using AnotherReplayReader.ReplayFile;
using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace AnotherReplayReader.Utils
{
    /// <summary>一段操作记录（一个时间分块）在全文中的位置与规模。</summary>
    internal sealed record EventSpan(TimeSpan Time, int StartIndex, int Length, int EstimatedTokens);

    /// <summary>机械分段得到的操作记录切片。</summary>
    internal sealed record ReplaySlice(
        int Index,
        TimeSpan Start,
        TimeSpan End,
        int StartIndex,
        int Length,
        int EventCount,
        int EstimatedTokens)
    {
        public string GetText(string fullText) => fullText.Substring(StartIndex, Length);
    }

    /// <summary>
    /// 机械分段：按 token 预算切分操作记录，相邻段重叠前一段尾部。
    /// </summary>
    internal static class MechanicalSegmenter
    {
        public const int MinSliceTokens = 2_000;
        public const int MaxSlices = 20;

        public static (ImmutableArray<ReplaySlice> Slices, ImmutableArray<string> Warnings) Slice(
            string fullText,
            ImmutableArray<EventSpan> spans,
            int sliceTokenBudget,
            int overlapTokenBudget)
        {
            var warnings = ImmutableArray.CreateBuilder<string>();
            if (string.IsNullOrWhiteSpace(fullText) || spans.IsEmpty)
            {
                return (ImmutableArray<ReplaySlice>.Empty, warnings.ToImmutable());
            }

            var budget = Math.Max(sliceTokenBudget, MinSliceTokens);
            var overlap = Math.Max(overlapTokenBudget, 200);
            var slices = SliceCore(fullText, spans, budget, overlap);

            if (slices.Count > MaxSlices)
            {
                var totalTokens = spans.Sum(s => s.EstimatedTokens);
                var raisedBudget = Math.Max(budget, (int)Math.Ceiling(totalTokens / (double)MaxSlices));
                slices = SliceCore(fullText, spans, raisedBudget, Math.Max(overlap, raisedBudget / 12));
                warnings.Add($"分段数超过上限 {MaxSlices}，已放宽单段预算到 {raisedBudget:N0} token。");
            }
            return (slices.ToImmutableArray(), warnings.ToImmutable());
        }

        private static List<ReplaySlice> SliceCore(
            string fullText,
            ImmutableArray<EventSpan> spans,
            int budget,
            int overlap)
        {
            var slices = new List<ReplaySlice>();
            var segStart = 0;
            var i = 0;
            var acc = 0;
            while (i < spans.Length)
            {
                var span = spans[i];
                if (acc > 0 && acc + span.EstimatedTokens > budget && acc >= MinSliceTokens)
                {
                    slices.Add(CreateSlice(slices.Count, fullText, spans, segStart, i));

                    // 下一段起点：重叠前一段尾部（重叠总 token ≤ overlap）
                    var overlapStart = i;
                    var overlapTokens = 0;
                    for (var j = i - 1; j >= segStart; --j)
                    {
                        if (overlapTokens + spans[j].EstimatedTokens > overlap)
                        {
                            break;
                        }
                        overlapTokens += spans[j].EstimatedTokens;
                        overlapStart = j;
                    }
                    segStart = overlapStart;
                    acc = 0;
                    for (var j = segStart; j < i; ++j)
                    {
                        acc += spans[j].EstimatedTokens;
                    }
                    continue;
                }
                acc += span.EstimatedTokens;
                ++i;
            }

            if (segStart < spans.Length)
            {
                slices.Add(CreateSlice(slices.Count, fullText, spans, segStart, spans.Length));
            }
            return slices;
        }

        private static ReplaySlice CreateSlice(
            int index,
            string fullText,
            ImmutableArray<EventSpan> spans,
            int start,
            int endExclusive)
        {
            var first = spans[start];
            var last = spans[endExclusive - 1];
            var tokens = 0;
            for (var j = start; j < endExclusive; ++j)
            {
                tokens += spans[j].EstimatedTokens;
            }
            return new ReplaySlice(
                index,
                first.Time,
                last.Time,
                first.StartIndex,
                last.StartIndex + last.Length - first.StartIndex,
                endExclusive - start,
                tokens);
        }
    }

    /// <summary>
    /// 确定性对局摘要：由 ReplayFactIndex + 规则采样生成，不依赖 LLM，保证同一次运行内稳定。
    /// </summary>
    internal static class MatchDigestBuilder
    {
        public static string Build(
            ReplayFactIndex factIndex,
            ImmutableSortedDictionary<int, Player> players,
            Mod mod,
            ImmutableArray<ReplaySlice> slices,
            string fullText)
        {
            var sb = new StringBuilder();
            var names = AIAnalyze.PlayerNamesForAI(mod, players);

            sb.AppendLine("# 玩家");
            foreach (var kv in players)
            {
                var factionName = ModData.GetFaction(mod, kv.Value.FactionId).Name;
                var kind = kv.Value.IsComputer ? "电脑" : "玩家";
                sb.AppendLine($"- 玩家#{kv.Key} {kv.Value.PlayerName}（{names[kv.Key]}），{factionName}，队伍{kv.Value.Team}，{kind}");
            }
            sb.AppendLine();

            sb.AppendLine("# 首次出兵时间表");
            foreach (var kv in factIndex.PlayerFirstProductionTime.OrderBy(k => k.Key))
            {
                var productions = kv.Value
                    .OrderBy(x => x.Value)
                    .Take(15)
                    .Select(x => $"{x.Key}@{FormatTime(x.Value)}");
                sb.AppendLine($"- 玩家#{kv.Key}（{names[kv.Key]}）：{string.Join("、", productions)}");
            }
            sb.AppendLine();

            sb.AppendLine("# 打包/展开");
            var packUnits = factIndex.UnitIdSpecialPowers
                .Where(kv2 => kv2.Value.Any(p => p.Contains("PackReplaceSelf") || p.Contains("UnpackReplaceSelf")))
                .OrderBy(kv2 => kv2.Key);
            foreach (var kv2 in packUnits)
            {
                var firstTime = factIndex.UnitIdFirstObservedTime.TryGetValue(kv2.Key, out var t)
                    ? FormatTime(t)
                    : "?";
                sb.AppendLine($"- UnitId {kv2.Key}（首次出现 {firstTime}）：{string.Join("、", kv2.Value.OrderBy(x => x))}");
            }
            sb.AppendLine();

            sb.AppendLine("# 建造者/出兵建筑");
            sb.AppendLine($"- 建造者：{string.Join("、", factIndex.BuilderUnitIds.OrderBy(x => x).Take(20))}");
            sb.AppendLine($"- 出兵建筑：{string.Join("、", factIndex.ProducerUnitIds.OrderBy(x => x).Take(20))}");
            sb.AppendLine();

            sb.AppendLine("# 分段");
            foreach (var slice in slices)
            {
                sb.AppendLine($"- 第{slice.Index + 1}段：{FormatTime(slice.Start)}~{FormatTime(slice.End)}，事件数 {slice.EventCount}，约 {slice.EstimatedTokens:N0} token");
            }
            sb.AppendLine();

            sb.AppendLine("# 各段关键事件采样");
            foreach (var slice in slices)
            {
                sb.AppendLine($"## 第{slice.Index + 1}段");
                foreach (var line in SampleKeyEvents(slice.GetText(fullText), 6))
                {
                    sb.AppendLine($"- {line}");
                }
            }

            return sb.ToString().Replace("\r", "");
        }

        private static ImmutableArray<string> SampleKeyEvents(string text, int maxEvents)
        {
            var result = new List<string>();
            var currentTime = "";
            foreach (var rawLine in text.Replace("\r", "").Split('\n'))
            {
                var line = rawLine.Trim();
                if (line.StartsWith("[") && line.Contains("]"))
                {
                    var end = line.IndexOf(']');
                    currentTime = line.Substring(1, end - 1);
                    var rest = line.Substring(end + 1).Trim();
                    if (IsKeyEventLine(rest))
                    {
                        result.Add($"[{currentTime}] {rest}");
                        if (result.Count >= maxEvents)
                        {
                            break;
                        }
                    }
                    continue;
                }
                if (IsKeyEventLine(line))
                {
                    result.Add($"[{currentTime}] {line}");
                    if (result.Count >= maxEvents)
                    {
                        break;
                    }
                }
            }
            return result.ToImmutableArray();
        }

        private static bool IsKeyEventLine(string line) =>
            line.Contains("开始建造") || line.Contains("摆放建筑") || line.Contains("出售建筑") ||
            line.Contains("释放特殊能力") || line.Contains("选择协议") || line.Contains("开始出兵") ||
            line.Contains("开始升级");

        public static string FormatTime(TimeSpan t) => $"{(int)t.TotalMinutes}:{t:ss\\.ff}";
    }

    internal sealed record SegmentOverview(
        int Index,
        string Title,
        string Description,
        ImmutableArray<string> BackqueryHints);

    internal sealed record OverviewResult(
        string Narrative,
        ImmutableArray<SegmentOverview> Segments);

    /// <summary>解析总览轮输出：[分段概述] 块之前的自由文本是整局叙述，块内是每段标题/概述。</summary>
    internal static class OverviewParser
    {
        private const string Marker = "[分段概述]";

        public static OverviewResult Parse(string response)
        {
            var markerIndex = response.LastIndexOf(Marker, StringComparison.OrdinalIgnoreCase);
            if (markerIndex < 0)
            {
                return new OverviewResult(response.Trim(), ImmutableArray<SegmentOverview>.Empty);
            }

            var narrative = response.Substring(0, markerIndex).Trim();
            var builder = ImmutableArray.CreateBuilder<SegmentOverview>();
            var hints = new List<string>();
            SegmentOverview? current = null;

            foreach (var rawLine in response.Substring(markerIndex + Marker.Length).Replace("\r", "").Split('\n'))
            {
                var line = rawLine.Trim();
                if (string.IsNullOrWhiteSpace(line))
                {
                    continue;
                }

                var match = Regex.Match(line, @"^#(\d+)\s*(.*)$");
                if (match.Success)
                {
                    if (current is not null)
                    {
                        builder.Add(current);
                    }
                    var index = int.Parse(match.Groups[1].Value);
                    var rest = match.Groups[2].Value.Trim();
                    var sep = rest.IndexOfAny(new[] { '：', ':' });
                    var title = sep > 0 ? rest.Substring(0, sep).Trim() : rest;
                    var description = sep > 0 ? rest.Substring(sep + 1).Trim() : "";
                    hints = new List<string>();
                    current = new SegmentOverview(index, title, description, ImmutableArray<string>.Empty);
                    continue;
                }

                if (current is not null && line.StartsWith("回查", StringComparison.OrdinalIgnoreCase))
                {
                    var sepIndex = line.IndexOfAny(new[] { '：', ':' });
                    if (sepIndex >= 0)
                    {
                        hints.Add(line.Substring(sepIndex + 1).Trim());
                    }
                    current = current with { BackqueryHints = hints.ToImmutableArray() };
                }
            }
            if (current is not null)
            {
                builder.Add(current);
            }

            return new OverviewResult(narrative, builder.ToImmutable());
        }
    }

    /// <summary>解析段回复中的 [回查] 标记（M3 使用）。</summary>
    internal static class BackqueryParser
    {
        public static ImmutableArray<(TimeSpan Start, TimeSpan End)> Parse(string response)
        {
            var result = ImmutableArray.CreateBuilder<(TimeSpan, TimeSpan)>();
            foreach (var rawLine in response.Replace("\r", "").Split('\n'))
            {
                var line = rawLine.Trim();
                if (line.IndexOf("[回查]", StringComparison.OrdinalIgnoreCase) < 0
                    && !line.StartsWith("回查", StringComparison.OrdinalIgnoreCase))
                {
                    continue;
                }

                var content = line.Replace("[回查]", "").Trim();
                var sep = content.IndexOfAny(new[] { '：', ':' });
                if (sep >= 0 && content.Substring(0, sep).Trim().Equals("回查", StringComparison.OrdinalIgnoreCase))
                {
                    content = content.Substring(sep + 1).Trim();
                }

                foreach (Match m in Regex.Matches(content, @"(\d+:\d+(?:\.\d+)?)\s*~\s*(\d+:\d+(?:\.\d+)?)"))
                {
                    if (AiTimeParser.TryParse(m.Groups[1].Value, out var start)
                        && AiTimeParser.TryParse(m.Groups[2].Value, out var end))
                    {
                        result.Add((start, end));
                    }
                }
            }
            return result.ToImmutable();
        }
    }

    /// <summary>按时间区间从全文切出回查所需的原始记录片段。</summary>
    internal static class BackquerySliceExtractor
    {
        public const int MaxBackqueryTokens = 10_000;

        public static (string? Text, string? Reason) Extract(
            string fullText,
            ImmutableArray<EventSpan> spans,
            TimeSpan start,
            TimeSpan end)
        {
            if (spans.IsEmpty)
            {
                return (null, "回放没有事件索引，无法回查。");
            }

            var first = -1;
            var last = -1;
            for (var i = 0; i < spans.Length; ++i)
            {
                if (first < 0 && spans[i].Time >= start)
                {
                    first = i;
                }
                if (spans[i].Time <= end)
                {
                    last = i;
                    continue;
                }
                break;
            }

            if (first < 0 || last < 0 || last < first)
            {
                return (null, $"区间 {MatchDigestBuilder.FormatTime(start)}~{MatchDigestBuilder.FormatTime(end)} 内没有事件。");
            }

            var text = fullText.Substring(
                spans[first].StartIndex,
                spans[last].StartIndex + spans[last].Length - spans[first].StartIndex);
            var tokens = AiContextBudget.EstimateTokens(text);
            if (tokens > MaxBackqueryTokens)
            {
                return (null, $"回查区间过大（约 {tokens:N0} token，上限 {MaxBackqueryTokens:N0}）。");
            }
            return (text, null);
        }
    }

    /// <summary>容错的时间解析：失败返回 false，不抛异常。</summary>
    internal static class AiTimeParser
    {
        public static bool TryParse(string input, out TimeSpan result)
        {
            result = TimeSpan.Zero;
            if (string.IsNullOrWhiteSpace(input))
            {
                return false;
            }
            input = input.Trim();
            var parts = input.Split(':');
            if (parts.Length == 0 || !float.TryParse(parts[parts.Length - 1], out var seconds) || seconds < 0)
            {
                return false;
            }

            var totalSeconds = (long)(int)seconds;
            var millis = (int)Math.Round((seconds - (int)seconds) * 1000);
            long multiplier = 60;
            for (var i = parts.Length - 2; i >= 0; --i)
            {
                if (!long.TryParse(parts[i], out var value) || value < 0)
                {
                    return false;
                }
                totalSeconds += value * multiplier;
                multiplier *= 60;
            }
            result = TimeSpan.FromSeconds(totalSeconds) + TimeSpan.FromMilliseconds(millis);
            return true;
        }
    }

    /// <summary>把验证过的机器可读声明格式化为"已发现事实"，供后续分段引用。</summary>
    internal static class ClaimFindingsFormatter
    {
        public static string Format(AIMachineReadableClaims claims)
        {
            var sb = new StringBuilder();
            foreach (var claim in claims.UnitClaims)
            {
                sb.AppendLine($"- UnitId {claim.UnitId}（{claim.Player}）：推测 {claim.Claim}，证据等级 {LevelName(claim.EvidenceLevel)}");
                if (!claim.Evidence.IsEmpty)
                {
                    sb.AppendLine($"  证据：{string.Join("；", claim.Evidence)}");
                }
                if (!claim.Alternatives.IsEmpty)
                {
                    sb.AppendLine($"  备选：{string.Join("；", claim.Alternatives)}");
                }
                if (!claim.NeedsConfirmation.IsEmpty)
                {
                    sb.AppendLine($"  待确认：{string.Join("；", claim.NeedsConfirmation)}");
                }
            }
            foreach (var claim in claims.EventClaims)
            {
                sb.AppendLine($"- 事件：{claim.Claim}（{LevelName(claim.EvidenceLevel)}）");
            }
            foreach (var claim in claims.TimelineClaims)
            {
                sb.AppendLine($"- 时间线：{claim.Claim}（{LevelName(claim.EvidenceLevel)}）");
            }
            return sb.ToString().TrimEnd();
        }

        public static string? ExtractSummary(string response)
        {
            foreach (var rawLine in response.Replace("\r", "").Split('\n'))
            {
                var line = rawLine.Trim();
                if (line.StartsWith("[小结]", StringComparison.OrdinalIgnoreCase))
                {
                    var text = line.Substring("[小结]".Length).Trim();
                    return string.IsNullOrWhiteSpace(text) ? null : text;
                }
            }
            return null;
        }

        private static string LevelName(AIEvidenceLevel level) => level switch
        {
            AIEvidenceLevel.Confirmed => "确定",
            AIEvidenceLevel.HighlyLikely => "高度可能",
            AIEvidenceLevel.Possible => "可能",
            AIEvidenceLevel.Uncertain => "不确定",
            AIEvidenceLevel.RuledOut => "已排除",
            _ => "未知",
        };
    }

    /// <summary>为修订 pass 生成与受影响声明相关的事实摘要。</summary>
    internal static class RelevantFactsFormatter
    {
        public static string Format(AIMachineReadableClaims claims, ReplayFactIndex factIndex)
        {
            var sb = new StringBuilder();
            foreach (var claim in claims.UnitClaims)
            {
                if (!uint.TryParse(claim.UnitId, out var unitId)
                    || !factIndex.UnitIdFirstObservedTime.TryGetValue(unitId, out var first))
                {
                    continue;
                }
                sb.AppendLine($"- UnitId {claim.UnitId}：首次出现 {MatchDigestBuilder.FormatTime(first)}；"
                    + (factIndex.UnitIdSpecialPowers.TryGetValue(unitId, out var powers) && powers.Count > 0
                        ? $"观察到的能力：{string.Join("、", powers.OrderBy(x => x))}"
                        : "未观察到特殊能力"));
                if (factIndex.BuilderUnitIds.Contains(unitId))
                {
                    sb.AppendLine("  该 UnitId 曾作为建造者出现");
                }
                if (factIndex.ProducerUnitIds.Contains(unitId))
                {
                    sb.AppendLine("  该 UnitId 曾作为出兵建筑出现");
                }
                foreach (var kv in factIndex.PlayerStrongOwnershipUnitIds)
                {
                    if (kv.Value.Contains(unitId))
                    {
                        sb.AppendLine($"  玩家 {kv.Key} 对它有强所有权证据");
                    }
                }
                foreach (var kv in factIndex.PlayerWeakOwnershipUnitIds)
                {
                    if (kv.Value.Contains(unitId))
                    {
                        sb.AppendLine($"  玩家 {kv.Key} 对它有弱所有权证据（选中过）");
                    }
                }
            }
            return sb.ToString().TrimEnd();
        }
    }
}