/**
 * state.js — Centralized reactive state for the modular synth
 * Uses a simple pub/sub pattern for React integration
 */
import { playConnect, playDisconnect, playModuleAdd, playModuleDelete } from './uiSounds.js';
import { getModuleDef } from './moduleRegistry.js';
import { invalidateConnectionCache } from './audioEngine.js';

let _listeners = new Set();
let _nextModuleId = 1;
let _nextConnectionId = 1;

export const state = {
  modules: [],        // { id, type, x, y, params, collapsed }
  connections: [],     // { id, from: {moduleId, port}, to: {moduleId, port} }

  // Interaction
  selectedModuleId: null,
  dragging: null,      // { moduleId, offsetX, offsetY }
  connecting: null,    // { moduleId, port, portType, direction, x, y } (temp wire)

  // Camera
  camX: 0, camY: 0, zoom: 1,
  panning: false, panStart: null,

  // Audio
  isRunning: false,
  masterVolume: -6,

  // UI
  showPalette: true,
  presetModal: null,  // null | 'save' | 'load'
};

export function subscribe(fn) {
  _listeners.add(fn);
  return () => _listeners.delete(fn);
}

export function emit() {
  _listeners.forEach(fn => fn());
}

export function addModule(type, x, y) {
  const id = _nextModuleId++;
  // Populate ALL default params so level checkers can read them immediately
  const def = getModuleDef(type);
  const defaults = def
    ? Object.fromEntries(Object.entries(def.params).map(([k, v]) => [k, v.default]))
    : {};
  state.modules.push({ id, type, x, y, params: defaults, collapsed: false });
  state.selectedModuleId = id;
  emit();
  playModuleAdd();
  return id;
}

export function removeModule(id) {
  state.modules = state.modules.filter(m => m.id !== id);
  state.connections = state.connections.filter(
    c => c.from.moduleId !== id && c.to.moduleId !== id
  );
  if (state.selectedModuleId === id) state.selectedModuleId = null;
  emit();
  playModuleDelete();
}

export function updateModulePosition(id, x, y) {
  const m = state.modules.find(m => m.id === id);
  if (m) { m.x = x; m.y = y; emit(); }
}

export function updateModuleParam(id, paramName, value) {
  const m = state.modules.find(m => m.id === id);
  if (m) { m.params[paramName] = value; emit(); }
}

export function addConnection(fromModuleId, fromPort, toModuleId, toPort) {
  // Prevent duplicates
  const exists = state.connections.find(c =>
    c.from.moduleId === fromModuleId && c.from.port === fromPort &&
    c.to.moduleId === toModuleId && c.to.port === toPort
  );
  if (exists) return null;

  // Prevent connecting to already-connected input
  const inputTaken = state.connections.find(c =>
    c.to.moduleId === toModuleId && c.to.port === toPort
  );
  if (inputTaken) {
    // Remove old connection to this input (silent — connect sound will play)
    removeConnection(inputTaken.id, true);
  }

  const id = _nextConnectionId++;
  state.connections.push({ id, from: { moduleId: fromModuleId, port: fromPort }, to: { moduleId: toModuleId, port: toPort } });
  invalidateConnectionCache();
  emit();
  playConnect();
  return id;
}

export function removeConnection(id, _silent = false) {
  state.connections = state.connections.filter(c => c.id !== id);
  invalidateConnectionCache();
  emit();
  if (!_silent) playDisconnect();
}

export function getModule(id) {
  return state.modules.find(m => m.id === id) || null;
}

export function isPortConnected(moduleId, portName, direction) {
  return state.connections.some(c =>
    direction === 'output'
      ? (c.from.moduleId === moduleId && c.from.port === portName)
      : (c.to.moduleId === moduleId && c.to.port === portName)
  );
}

// Serialization
export function serialize() {
  return {
    modules: state.modules.map(m => ({ id: m.id, type: m.type, x: m.x, y: m.y, params: { ...m.params } })),
    connections: state.connections.map(c => ({ ...c })),
    camera: { camX: state.camX, camY: state.camY, zoom: state.zoom },
    masterVolume: state.masterVolume,
  };
}

export function deserialize(data) {
  state.modules = data.modules || [];
  state.connections = data.connections || [];
  if (data.camera) {
    state.camX = data.camera.camX || 0;
    state.camY = data.camera.camY || 0;
    state.zoom = data.camera.zoom || 1;
  }
  state.masterVolume = data.masterVolume ?? -6;
  _nextModuleId = Math.max(1, ...state.modules.map(m => m.id)) + 1;
  _nextConnectionId = Math.max(1, ...state.connections.map(c => c.id)) + 1;
  state.selectedModuleId = null;
  emit();
}