using System.Text.Json;
using CvMatcher.Data;
using CvMatcher.Data.Entities;
using CvMatcher.Data.Repositories.Contracts;
using CvMatcher.Models.Responses;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace CvMatcher.Data.Repositories;

public sealed class EfMatcherRepository : IMatcherRepository
{
    private readonly CvMatcherDbContext _db;
    private readonly ILogger<EfMatcherRepository> _logger;

    public EfMatcherRepository(CvMatcherDbContext db, ILogger<EfMatcherRepository> logger)
    {
        _db = db;
        _logger = logger;
    }

    public async Task InitializeAsync(CancellationToken ct)
    {
        _logger.LogInformation("Ensuring CV matcher database schema exists using EF Core");
        //await _db.Database.EnsureCreatedAsync(ct);
    }

    public async Task<JobMatchResponse?> GetMatchAsync(string cvDocumentId, string jobDocumentId, string language, CancellationToken ct)
    {
        var json = await _db.CvMatchResults
            .AsNoTracking()
            .Where(x => x.CvDocumentId == cvDocumentId && x.JobDocumentId == jobDocumentId && x.Language == language)
            .Select(x => x.ResultJson)
            .FirstOrDefaultAsync(ct);

        if (string.IsNullOrWhiteSpace(json)) return null;

        var result = JsonSerializer.Deserialize<JobMatchResponse>(json, new JsonSerializerOptions(JsonSerializerDefaults.Web));
        if (result is not null) result.Cached = true;
        return result;
    }

    public async Task SaveMatchAsync(string cvDocumentId, string jobDocumentId, string language, JobMatchResponse response, string? email, string? clientIpAddress, CancellationToken ct)
    {
        var exists = await _db.CvMatchResults.AnyAsync(
            x => x.CvDocumentId == cvDocumentId && x.JobDocumentId == jobDocumentId && x.Language == language,
            ct);

        if (exists) return;

        try
        {
            _db.CvMatchResults.Add(new CvMatchResultEntity
            {
                Id = Guid.NewGuid().ToString("N"),
                CvDocumentId = cvDocumentId,
                JobDocumentId = jobDocumentId,
                Language = language,
                ResultJson = JsonSerializer.Serialize(response, new JsonSerializerOptions(JsonSerializerDefaults.Web)),
                Score = response.Score,
                Email = email,
                ClientIpAddress = clientIpAddress,
                CreatedAt = DateTime.UtcNow
            });

            await _db.SaveChangesAsync(ct);
        }
        catch (DbUpdateException ex) when (ex.InnerException?.Message.Contains("IX_Results_CvDocumentId_JobDocumentId_Language") == true
                                          || ex.InnerException?.Message.Contains("unique") == true)
        {
            // Duplicate key violation: record was inserted between the AnyAsync check and SaveChangesAsync.
            // This is safe to ignore — the match result already exists in the database.
            _logger.LogWarning(
                "Duplicate match result ignored: CV={CvDocumentId} Job={JobDocumentId} Language={Language}. " +
                "Record was likely inserted concurrently. This is expected behavior in high-concurrency scenarios.",
                cvDocumentId, jobDocumentId, language);
        }
    }

    public async Task<string?> GetChatCompletionAsync(string cacheKey, CancellationToken ct)
    {
        return await _db.CvMatcherChatCache
            .AsNoTracking()
            .Where(x => x.CacheKey == cacheKey)
            .Select(x => x.ResponseText)
            .FirstOrDefaultAsync(ct);
    }

    public async Task SaveChatCompletionAsync(string cacheKey, string model, decimal temperature, string responseText, CancellationToken ct)
    {
        var exists = await _db.CvMatcherChatCache.AnyAsync(x => x.CacheKey == cacheKey, ct);
        if (exists) return;

        _db.CvMatcherChatCache.Add(new CvMatcherChatCacheEntity
        {
            CacheKey = cacheKey,
            Model = model,
            Temperature = temperature,
            ResponseText = responseText,
            CreatedAt = DateTime.UtcNow
        });

        await _db.SaveChangesAsync(ct);
    }
}
