import * as Schema from "effect/Schema";
import * as Record from "effect/Record";
import { useSyncExternalStore } from "react";

export class LocalStorageOperationError extends Schema.TaggedError<LocalStorageOperationError>()(
  "LocalStorageOperationError",
  {
    operation: Schema.Literals(["read", "decode", "encode", "update", "write", "remove", "notify"]),
    storageKey: Schema.String,
    cause: Schema.Defect(),
  },
) {
  override get message(): string {
    return `Failed to ${this.operation} local storage item ${this.storageKey}.`;
  }
}

const fallbackStorage: Storage = (() => {
  const store = new Map<string, string>();
  return {
    clear: () => store.clear(),
    getItem: (_) => store.get(_) ?? null,
    key: (_) => Record.keys(store).at(_) ?? null,
    get length() {
      return store.size;
    },
    removeItem: (_) => store.delete(_),
    setItem: (_, value) => store.set(_, value),
  };
})();

const getStorage = (): Storage =>
  typeof window !== "undefined" ? window.localStorage : fallbackStorage;

const read = (key: string) => {
  try {
    return getStorage().getItem(key);
  } catch (cause) {
    throw new LocalStorageOperationError({ operation: "read", storageKey: key, cause });
  }
};

const decode = <T, E>(key: string, schema: Schema.Codec<T, E>, value: string) => {
  try {
    return Schema.decodeSync(Schema.fromJsonString(schema))(value);
  } catch (cause) {
    throw new LocalStorageOperationError({ operation: "decode", storageKey: key, cause });
  }
};

const encode = <T, E>(key: string, schema: Schema.Codec<T, E>, value: T) => {
  try {
    return Schema.encodeSync(Schema.fromJsonString(schema))(value);
  } catch (cause) {
    throw new LocalStorageOperationError({ operation: "encode", storageKey: key, cause });
  }
};

export const getLocalStorageItem = <T, E>(key: string, schema: Schema.Codec<T, E>): T | null => {
  const item = read(key);
  return item === null ? null : decode(key, schema, item);
};

export const setLocalStorageItem = <T, E>(key: string, value: T, schema: Schema.Codec<T, E>) => {
  const valueToSet = encode(key, schema, value);
  try {
    getStorage().setItem(key, valueToSet);
  } catch (cause) {
    throw new LocalStorageOperationError({ operation: "write", storageKey: key, cause });
  }
};

export const removeLocalStorageItem = (key: string) => {
  try {
    getStorage().removeItem(key);
  } catch (cause) {
    throw new LocalStorageOperationError({ operation: "remove", storageKey: key, cause });
  }
};

const LOCAL_STORAGE_CHANGE_EVENT = "t3code:local_storage_change";

interface LocalStorageChangeDetail {
  key: string;
}

function dispatchLocalStorageChange(key: string) {
  if (typeof window === "undefined") return;
  try {
    window.dispatchEvent(
      new CustomEvent<LocalStorageChangeDetail>(LOCAL_STORAGE_CHANGE_EVENT, {
        detail: { key },
      }),
    );
  } catch (cause) {
    throw new LocalStorageOperationError({ operation: "notify", storageKey: key, cause });
  }
}

function readSerializedValue(key: string): string | null {
  try {
    return read(key);
  } catch (error) {
    console.error("[LOCALSTORAGE] Could not read stored value.", error);
    return null;
  }
}

function decodeOrInitial<T, E>(
  key: string,
  schema: Schema.Codec<T, E>,
  serializedValue: string | null,
  initialValue: T,
): T {
  if (serializedValue === null) {
    return initialValue;
  }
  try {
    return decode(key, schema, serializedValue);
  } catch (error) {
    console.error("[LOCALSTORAGE] Could not decode stored value.", error);
    return initialValue;
  }
}

export function writeLocalStorageValue<T, E>(
  key: string,
  value: T | ((val: T) => T),
  initialValue: T,
  schema: Schema.Codec<T, E>,
): void {
  try {
    let valueToStore: T;
    if (typeof value === "function") {
      // Fall back to the initial value so corrupt storage cannot block later writes.
      let currentValue = initialValue;
      try {
        currentValue = getLocalStorageItem(key, schema) ?? initialValue;
      } catch (error) {
        console.error("[LOCALSTORAGE] Could not read stored value.", error);
      }
      try {
        valueToStore = (value as (val: T) => T)(currentValue);
      } catch (cause) {
        throw new LocalStorageOperationError({
          operation: "update",
          storageKey: key,
          cause,
        });
      }
    } else {
      valueToStore = value;
    }
    if (valueToStore === null) {
      removeLocalStorageItem(key);
    } else {
      setLocalStorageItem(key, valueToStore, schema);
    }
    dispatchLocalStorageChange(key);
  } catch (error) {
    console.error("[LOCALSTORAGE] Could not update stored value.", error);
  }
}

export function useLocalStorage<T, E>(
  key: string,
  initialValue: T,
  schema: Schema.Codec<T, E>,
): [T, (value: T | ((val: T) => T)) => void] {
  const getSnapshot = () => readSerializedValue(key);

  const subscribe = (onStoreChange: () => void) => {
    const handleStorageChange = (event: StorageEvent) => {
      if (event.key === key) {
        onStoreChange();
      }
    };
    const handleLocalChange = (event: CustomEvent<LocalStorageChangeDetail>) => {
      if (event.detail.key === key) {
        onStoreChange();
      }
    };

    window.addEventListener("storage", handleStorageChange);
    window.addEventListener(LOCAL_STORAGE_CHANGE_EVENT, handleLocalChange as EventListener);
    return () => {
      window.removeEventListener("storage", handleStorageChange);
      window.removeEventListener(LOCAL_STORAGE_CHANGE_EVENT, handleLocalChange as EventListener);
    };
  };

  const serializedValue = useSyncExternalStore(subscribe, getSnapshot, getSnapshot);
  const storedValue = decodeOrInitial(key, schema, serializedValue, initialValue);

  const setValue = (value: T | ((val: T) => T)) => {
    writeLocalStorageValue(key, value, initialValue, schema);
  };

  return [storedValue, setValue];
}