// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License - see LICENSE file in this repo.
namespace Microsoft.SqlServer.Utils.Misc.SQLCallStackResolver {
    using System;
    using System.Collections.Generic;
    using System.Diagnostics;
    using System.Diagnostics.Contracts;
    using System.Globalization;
    using System.IO;
    using System.Runtime.InteropServices;
    using System.Text;

    public static class SymSrvHelpers {
        static readonly int processId = Process.GetCurrentProcess().Id;

        /// Wrapper around the symsrv.dll functionality to initialize the symbol load handler for this process.
        private static bool InitSymSrv(string symPath) {
            return SafeNativeMethods.SymInitialize((IntPtr)processId, symPath, false);
        }

        /// Un-initialize the symbol load handler for this process.
        private static bool CleanupSymSrv() {
            return SafeNativeMethods.SymCleanup((IntPtr)processId);
        }

        /// Private method to locate the local path for a matching PDB. Implicitly handles symbol download if needed.
        private static string GetLocalSymbolFolderForModule(string pdbFilename, string pdbGuid, int pdbAge) {
            const int MAX_PATH = 4096;
            StringBuilder outPath = new StringBuilder(MAX_PATH);
            var guid = Guid.Parse(pdbGuid);
            int rawsize = Marshal.SizeOf(guid);
            IntPtr buffer = Marshal.AllocHGlobal(rawsize);
            Marshal.StructureToPtr(guid, buffer, false);
            bool success = SafeNativeMethods.SymFindFileInPath((IntPtr)processId, null, pdbFilename, buffer, pdbAge, 0, 8, outPath, IntPtr.Zero, IntPtr.Zero);
            if (!success) {
                return String.Empty;
            }
            return outPath.ToString();
        }

        /// <summary>
        /// Public method to return local PDB file paths for specified symbols.
        /// </summary>
        public static List<string> GetFolderPathsForPDBs(StackResolver parent, string symPath, List<Symbol> syms) {
            var retval = new List<string>();
            Contract.Requires(null != syms);
            Contract.Requires(null != parent);
            if (!InitSymSrv(symPath)) {
                return retval;
            }
            int progress = 0;
            foreach (var sym in syms) {
                parent.StatusMessage = string.Format(CultureInfo.CurrentCulture, $"Finding local PDB path for {sym.PDBName}");
                var path = GetLocalSymbolFolderForModule(sym.PDBName, sym.PDBGuid, sym.PDBAge);
                if (!string.IsNullOrEmpty(path)) {
                    retval.Add(Path.GetDirectoryName(path));
                    parent.StatusMessage = string.Format(CultureInfo.CurrentCulture, $"Successfully found local PDB at {path}");
                }
                else {
                    parent.StatusMessage = string.Format(CultureInfo.CurrentCulture, $"Could not find local PDB for {sym.PDBName}");
                }

                progress++;
                parent.PercentComplete = (int)((double)progress / syms.Count * 100.0);
            }

            CleanupSymSrv();
            return retval;
        }
    }
}