/**
 * Transcriptions store - manages the list of transcription items
 * received from the backend via WebSocket.
 */

export interface TranscriptionItem {
  id: string;
  text: string;
  userName: string;
  timestamp: string;
  isPreview: boolean;
}

let items = $state<TranscriptionItem[]>([]);
let nextId = 0;

function generateId(): string {
  return `t-${Date.now()}-${nextId++}`;
}

function addTranscription(data: {
  text?: string;
  user_name?: string;
  timestamp?: string;
}) {
  // When a final transcription arrives, remove any existing preview
  const previewIndex = items.findIndex((item) => item.isPreview);
  if (previewIndex !== -1) {
    items.splice(previewIndex, 1);
  }

  items.push({
    id: generateId(),
    text: data.text ?? "",
    userName: data.user_name ?? "",
    timestamp: data.timestamp ?? "",
    isPreview: false,
  });

  // Keep a reasonable limit
  if (items.length > 500) {
    items.splice(0, items.length - 500);
  }
}

function setPreview(data: {
  text?: string;
  user_name?: string;
  timestamp?: string;
}) {
  const existingIndex = items.findIndex((item) => item.isPreview);
  const previewItem: TranscriptionItem = {
    id: existingIndex !== -1 ? items[existingIndex].id : generateId(),
    text: data.text ?? "",
    userName: data.user_name ?? "",
    timestamp: data.timestamp ?? "",
    isPreview: true,
  };

  if (existingIndex !== -1) {
    items[existingIndex] = previewItem;
  } else {
    items.push(previewItem);
  }
}

function clearAll() {
  items.length = 0;
}

function getPlainText(): string {
  return items
    .filter((item) => !item.isPreview)
    .map((item) => {
      let line = "";
      if (item.timestamp) line += `[${item.timestamp}] `;
      if (item.userName) line += `${item.userName}: `;
      line += item.text;
      return line;
    })
    .join("\n");
}

// Listen for backend events
if (typeof window !== "undefined") {
  window.addEventListener("backend:transcription", ((e: CustomEvent) => {
    addTranscription(e.detail);
  }) as EventListener);

  window.addEventListener("backend:preview", ((e: CustomEvent) => {
    setPreview(e.detail);
  }) as EventListener);
}

export const transcriptionStore = {
  get items() {
    return items;
  },
  get currentPreview(): TranscriptionItem | null {
    return items.find((item) => item.isPreview) ?? null;
  },
  get transcriptions(): TranscriptionItem[] {
    return items.filter((item) => !item.isPreview);
  },
  addTranscription,
  setPreview,
  clearAll,
  getPlainText,
};