using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;
using Firebase.Database.Query;

namespace Firebase.Database.Offline {
    public static class DatabaseExtensions {
        /// <summary>
        ///     Create new instances of the <see cref="RealtimeDatabase{T}" />.
        /// </summary>
        /// <typeparam name="T"> Type of elements. </typeparam>
        /// <param name="filenameModifier"> Custom string which will get appended to the file name. </param>
        /// <param name="elementRoot"> Optional custom root element of received json items. </param>
        /// <param name="streamingOptions"> Realtime streaming options. </param>
        /// <param name="initialPullStrategy"> Specifies what strategy should be used for initial pulling of server data. </param>
        /// <param name="pushChanges">
        ///     Specifies whether changed items should actually be pushed to the server. It this is false,
        ///     then Put / Post / Delete will not affect server data.
        /// </param>
        /// <returns> The <see cref="RealtimeDatabase{T}" />. </returns>
        public static RealtimeDatabase<T> AsRealtimeDatabase<T>(this ChildQuery query, string filenameModifier = "",
            string elementRoot = "", StreamingOptions streamingOptions = StreamingOptions.LatestOnly,
            InitialPullStrategy initialPullStrategy = InitialPullStrategy.MissingOnly, bool pushChanges = true)
            where T : class {
            return new RealtimeDatabase<T>(query, elementRoot, query.Client.Options.OfflineDatabaseFactory,
                filenameModifier, streamingOptions, initialPullStrategy, pushChanges);
        }

        /// <summary>
        ///     Create new instances of the <see cref="RealtimeDatabase{T}" />.
        /// </summary>
        /// <typeparam name="T"> Type of elements. </typeparam>
        /// <typeparam name="TSetHandler"> Type of the custom <see cref="ISetHandler{T}" /> to use. </typeparam>
        /// <param name="filenameModifier"> Custom string which will get appended to the file name. </param>
        /// <param name="elementRoot"> Optional custom root element of received json items. </param>
        /// <param name="streamingOptions"> Realtime streaming options. </param>
        /// <param name="initialPullStrategy"> Specifies what strategy should be used for initial pulling of server data. </param>
        /// <param name="pushChanges">
        ///     Specifies whether changed items should actually be pushed to the server. It this is false,
        ///     then Put / Post / Delete will not affect server data.
        /// </param>
        /// <returns> The <see cref="RealtimeDatabase{T}" />. </returns>
        public static RealtimeDatabase<T> AsRealtimeDatabase<T, TSetHandler>(this ChildQuery query,
            string filenameModifier = "", string elementRoot = "",
            StreamingOptions streamingOptions = StreamingOptions.LatestOnly,
            InitialPullStrategy initialPullStrategy = InitialPullStrategy.MissingOnly, bool pushChanges = true)
            where T : class
            where TSetHandler : ISetHandler<T>, new() {
            return new RealtimeDatabase<T>(query, elementRoot, query.Client.Options.OfflineDatabaseFactory,
                filenameModifier, streamingOptions, initialPullStrategy, pushChanges,
                Activator.CreateInstance<TSetHandler>());
        }

        /// <summary>
        ///     Overwrites existing object with given key leaving any missing properties intact in firebase.
        /// </summary>
        /// <param name="key"> The key. </param>
        /// <param name="obj"> The object to set. </param>
        /// <param name="syncOnline"> Indicates whether the item should be synced online. </param>
        /// <param name="priority">
        ///     The priority. Objects with higher priority will be synced first. Higher number indicates higher
        ///     priority.
        /// </param>
        public static void Patch<T>(this RealtimeDatabase<T> db, string key, T obj, bool syncOnline = true,
            int priority = 1)
            where T : class {
            db.Set(key, obj, syncOnline ? SyncOptions.Patch : SyncOptions.None, priority);
        }

        /// <summary>
        ///     Overwrites existing object with given key.
        /// </summary>
        /// <param name="key"> The key. </param>
        /// <param name="obj"> The object to set. </param>
        /// <param name="syncOnline"> Indicates whether the item should be synced online. </param>
        /// <param name="priority">
        ///     The priority. Objects with higher priority will be synced first. Higher number indicates higher
        ///     priority.
        /// </param>
        public static void Put<T>(this RealtimeDatabase<T> db, string key, T obj, bool syncOnline = true,
            int priority = 1)
            where T : class {
            db.Set(key, obj, syncOnline ? SyncOptions.Put : SyncOptions.None, priority);
        }

        /// <summary>
        ///     Adds a new entity to the Database.
        /// </summary>
        /// <param name="obj"> The object to add.  </param>
        /// <param name="syncOnline"> Indicates whether the item should be synced online. </param>
        /// <param name="priority">
        ///     The priority. Objects with higher priority will be synced first. Higher number indicates higher
        ///     priority.
        /// </param>
        /// <returns> The generated key for this object. </returns>
        public static string Post<T>(this RealtimeDatabase<T> db, T obj, bool syncOnline = true, int priority = 1)
            where T : class {
            var key = FirebaseKeyGenerator.Next();

            db.Set(key, obj, syncOnline ? SyncOptions.Put : SyncOptions.None, priority);

            return key;
        }

        /// <summary>
        ///     Deletes the entity with the given key.
        /// </summary>
        /// <param name="key"> The key. </param>
        /// <param name="syncOnline"> Indicates whether the item should be synced online. </param>
        /// <param name="priority">
        ///     The priority. Objects with higher priority will be synced first. Higher number indicates higher
        ///     priority.
        /// </param>
        public static void Delete<T>(this RealtimeDatabase<T> db, string key, bool syncOnline = true, int priority = 1)
            where T : class {
            db.Set(key, null, syncOnline ? SyncOptions.Put : SyncOptions.None, priority);
        }

        /// <summary>
        ///     Do a Put for a nested property specified by <paramref name="propertyExpression" /> of an object with key
        ///     <paramref name="key" />.
        /// </summary>
        /// <typeparam name="T"> Type of the root elements. </typeparam>
        /// <typeparam name="TProperty"> Type of the property being modified</typeparam>
        /// <param name="db"> Database instance. </param>
        /// <param name="key"> Key of the root element to modify. </param>
        /// <param name="propertyExpression"> Expression on the root element leading to target value to modify. </param>
        /// <param name="value"> Value to put. </param>
        /// <param name="syncOnline"> Indicates whether the item should be synced online. </param>
        /// <param name="priority">
        ///     The priority. Objects with higher priority will be synced first. Higher number indicates higher
        ///     priority.
        /// </param>
        public static void Put<T, TProperty>(this RealtimeDatabase<T> db, string key,
            Expression<Func<T, TProperty>> propertyExpression, TProperty value, bool syncOnline = true,
            int priority = 1)
            where T : class {
            db.Set(key, propertyExpression, value, syncOnline ? SyncOptions.Put : SyncOptions.None, priority);
        }

        /// <summary>
        ///     Do a Patch for a nested property specified by <paramref name="propertyExpression" /> of an object with key
        ///     <paramref name="key" />.
        /// </summary>
        /// <typeparam name="T"> Type of the root elements. </typeparam>
        /// <typeparam name="TProperty"> Type of the property being modified</typeparam>
        /// <param name="db"> Database instance. </param>
        /// <param name="key"> Key of the root element to modify. </param>
        /// <param name="propertyExpression"> Expression on the root element leading to target value to modify. </param>
        /// <param name="value"> Value to patch. </param>
        /// <param name="syncOnline"> Indicates whether the item should be synced online. </param>
        /// <param name="priority">
        ///     The priority. Objects with higher priority will be synced first. Higher number indicates higher
        ///     priority.
        /// </param>
        public static void Patch<T, TProperty>(this RealtimeDatabase<T> db, string key,
            Expression<Func<T, TProperty>> propertyExpression, TProperty value, bool syncOnline = true,
            int priority = 1)
            where T : class {
            db.Set(key, propertyExpression, value, syncOnline ? SyncOptions.Patch : SyncOptions.None, priority);
        }

        /// <summary>
        ///     Delete a nested property specified by <paramref name="propertyExpression" /> of an object with key
        ///     <paramref name="key" />. This basically does a Put with null value.
        /// </summary>
        /// <typeparam name="T"> Type of the root elements. </typeparam>
        /// <typeparam name="TProperty"> Type of the property being modified</typeparam>
        /// <param name="db"> Database instance. </param>
        /// <param name="key"> Key of the root element to modify. </param>
        /// <param name="propertyExpression"> Expression on the root element leading to target value to modify. </param>
        /// <param name="value"> Value to put. </param>
        /// <param name="syncOnline"> Indicates whether the item should be synced online. </param>
        /// <param name="priority">
        ///     The priority. Objects with higher priority will be synced first. Higher number indicates higher
        ///     priority.
        /// </param>
        public static void Delete<T, TProperty>(this RealtimeDatabase<T> db, string key,
            Expression<Func<T, TProperty>> propertyExpression, bool syncOnline = true, int priority = 1)
            where T : class
            where TProperty : class {
            db.Set(key, propertyExpression, null, syncOnline ? SyncOptions.Put : SyncOptions.None, priority);
        }

        /// <summary>
        ///     Post a new entity into the nested dictionary specified by <paramref name="propertyExpression" /> of an object with
        ///     key <paramref name="key" />.
        ///     The key of the new entity is automatically generated.
        /// </summary>
        /// <typeparam name="T"> Type of the root elements. </typeparam>
        /// <typeparam name="TSelector"> Type of the dictionary being modified</typeparam>
        /// <typeparam name="TProperty"> Type of the value within the dictionary being modified</typeparam>
        /// <param name="db"> Database instance. </param>
        /// <param name="key"> Key of the root element to modify. </param>
        /// <param name="propertyExpression"> Expression on the root element leading to target value to modify. </param>
        /// <param name="value"> Value to put. </param>
        /// <param name="syncOnline"> Indicates whether the item should be synced online. </param>
        /// <param name="priority">
        ///     The priority. Objects with higher priority will be synced first. Higher number indicates higher
        ///     priority.
        /// </param>
        public static void Post<T, TSelector, TProperty>(this RealtimeDatabase<T> db, string key,
            Expression<Func<T, TSelector>> propertyExpression, TProperty value, bool syncOnline = true,
            int priority = 1)
            where T : class
            where TSelector : IDictionary<string, TProperty> {
            var nextKey = FirebaseKeyGenerator.Next();
            var expression = Expression.Lambda<Func<T, TProperty>>(
                Expression.Call(propertyExpression.Body,
                    typeof(TSelector).GetRuntimeMethod("get_Item", new[] {typeof(string)}),
                    Expression.Constant(nextKey)), propertyExpression.Parameters);
            db.Set(key, expression, value, syncOnline ? SyncOptions.Put : SyncOptions.None, priority);
        }

        /// <summary>
        ///     Delete an entity with key <paramref name="dictionaryKey" /> in the nested dictionary specified by
        ///     <paramref name="propertyExpression" /> of an object with key <paramref name="key" />.
        ///     The key of the new entity is automatically generated.
        /// </summary>
        /// <typeparam name="T"> Type of the root elements. </typeparam>
        /// <typeparam name="TSelector"> Type of the dictionary being modified</typeparam>
        /// <typeparam name="TProperty"> Type of the value within the dictionary being modified</typeparam>
        /// <param name="db"> Database instance. </param>
        /// <param name="key"> Key of the root element to modify. </param>
        /// <param name="propertyExpression"> Expression on the root element leading to target value to modify. </param>
        /// <param name="dictionaryKey"> Key within the nested dictionary to delete. </param>
        /// <param name="syncOnline"> Indicates whether the item should be synced online. </param>
        /// <param name="priority">
        ///     The priority. Objects with higher priority will be synced first. Higher number indicates higher
        ///     priority.
        /// </param>
        public static void Delete<T, TProperty>(this RealtimeDatabase<T> db, string key,
            Expression<Func<T, IDictionary<string, TProperty>>> propertyExpression, string dictionaryKey,
            bool syncOnline = true, int priority = 1)
            where T : class {
            var expression = Expression.Lambda<Func<T, TProperty>>(
                Expression.Call(propertyExpression.Body,
                    typeof(IDictionary<string, TProperty>).GetRuntimeMethod("get_Item", new[] {typeof(string)}),
                    Expression.Constant(dictionaryKey)), propertyExpression.Parameters);
            db.Set(key, expression, null, syncOnline ? SyncOptions.Put : SyncOptions.None, priority);
        }
    }
}