using Microsoft.AspNetCore.Mvc;
using MyHomePage.Api.Common;
using MyHomePage.Api.Models.Dtos;
using MyHomePage.Api.Services;

namespace MyHomePage.Api.Controllers;

/// <summary>多端同步：拉取增量变更 + 全量快照。</summary>
[ApiController]
[Route("api/sync")]
public class SyncController : ControllerBase
{
    private readonly ISyncService _service;
    private readonly ILogger<SyncController> _logger;

    public SyncController(ISyncService service, ILogger<SyncController> logger)
    {
        _service = service;
        _logger = logger;
    }

    /// <summary>
    /// 拉取自 <paramref name="since"/> 之后的变更。
    /// <paramref name="since"/> 为空或解析失败时返回全量（P34.2 防御：避免前端传 ?since=undefined 触发 400）。
    /// </summary>
    [HttpGet("changes")]
    public async Task<ApiResponse<SyncChangesResponse>> Changes([FromQuery] string? since)
    {
        DateTime? sinceDt = null;
        if (!string.IsNullOrWhiteSpace(since))
        {
            // 严格解析（RoundtripKind 接受 ISO8601 字符串）；失败则降级为全量
            if (DateTime.TryParse(since, System.Globalization.CultureInfo.InvariantCulture,
                System.Globalization.DateTimeStyles.RoundtripKind, out var parsed))
            {
                sinceDt = parsed;
            }
            else
            {
                _logger.LogWarning("Sync changes received unparseable since={Since}, fallback to full snapshot", since);
            }
        }
        return ApiResponse<SyncChangesResponse>.Ok(await _service.GetChangesAsync(sinceDt));
    }
}