using System;
using System.Threading;
using System.Threading.Tasks;
using ServiceStack.Text;

namespace ServiceStack.Script
{
    /// <summary>
    /// Parse text contents into a list of string Key/Value pairs and assign to specified identifier
    /// Usage: {{#keyvalues list}}
    ///          Apples  2
    ///          Oranges 3
    ///        {{/keyvalues}}
    ///        {{#keyvalues list ':'}}
    ///          Grape Fruit:  2
    ///          Rock Melon:   3
    ///        {{/keyvalues}}
    /// </summary>
    public class KeyValuesScriptBlock : ScriptBlock
    {
        public override string Name => "keyvalues";
        public override ScriptLanguage Body => ScriptVerbatim.Language;
        
        public override Task WriteAsync(ScriptScopeContext scope, PageBlockFragment block, CancellationToken ct)
        {
            var literal = block.Argument.Span.ParseVarName(out var name);

            var delimiter = " ";
            literal = literal.AdvancePastWhitespace();
            if (literal.Length > 0)
            {
                literal = literal.ParseJsToken(out var token);
                if (!(token is JsLiteral litToken))
                    throw new NotSupportedException($"#keyvalues expected string delimiter but was {token.DebugToken()}");
                delimiter = litToken.Value.ToString();
            }
            
            var strFragment = (PageStringFragment)block.Body[0];
            var strDict = Context.DefaultMethods.parseKeyValues(strFragment.ValueString, delimiter);
            scope.PageResult.Args[name.ToString()] = strDict;

            return TypeConstants.EmptyTask;
        }
    }
}