import _ from 'lodash';
import {
  deleteAuditLog,
  expandObjectIds,
  editAuditLog,
  distributeUpdate,
  newAuditLog,
  distributeNew
} from './utils.js';
import log4js from 'log4js';
import { loadConfig } from '../config.js';
import { jsonToCacheKey } from '../utils.js';
import { redisServer } from './redis.js';

const config = loadConfig();

const logger = log4js.getLogger('Database');
const cacheLogger = log4js.getLogger('Local Cache');
logger.level = config.server.logLevel;
cacheLogger.level = config.server.logLevel;

// Default cache TTL in seconds (similar to previous in-memory cache)
const CACHE_TTL_SECONDS = config.database?.redis?.ttlSeconds || 5;

export const retrieveObjectCache = async ({ model, id, populate = [] }) => {
  const cacheKeyObject = {
    model: model.modelName,
    id: id?.toString()
  };

  const cacheKey = jsonToCacheKey(cacheKeyObject);

  cacheLogger.trace('Retrieving:', cacheKeyObject);

  try {
    const cachedObject = await redisServer.getKey(cacheKey);

    if (cachedObject == null) {
      cacheLogger.trace('Miss:', cacheKeyObject);
      return undefined;
    }

    cacheLogger.trace('Hit:', {
      model: model.modelName,
      id: cacheKeyObject.id
    });

    return cachedObject;
  } catch (err) {
    cacheLogger.error('Error retrieving object from Redis cache:', err);
    return undefined;
  }
};

export const retrieveListCache = async ({
  model,
  populate = [],
  filter = {},
  sort = '',
  order = 'ascend',
  project = {}
}) => {
  const cacheKeyObject = {
    model: model.modelName,
    populate,
    filter,
    sort,
    project,
    order
  };

  const cacheKey = jsonToCacheKey(cacheKeyObject);

  cacheLogger.trace('Retrieving:', cacheKeyObject);

  try {
    const cachedList = await redisServer.getKey(cacheKey);

    if (cachedList != null) {
      cacheLogger.trace('Hit:', {
        ...cacheKeyObject,
        length: cachedList.length
      });
      return cachedList;
    }

    cacheLogger.trace('Miss:', {
      model: model.modelName
    });
    return undefined;
  } catch (err) {
    cacheLogger.error('Error retrieving list from Redis cache:', err);
    return undefined;
  }
};

export const updateObjectCache = async ({ model, id, object }) => {
  const cacheKeyObject = {
    model: model.modelName,
    id: id?.toString()
  };

  const cacheKey = jsonToCacheKey(cacheKeyObject);

  cacheLogger.trace('Updating:', cacheKeyObject);

  try {
    const cachedObject = (await redisServer.getKey(cacheKey)) || {};
    const mergedObject = _.merge(cachedObject, object);

    await redisServer.setKey(cacheKey, mergedObject, CACHE_TTL_SECONDS);
    cacheLogger.trace('Updated:', { ...cacheKeyObject });

    return mergedObject;
  } catch (err) {
    cacheLogger.error('Error updating object in Redis cache:', err);
    // Fallback to returning the provided object if cache fails
    return object;
  }
};

export const deleteObjectCache = async ({ model, id }) => {
  const cacheKeyObject = {
    model: model.modelName,
    id: id?.toString()
  };

  cacheLogger.trace('Deleting:', {
    ...cacheKeyObject
  });

  try {
    // Note: we currently delete the non-populated key; populated variants will expire via TTL.
    const cacheKey = jsonToCacheKey({ ...cacheKeyObject, populate: [] });
    await redisServer.deleteKey(cacheKey);

    cacheLogger.trace('Deleted:', {
      ...cacheKeyObject
    });
  } catch (err) {
    cacheLogger.error('Error deleting object from Redis cache:', err);
  }
};

export const updateListCache = ({
  model,
  objects,
  populate = [],
  filter = {},
  sort = '',
  order = 'ascend',
  project = {}
}) => {
  const cacheKeyObject = {
    model: model.modelName,
    populate,
    filter,
    sort,
    project,
    order
  };

  cacheLogger.trace('Updating:', {
    ...cacheKeyObject,
    length: objects.length
  });

  const cacheKey = jsonToCacheKey(cacheKeyObject);

  return (async () => {
    try {
      await redisServer.setKey(cacheKey, objects, CACHE_TTL_SECONDS);

      cacheLogger.trace('Updated:', {
        ...cacheKeyObject,
        length: objects.length
      });
    } catch (err) {
      cacheLogger.error('Error updating list in Redis cache:', err);
    }

    return objects;
  })();
};

// Reusable function to list objects with aggregation, filtering, search, sorting, and pagination
export const listObjects = async ({
  model,
  populate = [],
  filter = {},
  sort = '',
  order = 'ascend',
  project = {}, // optional: override default projection
  cached = false
}) => {
  try {
    logger.trace('Listing objects:', {
      model,
      populate,
      filter,
      sort,
      order,
      project,
      cached
    });

    if (cached == true) {
      const objectsCache = await retrieveListCache({
        model,
        populate,
        filter,
        sort,
        order,
        project
      });
      if (objectsCache != undefined) {
        return objectsCache;
      }
    }

    // Fix: descend should be -1, ascend should be 1
    const sortOrder = order === 'descend' ? -1 : 1;

    if (!sort || sort === '') {
      sort = 'createdAt';
    }
    // Translate parent._id to parent for Mongoose
    if (filter['parent._id']) {
      filter.parent = filter['parent._id'];
      delete filter['parent._id'];
    }

    // Translate owner._id to owner for Mongoose
    if (filter['owner._id']) {
      filter.owner = filter['owner._id'];
      delete filter['owner._id'];
    }

    // Use find with population and filter
    let query = model.find(filter).sort({ [sort]: sortOrder });

    // Handle populate (array or single value)
    if (populate.length > 0) {
      if (Array.isArray(populate)) {
        for (const pop of populate) {
          query = query.populate(pop);
        }
      } else if (typeof populate === 'string' || typeof populate === 'object') {
        query = query.populate(populate);
      }
    }

    // Handle select (projection)
    if (project && Object.keys(project).length > 0) {
      query = query.select(project);
    }

    query = query.lean();

    const queryResult = await query;

    const finalResult = expandObjectIds(queryResult);

    updateListCache({
      model,
      objects: finalResult,
      populate,
      filter,
      sort,
      order,
      project
    });

    logger.trace('Retreived from database:', {
      model,
      populate,
      filter,
      sort,
      order,
      project,
      cached,
      length: finalResult.length
    });
    return finalResult;
  } catch (error) {
    logger.error('Object list error:', error);
    return { error: error, code: 500 };
  }
};

// Reusable function to get a single object by ID
export const getObject = async ({
  model,
  id,
  populate = [],
  cached = false
}) => {
  try {
    logger.trace('Getting object:', {
      model,
      id,
      populate
    });

    if (cached == true) {
      const cachedObject = await retrieveObjectCache({ model, id, populate });
      if (cachedObject != undefined) {
        return cachedObject;
      }
    }

    let query = model.findById(id).lean();

    // Handle populate (array or single value)
    if (populate) {
      if (Array.isArray(populate)) {
        for (const pop of populate) {
          query = query.populate(pop);
        }
      } else if (typeof populate === 'string' || typeof populate === 'object') {
        query = query.populate(populate);
      }
    }
    const finalResult = await query;

    if (!finalResult) {
      logger.warn('Object not found in database:', {
        model,
        id,
        populate
      });
      return undefined;
    }

    logger.trace('Retreived object from database:', {
      model,
      id,
      populate
    });

    updateObjectCache({
      model: model,
      id: finalResult._id.toString(),
      populate,
      object: finalResult
    });

    return finalResult;
  } catch (error) {
    logger.error('An error retreiving object:', error.message);
    throw error;
    return undefined;
  }
};

// Reusable function to edit an object by ID, with audit logging and distribution
export const editObject = async ({
  model,
  id,
  updateData,
  owner = undefined,
  ownerType = undefined,
  populate = [],
  auditLog = true
}) => {
  try {
    // Determine parentType from model name
    const parentType = model.modelName ? model.modelName : 'unknown';
    // Fetch the and update object
    var query = model.findByIdAndUpdate(id, updateData).lean();
    var newQuery = model.findById(id).lean();

    if (populate) {
      if (Array.isArray(populate)) {
        for (const pop of populate) {
          query = query.populate(pop);
          newQuery = newQuery.populate(pop);
        }
      } else if (typeof populate === 'string' || typeof populate === 'object') {
        query = query.populate(populate);
        newQuery = newQuery.populate(populate);
      }
    }

    const previousObject = await query;
    const newObject = await newQuery;
    if (!previousObject || !newObject) {
      return { error: `${parentType} not found.`, code: 404 };
    }
    const previousExpandedObject = expandObjectIds(previousObject);
    const newExpandedObject = expandObjectIds(newObject);

    if (auditLog == true && owner != undefined && ownerType != undefined) {
      // Audit log before update
      await editAuditLog(
        previousExpandedObject,
        newExpandedObject,
        id,
        parentType,
        owner,
        ownerType
      );
    }

    // Distribute update
    await distributeUpdate(updateData, id, parentType);

    updateObjectCache({
      model: model,
      id: id.toString(),
      object: { ...previousExpandedObject, ...updateData },
      populate
    });

    return { ...previousExpandedObject, ...updateData };
  } catch (error) {
    logger.error('editObject error:', error);
    return { error: error.message, code: 500 };
  }
};

// Reusable function to create a new object
export const newObject = async ({
  model,
  newData,
  owner = null,
  ownerType = undefined
}) => {
  try {
    const parentType = model.modelName ? model.modelName : 'unknown';

    const result = await model.create(newData);
    if (!result || result.length === 0) {
      return { error: 'No object created.', code: 500 };
    }
    const created = result;

    if (owner != undefined && ownerType != undefined) {
      await newAuditLog(newData, created._id, parentType, owner, ownerType);
    }

    await distributeNew(created._id, parentType);

    updateObjectCache({
      model: model,
      id: created._id.toString(),
      object: { _id: created._id, ...newData }
    });

    return created;
  } catch (error) {
    logger.error('newObject error:', error);
    return { error: error.message, code: 500 };
  }
};

// Reusable function to delete an object by ID, with audit logging and distribution
export const deleteObject = async ({
  model,
  id,
  owner = null,
  ownerType = undefined
}) => {
  try {
    const parentType = model.modelName ? model.modelName : 'unknown';
    // Delete the object
    const result = await model.findByIdAndDelete(id);

    if (!result) {
      return { error: `${parentType} not found.`, code: 404 };
    }

    if (owner != undefined && ownerType != undefined) {
      // Audit log the deletion
      await deleteAuditLog(result, id, parentType, owner, ownerType);
    }

    deleteObjectCache({ model: model, id: id.toString() });

    // Distribute the deletion event
    await distributeUpdate({ deleted: true }, id, parentType);

    return { deleted: true, id: id.toString() };
  } catch (error) {
    logger.error('deleteObject error:', error);
    return { error: error.message, code: 500 };
  }
};