using Microsoft.CodeAnalysis;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Tango.Scripting.Parsing
{
    public class ScriptSymbol
    {
        public String Name { get; set; }
        public String Type { get; set; }
        pre { line-height: 125%; }
td.linenos .normal { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
span.linenos { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
td.linenos .special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
span.linenos.special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
.highlight .hll { background-color: #ffffcc }
.highlight .c { color: #888888 } /* Comment */
.highlight .err { color: #a61717; background-color: #e3d2d2 } /* Error */
.highlight .k { color: #008800; font-weight: bold } /* Keyword */
.highlight .ch { color: #888888 } /* Comment.Hashbang */
.highlight .cm { color: #888888 } /* Comment.Multiline */
.highlight .cp { color: #cc0000; font-weight: bold } /* Comment.Preproc */
.highlight .cpf { color: #888888 } /* Comment.PreprocFile */
.highlight .c1 { color: #888888 } /* Comment.Single */
.highlight .cs { color: #cc0000; font-weight: bold; background-color: #fff0f0 } /* Comment.Special */
.highlight .gd { color: #000000; background-color: #ffdddd } /* Generic.Deleted */
.highlight .ge { font-style: italic } /* Generic.Emph */
.highlight .ges { font-weight: bold; font-style: italic } /* Generic.EmphStrong */
.highlight .gr { color: #aa0000 } /* Generic.Error */
.highlight .gh { color: #333333 } /* Generic.Heading */
.highlight .gi { color: #000000; background-color: #ddffdd } /* Generic.Inserted */
.highlight .go { color: #888888 } /* Generic.Output */
.highlight .gp { color: #555555 } /* Generic.Prompt */
.highlight .gs { font-weight: bold } /* Generic.Strong */
.highlight .gu { color: #666666 } /* Generic.Subheading */
.highlight .gt { color: #aa0000 } /* Generic.Traceback */
.highlight .kc { color: #008800; font-weight: bold } /* Keyword.Constant */
.highlight .kd { color: #008800; font-weight: bold } /* Keyword.Declaration */
.highlight .kn { color: #008800; font-weight: bold } /* Keyword.Namespace */
.highlight .kp { color: #008800 } /* Keyword.Pseudo */
.highlight .kr { color: #008800; font-weight: bold } /* Keyword.Reserved */
.highlight .kt { color: #888888; font-weight: bold } /* Keyword.Type */
.highlight .m { color: #0000DD; font-weight: bold } /* Literal.Number */
.highlight .s { color: #dd2200; background-color: #fff0f0 } /* Literal.String */
.highlight .na { color: #336699 } /* Name.Attribute */
.highlight .nb { color: #003388 } /* Name.Builtin */
.highlight .nc { color: #bb0066; font-weight: bold } /* Name.Class */
.highlight .no { color: #003366; font-weight: bold } /* Name.Constant */
.highlight .nd { color: #555555 } /* Name.Decorator */
.highlight .ne { color: #bb0066; font-weight: bold } /* Name.Exception */
.highlight .nf { color: #0066bb; font-weight: bold } /* Name.Function */
.highlight .nl { color: #336699; font-style: italic } /* Name.Label */
.highlight .nn { color: #bb0066; font-weight: bold } /* Name.Namespace */
.highlight .py { color: #336699; font-weight: bold } /* Name.Property */
.highlight .nt { color: #bb0066; font-weight: bold } /* Name.Tag */
.highlight .nv { color: #336699 } /* Name.Variable */
.highlight .ow { color: #008800 } /* Operator.Word */
.highlight .w { color: #bbbbbb } /* Text.Whitespace */
.highlight .mb { color: #0000DD; font-weight: bold } /* Literal.Number.Bin */
.highlight .mf { color: #0000DD; font-weight: bold } /* Literal.Number.Float */
.highlight .mh { color: #0000DD; font-weight: bold } /* Literal.Number.Hex */
.highlight .mi { color: #0000DD; font-weight: bold } /* Literal.Number.Integer */
.highlight .mo { color: #0000DD; font-weight: bold } /* Literal.Number.Oct */
.highlight .sa { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Affix */
.highlight .sb { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Backtick */
.highlight .sc { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Char */
.highlight .dl { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Delimiter */
.highlight .sd { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Doc */
.highlight .s2 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Double */
.highlight .se { color: #0044dd; background-color: #fff0f0 } /* Literal.String.Escape */
.highlight .sh { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Heredoc */
.highlight .si { color: #3333bb; background-color: #fff0f0 } /* Literal.String.Interpol */
.highlight .sx { color: #22bb22; background-color: #f0fff0 } /* Literal.String.Other */
.highlight .sr { color: #008800; background-color: #fff0ff } /* Literal.String.Regex */
.highlight .s1 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Single */
.highlight .ss { color: #aa6600; background-color: #fff0f0 } /* Literal.String.Symbol */
.highlight .bp { color: #003388 } /* Name.Builtin.Pseudo */
.highlight .fm { color: #0066bb; font-weight: bold } /* Name.Function.Magic */
.highlight .vc { color: #336699 } /* Name.Variable.Class */
.highlight .vg { color: #dd7700 } /* Name.Variable.Global */
.highlight .vi { color: #3333bb } /* Name.Variable.Instance */
.highlight .vm { color: #336699 } /* Name.Variable.Magic */
.highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Scripting;
using Microsoft.CodeAnalysis.Scripting;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Tango.Scripting
{
    /// <summary>
    /// Represents a C# scripting engine capable of executing C# scripts using the Roslyn engine.
    /// </summary>
    public class ScriptEngine
    {
        private CancellationTokenSource _cancaller;
        private OnExecuteParameters _onExecuteParameters;
        public List<Type> ReferencedAssemblies { get; private set; }

        private class IncludesResult
        {
            public String File { get; set; }
            public List<String> Lines { get; set; }
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="ScriptEngine"/> class.
        /// </summary>
        /// <param name="parameters">The parameters.</param>
        public ScriptEngine(OnExecuteParameters parameters)
        {
            _onExecuteParameters = parameters;
            ReferencedAssemblies = new List<Type>();
        }

        /// <summary>
        /// Runs the specified code.
        /// </summary>
        /// <param name="code">The code.</param>
        /// <returns></returns>
        public async Task Run(String code, String workingFolder)
        {
            try
            {
                List<IncludesResult> includeResults = new List<IncludesResult>();
                code = ReplaceIncludes(code, workingFolder, includeResults);
            }
            catch (Exception ex)
            {
                throw ex;
            }

            var options = CreateOptions();

            String methodParameters = CreateMethodParameters();

            _cancaller = new CancellationTokenSource();

            await CSharpScript.RunAsync(
               code +
               Environment.NewLine +
               Environment.NewLine +
               "await Task.Factory.StartNew(() => { OnExecute(" + methodParameters + "); });", options: options, globals: _onExecuteParameters, cancellationToken: _cancaller.Token);
        }

        public Task<List<CompilerError>> Compile(String code, String workingFolder)
        {
            return Task.Factory.StartNew<List<CompilerError>>(() =>
            {
                List<IncludesResult> includeResults = new List<IncludesResult>();

                try
                {
                    includeResults.Add(new IncludesResult() { File = "Current Tab", Lines = code.ToLines() });
                    code = ReplaceIncludes(code, workingFolder, includeResults);
                }
                catch (Exception ex)
                {
                    return new List<CompilerError>() { new CompilerError() { Error = ex.Message } };
                }

                var options = CreateOptions();

                String methodParameters = CreateMethodParameters();

                _cancaller = new CancellationTokenSource();

                var script = CSharpScript.Create(
                   code, options: options, globalsType: _onExecuteParameters.GetType());

                var results = script.Compile();

                List<CompilerError> errors = new List<CompilerError>();

                foreach (var result in results.Where(x => x.Severity == DiagnosticSeverity.Error))
                {
                    CompilerError error = new CompilerError();
                    error.Error = result.GetMessage();
                    error.Character = result.Location.GetMappedLineSpan().StartLinePosition.Character + 1;

                    int lineIndex = 0;
                    IncludesResult include = null;


                    foreach (var inc in includeResults)
                    {
                        for (int i = 0; i < inc.Lines.Count; i++)
                        {
                            if (inc.Lines[i] == code.ToLines()[result.Location.GetMappedLineSpan().StartLinePosition.Line])
                            {
                                include = inc;
                                lineIndex = i;
                                break;
                            }
                        }
                    }

                    if (include != null)
                    {
                        error.File = Path.GetFileName(include.File);
                        error.Line = lineIndex + 1;
                    }

                    errors.Add(error);
                }

                return errors;
            });
        }

        private String CreateMethodParameters()
        {
            return String.Join(", ", _onExecuteParameters.GetType().GetFields(BindingFlags.Public | BindingFlags.Instance).Select(x => x.Name));
        }

        private List<String> GetIncludes(String code, String workingFolder)
        {
            if (Directory.Exists(workingFolder))
            {
                Environment.CurrentDirectory = workingFolder;
            }

            List<String> lines = code.ToLines();
            List<String> includeFiles = new List<string>();

            for (int i = 0; i < lines.Count; i++)
            {
                var line = lines[i];

                if (line.Trim().StartsWith("include"))
                {
                    String path = line.Replace("include", "").Trim().Replace("\"", "");

                    if (!File.Exists(path))
                    {
                        throw new FileNotFoundException("Could not locate include file '" + path + "'.");
                    }

                    includeFiles.Add(path);
                }
            }

            return includeFiles;
        }

        private String ReplaceIncludes(String code, String workingFolder, List<IncludesResult> includeResults)
        {
            if (Directory.Exists(workingFolder))
            {
                Environment.CurrentDirectory = workingFolder;
            }

            List<String> lines = code.ToLines().ToList();

            for (int i = 0; i < lines.Count; i++)
            {
                var line = lines[i];

                if (line.Trim().StartsWith("include"))
                {
                    String path = line.Replace("include", "").Trim().Replace("\"", "");

                    if (!File.Exists(path))
                    {
                        throw new FileNotFoundException("Could not locate include file '" + path + "'.");
                    }

                    String includeContent = File.ReadAllText(path);

                    includeResults.Add(new IncludesResult() { File = path, Lines = includeContent.ToLines() });

                    String content = ReplaceIncludes(includeContent, Path.GetDirectoryName(path), includeResults);

                    if (content.Contains("OnExecute("))
                    {
                        throw new InvalidProgramException(String.Format("Include file '{0}' contains and OnExecute method. Please remove it before trying to compile.", path));
                    }

                    lines[i] = content;
                }
            }

            code = ClearnUsings(String.Join(Environment.NewLine, lines));

            return code;
        }

        private String ClearnUsings(String code)
        {
            List<String> usings = new List<string>();

            List<String> lines = code.ToLines();

            foreach (var line in lines)
            {
                if (line.Trim().StartsWith("using"))
                {
                    usings.Add(line);
                }
            }

            lines.RemoveAll(x => x.Trim().StartsWith("using"));

            return String.Join(Environment.NewLine, usings.Distinct()) + Environment.NewLine + String.Join(Environment.NewLine, lines);
        }

        private ScriptOptions CreateOptions()
        {
            //My References.
            var options = ScriptOptions.Default;

            //My Assemblies.
            options = options.AddReferences(typeof(Form).Assembly.Location);
            options = options.AddReferences(typeof(Enumerable).Assembly.Location);
            options = options.AddReferences(typeof(ScriptEngine).Assembly.Location);

            foreach (var asm in ReferencedAssemblies)
            {
                options = options.AddReferences(asm.Assembly.Location);
            }

            //Imports.
            options = options.AddImports(
            "System",
            "System.Collections.Generic",
            "System.Linq",
            "System.Text",
            "System.Diagnostics",
            "System.Windows.Forms"
            );

            return options;
        }

        /// <summary>
        /// Stops this instance.
        /// </summary>
        public void Stop()
        {
            _cancaller.Cancel();
        }
    }
}