// Assets/_Project/Scripts/Editor/Gameplay/EncounterGoldEntryDrawer.cs
using UnityEditor;
using UnityEngine;
using TD.Gameplay;

namespace TD.Editor.Gameplay
{
    /// <summary>
    /// Custom property drawer for <see cref="EncounterGoldEntry"/>. Labels each element by its
    /// run position ("Encounter 3") rather than "Element 2", and renders a projected-earnings
    /// line beneath the fields so the economy can be tuned without arithmetic.
    /// </summary>
    /// <remarks>
    /// <b>Projections are estimates by necessity.</b> Kill income depends on how many enemies the
    /// encounter spawns, and the wave filling each slot is drawn at runtime from a phase pool —
    /// so the drawer multiplies against <see cref="GoldConfig.PreviewEnemiesPerEncounter"/>
    /// instead. The cumulative figure is the number worth watching: it answers "how much could a
    /// player have banked by this point in the run", which is what tower prices get balanced
    /// against.
    /// </remarks>
    [CustomPropertyDrawer(typeof(EncounterGoldEntry))]
    public class EncounterGoldEntryDrawer : PropertyDrawer
    {
        private const float PreviewLineExtraHeight = 4f;

        public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
        {
            if (!property.isExpanded) return EditorGUIUtility.singleLineHeight;

            float h = EditorGUIUtility.singleLineHeight;      // foldout
            h += SpacedLineHeight() * 3;                      // the three gold fields
            h += SpacedLineHeight() * 2 + PreviewLineExtraHeight; // projection + cumulative
            return h;
        }

        public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
        {
            int encounterNumber = EncounterNumberFrom(property);

            // Re-label the foldout by run position. Element indices are 0-based and read as
            // off-by-one against everything else in the run (RunState, the HUD, the checklist),
            // which made miscounting the boss slot easy.
            var header = new GUIContent(encounterNumber > 0
                ? $"Encounter {encounterNumber}"
                : label.text);

            Rect headerRect = new Rect(position.x, position.y, position.width,
                                       EditorGUIUtility.singleLineHeight);
            property.isExpanded = EditorGUI.Foldout(headerRect, property.isExpanded, header,
                                                   toggleOnLabelClick: true);
            if (!property.isExpanded) return;

            float y = position.y + SpacedLineHeight();
            const float indent = 14f;
            Rect Row()
            {
                Rect r = new Rect(position.x + indent, y, position.width - indent,
                                  EditorGUIUtility.singleLineHeight);
                y += SpacedLineHeight();
                return r;
            }

            var perEnemyProp   = property.FindPropertyRelative("GoldPerEnemy");
            var completionProp = property.FindPropertyRelative("CompletionBonus");
            var noLeaksProp    = property.FindPropertyRelative("NoLeaksBonus");

            EditorGUI.PropertyField(Row(), perEnemyProp);
            EditorGUI.PropertyField(Row(), completionProp);
            EditorGUI.PropertyField(Row(), noLeaksProp);

            // Read values off the SerializedProperties rather than the backing object: edits
            // aren't applied to the instance until ApplyModifiedProperties runs at end of frame,
            // so the object would show stale numbers while the designer is still typing.
            int perEnemy   = perEnemyProp.intValue;
            int completion = completionProp.intValue;
            int noLeaks    = noLeaksProp.intValue;

            var config = property.serializedObject.targetObject as GoldConfig;
            int assumed = config != null ? config.PreviewEnemiesPerEncounter : 0;

            int projected = perEnemy * assumed + completion + noLeaks;

            y += PreviewLineExtraHeight;
            var style = new GUIStyle(EditorStyles.miniLabel) { fontStyle = FontStyle.Italic };

            using (new EditorGUI.DisabledScope(true))
            {
                EditorGUI.LabelField(
                    Row(),
                    $"Projected: {projected} g   ({perEnemy} × {assumed} enemies " +
                    $"+ {completion} clear + {noLeaks} no-leak)",
                    style);

                // Cumulative only makes sense once we know where this entry sits in the run.
                if (config != null && encounterNumber > 0)
                {
                    EditorGUI.LabelField(
                        Row(),
                        $"Cumulative by here: {config.ProjectedCumulativeThrough(encounterNumber)} g " +
                        $"(incl. {config.StartingGold} starting)",
                        style);
                }
            }
        }

        // Recovers the 1-based run position from a path like "Encounters.Array.data[2]".
        // Returns 0 when the entry isn't being drawn as an array element.
        private static int EncounterNumberFrom(SerializedProperty property)
        {
            string path = property.propertyPath;
            int open = path.LastIndexOf('[');
            int close = path.LastIndexOf(']');
            if (open < 0 || close < open) return 0;

            string inner = path.Substring(open + 1, close - open - 1);
            return int.TryParse(inner, out int index) ? index + 1 : 0;
        }

        private static float SpacedLineHeight()
            => EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;
    }
}