicy = JsonNamingPolicy.CamelCase
                }, statusCode: 200);
            }
            else
            {
                const string message = "Fail to get todos from GitHub.";
                logger.LogError(message);

                return Results.Json(new
                {
                    message
                }, statusCode: StatusCodes.Status503ServiceUnavailable);
            }
        });

        app.Run();
    }
}