using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using StopShopping.EF;
using StopShopping.Services.Models.Req;
using StopShopping.Services.Models.Resp;
using O = StopShopping.OpenPlatform;

namespace StopShopping.Services.Implementions;

public class DistrictService : IDistrictService
{
    public DistrictService(
        StopShoppingContext dbContext,
        O.IDistrictService districtService,
        ILogger<DistrictService> logger)
    {
        _dbContext = dbContext;
        _oDistrictService = districtService;
        _logger = logger;
    }

    private readonly StopShoppingContext _dbContext;
    private readonly O.IDistrictService _oDistrictService;
    private readonly ILogger<DistrictService> _logger;

    public async Task InitialDatabaseAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("开始初始化行政区划");

        if (await _dbContext.Districts.AnyAsync(cancellationToken))
        {
            _logger.LogInformation("已经存在数据，无需初始化");
        }
        else
        {
            var districtsResp = await _oDistrictService.GetTop3LevelDistrictsAsync(cancellationToken);
            if (districtsResp?.IsSucced ?? false)
            {
                if (null != districtsResp?.Districts)
                {
                    using var transaction = await _dbContext.Database.BeginTransactionAsync(cancellationToken);

                    short order = 1;
                    int parentId = 0;
                    var districtsProvince = districtsResp.Districts
                        .Select(d => Cast(d, parentId, order++))
                        .ToList();
                    await _dbContext.Districts.AddRangeAsync(districtsProvince, cancellationToken);
                    await _dbContext.SaveChangesAsync(cancellationToken);

                    foreach (var province in districtsResp.Districts)
                    {
                        parentId = districtsProvince.First(p => p.Code == province.Code).Id;
                        order = 1;

                        var citys = province.Districts;

                        if (null == citys)
                        {
                            await transaction.RollbackAsync(cancellationToken);
                            _logger.LogError("行政区划下级数据不完整：{Name}", province.Name);
                            return;
                        }

                        var districtsCity = citys
                            .Select(d => Cast(d, parentId, order++))
                            .ToList();
                        await _dbContext.Districts.AddRangeAsync(districtsCity, cancellationToken);
                        await _dbContext.SaveChangesAsync(cancellationToken);

                        // 直辖市下属区
                        // var directlyCitysDistrict = citys
                        //     .Where(d => d.Districts?.Count == 0)
                        //     .ToList();
                        // if (0 == directlyCitysDistrict.Count)
                        // {
                        //     await transaction.RollbackAsync(cancellationToken);
                        //     _logger.LogError("行政区划数据不完整，缺少直辖市数据");
                        //     return;
                        // }

                        var semaphoreSlim = new SemaphoreSlim(50);
                        //(parent id, district response)
                        List<Task<(int, O.DistrictResponse?)>> districtTasks = [];

                        foreach (var city in citys)
                        {
                            parentId = districtsCity.First(c => c.Code == city.Code).Id;
                            order = 1;
                            if (city.Districts == null || city.Districts.Count == 0)//直辖市
                            {
                                try
                                {
                                    await semaphoreSlim.WaitAsync(cancellationToken);
                                    districtTasks.Add(
                                        Task.FromResult((
                                            parentId
                                            , await _oDistrictService.GetChildrenAsync(city.Code, cancellationToken)))
                                    );
                                }
                                finally
                                {
                                    semaphoreSlim.Release();
                                }
                            }
                            else
                            {
                                var districtsDistrict = city.Districts
                                    .Select(d => Cast(d, parentId, order++))
                                    .ToList();
                                await _dbContext.Districts.AddRangeAsync(districtsDistrict, cancellationToken);
                                await _dbContext.SaveChangesAsync(cancellationToken);

                                var districtTask = city.Districts!.Select(async (d) =>
                                {
                                    try
                                    {
                                        await semaphoreSlim.WaitAsync();

                                        return (
                                            districtsDistrict.First(dd => dd.Code == d.Code).Id
                                            , await _oDistrictService.GetChildrenAsync(d.Code, cancellationToken)
                                        );
                                    }
                                    finally
                                    {
                                        semaphoreSlim.Release();
                                    }
                                });

                                districtTasks.AddRange(districtTask);
                            }
                        }

                        var streets = await Task.WhenAll(districtTasks);
                        foreach (var s in streets)
                        {
                            order = 1;
                            parentId = s.Item1;
                            if (s.Item2?.IsSucced ?? false)
                            {
                                var districtsStreet = s.Item2.Districts
                                    ?.Select(ds => Cast(ds, parentId, order++))
                                    .ToList();

                                if (null != districtsStreet)
                                {
                                    await _dbContext.Districts.AddRangeAsync(districtsStreet, cancellationToken);
                                    await _dbContext.SaveChangesAsync(cancellationToken);
                                }
                            }
                            else
                            {
                                await transaction.RollbackAsync(cancellationToken);
                                _logger.LogError("街道数据请求失败：{Message}", s.Item2?.Message);
                                return;
                            }
                        }
                    }
                    await transaction.CommitAsync(cancellationToken);
                }
            }
            else
            {
                _logger.LogError("行政区划接口错误：{Message}", districtsResp?.Message);
            }
        }

        _logger.LogInformation("结束初始化行政区划");
    }

    public async Task<ApiResponse<List<District>>> GetTop3LevelDistrictsAsync()
    {
        List<District> districts = [];

        var top3Districts = await _dbContext.Districts
            .Where(d => d.Level <= 3)
            .AsNoTracking()
            .ToListAsync();

        if (0 != top3Districts.Count)
        {
            Dictionary<int, District> idDicts = [];
            foreach (var dbDistrict in top3Districts)
            {
                idDicts.Add(dbDistrict.Id, Cast(dbDistrict));
            }
            foreach (var kv in idDicts)
            {
                if (kv.Value.ParentId > 0)
                    idDicts[kv.Value.ParentId].Children.Add(kv.Value);
                else
                    districts.Add(kv.Value);
            }
        }

        var result = new ApiResponse<List<District>>(districts);

        return result;
    }

    public ApiResponse<List<District>> GetChildren(DistrictParentIdParams model)
    {
        var children = _dbContext.Districts
            .Where(d => d.ParentId == model.ParentId)
            .AsNoTracking()
            .Select(Cast)
            .ToList();

        return new ApiResponse<List<District>>(children);
    }

    private District Cast(EF.Models.District district)
    {
        return new District
        {
            Children = [],
            FullName = district.FullName,
            Id = district.Id,
            Level = district.Level,
            ParentId = district.ParentId
        };
    }

    private EF.Models.District Cast(O.DistrictResponse.District district, int parentId, short order)
    {
        return new EF.Models.District
        {
            Code = district.Code,
            FullName = district.FullName,
            Latitude = district.Latitude.ToString(),
            Level = (short)(district.Level ?? 0),
            Longitude = district.Longitude.ToString(),
            Name = district.Name,
            Order = order,
            ParentId = parentId,
            Pinyin = district.PinYin ?? ""
        };
    }
}