﻿// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#nullable disable

using System.Linq;
using System.Xml.Linq;
using Microsoft.CodeAnalysis;
using Roslyn.Utilities;

namespace Microsoft.VisualStudio.LanguageServices.Implementation.SolutionExplorer
{
    internal static class RuleSetDocumentExtensions
    {
        internal static void SetSeverity(this XDocument ruleSet, string analyzerId, string ruleId, ReportDiagnostic value)
        {
            var newAction = ConvertReportDiagnosticToAction(value);

            var rules = FindOrCreateRulesElement(ruleSet, analyzerId);
            var rule = FindOrCreateRuleElement(rules, ruleId);

            if (value == ReportDiagnostic.Default)
            {
                // If the new severity is 'Default' we just delete the entry for the rule from the ruleset file.
                // In the absence of an explicit entry in the ruleset file, the rule reverts back to its 'Default'
                // severity (so far as the 'current' ruleset file is concerned - the rule's effective severity
                // could still be decided by other factors such as project settings or a base ruleset file).
                rule.Remove();
            }
            else
            {
                rule.Attribute("Action").Value = newAction;
            }

            var allMatchingRules = ruleSet.Root
                                       .Descendants("Rule")
                                       .Where(r => r.Attribute("Id").Value.Equals(ruleId))
                                       .ToList();

            foreach (var matchingRule in allMatchingRules)
            {
                if (value == ReportDiagnostic.Default)
                {
                    // If the new severity is 'Default' we just delete the entry for the rule from the ruleset file.
                    // In the absence of an explicit entry in the ruleset file, the rule reverts back to its 'Default'
                    // severity (so far as the 'current' ruleset file is concerned - the rule's effective severity
                    // could still be decided by other factors such as project settings or a base ruleset file).
                    matchingRule.Remove();
                }
                else
                {
                    matchingRule.Attribute("Action").Value = newAction;
                }
            }
        }

        private static string ConvertReportDiagnosticToAction(ReportDiagnostic value)
        {
            switch (value)
            {
                case ReportDiagnostic.Default:
                    return "Default";
                case ReportDiagnostic.Error:
                    return "Error";
                case ReportDiagnostic.Warn:
                    return "Warning";
                case ReportDiagnostic.Info:
                    return "Info";
                case ReportDiagnostic.Hidden:
                    return "Hidden";
                case ReportDiagnostic.Suppress:
                    return "None";
                default:
                    throw ExceptionUtilities.Unreachable;
            }
        }

        private static XElement FindOrCreateRuleElement(XElement rules, string id)
        {
            var ruleElement = rules
                              .Elements("Rule")
                              .FirstOrDefault(r => r.Attribute("Id").Value.Equals(id));

            if (ruleElement == null)
            {
                ruleElement = new XElement("Rule",
                                    new XAttribute("Id", id),
                                    new XAttribute("Action", "Warning"));
                rules.Add(ruleElement);
            }

            return ruleElement;
        }

        private static XElement FindOrCreateRulesElement(XDocument ruleSetDocument, string analyzerID)
        {
            var rulesElement = ruleSetDocument.Root
                               .Elements("Rules")
                               .FirstOrDefault(r => r.Attribute("AnalyzerId").Value.Equals(analyzerID));

            if (rulesElement == null)
            {
                rulesElement = new XElement("Rules",
                                    new XAttribute("AnalyzerId", analyzerID),
                                    new XAttribute("RuleNamespace", analyzerID));
                ruleSetDocument.Root.Add(rulesElement);
            }

            return rulesElement;
        }
    }
}
