using Core.Entities;

namespace Core.Models;

/// <summary>
/// Result of parsing a student event ranking CSV.
/// </summary>
public class StudentEventRankingParseResult
{
    /// <summary>
    /// Accepted ranking matches, including the raw CSV text and fuzzy scores.
    /// </summary>
    public List<StudentEventRankingMatch> Matches { get; set; } = [];

    /// <summary>
    /// Unmatched students, unmatched or ambiguous events, and other row-level issues.
    /// </summary>
    public List<StudentEventRankingIssue> Issues { get; set; } = [];

    /// <summary>
    /// Critical errors that prevented parsing (for example a missing header).
    /// </summary>
    public List<string> Errors { get; set; } = [];

    /// <summary>
    /// Non-critical warnings about the file as a whole.
    /// </summary>
    public List<string> Warnings { get; set; } = [];

    /// <summary>
    /// Accepted rankings without match metadata.
    /// </summary>
    public IReadOnlyList<StudentEventRanking> Rankings => [.. Matches.Select(m => m.Ranking)];

    /// <summary>
    /// Number of accepted ranking rows.
    /// </summary>
    public int TotalParsed => Matches.Count;

    /// <summary>
    /// Distinct students who have at least one accepted rank.
    /// Uses Id when assigned, otherwise first and last name, so unsaved parsed students stay distinct.
    /// </summary>
    public IReadOnlyList<Student> StudentsWithAcceptedRanks =>
        [.. Matches
            .Select(m => m.Ranking.Student)
            .GroupBy(s => s.Id != 0 ? $"id:{s.Id}" : $"name:{s.FirstName}|{s.LastName}")
            .Select(g => g.First())];

    /// <summary>
    /// True when no critical parse errors were recorded.
    /// </summary>
    public bool IsSuccess => Errors.Count == 0;
}

/// <summary>
/// A successfully matched ranking cell from the CSV.
/// </summary>
public class StudentEventRankingMatch
{
    public required StudentEventRanking Ranking { get; set; }

    public string RawStudentName { get; set; } = string.Empty;

    public string RawEventName { get; set; } = string.Empty;

    public int StudentScore { get; set; }

    public int EventScore { get; set; }

    public int RowNumber { get; set; }
}

/// <summary>
/// A row-level problem encountered while parsing rankings.
/// </summary>
public class StudentEventRankingIssue
{
    public int RowNumber { get; set; }

    public int Rank { get; set; }

    public string RawStudentName { get; set; } = string.Empty;

    public string RawEventName { get; set; } = string.Empty;

    public StudentEventRankingIssueType IssueType { get; set; }

    public string Message { get; set; } = string.Empty;

    public string? SuggestedEventName { get; set; }

    public int? Score { get; set; }
}

/// <summary>
/// Types of issues reported while parsing student event rankings.
/// </summary>
public enum StudentEventRankingIssueType
{
    UnmatchedStudent,
    UnmatchedEvent,
    AmbiguousEvent,
    DuplicateEvent,
    DuplicateRank,
    InvalidFormat
}