import { DungeonGenerator } from '../dungeon/DungeonGenerator.js';
import { TurnManager } from './TurnManager.js';
import { MonsterAI } from './MonsterAI.js';
import { HERO_DEFINITIONS } from '../data/Heroes.js';
import { MONSTER_DEFINITIONS } from '../data/Monsters.js';
import { createEventDeck, EVENT_TYPES } from '../data/Events.js';

/**
 * GameEngine for Manual Dungeon Construction with Player Movement
 */
export class GameEngine {
    constructor() {
        this.dungeon = new DungeonGenerator();
        this.turnManager = new TurnManager();
        this.ai = new MonsterAI(this); // Init AI
        this.player = null;
        this.selectedEntity = null;
        this.isRunning = false;
        this.plannedPath = []; // Array of {x,y}
        this.eventDeck = createEventDeck();

        // Callbacks
        this.onEntityUpdate = null;
        this.onEntityMove = null;
        this.onEntitySelect = null;
        this.onPathChange = null;
    }

    startMission(missionConfig) {

        this.dungeon.startDungeon(missionConfig);

        // Create Party (4 Heroes)
        this.createParty();

        this.isRunning = true;
        this.turnManager.startGame();

        // Listen for Phase Changes to Reset Moves
        this.turnManager.on('phase_changed', (phase) => {
            if (phase === 'hero') {
                this.resetHeroMoves();
            }
        });
    }

    resetHeroMoves() {
        if (!this.heroes) return;
        this.heroes.forEach(hero => {
            hero.currentMoves = hero.stats.move;
            hero.hasAttacked = false;
        });
        console.log("Refilled Hero Moves");
    }

    createParty() {
        this.heroes = [];
        this.monsters = []; // Initialize monsters array

        // Definition Keys
        const heroKeys = ['barbarian', 'dwarf', 'elf', 'wizard'];
        // Find valid spawn points dynamically
        const startPositions = this.findSpawnPoints(4);

        if (startPositions.length < 4) {
            console.error("Could not find enough spawn points!");
            // Fallback
            startPositions.push({ x: 0, y: 0 }, { x: 1, y: 0 }, { x: 0, y: 1 }, { x: 1, y: 1 });
        }

        heroKeys.forEach((key, index) => {
            const definition = HERO_DEFINITIONS[key];
            const pos = startPositions[index];

            const hero = {
                id: `hero_${key}`,
                type: 'hero',
                key: key,
                name: definition.name,
                x: pos.x,
                y: pos.y,
                texturePath: definition.portrait,
                stats: { ...definition.stats },
                // Game State
                currentMoves: definition.stats.move,
                hasAttacked: false,
                isConscious: true,
                hasLantern: key === 'barbarian' // Default leader
            };

            this.heroes.push(hero);

            if (this.onEntityUpdate) {
                this.onEntityUpdate(hero);
            }
        });

        // Set First Player as Active
        this.activeHeroIndex = 0;

        // Legacy support for single player var (getter proxy)
        this.player = this.heroes[0];
    }

    spawnMonster(monsterKey, x, y) {
        const definition = MONSTER_DEFINITIONS[monsterKey];
        if (!definition) {
            console.error(`Monster definition not found: ${monsterKey}`);
            return;
        }

        // Ensure unique ID even in tight loops
        if (!this._monsterIdCounter) this._monsterIdCounter = 0;
        this._monsterIdCounter++;
        const id = `monster_${monsterKey}_${Date.now()}_${this._monsterIdCounter}`;

        console.log(`[GameEngine] Creating monster ${id} at ${x},${y}`);

        const monster = {
            id: id,
            type: 'monster',
            key: monsterKey,
            name: definition.name,
            x: x,
            y: y,
            texturePath: definition.portrait,
            stats: { ...definition.stats },
            // Game State
            currentWounds: definition.stats.wounds,
            isDead: false
        };

        this.monsters.push(monster);

        if (this.onEntityUpdate) {
            this.onEntityUpdate(monster);
        }

        return monster;
    }

    onCellClick(x, y) {
        // 1. Check for Hero/Monster Selection
        const clickedHero = this.heroes.find(h => h.x === x && h.y === y);
        const clickedMonster = this.monsters ? this.monsters.find(m => m.x === x && m.y === y) : null;

        const clickedEntity = clickedHero || clickedMonster;

        if (clickedEntity) {
            if (this.selectedEntity === clickedEntity) {
                // Toggle Deselect
                this.deselectEntity();
            } else {
                // Select new entity
                if (this.selectedEntity) this.deselectEntity();

                this.selectedEntity = clickedEntity;
                if (this.onEntitySelect) {
                    this.onEntitySelect(clickedEntity.id, true);
                }
            }
            return;
        }

        // 2. PLAN MOVEMENT (If entity selected and we clicked empty space)
        if (this.selectedEntity) {
            this.planStep(x, y);
        }
    }

    deselectEntity() {
        if (!this.selectedEntity) return;
        const id = this.selectedEntity.id;
        this.selectedEntity = null;
        this.plannedPath = [];
        if (this.onEntitySelect) this.onEntitySelect(id, false);
        if (this.onPathChange) this.onPathChange([]);
    }

    // Alias for legacy calls if any
    deselectPlayer() {
        this.deselectEntity();
    }

    planStep(x, y) {
        if (!this.selectedEntity) return;

        // Determine start point
        const lastStep = this.plannedPath.length > 0
            ? this.plannedPath[this.plannedPath.length - 1]
            : { x: this.selectedEntity.x, y: this.selectedEntity.y };

        // Check Adjacency
        const dx = Math.abs(x - lastStep.x);
        const dy = Math.abs(y - lastStep.y);
        const isAdjacent = (dx + dy) === 1;

        // Check Walkability
        const isWalkable = this.canMoveTo(x, y);

        // Check against Max Move Stats
        const maxMove = this.selectedEntity.currentMoves || 0;

        // Also account for the potential next step
        if (this.plannedPath.length >= maxMove && !(this.plannedPath.length > 0 && x === lastStep.x && y === lastStep.y)) {
            // Allow undo (next block), but block new steps
            if (isAdjacent && isWalkable) {
                // Prevent adding more steps
                return;
            }
        }

        // Undo Logic
        if (this.plannedPath.length > 0 && x === lastStep.x && y === lastStep.y) {
            this.plannedPath.pop();
            this.onPathChange && this.onPathChange(this.plannedPath);
            return;
        }

        if (isAdjacent && isWalkable) {
            const alreadyInPath = this.plannedPath.some(p => p.x === x && p.y === y);
            const isEntityPos = this.selectedEntity.x === x && this.selectedEntity.y === y;

            // Also check if occupied by OTHER heroes?
            const isOccupiedByHero = this.heroes.some(h => h.x === x && h.y === y && h !== this.selectedEntity);

            if (!alreadyInPath && !isEntityPos && !isOccupiedByHero) {
                this.plannedPath.push({ x, y });
                this.onPathChange && this.onPathChange(this.plannedPath);
            }
        }
    }

    executeMovePath() {
        if (!this.selectedEntity || !this.plannedPath.length) return;

        const path = [...this.plannedPath];
        const entity = this.selectedEntity;

        // Update verify immediately
        const finalDest = path[path.length - 1];
        entity.x = finalDest.x;
        entity.y = finalDest.y;

        // Visual animation
        if (this.onEntityMove) {
            this.onEntityMove(entity, path);
        }

        // Deduct Moves
        if (entity.currentMoves !== undefined) {
            entity.currentMoves -= path.length;
            if (entity.currentMoves < 0) entity.currentMoves = 0;
        }

        this.deselectEntity();
    }

    canMoveTo(x, y) {
        // Check if cell is walkable (occupied by a tile)
        return this.dungeon.grid.isOccupied(x, y);
    }

    // Deprecated direct move
    movePlayer(x, y) {
        this.player.x = x;
        this.player.y = y;
        if (this.onEntityMove) this.onEntityMove(this.player, [{ x, y }]);
    }

    // Check if the Leader (Lamp Bearer) is adjacent to the door
    isLeaderAdjacentToDoor(doorCells) {
        if (!this.heroes || this.heroes.length === 0) return false;

        const leader = this.getLeader();
        if (!leader) return false;

        const cells = Array.isArray(doorCells) ? doorCells : [doorCells];

        for (const cell of cells) {
            const dx = Math.abs(leader.x - cell.x);
            const dy = Math.abs(leader.y - cell.y);
            // Orthogonal adjacency check (Manhattan distance === 1)
            if ((dx === 1 && dy === 0) || (dx === 0 && dy === 1)) {
                return true;
            }
        }
        return false;
    }

    getLeader() {
        // Find hero with lantern, default to barbarian if something breaks, or first hero
        return this.heroes.find(h => h.hasLantern) || this.heroes.find(h => h.key === 'barbarian') || this.heroes[0];
    }

    // Deprecated generic adjacency (kept for safety or other interactions)
    isPlayerAdjacentToDoor(doorCells) {
        return this.isLeaderAdjacentToDoor(doorCells);
    }

    update(time) {
        // Minimal update loop
    }
    findSpawnPoints(count) {
        const points = [];
        const queue = [{ x: 1, y: 1 }]; // Start search near origin but ensure not 0,0 which might be tricky if it's door
        // Actually, just scan the grid or BFS from center of first tile?
        // First tile is placed at 0,0. Let's scan from 0,0.

        const startNode = { x: 0, y: 0 };
        const searchQueue = [startNode];
        const visited = new Set(['0,0']);

        let loops = 0;
        while (searchQueue.length > 0 && points.length < count && loops < 200) {
            const current = searchQueue.shift();

            if (this.dungeon.grid.isOccupied(current.x, current.y)) {
                points.push(current);
            }

            // Neighbors
            const neighbors = [
                { x: current.x + 1, y: current.y },
                { x: current.x - 1, y: current.y },
                { x: current.x, y: current.y + 1 },
                { x: current.x, y: current.y - 1 }
            ];

            for (const n of neighbors) {
                const key = `${n.x},${n.y}`;
                if (!visited.has(key)) {
                    visited.add(key);
                    searchQueue.push(n);
                }
            }
            loops++;
        }

        return points;
    }

    onRoomRevealed(cells) {
        console.log("[GameEngine] Room Revealed!");

        // 1. Draw Event Card
        if (this.eventDeck.length === 0) {
            console.warn("Event deck empty, reshaping...");
            this.eventDeck = createEventDeck();
        }

        const card = this.eventDeck.pop();
        console.log(`[GameEngine] Event Drawn: ${card.name}`);

        if (card.type === EVENT_TYPES.MONSTER) {
            // 2. Determine Count
            let count = 0;
            if (typeof card.resolve === 'function') {
                count = card.resolve(this, { cells });
            } else {
                count = 1; // Fallback
            }

            console.log(`[GameEngine] Spawning ${count} ${card.monsterKey}s`);

            // 3. Find valid spawn spots
            const availableCells = cells.filter(cell => {
                const isHero = this.heroes.some(h => h.x === cell.x && h.y === cell.y);
                const isMonster = this.monsters.some(m => m.x === cell.x && m.y === cell.y);
                return !isHero && !isMonster;
            });

            console.log(`[GameEngine] Available Spawn Cells: ${availableCells.length}`, availableCells);

            // Shuffle
            for (let i = availableCells.length - 1; i > 0; i--) {
                const j = Math.floor(Math.random() * (i + 1));
                [availableCells[i], availableCells[j]] = [availableCells[j], availableCells[i]];
            }

            // 4. Spawn
            let spawnedCount = 0;
            for (let i = 0; i < count; i++) {
                if (i < availableCells.length) {
                    const pos = availableCells[i];
                    console.log(`[GameEngine] Spawning at ${pos.x},${pos.y}`);
                    this.spawnMonster(card.monsterKey, pos.x, pos.y);
                    spawnedCount++;
                } else {
                    console.warn("[GameEngine] Not enough space!");
                    break;
                }
            }

            return {
                type: 'MONSTER_SPAWN',
                monsterKey: card.monsterKey,
                count: spawnedCount,
                cardName: card.name
            };
        }

        return null;
    }

    // =========================================
    // MONSTER AI & TURN LOGIC
    // =========================================

    playMonsterTurn() {
        if (this.ai) {
            this.ai.executeTurn();
        }
    }

    // AI Helper methods moved to MonsterAI.js
    isLeaderAdjacentToDoor(doorCells) {
        // ... (Keep this one as it's used by main.js logic for doors)
        if (!this.heroes || this.heroes.length === 0) return false;

        const leader = this.getLeader();
        if (!leader) return false;

        const cells = Array.isArray(doorCells) ? doorCells : [doorCells];

        for (const cell of cells) {
            const dx = Math.abs(leader.x - cell.x);
            const dy = Math.abs(leader.y - cell.y);
            // Orthogonal adjacency check (Manhattan distance === 1)
            if ((dx === 1 && dy === 0) || (dx === 0 && dy === 1)) {
                return true;
            }
        }
        return false;
    }
}