using System.Security.Claims;
using MiaoJiZhang.Api.Contracts;
using MiaoJiZhang.Api.Services;
using MiaoJiZhang.Domain.Entities;
using MiaoJiZhang.Infrastructure.Persistence;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace MiaoJiZhang.Api.Controllers;

[ApiController]
[Authorize]
[Route("api/push")]
public class PushController(AppDbContext db, PushTokenProtector tokenProtector) : ControllerBase
{
    private long Uid => long.Parse(
        User.FindFirstValue(ClaimTypes.NameIdentifier) ?? User.FindFirstValue("sub")!);

    [HttpGet("preferences")]
    public async Task<ActionResult<PushPreferencesResponse>> Preferences(CancellationToken ct)
    {
        var enabled = await db.UserPushPreferences
            .Where(item => item.UserId == Uid && item.IsEnabled)
            .Select(item => item.Category)
            .ToListAsync(ct);
        return Ok(new PushPreferencesResponse(
            enabled.Contains(PushCategories.System),
            enabled.Contains(PushCategories.Budget),
            enabled.Contains(PushCategories.Operations)));
    }

    [HttpPut("preferences")]
    public async Task<ActionResult<PushPreferencesResponse>> UpdatePreferences(
        UpdatePushPreferencesRequest request,
        CancellationToken ct)
    {
        var desired = new Dictionary<string, bool>
        {
            [PushCategories.System] = request.System,
            [PushCategories.Budget] = request.Budget,
            [PushCategories.Operations] = request.Operations,
        };
        var existing = await db.UserPushPreferences
            .Where(item => item.UserId == Uid)
            .ToDictionaryAsync(item => item.Category, ct);
        var now = DateTime.UtcNow;
        foreach (var (category, enabled) in desired)
        {
            if (!existing.TryGetValue(category, out var preference))
            {
                preference = new UserPushPreference
                {
                    UserId = Uid,
                    Category = category,
                };
                db.UserPushPreferences.Add(preference);
            }
            preference.IsEnabled = enabled;
            preference.UpdatedAt = now;
        }
        if (!desired.Values.Any(value => value))
        {
            var devices = await db.PushDevices
                .Where(device => device.UserId == Uid && device.IsActive)
                .ToListAsync(ct);
            foreach (var device in devices)
            {
                device.IsActive = false;
                device.DisabledReason = "all_categories_disabled";
                device.UpdatedAt = now;
            }
        }
        await db.SaveChangesAsync(ct);
        return Ok(new PushPreferencesResponse(request.System, request.Budget, request.Operations));
    }

    [HttpPut("devices/{installationId}")]
    public async Task<ActionResult<PushDeviceRegistrationResponse>> RegisterDevice(
        string installationId,
        RegisterPushDeviceRequest request,
        CancellationToken ct)
    {
        var validation = ValidateDevice(installationId, request);
        if (validation is not null) return validation;
        if (!tokenProtector.IsConfigured)
            return StatusCode(StatusCodes.Status503ServiceUnavailable,
                new ApiError("PUSH_NOT_CONFIGURED", "推送服务尚未完成安全配置"));

        var provider = request.Provider.Trim().ToLowerInvariant();
        var token = request.Token.Trim();
        var tokenHash = PushTokenProtector.Hash(token);
        var duplicate = await db.PushDevices.FirstOrDefaultAsync(device =>
            device.Provider == provider &&
            device.PackageName == request.PackageName &&
            device.TokenHash == tokenHash &&
            device.InstallationId != installationId, ct);
        if (duplicate is not null) db.PushDevices.Remove(duplicate);

        var device = await db.PushDevices.FirstOrDefaultAsync(item =>
            item.PackageName == request.PackageName &&
            item.InstallationId == installationId, ct);
        var now = DateTime.UtcNow;
        if (device is null)
        {
            device = new PushDevice
            {
                UserId = Uid,
                InstallationId = installationId,
                PackageName = request.PackageName,
                CreatedAt = now,
            };
            db.PushDevices.Add(device);
        }

        var unbindToken = PushTokenProtector.CreateUnbindToken();
        device.UserId = Uid;
        device.Provider = provider;
        device.TokenCiphertext = tokenProtector.Protect(token);
        device.TokenHash = tokenHash;
        device.UnbindTokenHash = PushTokenProtector.Hash(unbindToken);
        device.Flavor = request.Flavor.Trim().ToLowerInvariant();
        device.AppVersion = request.AppVersion.Trim();
        device.VersionCode = request.VersionCode;
        device.NotificationsAllowed = request.NotificationsAllowed;
        device.IsActive = request.NotificationsAllowed;
        device.DisabledReason = request.NotificationsAllowed ? null : "notification_permission_denied";
        device.UpdatedAt = now;
        device.LastSeenAt = now;
        await db.SaveChangesAsync(ct);

        return Ok(new PushDeviceRegistrationResponse(
            device.Id,
            device.InstallationId,
            device.Provider,
            device.IsActive,
            unbindToken));
    }

    [HttpDelete("devices/{installationId}")]
    [AllowAnonymous]
    public async Task<IActionResult> UnregisterDevice(
        string installationId,
        [FromHeader(Name = "X-Push-Unbind-Token")] string? unbindToken,
        CancellationToken ct)
    {
        var userIdValue = User.FindFirstValue(ClaimTypes.NameIdentifier) ?? User.FindFirstValue("sub");
        var hasUser = long.TryParse(userIdValue, out var userId);
        var unbindHash = string.IsNullOrWhiteSpace(unbindToken)
            ? null
            : PushTokenProtector.Hash(unbindToken);
        var device = await db.PushDevices.FirstOrDefaultAsync(item =>
            item.InstallationId == installationId &&
            ((hasUser && item.UserId == userId) ||
             (unbindHash != null && item.UnbindTokenHash == unbindHash)), ct);
        if (device is null)
            return hasUser || unbindHash is not null ? NoContent() : Unauthorized();

        db.PushDevices.Remove(device);
        await db.SaveChangesAsync(ct);
        return NoContent();
    }

    private ActionResult? ValidateDevice(string installationId, RegisterPushDeviceRequest request)
    {
        if (!Guid.TryParse(installationId, out _))
            return BadRequest(new ApiError("INSTALLATION_ID_INVALID", "设备安装标识无效"));
        if (!PushProviders.All.Contains(request.Provider))
            return BadRequest(new ApiError("PUSH_PROVIDER_INVALID", "不支持该设备推送厂商"));
        if (string.IsNullOrWhiteSpace(request.Token) || request.Token.Length > 4096)
            return BadRequest(new ApiError("PUSH_TOKEN_INVALID", "推送令牌无效"));
        var expectedFlavor = request.PackageName switch
        {
            "com.nx.miaoji" => "production",
            "com.nx.miaoji.internal" => "internal",
            _ => null,
        };
        if (expectedFlavor is null || !string.Equals(expectedFlavor, request.Flavor, StringComparison.OrdinalIgnoreCase))
            return BadRequest(new ApiError("PUSH_PACKAGE_INVALID", "推送包名或环境无效"));
        if (request.AppVersion.Length is < 1 or > 32 || request.VersionCode < 1)
            return BadRequest(new ApiError("APP_VERSION_INVALID", "应用版本无效"));
        return null;
    }
}