using System.ComponentModel.DataAnnotations;
using Jiaowu.Api.Domain.Academic;
using Jiaowu.Api.Domain.Identity;
using Jiaowu.Api.Infrastructure.Persistence;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace Jiaowu.Api.Controllers;

[ApiController]
[Authorize(Roles = SystemRoles.SuperAdmin + "," + SystemRoles.AcademicAdmin)]
[Route("api/venue-display-announcements")]
public sealed class VenueDisplayAnnouncementsController(AppDbContext db) : ControllerBase
{
    [HttpGet]
    public async Task<ActionResult> Get(CancellationToken cancellationToken) => Ok(await db.VenueDisplayAnnouncements.AsNoTracking()
        .OrderByDescending(x => x.IsPinned).ThenByDescending(x => x.IsUrgent).ThenByDescending(x => x.Priority).ThenByDescending(x => x.UpdatedAt)
        .Select(x => new { x.Id, x.Title, x.Content, x.Scope, x.TargetId, x.IsPublished, x.IsPinned, x.IsUrgent, x.Priority, x.StartsAt, x.EndsAt, x.UpdatedAt })
        .ToListAsync(cancellationToken));

    [HttpGet("options")]
    public async Task<ActionResult> Options(CancellationToken cancellationToken) => Ok(new
    {
        Campuses = await db.Campuses.AsNoTracking().Where(x => x.IsEnabled).OrderBy(x => x.Name).Select(x => new { x.Id, x.Name }).ToListAsync(cancellationToken),
        Buildings = await db.Buildings.AsNoTracking().Where(x => x.IsEnabled).OrderBy(x => x.Name).Select(x => new { x.Id, x.Name, x.CampusId }).ToListAsync(cancellationToken),
        Classrooms = await db.Classrooms.AsNoTracking().Where(x => x.IsEnabled).OrderBy(x => x.Building!.Name).ThenBy(x => x.Code).Select(x => new { x.Id, x.Name, x.BuildingId, BuildingName = x.Building!.Name }).ToListAsync(cancellationToken)
    });

    [HttpPost]
    public async Task<ActionResult> Create(UpsertVenueDisplayAnnouncementRequest request, CancellationToken cancellationToken)
    {
        var announcement = new VenueDisplayAnnouncement { Title = request.Title.Trim(), Content = request.Content.Trim() };
        var error = Validate(announcement, request);
        if (error is not null) return ValidationProblem(error);
        if (!await TargetExistsAsync(request.Scope, request.TargetId, cancellationToken)) return ValidationProblem("公告投放目标不存在或已停用。");
        Apply(announcement, request);
        db.VenueDisplayAnnouncements.Add(announcement);
        await db.SaveChangesAsync(cancellationToken);
        return CreatedAtAction(nameof(Get), new { announcement.Id }, new { announcement.Id });
    }

    [HttpPut("{id:guid}")]
    public async Task<ActionResult> Update(Guid id, UpsertVenueDisplayAnnouncementRequest request, CancellationToken cancellationToken)
    {
        var announcement = await db.VenueDisplayAnnouncements.FindAsync([id], cancellationToken);
        if (announcement is null) return NotFound();
        announcement.Title = request.Title.Trim(); announcement.Content = request.Content.Trim();
        var error = Validate(announcement, request);
        if (error is not null) return ValidationProblem(error);
        if (!await TargetExistsAsync(request.Scope, request.TargetId, cancellationToken)) return ValidationProblem("公告投放目标不存在或已停用。");
        Apply(announcement, request);
        await db.SaveChangesAsync(cancellationToken);
        return NoContent();
    }

    [HttpDelete("{id:guid}")]
    public async Task<ActionResult> Delete(Guid id, CancellationToken cancellationToken)
    {
        var announcement = await db.VenueDisplayAnnouncements.FindAsync([id], cancellationToken);
        if (announcement is null) return NotFound();
        db.VenueDisplayAnnouncements.Remove(announcement);
        await db.SaveChangesAsync(cancellationToken);
        return NoContent();
    }

    private static string? Validate(VenueDisplayAnnouncement announcement, UpsertVenueDisplayAnnouncementRequest request)
    {
        if (announcement.Title.Length is < 1 or > 120) return "公告标题需为 1 至 120 个字符。";
        if (announcement.Content.Length is < 1 or > 1000) return "公告内容需为 1 至 1000 个字符。";
        if (request.Scope != VenueDisplayAnnouncementScope.School && !request.TargetId.HasValue) return "请选择公告投放目标。";
        if (request.Scope == VenueDisplayAnnouncementScope.School && request.TargetId.HasValue) return "全校公告不应指定目标。";
        if (request.EndsAt.HasValue && request.StartsAt.HasValue && request.EndsAt <= request.StartsAt) return "结束时间必须晚于开始时间。";
        return null;
    }

    private static void Apply(VenueDisplayAnnouncement announcement, UpsertVenueDisplayAnnouncementRequest request)
    {
        announcement.Scope = request.Scope; announcement.TargetId = request.Scope == VenueDisplayAnnouncementScope.School ? null : request.TargetId;
        announcement.IsPublished = request.IsPublished; announcement.IsPinned = request.IsPinned; announcement.IsUrgent = request.IsUrgent;
        announcement.Priority = request.Priority; announcement.StartsAt = request.StartsAt; announcement.EndsAt = request.EndsAt; announcement.UpdatedAt = DateTime.UtcNow;
    }

    private Task<bool> TargetExistsAsync(VenueDisplayAnnouncementScope scope, Guid? targetId, CancellationToken cancellationToken) => scope switch
    {
        VenueDisplayAnnouncementScope.School => Task.FromResult(true),
        VenueDisplayAnnouncementScope.Campus => db.Campuses.AnyAsync(x => x.Id == targetId && x.IsEnabled, cancellationToken),
        VenueDisplayAnnouncementScope.Building => db.Buildings.AnyAsync(x => x.Id == targetId && x.IsEnabled, cancellationToken),
        VenueDisplayAnnouncementScope.Classroom => db.Classrooms.AnyAsync(x => x.Id == targetId && x.IsEnabled, cancellationToken),
        _ => Task.FromResult(false)
    };
}

public sealed record UpsertVenueDisplayAnnouncementRequest(
    [param: Required, StringLength(120)] string Title,
    [param: Required, StringLength(1000)] string Content,
    VenueDisplayAnnouncementScope Scope,
    Guid? TargetId,
    bool IsPublished,
    bool IsPinned,
    bool IsUrgent,
    [param: Range(0, 100)] int Priority,
    DateTime? StartsAt,
    DateTime? EndsAt);