using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Sozsoft.Platform.Entities;
using Sozsoft.Platform.Extensions;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Volo.Abp.Domain.Repositories;
using Volo.Abp.Identity;

namespace Sozsoft.Platform.OrgChart;

[Authorize]
[Route("api/app/org-chart")]
public class OrgChartAppService : PlatformAppService
{
    private readonly IRepository<Department, Guid> _departmentRepository;
    private readonly IRepository<JobPosition, Guid> _jobPositionRepository;
    private readonly IIdentityUserRepository _userRepository;

    public OrgChartAppService(
        IRepository<Department, Guid> departmentRepository,
        IRepository<JobPosition, Guid> jobPositionRepository,
        IIdentityUserRepository userRepository)
    {
        _departmentRepository = departmentRepository;
        _jobPositionRepository = jobPositionRepository;
        _userRepository = userRepository;
    }

    [HttpGet("departments")]
    public async Task<List<OrgChartNodeDto>> GetDepartmentsAsync()
    {
        var departments = await _departmentRepository.GetListAsync();
        var jobPositions = await _jobPositionRepository.GetListAsync();
        var users = await _userRepository.GetListAsync();

        var jobById = jobPositions.ToDictionary(x => x.Id);
        var topPositionByDepartment = new Dictionary<Guid, JobPosition>();

        foreach (var department in departments)
        {
            var departmentPositions = jobPositions
                .Where(x => x.DepartmentId == department.Id)
                .ToList();

            if (!departmentPositions.Any())
            {
                continue;
            }

            // Top position means: no parent, parent missing, or parent belongs to another department.
            var topCandidates = departmentPositions
                .Where(position =>
                    !position.ParentId.HasValue ||
                    !jobById.ContainsKey(position.ParentId.Value) ||
                    jobById[position.ParentId.Value].DepartmentId != department.Id)
                .OrderBy(position => position.Name)
                .ToList();

            var selectedTop = topCandidates.FirstOrDefault() ?? departmentPositions
                .OrderBy(position => position.Name)
                .First();

            topPositionByDepartment[department.Id] = selectedTop;
        }

        var nodes = departments.Select(d => new OrgChartNodeDto
        {
            Id = d.Id,
            Name = d.Name,
            ParentId = d.ParentId,
            Users = users
                .Where(u =>
                    topPositionByDepartment.TryGetValue(d.Id, out var topPosition) &&
                    u.GetJobPositionId() == topPosition.Id)
                .Select(u => new OrgChartUserDto
                {
                    Id = u.Id,
                    FullName = u.GetFullName(),
                    Email = u.Email,
                    UserName = u.UserName,
                })
                .ToList(),
        }).ToList();

        return nodes;
    }

    [HttpGet("job-positions")]
    public async Task<List<OrgChartNodeDto>> GetJobPositionsAsync()
    {
        var jobPositions = await _jobPositionRepository.GetListAsync();
        var departments = await _departmentRepository.GetListAsync();
        var users = await _userRepository.GetListAsync();

        var deptDict = departments.ToDictionary(d => d.Id, d => d.Name);

        var nodes = jobPositions.Select(jp => new OrgChartNodeDto
        {
            Id = jp.Id,
            Name = jp.Name,
            ParentId = jp.ParentId,
            DepartmentId = jp.DepartmentId,
            DepartmentName = deptDict.TryGetValue(jp.DepartmentId, out var name) ? name : null,
            Users = users
                .Where(u => u.GetJobPositionId() == jp.Id)
                .Select(u => new OrgChartUserDto
                {
                    Id = u.Id,
                    FullName = u.GetFullName(),
                    Email = u.Email,
                    UserName = u.UserName,
                })
                .ToList(),
        }).ToList();

        return nodes;
    }
}