using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web.Mvc;

namespace Umbraco.Web
{
    internal static class ModelStateExtensions
    {

        /// <summary>
        /// Merges ModelState that has names matching the prefix
        /// </summary>
        /// <param name="state"></param>
        /// <param name="dictionary"></param>
        /// <param name="prefix"></param>
        public static void Merge(this ModelStateDictionary state, ModelStateDictionary dictionary, string prefix)
        {
            if (dictionary == null)
                return;
            foreach (var keyValuePair in dictionary
                //It can either equal the prefix exactly (model level errors) or start with the prefix. (property level errors)
                .Where(keyValuePair => keyValuePair.Key == prefix || keyValuePair.Key.StartsWith(prefix + ".")))
            {
                state[keyValuePair.Key] = keyValuePair.Value;
            }
        }

        /// <summary>
        /// Checks if there are any model errors on any fields containing the prefix
        /// </summary>
        /// <param name="state"></param>
        /// <param name="prefix"></param>
        /// <returns></returns>
        public static bool IsValid(this ModelStateDictionary state, string prefix)
        {
            return state.Where(v => v.Key.StartsWith(prefix + ".")).All(v => !v.Value.Errors.Any());
        }


        //NOTE: we used this alot in v5 when we had editors in MVC, this was really handy for knockout editors using JS

        ///// <summary>
        ///// Adds an error to the model state that has to do with data validation, this is generally used for JSON responses
        ///// </summary>
        ///// <param name="state"></param>
        ///// <param name="errorMessage"></param>
        //public static void AddDataValidationError(this ModelStateDictionary state, string errorMessage)
        //{
        //    state.AddModelError("DataValidation", errorMessage);
        //}

        /// <summary>
        /// Adds the error to model state correctly for a property so we can use it on the client side.
        /// </summary>
        /// <param name="modelState"></param>
        /// <param name="result"></param>
        /// <param name="propertyAlias"></param>
        internal static void AddPropertyError(this System.Web.Http.ModelBinding.ModelStateDictionary modelState, ValidationResult result, string propertyAlias)
        {
            modelState.AddValidationError(result, "_Properties", propertyAlias);
        }

        internal static void AddValidationError(this System.Web.Http.ModelBinding.ModelStateDictionary modelState, ValidationResult result, string prefix, string owner)
        {
            // if there are assigned member names, we combine the member name with the owner name
            // so that we can try to match it up to a real field. otherwise, we assume that the
            // validation message is for the overall owner.
            var withNames = false;
            foreach (var memberName in result.MemberNames)
            {
                modelState.AddModelError($"{prefix}.{owner}.{memberName}", result.ErrorMessage);
                withNames = true;
            }
            if (!withNames)
                modelState.AddModelError($"{prefix}.{owner}", result.ErrorMessage);
        }

        public static IDictionary<string, object> ToErrorDictionary(this System.Web.Http.ModelBinding.ModelStateDictionary modelState)
        {
            var modelStateError = new Dictionary<string, object>();
            foreach (var keyModelStatePair in modelState)
            {
                var key = keyModelStatePair.Key;
                var errors = keyModelStatePair.Value.Errors;
                if (errors != null && errors.Count > 0)
                {
                    modelStateError.Add(key, errors.Select(error => error.ErrorMessage));
                }
            }
            return modelStateError;
        }

        /// <summary>
        /// Serializes the ModelState to JSON for JavaScript to interrogate the errors
        /// </summary>
        /// <param name="state"></param>
        /// <returns></returns>
        public static JsonResult ToJsonErrors(this ModelStateDictionary state)
        {
            return new JsonResult
                {
                    Data = new
                        {
                            success = state.IsValid.ToString().ToLower(),
                            failureType = "ValidationError",
                            validationErrors = from e in state
                                               where e.Value.Errors.Count > 0
                                               select new
                                                   {
                                                       name = e.Key,
                                                       errors = e.Value.Errors.Select(x => x.ErrorMessage)
                                                   .Concat(
                                                       e.Value.Errors.Where(x => x.Exception != null).Select(x => x.Exception.Message))
                                                   }
                        }
                };
        }

    }
}