/**
 * @typedef {import("./types.js").RunData} RunData
 * @typedef {import("../grid/types.js").Position} Position
 * @typedef {import("../units/Unit.js").Unit} Unit
 * @typedef {import("../ui/combat-hud.d.ts").CombatState} CombatState
 * @typedef {import("../ui/combat-hud.d.ts").UnitStatus} UnitStatus
 * @typedef {import("../ui/combat-hud.d.ts").QueueEntry} QueueEntry
 */

import * as THREE from "three";
import { OrbitControls } from "three/examples/jsm/controls/OrbitControls.js";
import { VoxelGrid } from "../grid/VoxelGrid.js";
import { VoxelManager } from "../grid/VoxelManager.js";
import { UnitManager } from "../managers/UnitManager.js";
import { CaveGenerator } from "../generation/CaveGenerator.js";
import { RuinGenerator } from "../generation/RuinGenerator.js";
import { InputManager } from "./InputManager.js";
import { MissionManager } from "../managers/MissionManager.js";

/**
 * Main game loop managing rendering, input, and game state.
 * @class
 */
export class GameLoop {
  constructor() {
    /** @type {boolean} */
    this.isRunning = false;

    // 1. Core Systems
    /** @type {THREE.Scene} */
    this.scene = new THREE.Scene();
    /** @type {THREE.PerspectiveCamera | null} */
    this.camera = null;
    /** @type {THREE.WebGLRenderer | null} */
    this.renderer = null;
    /** @type {OrbitControls | null} */
    this.controls = null;
    /** @type {InputManager | null} */
    this.inputManager = null;

    /** @type {VoxelGrid | null} */
    this.grid = null;
    /** @type {VoxelManager | null} */
    this.voxelManager = null;
    /** @type {UnitManager | null} */
    this.unitManager = null;

    /** @type {Map<string, THREE.Mesh>} */
    this.unitMeshes = new Map();
    /** @type {RunData | null} */
    this.runData = null;
    /** @type {Position[]} */
    this.playerSpawnZone = [];
    /** @type {Position[]} */
    this.enemySpawnZone = [];

    // Input Logic State
    /** @type {number} */
    this.lastMoveTime = 0;
    /** @type {number} */
    this.moveCooldown = 120; // ms between cursor moves
    /** @type {"MOVEMENT" | "TARGETING"} */
    this.selectionMode = "MOVEMENT"; // MOVEMENT, TARGETING
    /** @type {MissionManager} */
    this.missionManager = new MissionManager(this); // Init Mission Manager

    // Deployment State
    /** @type {{ selectedUnitIndex: number; deployedUnits: Map<number, Unit> }} */
    this.deploymentState = {
      selectedUnitIndex: -1,
      deployedUnits: new Map(), // Map<Index, UnitInstance>
    };

    /** @type {import("./GameStateManager.js").GameStateManagerClass | null} */
    this.gameStateManager = null;
  }

  /**
   * Initializes the game loop with Three.js setup.
   * @param {HTMLElement} container - DOM element to attach the renderer to
   */
  init(container) {
    // Setup Three.js
    this.camera = new THREE.PerspectiveCamera(
      45,
      window.innerWidth / window.innerHeight,
      0.1,
      1000
    );
    this.camera.position.set(20, 20, 20);
    this.camera.lookAt(0, 0, 0);

    this.renderer = new THREE.WebGLRenderer({ antialias: true });
    this.renderer.setSize(window.innerWidth, window.innerHeight);
    this.renderer.setClearColor(0x111111);
    container.appendChild(this.renderer.domElement);

    this.controls = new OrbitControls(this.camera, this.renderer.domElement);
    this.controls.enableDamping = true;
    this.controls.dampingFactor = 0.05;

    // --- SETUP INPUT MANAGER ---
    this.inputManager = new InputManager(
      this.camera,
      this.scene,
      this.renderer.domElement
    );

    // Bind Buttons (Events)
    this.inputManager.addEventListener("gamepadbuttondown", (e) =>
      this.handleButtonInput(e.detail)
    );
    this.inputManager.addEventListener("keydown", (e) =>
      this.handleKeyInput(e.detail)
    );

    // Default Validator: Movement Logic (Will be overridden in startLevel)
    this.inputManager.setValidator(this.validateCursorMove.bind(this));

    const ambient = new THREE.AmbientLight(0xffffff, 0.6);
    const dirLight = new THREE.DirectionalLight(0xffffff, 0.8);
    dirLight.position.set(10, 20, 10);
    this.scene.add(ambient);
    this.scene.add(dirLight);

    window.addEventListener("resize", () => {
      this.camera.aspect = window.innerWidth / window.innerHeight;
      this.camera.updateProjectionMatrix();
      this.renderer.setSize(window.innerWidth, window.innerHeight);
    });

    this.animate = this.animate.bind(this);
  }

  /**
   * Validation Logic for Standard Movement.
   * @param {number} x - X coordinate
   * @param {number} y - Y coordinate
   * @param {number} z - Z coordinate
   * @returns {false | Position} - False if invalid, or adjusted position object
   */
  validateCursorMove(x, y, z) {
    if (!this.grid) return true; // Allow if grid not ready

    // 1. Basic Bounds Check
    if (!this.grid.isValidBounds({ x, y: 0, z })) return false;

    // 2. Scan Column for Surface (Climb/Drop Logic)
    let bestY = null;

    if (this.isWalkable(x, y, z)) bestY = y;
    else if (this.isWalkable(x, y + 1, z)) bestY = y + 1;
    else if (this.isWalkable(x, y - 1, z)) bestY = y - 1;
    else if (this.isWalkable(x, y - 2, z)) bestY = y - 2;

    if (bestY !== null) {
      return { x, y: bestY, z };
    }

    return false;
  }

  /**
   * Validation Logic for Deployment Phase.
   * @param {number} x - X coordinate
   * @param {number} y - Y coordinate
   * @param {number} z - Z coordinate
   * @returns {false | Position} - False if invalid, or valid spawn position
   */
  validateDeploymentCursor(x, y, z) {
    if (!this.grid || this.playerSpawnZone.length === 0) return false;

    // Check if the target X,Z is inside the spawn zone list
    const validSpot = this.playerSpawnZone.find((t) => t.x === x && t.z === z);

    if (validSpot) {
      // Snap Y to the valid floor height defined in the zone
      return { x: validSpot.x, y: validSpot.y, z: validSpot.z };
    }

    return false; // Cursor cannot leave the spawn zone
  }

  /**
   * Checks if a position is walkable.
   * @param {number} x - X coordinate
   * @param {number} y - Y coordinate
   * @param {number} z - Z coordinate
   * @returns {boolean} - True if walkable
   */
  isWalkable(x, y, z) {
    if (this.grid.getCell(x, y, z) !== 0) return false;
    if (this.grid.getCell(x, y - 1, z) === 0) return false;
    if (this.grid.getCell(x, y + 1, z) !== 0) return false;
    return true;
  }

  /**
   * Validates an interaction target position.
   * @param {number} x - X coordinate
   * @param {number} y - Y coordinate
   * @param {number} z - Z coordinate
   * @returns {boolean} - True if valid
   */
  validateInteractionTarget(x, y, z) {
    if (!this.grid) return true;
    return this.grid.isValidBounds({ x, y, z });
  }

  /**
   * Handles gamepad button input.
   * @param {{ buttonIndex: number; gamepadIndex: number }} detail - Button input detail
   */
  handleButtonInput(detail) {
    if (detail.buttonIndex === 0) {
      // A / Cross
      this.triggerSelection();
    }
  }

  /**
   * Handles keyboard input.
   * @param {string} code - Key code
   */
  handleKeyInput(code) {
    if (code === "Space" || code === "Enter") {
      this.triggerSelection();
    }
    if (code === "Tab") {
      this.selectionMode =
        this.selectionMode === "MOVEMENT" ? "TARGETING" : "MOVEMENT";
      const validator =
        this.selectionMode === "MOVEMENT"
          ? this.validateCursorMove.bind(this)
          : this.validateInteractionTarget.bind(this);

      this.inputManager.setValidator(validator);
    }
  }

  /**
   * Called by UI when a unit is clicked in the Roster.
   * @param {number} index - The index of the unit in the squad to select.
   */
  selectDeploymentUnit(index) {
    this.deploymentState.selectedUnitIndex = index;
    console.log(`Deployment: Selected Unit Index ${index}`);
  }

  /**
   * Triggers selection action at cursor position.
   */
  triggerSelection() {
    const cursor = this.inputManager.getCursorPosition();
    console.log("Action at:", cursor);

    if (
      this.gameStateManager &&
      this.gameStateManager.currentState === "STATE_DEPLOYMENT"
    ) {
      const selIndex = this.deploymentState.selectedUnitIndex;

      if (selIndex !== -1) {
        // Attempt to deploy OR move the selected unit
        const unitDef = this.runData.squad[selIndex];
        const existingUnit = this.deploymentState.deployedUnits.get(selIndex);

        const resultUnit = this.deployUnit(unitDef, cursor, existingUnit);

        if (resultUnit) {
          // Track it
          this.deploymentState.deployedUnits.set(selIndex, resultUnit);

          // Notify UI
          window.dispatchEvent(
            new CustomEvent("deployment-update", {
              detail: {
                deployedIndices: Array.from(
                  this.deploymentState.deployedUnits.keys()
                ),
              },
            })
          );
        }
      } else {
        console.log("No unit selected.");
      }
    }
  }

  /**
   * Starts a mission by ID.
   * @param {string} missionId - Mission identifier
   * @returns {Promise<void>}
   */
  async startMission(missionId) {
    const mission = await fetch(
      `assets/data/missions/${missionId.toLowerCase()}.json`
    );
    const missionData = await mission.json();
    this.missionManager.startMission(missionData);
  }

  /**
   * Starts a level with the given run data.
   * @param {RunData} runData - Run data containing mission and squad info
   * @returns {Promise<void>}
   */
  async startLevel(runData) {
    console.log("GameLoop: Generating Level...");
    this.runData = runData;
    this.isRunning = true;
    this.clearUnitMeshes();

    // Reset Deployment State
    this.deploymentState = {
      selectedUnitIndex: -1,
      deployedUnits: new Map(), // Map<Index, UnitInstance>
    };

    this.grid = new VoxelGrid(20, 10, 20);
    const generator = new RuinGenerator(this.grid, runData.seed);
    generator.generate();

    if (generator.generatedAssets.spawnZones) {
      this.playerSpawnZone = generator.generatedAssets.spawnZones.player || [];
      this.enemySpawnZone = generator.generatedAssets.spawnZones.enemy || [];
    }

    if (this.playerSpawnZone.length === 0)
      this.playerSpawnZone.push({ x: 2, y: 1, z: 2 });
    if (this.enemySpawnZone.length === 0)
      this.enemySpawnZone.push({ x: 18, y: 1, z: 18 });

    this.voxelManager = new VoxelManager(this.grid, this.scene);
    this.voxelManager.updateMaterials(generator.generatedAssets);
    this.voxelManager.update();

    if (this.controls) this.voxelManager.focusCamera(this.controls);

    const mockRegistry = {
      get: (id) => {
        if (id.startsWith("CLASS_"))
          return { type: "EXPLORER", name: id, stats: { hp: 100 } };
        return {
          type: "ENEMY",
          name: "Enemy",
          stats: { hp: 50 },
          ai_archetype: "BRUISER",
        };
      },
    };
    this.unitManager = new UnitManager(mockRegistry);
    this.highlightZones();

    if (this.playerSpawnZone.length > 0) {
      let sumX = 0,
        sumY = 0,
        sumZ = 0;
      for (const spot of this.playerSpawnZone) {
        sumX += spot.x;
        sumY += spot.y;
        sumZ += spot.z;
      }
      const centerX = sumX / this.playerSpawnZone.length;
      const centerY = sumY / this.playerSpawnZone.length;
      const centerZ = sumZ / this.playerSpawnZone.length;

      const start = this.playerSpawnZone[0];
      this.inputManager.setCursor(start.x, start.y, start.z);

      if (this.controls) {
        this.controls.target.set(centerX, centerY, centerZ);
        this.controls.update();
      }
    }

    this.inputManager.setValidator(this.validateDeploymentCursor.bind(this));

    this.animate();
  }

  /**
   * Deploys or moves a unit to a target tile.
   * @param {import("./types.js").SquadMember} unitDef - Unit definition
   * @param {Position} targetTile - Target position
   * @param {Unit | null} [existingUnit] - Existing unit to move, or null to create new
   * @returns {Unit | null} - The deployed/moved unit, or null if failed
   */
  deployUnit(unitDef, targetTile, existingUnit = null) {
    if (
      !this.gameStateManager ||
      this.gameStateManager.currentState !== "STATE_DEPLOYMENT"
    )
      return null;

    const isValid = this.validateDeploymentCursor(
      targetTile.x,
      targetTile.y,
      targetTile.z
    );

    // Check collision
    if (!isValid) {
      console.warn("Invalid spawn zone");
      return null;
    }

    // If tile occupied...
    if (this.grid.isOccupied(targetTile)) {
      // If occupied by SELF (clicking same spot), that's valid, just do nothing
      if (
        existingUnit &&
        existingUnit.position.x === targetTile.x &&
        existingUnit.position.z === targetTile.z
      ) {
        return existingUnit;
      }
      console.warn("Tile occupied");
      return null;
    }

    if (existingUnit) {
      // MOVE logic
      this.grid.moveUnit(existingUnit, targetTile, { force: true }); // Force to bypass standard move checks if any
      // Update Mesh
      const mesh = this.unitMeshes.get(existingUnit.id);
      if (mesh) {
        mesh.position.set(targetTile.x, targetTile.y + 0.6, targetTile.z);
      }
      console.log(
        `Moved ${existingUnit.name} to ${targetTile.x},${targetTile.y},${targetTile.z}`
      );
      return existingUnit;
    } else {
      // CREATE logic
      const unit = this.unitManager.createUnit(
        unitDef.classId || unitDef.id,
        "PLAYER"
      );
      if (unitDef.name) unit.name = unitDef.name;

      this.grid.placeUnit(unit, targetTile);
      this.createUnitMesh(unit, targetTile);

      console.log(
        `Deployed ${unit.name} at ${targetTile.x},${targetTile.y},${targetTile.z}`
      );
      return unit;
    }
  }

  /**
   * Finalizes deployment phase and starts combat.
   */
  finalizeDeployment() {
    if (
      !this.gameStateManager ||
      this.gameStateManager.currentState !== "STATE_DEPLOYMENT"
    )
      return;
    const enemyCount = 2;
    for (let i = 0; i < enemyCount; i++) {
      const spotIndex = Math.floor(Math.random() * this.enemySpawnZone.length);
      const spot = this.enemySpawnZone[spotIndex];
      if (spot && !this.grid.isOccupied(spot)) {
        const enemy = this.unitManager.createUnit("ENEMY_DEFAULT", "ENEMY");
        this.grid.placeUnit(enemy, spot);
        this.createUnitMesh(enemy, spot);
        this.enemySpawnZone.splice(spotIndex, 1);
      }
    }

    // Switch to standard movement validator for the game
    this.inputManager.setValidator(this.validateCursorMove.bind(this));

    // Notify GameStateManager about state change
    if (this.gameStateManager) {
      this.gameStateManager.transitionTo("STATE_COMBAT");
    }

    // Initialize combat state
    this.updateCombatState();

    console.log("Combat Started!");
  }

  /**
   * Clears all unit meshes from the scene.
   */
  clearUnitMeshes() {
    this.unitMeshes.forEach((mesh) => this.scene.remove(mesh));
    this.unitMeshes.clear();
  }

  /**
   * Creates a visual mesh for a unit.
   * @param {Unit} unit - The unit instance
   * @param {Position} pos - Position to place the mesh
   */
  createUnitMesh(unit, pos) {
    const geometry = new THREE.BoxGeometry(0.6, 1.2, 0.6);
    let color = 0xcccccc;
    if (unit.id.includes("VANGUARD")) color = 0xff3333;
    else if (unit.team === "ENEMY") color = 0x550000;
    const material = new THREE.MeshStandardMaterial({ color: color });
    const mesh = new THREE.Mesh(geometry, material);
    mesh.position.set(pos.x, pos.y + 0.6, pos.z);
    this.scene.add(mesh);
    this.unitMeshes.set(unit.id, mesh);
  }

  /**
   * Highlights spawn zones with visual indicators.
   */
  highlightZones() {
    const highlightMatPlayer = new THREE.MeshBasicMaterial({
      color: 0x00ff00,
      transparent: true,
      opacity: 0.3,
    });
    const highlightMatEnemy = new THREE.MeshBasicMaterial({
      color: 0xff0000,
      transparent: true,
      opacity: 0.3,
    });
    const geo = new THREE.PlaneGeometry(1, 1);
    geo.rotateX(-Math.PI / 2);
    this.playerSpawnZone.forEach((pos) => {
      const mesh = new THREE.Mesh(geo, highlightMatPlayer);
      mesh.position.set(pos.x, pos.y + 0.05, pos.z);
      this.scene.add(mesh);
    });
    this.enemySpawnZone.forEach((pos) => {
      const mesh = new THREE.Mesh(geo, highlightMatEnemy);
      mesh.position.set(pos.x, pos.y + 0.05, pos.z);
      this.scene.add(mesh);
    });
  }

  /**
   * Main animation loop.
   */
  animate() {
    if (!this.isRunning) return;
    requestAnimationFrame(this.animate);

    if (this.inputManager) this.inputManager.update();
    if (this.controls) this.controls.update();

    const now = Date.now();
    if (now - this.lastMoveTime > this.moveCooldown) {
      let dx = 0;
      let dz = 0;

      if (
        this.inputManager.isKeyPressed("KeyW") ||
        this.inputManager.isKeyPressed("ArrowUp")
      )
        dz = -1;
      if (
        this.inputManager.isKeyPressed("KeyS") ||
        this.inputManager.isKeyPressed("ArrowDown")
      )
        dz = 1;
      if (
        this.inputManager.isKeyPressed("KeyA") ||
        this.inputManager.isKeyPressed("ArrowLeft")
      )
        dx = -1;
      if (
        this.inputManager.isKeyPressed("KeyD") ||
        this.inputManager.isKeyPressed("ArrowRight")
      )
        dx = 1;

      if (dx !== 0 || dz !== 0) {
        const currentPos = this.inputManager.getCursorPosition();
        const newX = currentPos.x + dx;
        const newZ = currentPos.z + dz;

        this.inputManager.setCursor(newX, currentPos.y, newZ);
        this.lastMoveTime = now;
      }
    }

    const time = Date.now() * 0.002;
    this.unitMeshes.forEach((mesh) => {
      mesh.position.y += Math.sin(time) * 0.002;
    });

    this.renderer.render(this.scene, this.camera);
  }

  /**
   * Stops the game loop and cleans up resources.
   */
  stop() {
    this.isRunning = false;
    if (this.inputManager) this.inputManager.detach();
    if (this.controls) this.controls.dispose();
  }

  /**
   * Updates the combat state in GameStateManager.
   * Called when combat starts or when combat state changes (turn changes, etc.)
   */
  updateCombatState() {
    if (!this.gameStateManager || !this.grid || !this.unitManager) {
      return;
    }

    // Get all units from the grid
    const allUnits = Array.from(this.grid.unitMap.values()).filter(
      (unit) => unit.isAlive && unit.isAlive()
    );

    if (allUnits.length === 0) {
      // No units, clear combat state
      this.gameStateManager.setCombatState(null);
      return;
    }

    // Build turn queue sorted by initiative (chargeMeter)
    const turnQueue = allUnits
      .map((unit) => {
        // Get portrait path (placeholder for now)
        const portrait =
          unit.team === "PLAYER"
            ? "/assets/images/portraits/default.png"
            : "/assets/images/portraits/enemy.png";

        return {
          unitId: unit.id,
          portrait: portrait,
          team: unit.team || "ENEMY",
          initiative: unit.chargeMeter || 0,
        };
      })
      .sort((a, b) => b.initiative - a.initiative); // Sort by initiative descending

    // Get active unit (first in queue)
    const activeUnitId = turnQueue.length > 0 ? turnQueue[0].unitId : null;
    const activeUnit = allUnits.find((u) => u.id === activeUnitId);

    // Build active unit status if we have an active unit
    let unitStatus = null;
    if (activeUnit) {
      // Get max AP (default to 10 for now, can be derived from stats later)
      const maxAP = 10;

      // Convert status effects to status icons
      const statuses = (activeUnit.statusEffects || []).map((effect) => ({
        id: effect.id || "unknown",
        icon: effect.icon || "❓",
        turnsRemaining: effect.duration || 0,
        description: effect.description || effect.name || "Status Effect",
      }));

      // Build skills (placeholder for now - will be populated from unit's actions/skill tree)
      const skills = (activeUnit.actions || []).map((action, index) => ({
        id: action.id || `skill_${index}`,
        name: action.name || "Unknown Skill",
        icon: action.icon || "⚔",
        costAP: action.costAP || 0,
        cooldown: action.cooldown || 0,
        isAvailable:
          activeUnit.currentAP >= (action.costAP || 0) &&
          (action.cooldown || 0) === 0,
      }));

      // If no skills from actions, provide a default attack skill
      if (skills.length === 0) {
        skills.push({
          id: "attack",
          name: "Attack",
          icon: "⚔",
          costAP: 3,
          cooldown: 0,
          isAvailable: activeUnit.currentAP >= 3,
        });
      }

      unitStatus = {
        id: activeUnit.id,
        name: activeUnit.name,
        portrait:
          activeUnit.team === "PLAYER"
            ? "/assets/images/portraits/default.png"
            : "/assets/images/portraits/enemy.png",
        hp: {
          current: activeUnit.currentHealth,
          max: activeUnit.maxHealth,
        },
        ap: {
          current: activeUnit.currentAP,
          max: maxAP,
        },
        charge: activeUnit.chargeMeter || 0,
        statuses: statuses,
        skills: skills,
      };
    }

    // Build combat state
    const combatState = {
      activeUnit: unitStatus,
      turnQueue: turnQueue,
      targetingMode: false, // Will be set when player selects a skill
      roundNumber: 1, // TODO: Track actual round number
    };

    // Update GameStateManager
    this.gameStateManager.setCombatState(combatState);
  }
}