/*
    Copyright (C) 2012-2014 de4dot@gmail.com

    Permission is hereby granted, free of charge, to any person obtaining
    a copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
    IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
    CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
    TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

﻿using System.Collections.Generic;
using System.Text;
using dnlib.Threading;

namespace dnlib.DotNet.Emit {
	/// <summary>
	/// Converts instructions to strings
	/// </summary>
	public static class InstructionPrinter {
		/// <summary>
		/// Converts an instruction to a string
		/// </summary>
		/// <param name="instr">The instruction</param>
		/// <returns>The result</returns>
		public static string ToString(Instruction instr) {
			if (instr == null)
				return string.Empty;

			var sb = new StringBuilder();

			sb.Append(string.Format("IL_{0:X4}: ", instr.Offset));
			sb.Append(instr.OpCode.Name);
			AddOperandString(sb, instr, " ");

			return sb.ToString();
		}

		/// <summary>
		/// Gets the instruction's operand as a string
		/// </summary>
		/// <param name="instr">The instruction</param>
		/// <returns>The operand as a string</returns>
		public static string GetOperandString(Instruction instr) {
			var sb = new StringBuilder();
			AddOperandString(sb, instr, string.Empty);
			return sb.ToString();
		}

		/// <summary>
		/// Add an instruction's operand to <paramref name="sb"/>
		/// </summary>
		/// <param name="sb">Place result here</param>
		/// <param name="instr">The instruction</param>
		public static void AddOperandString(StringBuilder sb, Instruction instr) {
			AddOperandString(sb, instr, string.Empty);
		}

		/// <summary>
		/// Add an instruction's operand to <paramref name="sb"/>
		/// </summary>
		/// <param name="sb">Place result here</param>
		/// <param name="instr">The instruction</param>
		/// <param name="extra">A string that will be added before the operand, if there's
		/// an operand.</param>
		public static void AddOperandString(StringBuilder sb, Instruction instr, string extra) {
			var op = instr.Operand;
			switch (instr.OpCode.OperandType) {
			case OperandType.InlineBrTarget:
			case OperandType.ShortInlineBrTarget:
				sb.Append(extra);
				AddInstructionTarget(sb, op as Instruction);
				break;

			case OperandType.InlineField:
			case OperandType.InlineMethod:
			case OperandType.InlineTok:
			case OperandType.InlineType:
				sb.Append(extra);
				if (op is IFullName)
					sb.Append((op as IFullName).FullName);
				else if (op != null)
					sb.Append(op.ToString());
				else
					sb.Append("null");
				break;

			case OperandType.InlineI:
			case OperandType.InlineI8:
			case OperandType.InlineR:
			case OperandType.ShortInlineI:
			case OperandType.ShortInlineR:
				sb.Append(string.Format("{0}{1}", extra, op));
				break;

			case OperandType.InlineSig:
				sb.Append(extra);
				sb.Append(FullNameCreator.MethodFullName(null, (UTF8String)null, op as MethodSig));
				break;

			case OperandType.InlineString:
				sb.Append(extra);
				EscapeString(sb, op as string, true);
				break;

			case OperandType.InlineSwitch:
				var targets = op as IList<Instruction>;
				if (targets == null)
					sb.Append("null");
				else {
					sb.Append('(');
					for (int i = 0; i < targets.Count; i++) {
						if (i != 0)
							sb.Append(',');
						AddInstructionTarget(sb, targets.Get(i, null));
					}
					sb.Append(')');
				}
				break;

			case OperandType.InlineVar:
			case OperandType.ShortInlineVar:
				sb.Append(extra);
				if (op == null)
					sb.Append("null");
				else
					sb.Append(op.ToString());
				break;

			case OperandType.InlineNone:
			case OperandType.InlinePhi:
			default:
				break;
			}
		}

		static void AddInstructionTarget(StringBuilder sb, Instruction targetInstr) {
			if (targetInstr == null)
				sb.Append("null");
			else
				sb.Append(string.Format("IL_{0:X4}", targetInstr.Offset));
		}

		static void EscapeString(StringBuilder sb, string s, bool addQuotes) {
			if (s == null) {
				sb.Append("null");
				return;
			}

			if (addQuotes)
				sb.Append('"');

			foreach (var c in s) {
				if ((int)c < 0x20) {
					switch (c) {
					case '\a': sb.Append(@"\a"); break;
					case '\b': sb.Append(@"\b"); break;
					case '\f': sb.Append(@"\f"); break;
					case '\n': sb.Append(@"\n"); break;
					case '\r': sb.Append(@"\r"); break;
					case '\t': sb.Append(@"\t"); break;
					case '\v': sb.Append(@"\v"); break;
					default:
						sb.Append(string.Format(@"\u{0:X4}", (int)c));
						break;
					}
				}
				else if (c == '\\' || c == '"') {
					sb.Append('\\');
					sb.Append(c);
				}
				else
					sb.Append(c);
			}

			if (addQuotes)
				sb.Append('"');
		}
	}
}
