//
// Copyright (c) 2010-2024 Antmicro
//
// This file is licensed under the MIT License.
// Full license text is available in 'licenses/MIT.txt'.
//
using System;
using System.Reflection;
using System.Text;
using System.Linq;
using System.IO;
using System.Collections.Generic;

using Antmicro.Renode.Exceptions;
using Antmicro.Renode.Utilities;

namespace Antmicro.Renode.Peripherals.CPU
{
    public static class RiscvOpcodesExtensions
    {
        public static void EnableRiscvOpcodesCounting(this BaseRiscV cpu, ReadFilePath file)
        {
            foreach(var x in RiscVOpcodesParser.Parse(file))
            {
                cpu.InstallOpcodeCounterPattern(x.Item1, x.Item2);
            }

            cpu.EnableOpcodesCounting = true;
        }

        public static void EnableRiscvOpcodesCounting(this BaseRiscV cpu)
        {
            foreach(var set in cpu.ArchitectureSets)
            {
                cpu.EnableRiscvOpcodesCounting(set);
            }
        }
        
        public static void EnableRiscvOpcodesCountingFromEmbeddedResource(this BaseRiscV cpu, string name)
        {
            var assembly = Assembly.GetExecutingAssembly();
            if(!assembly.TryFromResourceToTemporaryFile($"{ResourceNamePrefix}.{name}", out var file))
            {
                var availableResources = string.Join("\n", cpu.GetRiscvOpcodesEmbeddedResourceNames());
                throw new RecoverableException($"Couldn't load the {name} resource - please choose from:\n{availableResources}");
            }
            cpu.EnableRiscvOpcodesCounting(file);
        }
        
        public static IEnumerable<string> GetRiscvOpcodesEmbeddedResourceNames(this BaseRiscV cpu)
        {
            var assembly = Assembly.GetExecutingAssembly();
            return assembly.GetManifestResourceNames().Where(x => x.StartsWith(ResourceNamePrefix)).Select(x => x.Substring(ResourceNamePrefix.Length + 1));
        }
        
        public static void EnableRiscvOpcodesCounting(this BaseRiscV cpu, BaseRiscV.InstructionSet instructionSet)
        {
            Dictionary<BaseRiscV.InstructionSet, IEnumerable<string>> map = null;
            if(cpu.Architecture == "riscv")
            {
                map = opcodesFilesMap32;
            }
            else if(cpu.Architecture == "riscv64")
            {
                map = opcodesFilesMap64;
            }
            else
            {
                throw new RecoverableException($"Unsupported CPU type: {cpu.GetType()}");
            }
            
            if(!map.TryGetValue(instructionSet, out var resourceNames))
            {
                throw new RecoverableException($"Opcodes counting for the {instructionSet} extension not supported");
            }
            
            foreach(var resourceName in resourceNames)
            {
                var assembly = Assembly.GetExecutingAssembly();
                if(!assembly.TryFromResourceToTemporaryFile(resourceName, out var file))
                {
                    throw new RecoverableException($"Couldn't load the {resourceName} resource - this might indicate a broken compilation");
                }

                cpu.EnableRiscvOpcodesCounting(file);
            }
        }
        
        private const string ResourceNamePrefix = "Antmicro.Renode.Cores.RiscV.Opcodes";

        private static readonly Dictionary<BaseRiscV.InstructionSet, IEnumerable<string>> opcodesFilesMap32 = new Dictionary<BaseRiscV.InstructionSet, IEnumerable<string>>
        {
            { BaseRiscV.InstructionSet.I, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.System",  "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32i" } },
            { BaseRiscV.InstructionSet.M, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32m" } },
            { BaseRiscV.InstructionSet.A, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32a" } },
            { BaseRiscV.InstructionSet.F, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32f" } },
            { BaseRiscV.InstructionSet.D, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32d", "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32d-zfh" } },
            { BaseRiscV.InstructionSet.C, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rvc", "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32c" } },
            { BaseRiscV.InstructionSet.V, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rvv", "Antmicro.Renode.Cores.RiscV.Opcodes.Rvv-pseudo" } },
            { BaseRiscV.InstructionSet.S, Array.Empty<string>() },
            { BaseRiscV.InstructionSet.U, Array.Empty<string>() },
        };
        
        private static readonly Dictionary<BaseRiscV.InstructionSet, IEnumerable<string>> opcodesFilesMap64 = new Dictionary<BaseRiscV.InstructionSet, IEnumerable<string>>
        {
            { BaseRiscV.InstructionSet.I, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.System", "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32i", "Antmicro.Renode.Cores.RiscV.Opcodes.Rv64i" } },
            { BaseRiscV.InstructionSet.M, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32m", "Antmicro.Renode.Cores.RiscV.Opcodes.Rv64m" } },
            { BaseRiscV.InstructionSet.A, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32a", "Antmicro.Renode.Cores.RiscV.Opcodes.Rv64a" } },
            { BaseRiscV.InstructionSet.F, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32f", "Antmicro.Renode.Cores.RiscV.Opcodes.Rv64f" } },
            { BaseRiscV.InstructionSet.D, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rv32d", "Antmicro.Renode.Cores.RiscV.Opcodes.Rv64d" } },
            { BaseRiscV.InstructionSet.C, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rvc", "Antmicro.Renode.Cores.RiscV.Opcodes.Rv64c" } },
            { BaseRiscV.InstructionSet.V, new [] { "Antmicro.Renode.Cores.RiscV.Opcodes.Rvv", "Antmicro.Renode.Cores.RiscV.Opcodes.Rvv-pseudo" } },
            { BaseRiscV.InstructionSet.S, Array.Empty<string>() },
            { BaseRiscV.InstructionSet.U, Array.Empty<string>() },
        };
    }
    
    public static class RiscVOpcodesParser
    {
        public static IEnumerable<Tuple<string, string>> Parse(string file)
        {
            var result = new List<Tuple<string, string>>();
            
            try
            {
                foreach(var line in File.ReadLines(file).Select(x => RemoveComments(x)))
                {
                    if(line.Length == 0)
                    {
                        continue;
                    }
                    
                    result.Add(ParseLine(line));
                }
            }
            catch(IOException e)
            {
                throw new RecoverableException($"There was na error when parsing RISC-V opcodes from {file}:\n{e.Message}");
            }
            
            return result;
        }

        private static string RemoveComments(string line)
        {
            var pos = line.IndexOf("#");
            if(pos != -1)
            {
                line = line.Remove(pos);
            }
            return line.Trim();
        }

        private static Tuple<string, string> ParseLine(string lineContent, int opcodeLength = 32)
        {
            var pattern = new StringBuilder(new String('_', opcodeLength));
            
            var elems = lineContent.Split(LineSplitPatterns, StringSplitOptions.RemoveEmptyEntries);
            if(elems.Length < 2)
            {
                throw new RecoverableException($"Couldn't split line: {lineContent}");
            }

            var instructionName = elems[0];
            foreach(var elem in elems.Skip(1))
            {
                var parts = elem.Split(PartSplitPatterns);
                if(parts.Length != 2)
                {
                    // let's ignore all non-explicit ranges
                    continue;
                }

                if(!BitsRange.TryParse(parts[0], out var range))
                {
                    throw new RecoverableException($"Couldn't parse range: {parts[0]}");
                }

                if(!BitsValue.TryParse(parts[1], out var value))
                {
                    throw new RecoverableException($"Couldn't parse value: {parts[1]}");
                }

                if(!range.TryApply(pattern, value))
                {
                    throw new RecoverableException($"Couldn't apply value {value} in range {range} to pattern {pattern}");
                }
            }

            return Tuple.Create(instructionName, pattern.ToString());
        }
        
        private static readonly char[] PartSplitPatterns = new [] { '=' };
        private static readonly char[] LineSplitPatterns = new [] { ' ', '\t' };
        private static readonly string[] BitRangeSplitPatterns = new [] { ".." };

        private struct BitsValue
        {
            public static bool TryParse(string s, out BitsValue bv)
            {
                if(s == "ignore")
                {
                    bv = new BitsValue(-1, ignored: true);
                    return true;
                }
                
                if(SmartParser.Instance.TryParse(s, typeof(int), out var result))
                {
                    bv = new BitsValue((int)result);
                    return true;
                }
                
                bv = new BitsValue(-1);
                return false;
            }

            public bool TryGetBinaryPattern(int length, out string result)
            {
                if(Ignored)
                {
                    result = new String('x', length);
                    return true;
                }
                
                result = Convert.ToString(Value, 2);
                if(result.Length > length)
                {
                    return false;
                }

                result = result.PadLeft(length, '0');
                return true;
            }

            private BitsValue(int value, bool ignored = false)
            {
                Value = value;
                Ignored = ignored;
            }

            public int Value { get; }
            public bool Ignored { get; }

            public override string ToString()
            {
                return $"[BitsValue: {Value}, ignored: {Ignored}]";
            }
        }

        private struct BitsRange
        {
            // There are two expected formats:
            // * hi..lo (hi, lo being integers)
            // * bit (bit being an integer; treated as bit..bit)
            public static bool TryParse(string s, out BitsRange br)
            {
                var x = s.Split(BitRangeSplitPatterns, StringSplitOptions.None);
                if(x.Length == 1)
                {
                    if(int.TryParse(x[0], out var bit))
                    {
                        br = new BitsRange(bit, bit);
                        return true;
                    }
                }
                else if(x.Length == 2)
                {
                    if(int.TryParse(x[0], out var upperBit)
                        && int.TryParse(x[1], out var lowerBit))
                    {
                        br = new BitsRange(lowerBit, upperBit);
                        return true;
                    }
                }

                br = new BitsRange(-1, -1);
                return false;
            }

            public bool TryApply(StringBuilder s, BitsValue v)
            {
                if(!v.TryGetBinaryPattern(this.Width, out var pattern))
                {
                    return false;
                }

                if(Higher >= s.Length)
                {
                    return false;
                }

                var pIdx = pattern.Length - 1;
                var sIdx = s.Length - Lower - 1;
                
                for(var i = Lower; i <= Higher; i++, pIdx--, sIdx--)
                {
                    if(s[sIdx] == '1' || s[sIdx] == '0')
                    {
                        return false;
                    }

                    s[sIdx] = pattern[pIdx];
                }
                
                return true;
            }
            
            public override string ToString()
            {
                return $"[BitsRange: {Lower} - {Higher}]";
            }

            private BitsRange(int lower, int higher)
            {
                Lower = lower;
                Higher = higher;
            }

            public int Lower { get; }
            public int Higher { get; }

            public int Width => Higher - Lower + 1;
        }
    }
}