using System.Collections.Generic;
using UnityEngine;

namespace MazeGen
{
    /// <summary>
    /// Represents a single monster encounter in a room: which monsters are present,
    /// their health state, and visibility to the agent (for the peek mechanic).
    /// </summary>
    public class MonsterEncounter
    {
        public class MonsterInstance
        {
            public Monster Template;
            public CharacterSheet CharacterSheet;
            public bool IsDefeated => !CharacterSheet.Stats.IsAlive;

            public MonsterInstance(Monster template)
            {
                Template = template;
                CharacterSheet = template.CreateCharacterSheet();
            }
        }

        private List<MonsterInstance> _monsters = new List<MonsterInstance>();
        private int _visibleMonsterCount; // Partial info: agent sees this many, not the full count

        public IReadOnlyList<MonsterInstance> Monsters => _monsters.AsReadOnly();
        public int AliveMonsterCount
        {
            get
            {
                int count = 0;
                foreach (var m in _monsters)
                    if (!m.IsDefeated) count++;
                return count;
            }
        }

        /// <summary>
        /// How many monsters the agent can actually see in the room.
        /// This is less than or equal to AliveMonsterCount (incomplete information).
        /// </summary>
        public int VisibleMonsterCount => _visibleMonsterCount;

        public bool HasLivingMonsters => AliveMonsterCount > 0;

        /// <summary>Spawn monsters for this encounter based on a template.</summary>
        public void SpawnMonsters(Monster[] monsterTemplates, int minCount, int maxCount)
        {
            _monsters.Clear();

            int count = Random.Range(minCount, maxCount + 1);
            for (int i = 0; i < count; i++)
            {
                Monster template = monsterTemplates[Random.Range(0, monsterTemplates.Length)];
                _monsters.Add(new MonsterInstance(template));
            }

            // Agent sees 60-100% of the actual monsters (incomplete info)
            _visibleMonsterCount = Mathf.RoundToInt(AliveMonsterCount * Random.Range(0.6f, 1.0f));
            _visibleMonsterCount = Mathf.Max(1, _visibleMonsterCount); // At least see 1 if any exist
        }

        /// <summary>Mark a monster as defeated (called after combat resolution).</summary>
        public void DefeateMonster(int index)
        {
            if (index >= 0 && index < _monsters.Count)
            {
                _monsters[index].CharacterSheet.Stats.CurrentHealth = 0;
            }
        }

        /// <summary>
        /// Get the perceived challenge level from the agent's perspective.
        /// This is based on visible monsters only, not actual count.
        /// </summary>
        public float GetPerceivedChallengeRating(CharacterSheet agentStats)
        {
            if (_visibleMonsterCount == 0)
                return 0;

            // Simple calculation: sum the "threat" of visible monsters
            float totalThreat = 0;
            int counted = 0;

            foreach (var monster in _monsters)
            {
                if (monster.IsDefeated) continue;
                if (counted >= _visibleMonsterCount) break;

                float monsterThreat = monster.CharacterSheet.GetEffectiveAttack() +
                                    monster.CharacterSheet.Stats.CurrentHealth * 0.1f;
                totalThreat += monsterThreat;
                counted++;
            }

            float agentPower = agentStats.GetEffectiveAttack() + agentStats.GetEffectiveDefense();
            return agentPower > 0 ? totalThreat / agentPower : totalThreat;
        }

        /// <summary>
        /// Get the actual challenge rating (true difficulty, not visible to agent).
        /// This is what combat system would use internally.
        /// </summary>
        public float GetActualChallengeRating(CharacterSheet agentStats)
        {
            if (_monsters.Count == 0)
                return 0;

            float totalThreat = 0;
            foreach (var monster in _monsters)
            {
                if (monster.IsDefeated) continue;

                float monsterThreat = monster.CharacterSheet.GetEffectiveAttack() +
                                    monster.CharacterSheet.Stats.CurrentHealth * 0.1f;
                totalThreat += monsterThreat;
            }

            float agentPower = agentStats.GetEffectiveAttack() + agentStats.GetEffectiveDefense();
            return agentPower > 0 ? totalThreat / agentPower : totalThreat;
        }

        /// <summary>Reset all monsters' health for a retry.</summary>
        public void ResetEncounter()
        {
            foreach (var monster in _monsters)
            {
                monster.CharacterSheet.ResetForNewFight();
            }
        }
    }
}