using Godot;
using System.Collections.Generic;
using System.Linq;
using Theriapolis.GodotHost.Scenes.Widgets;
using Theriapolis.GodotHost.UI;

namespace Theriapolis.GodotHost.Scenes.Steps;

/// <summary>
/// Step V — Abilities. Direct port of <c>StepStats</c> in
/// <c>src/steps.jsx</c> per GODOT_PORTING_GUIDE.md §7.4: pool of 6
/// dice, 6 ability slots, drag-and-drop assignment with pool→slot,
/// slot→slot (swap), and slot→pool semantics.
///
/// Two methods supported (CharacterDraft.StatMethod): "array" uses the
/// standard array [15, 14, 13, 12, 10, 8]; "roll" generates each pool
/// value as a 4d6-drop-lowest roll. A Reroll button is exposed in roll
/// mode. Auto-assign sorts the remaining pool descending and places the
/// largest values into the empty slots ordered by class primary
/// abilities first.
///
/// The step rebuilds the entire token tree on each Changed signal, so
/// drag handlers just compute the new state and call Patch — no manual
/// reparenting.
/// </summary>
public partial class StepStats : VBoxContainer, IStep
{
    private static readonly string[] Abilities =
        { "STR", "DEX", "CON", "INT", "WIS", "CHA" };

    private static readonly System.Random Rng = new();

    private CharacterDraft _draft = null!;
    private AbilityPool _pool = null!;
    private readonly Dictionary<string, AbilitySlot> _slots = new();
    private readonly Dictionary<string, TraitChip> _bonusChips = new();
    private readonly Dictionary<string, Label> _finalLabels = new();
    private readonly Dictionary<string, Label> _dModLabels = new();
    private Button _arrayBtn = null!;
    private Button _rollBtn = null!;
    private Button _rerollBtn = null!;
    private Button _autoBtn = null!;

    public void Bind(CharacterDraft draft)
    {
        _draft = draft;
        _draft.Changed += Refresh;
        Build();
    }

    public string? Validate()
    {
        int n = _draft?.StatAssign.Count ?? 0;
        return n == 6 ? null : $"Assign all six abilities ({n}/6).";
    }

    private void Build()
    {
        AddThemeConstantOverride("separation", 18);

        var intro = new VBoxContainer();
        intro.AddThemeConstantOverride("separation", 6);
        AddChild(intro);
        intro.AddChild(new Label { Text = "FOLIO VI · ABILITIES",        ThemeTypeVariation = "Eyebrow" });
        intro.AddChild(new Label { Text = "Assign your Ability Scores",  ThemeTypeVariation = "H2" });
        intro.AddChild(new Label
        {
            Text = "Pick a method, then drag a value from the pool into one of the six "
                 + "ability slots. Drag between slots to swap, or drag back to the "
                 + "pool to unassign. Auto Assign places the remaining pool into the "
                 + "empty slots, prioritising your calling's primary abilities.",
            AutowrapMode = TextServer.AutowrapMode.WordSmart,
        });

        // Method + action toolbar
        var toolbar = new HBoxContainer();
        toolbar.AddThemeConstantOverride("separation", 12);
        AddChild(toolbar);

        _arrayBtn = new Button { Text = "Standard Array" };
        _arrayBtn.Pressed += () => SwitchMethod("array");
        toolbar.AddChild(_arrayBtn);

        _rollBtn = new Button { Text = "Roll 4d6 (drop lowest)" };
        _rollBtn.Pressed += () => SwitchMethod("roll");
        toolbar.AddChild(_rollBtn);

        var spacer = new Control { SizeFlagsHorizontal = SizeFlags.ExpandFill };
        toolbar.AddChild(spacer);

        _rerollBtn = new Button { Text = "Reroll" };
        _rerollBtn.Pressed += Reroll;
        toolbar.AddChild(_rerollBtn);

        _autoBtn = new Button { Text = "Auto Assign" };
        _autoBtn.Pressed += AutoAssign;
        toolbar.AddChild(_autoBtn);

        var poolBox = new VBoxContainer();
        poolBox.AddThemeConstantOverride("separation", 6);
        AddChild(poolBox);
        poolBox.AddChild(new Label { Text = "AVAILABLE" });
        _pool = new AbilityPool();
        _pool.Dropped += OnPoolDropped;
        poolBox.AddChild(_pool);

        var slotsBox = new VBoxContainer();
        slotsBox.AddThemeConstantOverride("separation", 8);
        AddChild(slotsBox);
        slotsBox.AddChild(new Label { Text = "ABILITIES" });

        foreach (var ab in Abilities)
        {
            string captured = ab;  // capture for the closure below
            var row = new HBoxContainer();
            row.AddThemeConstantOverride("separation", 12);
            slotsBox.AddChild(row);

            row.AddChild(new Label
            {
                Text = captured,
                CustomMinimumSize = new Vector2(64, 0),
                VerticalAlignment = VerticalAlignment.Center,
            });

            var slot = new AbilitySlot { Ability = captured };
            slot.Dropped += (Godot.Collections.Dictionary payload)
                => HandleSlotDrop(payload, captured);
            _slots[captured] = slot;
            row.AddChild(slot);

            // Bonus chip — hover for the per-source breakdown.
            var bonus = new TraitChip { TraitName = "+0", Description = "" };
            bonus.CustomMinimumSize = new Vector2(56, 0);
            _bonusChips[captured] = bonus;
            row.AddChild(bonus);

            // Final score (= base + total bonus). Sized to match the
            // AbilityToken numeric label so the 'before / after' values
            // read at the same visual weight.
            var finalLbl = new Label
            {
                Text = "—",
                CustomMinimumSize = new Vector2(56, 0),
                HorizontalAlignment = HorizontalAlignment.Right,
                VerticalAlignment = VerticalAlignment.Center,
            };
            finalLbl.AddThemeFontSizeOverride("font_size", 22);
            _finalLabels[captured] = finalLbl;
            row.AddChild(finalLbl);

            // d20 modifier from final score.
            var dModLbl = new Label
            {
                Text = "",
                CustomMinimumSize = new Vector2(48, 0),
                HorizontalAlignment = HorizontalAlignment.Right,
                VerticalAlignment = VerticalAlignment.Center,
            };
            _dModLabels[captured] = dModLbl;
            row.AddChild(dModLbl);
        }

        Refresh();
    }

    // ──────────────────────────────────────────────────────────────────────
    // Refresh — rebuild token children from CharacterDraft state.

    private void Refresh()
    {
        if (_pool is null) return;
        // Scroll preservation now handled centrally by Wizard.UpdateChrome
        // / Wizard._Process, which snapshots before this Refresh fires.

        // Toolbar reflects current method and assignment state.
        bool isRoll = _draft.StatMethod == "roll";
        _rerollBtn.Visible = isRoll;
        _arrayBtn.Disabled = !isRoll;   // greyed when already on Array
        _rollBtn.Disabled = isRoll;     // greyed when already on Roll
        _autoBtn.Disabled = _draft.StatPool.Count == 0;

        // Pool: one token per StatPool entry. Free() (synchronous) so old
        // children disappear *before* AddChild runs and the layout pass
        // doesn't see a transient doubled-content state.
        foreach (var c in _pool.GetChildren()) c.Free();
        for (int i = 0; i < _draft.StatPool.Count; i++)
        {
            var token = new AbilityToken
            {
                Value = _draft.StatPool[i],
                Origin = "pool",
                OriginPoolIdx = i,
            };
            _pool.AddChild(token);
        }

        // Bonus / final / d20 mod per ability — updated in place from the
        // computed mod sources so the row stays stable across drops.
        foreach (var ab in Abilities)
        {
            int bonus = AbilityCalc.TotalBonus(ab, _draft);
            int baseScore = AbilityCalc.BaseScore(ab, _draft);
            int final = baseScore + bonus;
            int dMod = AbilityCalc.D20Modifier(final);

            _bonusChips[ab].SetTrait(
                AbilityCalc.FormatSigned(bonus),
                AbilityCalc.FormatBreakdown(AbilityCalc.Sources(ab, _draft)),
                tag: "bonus");
            _finalLabels[ab].Text = baseScore == 0 ? "—" : final.ToString();
            _dModLabels[ab].Text = baseScore == 0 ? "" : AbilityCalc.FormatSigned(dMod);
        }

        // Slots: token if assigned, otherwise dash placeholder.
        foreach (var (ab, slot) in _slots)
        {
            foreach (var c in slot.GetChildren()) c.Free();
            if (_draft.StatAssign.ContainsKey(ab))
            {
                int v = (int)_draft.StatAssign[ab];
                var token = new AbilityToken
                {
                    Value = v,
                    Origin = "slot",
                    OriginAbility = ab,
                };
                slot.AddChild(token);
            }
            else
            {
                slot.AddChild(new Label
                {
                    Text = "—",
                    HorizontalAlignment = HorizontalAlignment.Center,
                    VerticalAlignment = VerticalAlignment.Center,
                });
            }
        }

    }

    // ──────────────────────────────────────────────────────────────────────
    // Drop handlers — compute new state and Patch.
    // Mirrors handleDrop / dropToPool in steps.jsx exactly.

    private void HandleSlotDrop(Godot.Collections.Dictionary payload, string destAbility)
    {
        var pool = _draft.StatPool.Duplicate();
        var assign = (Godot.Collections.Dictionary)_draft.StatAssign.Duplicate();

        string from = payload["from"].AsString();
        int value = payload["value"].AsInt32();

        if (from == "pool")
        {
            // pool → slot
            int idx = payload["idx"].AsInt32();
            if (assign.ContainsKey(destAbility))
            {
                // Bump the existing slot value back to the pool.
                pool.Add((int)assign[destAbility]);
            }
            if (idx >= 0 && idx < pool.Count) pool.RemoveAt(idx);
            assign[destAbility] = value;
        }
        else if (from == "slot")
        {
            string srcAbility = payload["ability"].AsString();
            if (srcAbility == destAbility) return;
            // Swap if dest is filled, otherwise move.
            if (assign.ContainsKey(destAbility))
            {
                var dstV = assign[destAbility];
                assign[srcAbility] = dstV;
            }
            else
            {
                assign.Remove(srcAbility);
            }
            assign[destAbility] = value;
        }

        _draft.Patch(new Godot.Collections.Dictionary
        {
            { "stat_pool", pool },
            { "stat_assign", assign },
        });
    }

    // ──────────────────────────────────────────────────────────────────────
    // Method switch + roll + auto-assign

    private void SwitchMethod(string method)
    {
        var pool = method == "roll" ? RollSixSet() : ArrayPool();
        _draft.Patch(new Godot.Collections.Dictionary
        {
            { "stat_method", method },
            { "stat_pool", pool },
            { "stat_assign", new Godot.Collections.Dictionary() },
        });
    }

    private void Reroll()
    {
        if (_draft.StatMethod != "roll") return;
        _draft.Patch(new Godot.Collections.Dictionary
        {
            { "stat_pool", RollSixSet() },
            { "stat_assign", new Godot.Collections.Dictionary() },
        });
    }

    private void AutoAssign()
    {
        if (_draft.StatPool.Count == 0) return;

        // Empty slots, ordered DESCENDING by their clade+species bonus —
        // highest pool value goes to the ability with the highest bonus
        // already coming in, maximising the final score on each. Ties
        // broken by class.PrimaryAbility order.
        var cls = CodexContent.Class(_draft.ClassId);
        var primary = cls?.PrimaryAbility ?? System.Array.Empty<string>();
        var emptyAbilities = Abilities
            .Where(a => !_draft.StatAssign.ContainsKey(a))
            .OrderByDescending(a => AbilityCalc.TotalBonus(a, _draft))
            .ThenBy(a =>
            {
                int idx = System.Array.IndexOf(primary, a);
                return idx < 0 ? 99 : idx;
            })
            .ToList();

        // Pool sorted descending — biggest values go to highest priority.
        var sortedPool = _draft.StatPool.OrderByDescending(v => v).ToList();
        var assign = (Godot.Collections.Dictionary)_draft.StatAssign.Duplicate();
        var newPool = new Godot.Collections.Array<int>();

        for (int i = 0; i < sortedPool.Count; i++)
        {
            if (i < emptyAbilities.Count) assign[emptyAbilities[i]] = sortedPool[i];
            else newPool.Add(sortedPool[i]);
        }

        _draft.Patch(new Godot.Collections.Dictionary
        {
            { "stat_pool", newPool },
            { "stat_assign", assign },
        });
    }

    private static Godot.Collections.Array<int> ArrayPool() =>
        new() { 15, 14, 13, 12, 10, 8 };

    private static Godot.Collections.Array<int> RollSixSet()
    {
        var pool = new Godot.Collections.Array<int>();
        for (int i = 0; i < 6; i++) pool.Add(RollFourDropLowest());
        return pool;
    }

    private static int RollFourDropLowest()
    {
        // 4d6, drop lowest, sum the rest. Range [3, 18].
        int[] rolls = new int[4];
        for (int i = 0; i < 4; i++) rolls[i] = Rng.Next(1, 7);
        System.Array.Sort(rolls);
        return rolls[1] + rolls[2] + rolls[3];
    }

    // ──────────────────────────────────────────────────────────────────────

    private void OnPoolDropped(Godot.Collections.Dictionary payload)
    {
        if (payload["from"].AsString() != "slot") return;
        var assign = (Godot.Collections.Dictionary)_draft.StatAssign.Duplicate();
        var pool = _draft.StatPool.Duplicate();
        string ability = payload["ability"].AsString();
        if (!assign.ContainsKey(ability)) return;
        int v = (int)assign[ability];
        assign.Remove(ability);
        pool.Add(v);
        _draft.Patch(new Godot.Collections.Dictionary
        {
            { "stat_pool", pool },
            { "stat_assign", assign },
        });
    }

}
