F8WebAI/backend/AgriculturalPlatform.Api/Controllers/RegionsController.cs

using AgriculturalPlatform.Api.Data;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace AgriculturalPlatform.Api.Controllers;

/// <summary>
/// 行政区划接口：
/// 省、市、县、乡镇来自 AreaCity 全国公开行政区划数据（Regions 表，深 0~3）；
/// 村、组来自农户档案表（Famers 表已录入数据，去重后作为下拉选项）。
/// </summary>
[ApiController]
[Route("api/regions")]
[Authorize]
public class RegionsController(AppDbContext db) : ControllerBase
{
    /// <summary>省（自治区/直辖市）列表，热门省份（热度值高）优先</summary>
    [HttpGet("provinces")]
    public async Task<ActionResult<string[]>> Provinces()
    {
        var items = await db.Regions
            .Where(r => r.Deep == 0)
            .OrderByDescending(r => r.Hot)
            .ThenBy(r => r.Id)
            .Select(r => r.ExtName)
            .ToListAsync();
        return Ok(items);
    }

    /// <summary>
    /// 按省获取县（区/县级市）列表，附带所属地级市（city）用于前端分组，
    /// used=true 表示数据库农户表中已录入过该区县（前端优先展示）。
    /// </summary>
    [HttpGet("counties")]
    public async Task<ActionResult> Counties(string? province)
    {
        if (string.IsNullOrWhiteSpace(province)) return BadRequest(new { message = "请先选择省份" });
        var prov = await db.Regions.FirstOrDefaultAsync(r => r.Deep == 0 && r.ExtName == province);
        if (prov == null) return Ok(Array.Empty<object>());

        var items = await (from c in db.Regions
                           join city in db.Regions on c.Pid equals city.Id
                           where city.Pid == prov.Id && c.Deep == 2
                           orderby city.Id, c.Id
                           select new { name = c.ExtName, city = city.ExtName })
                          .ToListAsync();

        var usedNames = await db.Farmers
            .Where(f => f.County != null && f.County != "")
            .Select(f => f.County)
            .Distinct()
            .ToListAsync();
        var used = new HashSet<string>(usedNames, StringComparer.OrdinalIgnoreCase);

        return Ok(items.Select(c => new { c.name, c.city, used = used.Contains(c.name) }));
    }

    /// <summary>按县获取乡镇（街道）列表（公开数据 + 农户表已录入数据补充）</summary>
    [HttpGet("townships")]
    public async Task<ActionResult<string[]>> Townships(string? county, string? city)
    {
        if (string.IsNullOrWhiteSpace(county)) return BadRequest(new { message = "请先选择县（区）" });

        var countyQuery = db.Regions.Where(r => r.Deep == 2 && r.ExtName == county);
        if (!string.IsNullOrWhiteSpace(city))
        {
            var cityRow = await db.Regions.FirstOrDefaultAsync(r => r.Deep == 1 && r.ExtName == city);
            if (cityRow != null) countyQuery = countyQuery.Where(r => r.Pid == cityRow.Id);
        }
        var ids = await countyQuery.Select(r => r.Id).ToListAsync();

        var builtin = ids.Count > 0
            ? await db.Regions.Where(r => r.Deep == 3 && ids.Contains(r.Pid))
                .OrderBy(r => r.Id).Select(r => r.ExtName).ToListAsync()
            : [];

        var fromDb = await db.Farmers
            .Where(f => f.County == county && f.Township != null && f.Township != "")
            .Select(f => f.Township)
            .Distinct()
            .ToListAsync();
        return Ok(builtin.Union(fromDb).OrderBy(x => x).ToArray());
    }

    /// <summary>
    /// 村列表（来自农户表，按县/乡镇过滤去重），返回 { name, township } 对象数组。
    /// 不传 township 时返回全县所有村（含所属乡镇），供前端做同名村检测。
    /// </summary>
    [HttpGet("villages")]
    public async Task<ActionResult> Villages(string? county, string? township)
    {
        var q = db.Farmers.Where(f => f.Village != null && f.Village != "");
        if (!string.IsNullOrWhiteSpace(township))
            q = q.Where(f => f.Township == township);
        else if (!string.IsNullOrWhiteSpace(county))
            q = q.Where(f => f.County == county);
        var items = await q
            .Select(f => new { f.Village, f.Township })
            .Distinct()
            .OrderBy(x => x.Village)
            .ToListAsync();
        return Ok(items.Select(x => new { name = x.Village, township = x.Township ?? "" }));
    }

    /// <summary>组列表（来自农户表，按县/乡镇/村过滤去重）</summary>
    [HttpGet("groups")]
    public async Task<ActionResult<string[]>> Groups(string? county, string? township, string? village)
    {
        var q = db.Farmers.Where(f => f.GroupName != null && f.GroupName != "");
        if (!string.IsNullOrWhiteSpace(village))
            q = q.Where(f => f.Village == village);
        else if (!string.IsNullOrWhiteSpace(township))
            q = q.Where(f => f.Township == township);
        else if (!string.IsNullOrWhiteSpace(county))
            q = q.Where(f => f.County == county);
        var items = await q.Select(f => f.GroupName).Distinct().OrderBy(x => x).ToListAsync();
        return Ok(items);
    }
}