using YD_Event.Application.Scoring.Dtos;

namespace YD_Event.Application.Scoring;

/// <summary>
/// 成绩聚合与排名计算服务。
/// 规定赛：T1=3 名创意编排裁判创意分的平均值，T2=3 名完成质量裁判完成分的平均值，
/// T3=主裁违例扣分（每项扣 5 分）合计，总分=T1+T2-T3，均四舍五入保留两位小数。
/// 排名：总分高者在前，总分相同依次比较 T2、T1，全部相同则并列，其后名次按 N+M 规则顺延。
/// </summary>
public static class EntryResultCalculationService
{
    /// <summary>
    /// 把某个出场的各裁判评分单聚合成一条成绩。judgeNames 用于在计算明细里带上裁判姓名，可为空。
    /// </summary>
    public static EntryAggregateResult Aggregate(ScoreRuleConfig config, List<EventJudgeScoreSheet> sheets,
        IReadOnlyDictionary<long, string>? judgeNames = null)
    {
        var result = new EntryAggregateResult { Formula = BuildFormula(config) };
        var total = 0m;

        foreach (var role in config.RoleAggregations)
        {
            var symbol = new EntrySymbolScore
            {
                Symbol = role.Symbol, Label = role.Label, RoleType = role.RoleType,
                Aggregate = role.Aggregate, Sign = role.Sign
            };
            var roleSheets = sheets
                .Where(x => string.Equals(JudgeRoleSchemaService.NormalizeRoleType(x.JudgeRoleType), role.RoleType, StringComparison.OrdinalIgnoreCase))
                .OrderBy(x => x.JudgeRole).ThenBy(x => x.Id)
                .ToList();
            foreach (var sheet in roleSheets)
            {
                symbol.Judges.Add(new EntryJudgeScore
                {
                    ScoreSheetId = sheet.Id, RefereeId = sheet.RefereeId,
                    JudgeName = judgeNames != null && judgeNames.TryGetValue(sheet.RefereeId, out var name) ? name : null,
                    JudgeRole = sheet.JudgeRole, JudgeRoleType = sheet.JudgeRoleType,
                    Value = SheetValue(sheet, role.SourceField), IsDisqualified = sheet.IsDisqualified
                });
            }
            // 该类型暂无裁判提交时按 0 分计入，成绩是否可用由调用方按提交进度判断。
            symbol.Value = config.Round(Combine(symbol.Judges.Select(x => x.Value).ToList(), role.Aggregate));
            result.Symbols.Add(symbol);
            ApplyTargetField(result, role.TargetField, symbol.Value);
            total += role.Sign * symbol.Value;
        }

        result.TotalScore = config.Round(total);

        // 任一裁判判定取消资格即取消该出场成绩，取消资格后不计总分、不参与排名。
        var disqualified = sheets.FirstOrDefault(x => x.IsDisqualified);
        if (disqualified != null)
        {
            result.IsDisqualified = true;
            result.DisqualifyReasonCode = disqualified.DisqualifyReasonCode;
            result.TotalScore = 0m;
        }
        return result;
    }

    /// <summary>
    /// 按规则的并列比较顺序计算名次，名次并列时其后名次按 N+M 规则顺延（两个并列第一，下一名为第三名）
    /// </summary>
    public static void AssignRanks(List<RankCandidate> candidates, ScoreRuleConfig config)
    {
        var fields = ResolveTieBreakers(config);
        var ranked = new List<RankCandidate>();
        foreach (var candidate in candidates)
        {
            candidate.Rank = 0;
            if (candidate.IsRanked && !candidate.IsDisqualified) ranked.Add(candidate);
        }
        ranked.Sort((left, right) => Compare(left, right, fields));

        var rank = 1;
        var index = 0;
        while (index < ranked.Count)
        {
            // 所有比较字段都相等的视为并列。
            var tied = 1;
            while (index + tied < ranked.Count && Compare(ranked[index], ranked[index + tied], fields) == 0) tied++;
            for (var i = 0; i < tied; i++) ranked[index + i].Rank = rank;
            index += tied;
            rank += tied;
        }
    }

    /// <summary>
    /// 生成计分公式文本，如 T1 + T2 - T3
    /// </summary>
    public static string BuildFormula(ScoreRuleConfig config)
    {
        var text = new System.Text.StringBuilder();
        foreach (var role in config.RoleAggregations)
        {
            if (text.Length == 0) text.Append(role.Sign < 0 ? "-" + role.Symbol : role.Symbol);
            else text.Append(role.Sign < 0 ? " - " : " + ").Append(role.Symbol);
        }
        return text.ToString();
    }

    /// <summary>
    /// 计算明细 JSON，落库到成绩的 CalculationJson，成绩复核与申诉时可完整还原计算过程
    /// </summary>
    public static string BuildCalculationJson(EntryAggregateResult result, ScoreRuleConfig config)
    {
        return JsonConvert.SerializeObject(new
        {
            ruleType = config.RuleType,
            formula = result.Formula,
            scoreDecimals = config.ScoreDecimals,
            totalScore = result.TotalScore,
            isDisqualified = result.IsDisqualified,
            disqualifyReasonCode = result.DisqualifyReasonCode,
            symbols = result.Symbols.Select(x => new
            {
                x.Symbol, x.Label, x.RoleType, x.Aggregate, x.Sign, x.Value, x.JudgeCount,
                judges = x.Judges.Select(j => new { j.ScoreSheetId, j.RefereeId, j.JudgeName, j.JudgeRole, j.Value })
            })
        });
    }

    /// <summary>
    /// 解析并列比较字段，字段名前加“-”表示该项越小越靠前
    /// </summary>
    private static List<(string Field, bool Ascending)> ResolveTieBreakers(ScoreRuleConfig config)
    {
        var fields = new List<(string, bool)>();
        foreach (var raw in config.TieBreakers)
        {
            var text = (raw ?? string.Empty).Trim();
            if (text.Length == 0) continue;
            var ascending = text.StartsWith('-');
            fields.Add((ascending ? text[1..] : text, ascending));
        }
        if (fields.Count == 0) fields.Add((nameof(RankCandidate.TotalScore), false));
        return fields;
    }

    /// <summary>
    /// 按比较字段顺序比较两条成绩，返回负数表示 left 名次更靠前
    /// </summary>
    private static int Compare(RankCandidate left, RankCandidate right, List<(string Field, bool Ascending)> fields)
    {
        foreach (var (field, ascending) in fields)
        {
            var compared = left.FieldValue(field).CompareTo(right.FieldValue(field));
            if (compared == 0) continue;
            return ascending ? compared : -compared;
        }
        return 0;
    }

    /// <summary>
    /// 多名裁判之间的聚合。人数不固定时用平均值，因此裁判人数变化不影响计分口径。
    /// </summary>
    private static decimal Combine(List<decimal> values, string aggregate)
    {
        if (values.Count == 0) return 0m;
        return aggregate switch
        {
            ScoreRuleConfig.AggregateSum => values.Sum(),
            ScoreRuleConfig.AggregateMax => values.Max(),
            ScoreRuleConfig.AggregateMin => values.Min(),
            _ => values.Sum() / values.Count
        };
    }

    /// <summary>
    /// 按配置的字段名取评分单上的分值
    /// </summary>
    private static decimal SheetValue(EventJudgeScoreSheet sheet, string field) => field switch
    {
        nameof(EventJudgeScoreSheet.DifficultyScore) => sheet.DifficultyScore,
        nameof(EventJudgeScoreSheet.PerformanceScore) => sheet.PerformanceScore,
        nameof(EventJudgeScoreSheet.RequiredScore) => sheet.RequiredScore,
        nameof(EventJudgeScoreSheet.DeductionScore) => sheet.DeductionScore,
        nameof(EventJudgeScoreSheet.RequiredCompletedCount) => sheet.RequiredCompletedCount,
        nameof(EventJudgeScoreSheet.RequiredMissingCount) => sheet.RequiredMissingCount,
        nameof(EventJudgeScoreSheet.TotalScore) => sheet.TotalScore,
        // 宁可报错也不能按 0 分静默计入，避免规则配置写错却算出一份看似正常的成绩。
        _ => throw Oops.Bah($"计分规则配置的取值字段{field}无效")
    };

    /// <summary>
    /// 把聚合结果写入成绩对应的分值字段
    /// </summary>
    private static void ApplyTargetField(EntryAggregateResult result, string field, decimal value)
    {
        switch (field)
        {
            case nameof(EventResult.DifficultyScore): result.DifficultyScore = value; break;
            case nameof(EventResult.PerformanceScore): result.PerformanceScore = value; break;
            case nameof(EventResult.RequiredScore): result.RequiredScore = value; break;
            case nameof(EventResult.DeductionScore): result.DeductionScore = value; break;
            default: throw Oops.Bah($"计分规则配置的成绩字段{field}无效");
        }
    }
}