using System;
using System.Collections.Generic;
using System.Linq;
using Dalamud.Plugin.Services;
using FFXIVClientStructs.FFXIV.Client.Game;
using FFXIVClientStructs.FFXIV.Client.UI.Agent;
using Lumina.Excel.Sheets;

namespace MSQProgress;

/// <summary>
/// Builds and caches MSQ progress data from ScenarioTree + Quest + AgentScenarioTree.
/// </summary>
public sealed class MSQDataService
{
    private readonly IDataManager _data;
    private List<MSQStep>? _allSteps;
    private Dictionary<uint, ExpansionProgress>? _byExpansion;
    private int _currentGlobalIndex = -1;
    private uint _currentExpansionRowId;

    public MSQDataService(IDataManager data)
    {
        _data = data;
    }

    /// <summary>Ordered list of all MSQ steps (by ScenarioTree order).</summary>
    public IReadOnlyList<MSQStep> AllSteps
    {
        get { _ = EnsureBuilt(); return _allSteps!; }
    }

    /// <summary>Progress per expansion (key = ExVersion.RowId).</summary>
    public IReadOnlyDictionary<uint, ExpansionProgress> ByExpansion
    {
        get { _ = EnsureBuilt(); return _byExpansion!; }
    }

    /// <summary>Current step index in AllSteps, or -1 if unknown.</summary>
    public int CurrentGlobalIndex => _currentGlobalIndex;

    /// <summary>ExVersion.RowId for the expansion the player is currently in.</summary>
    public uint CurrentExpansionRowId => _currentExpansionRowId;

    private bool EnsureBuilt()
    {
        if (_byExpansion != null)
            return true;
        Build();
        return _byExpansion != null;
    }

    private void Build()
    {
        if (_allSteps != null)
            return;

        _allSteps = new List<MSQStep>();
        _byExpansion = new Dictionary<uint, ExpansionProgress>();

        var scenarioSheet = _data.GetExcelSheet<ScenarioTree>();
        var questSheet = _data.GetExcelSheet<Quest>();
        if (scenarioSheet == null || questSheet == null)
            return;

        var list = new List<(uint Key, ScenarioTree St, Quest Q, ExVersion Ex)>();

        foreach (var st in scenarioSheet)
        {
            if (!questSheet.TryGetRow(st.RowId, out var quest) || !quest.Expansion.IsValid)
                continue;
            var ex = quest.Expansion.Value;
            list.Add((st.RowId, st, quest, ex));
        }

        // Order by Unknown2 (scenario order within the game)
        list = list.OrderBy(x => x.St.Unknown2).ToList();

        // Group by (expansion, Unknown2). Collapse into one step when 2+ quests (alternate path: complete if any is complete).
        var grouped = list
            .GroupBy(x => (ExRowId: x.Ex.RowId, Order: x.St.Unknown2))
            .OrderBy(g => g.Min(x => x.St.Unknown2))
            .ToList();

        foreach (var group in grouped)
        {
            var first = group.First();
            var ex = first.Ex;
            var exName = ex.Name.ToString();
            if (string.IsNullOrEmpty(exName)) exName = $"Expansion {ex.RowId}";

            if (!_byExpansion.TryGetValue(ex.RowId, out var prog))
            {
                prog = new ExpansionProgress(exName, ex.RowId);
                _byExpansion[ex.RowId] = prog;
            }

            var questRowIds = group.Select(x => x.Q.RowId).Distinct().ToList();
            var step = new MSQStep(first.St.RowId, first.Q.RowId, ex.RowId, exName, questRowIds);
            _allSteps.Add(step);
            prog.TotalQuests++;
            if (group.Any(x => QuestManager.IsQuestComplete(x.St.RowId)))
                prog.CompletedQuests++;
        }

        // Apply wiki totals for display: total = wiki count when known; scale completed proportionally so e.g. ARR shows 241/241 when done
        foreach (var prog in _byExpansion.Values)
        {
            var stepsTotal = prog.TotalQuests;
            prog.StepsTotal = stepsTotal;
            var wikiTotal = GetWikiTotalForExpansion(prog.Name, prog.ExpansionRowId);
            if (wikiTotal is int total)
            {
                prog.TotalQuests = total;
                if (stepsTotal > 0)
                    prog.CompletedQuests = (int)Math.Round((double)prog.CompletedQuests / stepsTotal * total);
            }
        }

        // Set current expansion and index from agent
        UpdateCurrentFromAgent();
    }

    private void UpdateCurrentFromAgent()
    {
        _currentGlobalIndex = -1;
        _currentExpansionRowId = 0;

        unsafe
        {
            var agent = AgentScenarioTree.Instance();
            if (agent == null || agent->Data == null)
                return;

            var data = (byte*)agent->Data;
            if (data == null) return;
            // Prefer current MSQ (offset 0); fall back to last completed (offset 6) so "quests until unlock" uses the quest we're on.
            ushort index = *(ushort*)(data + 0);
            if (index == 0)
                index = *(ushort*)(data + 6);
            if (index == 0)
                return;

            var scenarioSheet = _data.GetExcelSheet<ScenarioTree>();
            if (scenarioSheet == null)
                return;

            var row = scenarioSheet.GetRow(index | 0x10000U);
            if (row.RowId == 0)
                return;

            var questSheet = _data.GetExcelSheet<Quest>();
            if (!questSheet.TryGetRow(row.RowId, out var quest))
                return;

            _currentExpansionRowId = quest.Expansion.IsValid ? quest.Expansion.Value.RowId : 0;

            for (int i = 0; i < _allSteps!.Count; i++)
            {
                if (_allSteps[i].ContainsQuest(row.RowId))
                {
                    _currentGlobalIndex = i;
                    break;
                }
            }
        }
    }

    /// <summary>Call when game state may have changed (e.g. after completing a quest). Refreshes completion counts and current index.</summary>
    public void Refresh()
    {
        if (_allSteps == null || _byExpansion == null)
            return;

        foreach (var prog in _byExpansion.Values)
            prog.CompletedQuests = 0;

        foreach (var step in _allSteps)
        {
            if (step.IsAnyQuestComplete() && _byExpansion.TryGetValue(step.ExpansionRowId, out var prog))
                prog.CompletedQuests++;
        }

        // Scale completed to wiki total when we use wiki totals (so e.g. 218/218 steps → 241/241 display for ARR)
        foreach (var prog in _byExpansion.Values)
        {
            if (prog.StepsTotal <= 0) continue;
            var completedSteps = prog.CompletedQuests;
            prog.CompletedQuests = (int)Math.Round((double)completedSteps / prog.StepsTotal * prog.TotalQuests);
        }

        UpdateCurrentFromAgent();
    }

    /// <summary>Index in AllSteps of the first step matching the given quest, or -1.</summary>
    public int GetStepIndexForQuest(uint questRowId)
    {
        var steps = AllSteps;
        for (int i = 0; i < steps.Count; i++)
        {
            if (steps[i].ContainsQuest(questRowId))
                return i;
        }
        return -1;
    }

    /// <summary>Number of MSQ quests from current position until the given quest is reached (counts quests in each step, not steps). Returns -1 if quest not in MSQ or already past.</summary>
    public int QuestsUntilQuest(uint questRowId)
    {
        var steps = AllSteps;
        if (_currentGlobalIndex < 0)
            return -1;
        int count = 0;
        for (int i = _currentGlobalIndex; i < steps.Count; i++)
        {
            count += steps[i].QuestCount;
            if (steps[i].ContainsQuest(questRowId))
                return count;
        }
        return -1;
    }

    /// <summary>Number of MSQ quests from the start (step 0) until the given quest. Used for "at least X quests" when current position is unknown.</summary>
    public int QuestsFromStartToQuest(uint questRowId)
    {
        var steps = AllSteps;
        int count = 0;
        for (int i = 0; i < steps.Count; i++)
        {
            count += steps[i].QuestCount;
            if (steps[i].ContainsQuest(questRowId))
                return count;
        }
        return -1;
    }

    public sealed class MSQStep
    {
        public uint ScenarioTreeRowId { get; }
        public uint QuestRowId { get; }
        public uint ExpansionRowId { get; }
        public string ExpansionName { get; }
        private readonly uint[] _questRowIds;

        public MSQStep(uint scenarioTreeRowId, uint questRowId, uint expansionRowId, string expansionName, List<uint> questRowIds)
        {
            ScenarioTreeRowId = scenarioTreeRowId;
            QuestRowId = questRowId;
            ExpansionRowId = expansionRowId;
            ExpansionName = expansionName;
            _questRowIds = questRowIds?.ToArray() ?? new[] { questRowId };
        }

        /// <summary>True if this step includes the given quest (handles 0x10000 vs raw format).</summary>
        public bool ContainsQuest(uint questRowId)
        {
            foreach (var id in _questRowIds)
            {
                if (StepsMatchQuest(id, questRowId)) return true;
            }
            return false;
        }

        private static bool StepsMatchQuest(uint stepQuestRowId, uint questRowId)
        {
            if (stepQuestRowId == questRowId) return true;
            if (questRowId < 0x10000 && (stepQuestRowId == (questRowId | 0x10000U))) return true;
            if (questRowId >= 0x10000 && (stepQuestRowId == (questRowId & 0xFFFF))) return true;
            return false;
        }

        /// <summary>True if the player has completed any quest in this step (used for branch paths).</summary>
        public bool IsAnyQuestComplete()
        {
            foreach (var id in _questRowIds)
            {
                if (QuestManager.IsQuestComplete(id)) return true;
            }
            return false;
        }

        /// <summary>Number of quests in this step (1 for linear, 2+ for alternate-path group). Used for "X quests until unlock" count.</summary>
        public int QuestCount => _questRowIds.Length;
    }

    public sealed class ExpansionProgress
    {
        public string Name { get; }
        public uint ExpansionRowId { get; }
        /// <summary>Total quest count for display (wiki-aligned when available).</summary>
        public int TotalQuests { get; set; }
        public int CompletedQuests { get; set; }
        public int RemainingQuests => TotalQuests - CompletedQuests;
        /// <summary>Number of MSQ steps we have for this expansion (used to scale completed to wiki total).</summary>
        public int StepsTotal { get; set; }

        public ExpansionProgress(string name, uint expansionRowId)
        {
            Name = name;
            ExpansionRowId = expansionRowId;
        }
    }

    /// <summary>MSQ quest counts per expansion from https://ffxiv.consolegameswiki.com/wiki/Main_Scenario_Quests (single-path).</summary>
    private static int? GetWikiTotalForExpansion(string expansionName, uint expansionRowId)
    {
        // RowId fallback for non-English clients (ExVersion.Name is localized)
        if (expansionRowId <= 5)
        {
            var byRowId = new[] { 241, 138, 162, 157, 155, 134 };
            return byRowId[expansionRowId];
        }
        if (string.IsNullOrEmpty(expansionName)) return null;
        var name = expansionName.Trim();
        return name switch
        {
            "A Realm Reborn" => 241,      // 160-161 (2.0) + 80 (2.1-2.55)
            "Heavensward" => 138,         // 94 + 25 + 19
            "Stormblood" => 162,          // 122 + 40
            "Shadowbringers" => 157,      // 106 + 32 + 19
            "Endwalker" => 155,           // 108 + 47
            "Dawntrail" => 134,           // 100 + 25 + 9
            _ => null
        };
    }
}