using System;
using UnityEngine;

namespace IdleSpectator;

/// <summary>
/// Owns Dossier/Saga tab selection, hover preview, and camera read-pause lease.
/// </summary>
public static class LifeSagaViewController
{
    public const string ReadPauseOwner = "saga_hover";
    /// <summary>Only used if an exit was deferred; glyph leave finishes immediately.</summary>
    public const float HoverExitGraceSeconds = 0.05f;

    public enum Tab
    {
        Dossier = 0,
        Saga = 1
    }

    private static Tab _selectedTab = Tab.Dossier;
    private static long _persistentSagaId;
    private static bool _persistentPinned;
    private static long _hoverPreviewId;
    private static Tab _tabBeforeHover = Tab.Dossier;
    private static float _hoverExitAt = -1f;
    private static bool _pauseHeld;
    private static bool _loreReturnToSaga;
    private static long _loreReturnSagaId;

    public static Tab SelectedTab => _selectedTab;
    public static long PersistentSagaId => _persistentSagaId;
    public static long HoverPreviewId => _hoverPreviewId;
    public static bool IsHoverPreview => _hoverPreviewId != 0;

    public static Tab EffectiveTab =>
        _hoverPreviewId != 0 ? Tab.Saga : _selectedTab;

    public static long EffectiveSagaId
    {
        get
        {
            if (_hoverPreviewId != 0)
            {
                return _hoverPreviewId;
            }

            return ResolvePersistentSagaId();
        }
    }

    public static void SelectTab(Tab tab)
    {
        // Explicit tab click wins over hover preview restore.
        if (_hoverPreviewId != 0 || _pauseHeld)
        {
            CancelPreviewAndPause();
            _tabBeforeHover = tab;
        }

        _selectedTab = tab;
        if (tab == Tab.Saga)
        {
            long watch = WatchedMcId();
            if (watch != 0)
            {
                _persistentSagaId = watch;
                _persistentPinned = true;
            }
            else if (!IsValidMc(_persistentSagaId) || !_persistentPinned)
            {
                _persistentSagaId = 0;
                _persistentPinned = false;
            }
        }

        WatchCaption.RequestRelayout();
    }

    public static void SetPersistentSaga(long unitId)
    {
        if (unitId == 0 || !LifeSagaRoster.IsMc(unitId))
        {
            return;
        }

        _persistentSagaId = unitId;
        _persistentPinned = true;
    }

    /// <summary>Stash Saga return target before opening Lore from the Saga panel.</summary>
    public static void StashLoreReturn(long unitId)
    {
        _loreReturnToSaga = true;
        _loreReturnSagaId = unitId;
    }

    /// <summary>
    /// After Lore closes, restore Saga tab + subject when a stash is present.
    /// Returns true when a restore was applied.
    /// </summary>
    public static bool TryRestoreAfterLore()
    {
        if (!_loreReturnToSaga)
        {
            return false;
        }

        long id = _loreReturnSagaId;
        _loreReturnToSaga = false;
        _loreReturnSagaId = 0;

        CancelPreviewAndPause();
        _selectedTab = Tab.Saga;
        _tabBeforeHover = Tab.Saga;
        if (IsValidMc(id))
        {
            _persistentSagaId = id;
            _persistentPinned = true;
        }
        else
        {
            long watch = WatchedMcId();
            if (watch != 0)
            {
                _persistentSagaId = watch;
                _persistentPinned = true;
            }
            else
            {
                _persistentSagaId = 0;
                _persistentPinned = false;
            }
        }

        WatchCaption.RequestRelayout();
        return true;
    }

    public static void BeginHoverPreview(long unitId)
    {
        if (unitId == 0)
        {
            return;
        }

        _hoverExitAt = -1f;
        if (_hoverPreviewId == 0)
        {
            _tabBeforeHover = _selectedTab;
        }

        _hoverPreviewId = unitId;
        if (!_pauseHeld)
        {
            InterestDirector.AcquireReadPause(ReadPauseOwner);
            _pauseHeld = true;
        }

        WatchCaption.RequestRelayout();
    }

    public static void EndHoverPreview()
    {
        if (_hoverPreviewId == 0 && !_pauseHeld)
        {
            return;
        }

        // Relayout / glyph→glyph can fire Exit while the pointer is still on a glyph.
        // Keep the preview in that case; otherwise restore Dossier immediately.
        if (LifeSagaRail.IsPointerOverGlyph())
        {
            _hoverExitAt = -1f;
            return;
        }

        FinishHoverExit();
    }

    public static void Tick()
    {
        if (_hoverPreviewId == 0)
        {
            return;
        }

        // Actively hovering (no exit armed) - keep preview until EndHoverPreview.
        if (_hoverExitAt < 0f)
        {
            return;
        }

        // Deferred exit was armed; cancel it if the pointer landed on another glyph.
        if (LifeSagaRail.IsPointerOverGlyph())
        {
            _hoverExitAt = -1f;
            return;
        }

        if (Time.unscaledTime < _hoverExitAt)
        {
            return;
        }

        FinishHoverExit();
    }

    public static void CancelPreviewAndPause()
    {
        _hoverExitAt = -1f;
        _hoverPreviewId = 0;
        if (_pauseHeld)
        {
            InterestDirector.ReleaseReadPause(ReadPauseOwner);
            _pauseHeld = false;
        }
    }

    public static void Clear()
    {
        CancelPreviewAndPause();
        _selectedTab = Tab.Dossier;
        _persistentSagaId = 0;
        _persistentPinned = false;
        _tabBeforeHover = Tab.Dossier;
        _loreReturnToSaga = false;
        _loreReturnSagaId = 0;
    }

    /// <summary>
    /// Harness: force-complete hover exit as if the pointer left every glyph.
    /// </summary>
    public static void HarnessTickExitAwayFromChrome()
    {
        if (_hoverPreviewId == 0 && !_pauseHeld)
        {
            return;
        }

        FinishHoverExit();
    }

    public static LifeSagaViewModel BuildEffectivePresentation()
    {
        long id = EffectiveSagaId;
        return id != 0 ? LifeSagaPresentation.Build(id) : new LifeSagaViewModel();
    }

    private static void FinishHoverExit()
    {
        _hoverExitAt = -1f;
        _hoverPreviewId = 0;
        _selectedTab = _tabBeforeHover;
        if (_pauseHeld)
        {
            InterestDirector.ReleaseReadPause(ReadPauseOwner);
            _pauseHeld = false;
        }

        WatchCaption.RequestRelayout();
    }

    /// <summary>
    /// Watched MC wins when on roster. Otherwise only an explicitly pinned alive MC.
    /// Never falls back to first-roster / stale last-active filler.
    /// </summary>
    private static long ResolvePersistentSagaId()
    {
        long watch = WatchedMcId();
        if (watch != 0)
        {
            _persistentSagaId = watch;
            _persistentPinned = true;
            return watch;
        }

        if (_persistentPinned && IsValidMc(_persistentSagaId))
        {
            return _persistentSagaId;
        }

        _persistentSagaId = 0;
        _persistentPinned = false;
        return 0;
    }

    private static bool IsValidMc(long unitId)
    {
        return unitId != 0
               && LifeSagaRoster.IsMc(unitId)
               && EventFeedUtil.FindAliveById(unitId) != null;
    }

    private static long WatchedMcId()
    {
        long watchId = EventFeedUtil.SafeId(
            MoveCamera.hasFocusUnit() ? MoveCamera._focus_unit : null);
        return watchId != 0 && LifeSagaRoster.IsMc(watchId) ? watchId : 0;
    }
}