using ExperionCrawler.Core.Application.Interfaces;
using ExperionCrawler.Core.Domain.Entities;
using ExperionCrawler.Infrastructure.Database;
using Microsoft.Extensions.Logging;
using Microsoft.EntityFrameworkCore;
using Npgsql;

namespace ExperionCrawler.Infrastructure.OpcUa;

/// <summary>
/// 메타데이터(desc, area, state0~7descriptor)를 OPC UA에서 읽어서 tag_metadata 테이블에 저장/갱신
/// </summary>
public class MetadataLoaderService : IMetadataLoaderService
{
    private readonly IExperionOpcClient _opcClient;
    private readonly ExperionDbContext _ctx;
    private readonly ILogger<MetadataLoaderService> _logger;

    // 로드할 메타데이터 속성 목록
    private static readonly string[] MetaAttributes =
    {
        "desc", "area",
        "state0descriptor", "state1descriptor", "state2descriptor",
        "state3descriptor", "state4descriptor", "state5descriptor",
        "state6descriptor", "state7descriptor"
    };

    public MetadataLoaderService(
        IExperionOpcClient opcClient,
        ExperionDbContext ctx,
        ILogger<MetadataLoaderService> logger)
    {
        _opcClient = opcClient;
        _ctx = ctx;
        _logger = logger;
    }

    public async Task<int> LoadMetadataAsync(ExperionServerConfig cfg, IEnumerable<string> baseTags)
    {
        var baseTagList = baseTags.ToList(); // 이중 열거 방지

        // ── Step 1: 모든 노드 ID 수집 ──────────────────────────────────────
        var nodeMap = new Dictionary<string, (string baseTag, string attr)>();
        foreach (var baseTag in baseTagList)
        {
            foreach (var attr in MetaAttributes)
            {
                var nodeId = $"{cfg.ServerHostName}:{baseTag}.{attr}";
                var fullNodeId = $"ns=1;s={nodeId}";
                nodeMap[fullNodeId] = (baseTag.ToLowerInvariant(), attr);
            }
        }

        // ── Step 2: 배치 읽기 (ReadTagsAsync 사용) ────────────────────────
        var results = await _opcClient.ReadTagsAsync(cfg, nodeMap.Keys);
        var entries = new List<(string baseTag, string attr, string? value, string nodeId)>();

        foreach (var result in results)
        {
            if (result.Success && result.Value != null && nodeMap.TryGetValue(result.NodeId, out var meta))
            {
                entries.Add((meta.baseTag, meta.attr, result.Value?.ToString(), result.NodeId));
            }
        }

        // ── Step 3: 단일 배치 UPSERT ──────────────────────────────────────
        if (entries.Count > 0)
        {
            // VALUES 절을 동적으로 생성하여 한 번에 INSERT
            // CTE 컬럼(5개)과 VALUES 값(5개) 일치: base_tag, attribute, value, node_id, loaded_at
            var valuesSql = string.Join(", ", entries.Select((e, i) =>
                $"(@bt{i}, @attr{i}, @val{i}, @nid{i}, NOW())"));

            await _ctx.Database.ExecuteSqlRawAsync(@"
                WITH new_data (base_tag, attribute, value, node_id, loaded_at) AS (
                    VALUES " + valuesSql + @"
                )
                INSERT INTO tag_metadata (base_tag, attribute, value, node_id, loaded_at)
                SELECT base_tag, attribute, value, node_id, loaded_at FROM new_data
                ON CONFLICT (base_tag, attribute)
                DO UPDATE SET value = excluded.value, node_id = excluded.node_id, loaded_at = NOW()",
                entries.SelectMany((e, i) => new object[] {
                    new NpgsqlParameter($"@bt{i}", e.baseTag),
                    new NpgsqlParameter($"@attr{i}", e.attr),
                    new NpgsqlParameter($"@val{i}", (object?)e.value ?? DBNull.Value),
                    new NpgsqlParameter($"@nid{i}", e.nodeId)
                }).ToArray());
        }

        // v_tag_summary는 일반 VIEW이므로 REFRESH 불필요 (조회 시 실시간 JOIN)
        _logger.LogInformation("[Metadata] 로드 완료: {Count}개 속성 ({TagCount}개 태그)", entries.Count, baseTagList.Count);
        return entries.Count;
    }

    public async Task<int> ReloadMetadataAsync(ExperionServerConfig cfg, IEnumerable<string>? baseTags = null)
    {
        // baseTags가 null이면 tag_metadata에서 전체 base_tag 조회
        var tags = baseTags?.ToList() ?? await _ctx.TagMetadata.Select(t => t.BaseTag).Distinct().ToListAsync();
        return await LoadMetadataAsync(cfg, tags);
    }
}