using Nuuru.Server.DTOs;
using Nuuru.Server.DTOs.Booru;

namespace Nuuru.Server.Services.Search;

/// <summary>
/// Service for searching booru posts with advanced query syntax.
/// </summary>
public interface IBooruSearchService
{
    /// <summary>
    /// Searches posts using the query string with full syntax support.
    /// </summary>
    /// <param name="query">The search query (tags, meta-tags, operators)</param>
    /// <param name="page">Page number (1-based)</param>
    /// <param name="pageSize">Number of results per page</param>
    /// <returns>Paginated search results with metadata</returns>
    Task<SearchResult> SearchPostsAsync(string? query, int page = 1, int pageSize = 20);

    /// <summary>
    /// Builds an EF Core query from the search string without executing it.
    /// </summary>
    /// <param name="query">The search query</param>
    /// <returns>Queryable of posts</returns>
    Task<IQueryable<Nuuru.Server.Models.Booru.Post>> BuildQueryAsync(string? query);

    /// <summary>
    /// Validates a search query without executing it.
    /// </summary>
    /// <param name="query">The query to validate</param>
    /// <returns>Validation result with any errors</returns>
    SearchValidationResult ValidateQuery(string query);
}

/// <summary>
/// Result of a search operation.
/// </summary>
public class SearchResult
{
    /// <summary>
    /// Paginated post results.
    /// </summary>
    public PagedResult<PostDto> Posts { get; set; } = new();

    /// <summary>
    /// Search metadata and diagnostics.
    /// </summary>
    public SearchMetadata Metadata { get; set; } = new();
}

/// <summary>
/// Metadata about the search execution.
/// </summary>
public class SearchMetadata
{
    /// <summary>
    /// The normalized/parsed query string.
    /// </summary>
    public string ParsedQuery { get; set; } = string.Empty;

    /// <summary>
    /// Non-fatal warnings during parsing.
    /// </summary>
    public List<string> Warnings { get; set; } = new();

    /// <summary>
    /// Query execution time in milliseconds.
    /// </summary>
    public double QueryTimeMs { get; set; }
}

/// <summary>
/// Result of query validation.
/// </summary>
public class SearchValidationResult
{
    /// <summary>
    /// Whether the query is valid.
    /// </summary>
    public bool IsValid { get; set; }

    /// <summary>
    /// Validation errors (fatal).
    /// </summary>
    public List<string> Errors { get; set; } = new();

    /// <summary>
    /// Validation warnings (non-fatal).
    /// </summary>
    public List<string> Warnings { get; set; } = new();
}