/* eslint-disable unicorn/prefer-add-event-listener */
/**
 * Persistence plugin for synchronizing signals with storage
 * Supports localStorage, sessionStorage, IndexedDB, and custom adapters
 */

import { isNil, kebabToCamel } from "$core/shared";
import type { Optional } from "$types/helpers";
import type { PluginContext, Scope, Signal, StorageAdapter } from "$types/volt";

const storageAdapterRegistry = new Map<string, StorageAdapter>();

/**
 * Register a custom storage adapter.
 *
 * @param name - Adapter name (used in data-volt-persist="signal:name")
 * @param adapter - Storage adapter implementation
 */
export function registerStorageAdapter(name: string, adapter: StorageAdapter): void {
  storageAdapterRegistry.set(name, adapter);
}

const localStorageAdapter = {
  get(key: string) {
    const value = localStorage.getItem(key);
    if (isNil(value)) return void 0;
    try {
      return JSON.parse(value);
    } catch {
      return value;
    }
  },
  set(key: string, value: unknown) {
    localStorage.setItem(key, JSON.stringify(value));
  },
  remove(key: string) {
    localStorage.removeItem(key);
  },
} satisfies StorageAdapter;

const sessionStorageAdapter = {
  get(key: string) {
    const value = sessionStorage.getItem(key);
    if (isNil(value)) return void 0;
    try {
      return JSON.parse(value);
    } catch {
      return value;
    }
  },
  set(key: string, value: unknown) {
    sessionStorage.setItem(key, JSON.stringify(value));
  },
  remove(key: string) {
    sessionStorage.removeItem(key);
  },
} satisfies StorageAdapter;

const idbAdapter = {
  async get(key: string) {
    const db = await openDB();
    return new Promise((resolve, reject) => {
      const transaction = db.transaction(["voltStore"], "readonly");
      const store = transaction.objectStore("voltStore");
      const request = store.get(key);

      request.onsuccess = () => {
        resolve(request.result?.value);
      };
      request.onerror = () => {
        reject(request.error);
      };
    });
  },
  async set(key: string, value: unknown) {
    const db = await openDB();
    return new Promise<void>((resolve, reject) => {
      const transaction = db.transaction(["voltStore"], "readwrite");
      const store = transaction.objectStore("voltStore");
      const request = store.put({ key, value });

      request.onsuccess = () => {
        resolve();
      };
      request.onerror = () => {
        reject(request.error);
      };
    });
  },
  async remove(key: string) {
    const db = await openDB();
    return new Promise<void>((resolve, reject) => {
      const transaction = db.transaction(["voltStore"], "readwrite");
      const store = transaction.objectStore("voltStore");
      const request = store.delete(key);

      request.onsuccess = () => {
        resolve();
      };
      request.onerror = () => {
        reject(request.error);
      };
    });
  },
} satisfies StorageAdapter;

let dbPromise: Optional<Promise<IDBDatabase>>;

/**
 * Open or create the IndexedDB database ({@link IDBDatabase})
 */
function openDB(): Promise<IDBDatabase> {
  if (dbPromise) return dbPromise;

  dbPromise = new Promise((resolve, reject) => {
    const request = indexedDB.open("voltDB", 1);

    request.onupgradeneeded = () => {
      const db = request.result;
      if (!db.objectStoreNames.contains("voltStore")) {
        db.createObjectStore("voltStore", { keyPath: "key" });
      }
    };

    request.onsuccess = () => {
      resolve(request.result);
    };

    request.onerror = () => {
      reject(request.error);
    };
  });

  return dbPromise;
}

function getStorageAdapter(type: string): Optional<StorageAdapter> {
  switch (type) {
    case "local": {
      return localStorageAdapter;
    }
    case "session": {
      return sessionStorageAdapter;
    }
    case "indexeddb": {
      return idbAdapter;
    }
    default: {
      return storageAdapterRegistry.get(type);
    }
  }
}

function resolveCanonicalPath(scope: Scope, rawPath: string): string {
  const trimmed = rawPath.trim();
  if (!trimmed) {
    return trimmed;
  }

  const parts = trimmed.split(".");
  const resolved: string[] = [];
  let current: unknown = scope;

  for (const part of parts) {
    if (isNil(current) || typeof current !== "object") {
      resolved.push(part);
      current = undefined;
      continue;
    }

    const record = current as Record<string, unknown>;

    if (Object.hasOwn(record, part)) {
      resolved.push(part);
      current = record[part];
      continue;
    }

    const camelCandidate = kebabToCamel(part);
    if (Object.hasOwn(record, camelCandidate)) {
      resolved.push(camelCandidate);
      current = record[camelCandidate];
      continue;
    }

    const lower = part.toLowerCase();
    const matchedKey = Object.keys(record).find((key) => key.toLowerCase() === lower);

    if (matchedKey) {
      resolved.push(matchedKey);
      current = record[matchedKey];
      continue;
    }

    resolved.push(part);
    current = undefined;
  }

  return resolved.join(".");
}

function resolveSignal(ctx: PluginContext, rawPath: string): Optional<{ path: string; signal: Signal<unknown> }> {
  const trimmed = rawPath.trim();
  if (!trimmed) {
    return undefined;
  }

  const canonicalPath = resolveCanonicalPath(ctx.scope, trimmed);
  const candidatePaths = new Set([canonicalPath, trimmed]);

  for (const candidate of candidatePaths) {
    const found = ctx.findSignal(candidate);
    if (found) {
      return { path: candidate, signal: found as Signal<unknown> };
    }
  }
}

function normalizeStorageType(type: string): { key: string; original: string } {
  const original = type.trim();
  const normalized = original.toLowerCase().replaceAll(/[\s_-]/g, "");

  switch (normalized) {
    case "local":
    case "localstorage": {
      return { key: "local", original };
    }
    case "session":
    case "sessionstorage": {
      return { key: "session", original };
    }
    case "indexeddb":
    case "indexed-db": {
      return { key: "indexeddb", original };
    }
    default: {
      return { key: original, original };
    }
  }
}

/**
 * Persist plugin handler.
 * Synchronizes signal values with persistent storage.
 *
 * Syntax: data-volt-persist="signalPath:storageType"
 * Examples:
 *   - data-volt-persist="count:local"
 *   - data-volt-persist="formData:session"
 *   - data-volt-persist="userData:indexeddb"
 *   - data-volt-persist="settings:customAdapter"
 */
export function persistPlugin(ctx: PluginContext, value: string): void {
  const parts = value.split(":");
  if (parts.length !== 2) {
    console.error(`Invalid persist binding: "${value}". Expected format: "signalPath:storageType"`);
    return;
  }

  const [signalPath, storageType] = parts;
  const resolvedSignal = resolveSignal(ctx, signalPath);

  if (!resolvedSignal) {
    console.error(`Signal "${signalPath.trim()}" not found in scope for persist binding`);
    return;
  }

  const { key: adapterKey, original } = normalizeStorageType(storageType);
  const adapter = getStorageAdapter(adapterKey) ?? (adapterKey === original ? undefined : getStorageAdapter(original));
  if (!adapter) {
    console.error(`Unknown storage type: "${storageType.trim()}"`);
    return;
  }

  const storageKey = `volt:${resolvedSignal.path}`;

  try {
    const result = adapter.get(storageKey);
    if (result instanceof Promise) {
      result.then((storedValue) => {
        if (storedValue !== undefined) {
          resolvedSignal.signal.set(storedValue);
        }
      }).catch((error) => {
        console.error(`Failed to load persisted value for "${signalPath.trim()}":`, error);
      });
    } else if (result !== undefined) {
      resolvedSignal.signal.set(result);
    }
  } catch (error) {
    console.error(`Failed to load persisted value for "${signalPath.trim()}":`, error);
  }

  const unsubscribe = resolvedSignal.signal.subscribe((newValue) => {
    try {
      const result = adapter.set(storageKey, newValue);
      if (result instanceof Promise) {
        result.catch((error) => {
          console.error(`Failed to persist value for "${signalPath.trim()}":`, error);
        });
      }
    } catch (error) {
      console.error(`Failed to persist value for "${signalPath.trim()}":`, error);
    }
  });

  ctx.addCleanup(unsubscribe);
}