//-----------------------------------------------------------------------------
//
// Copyright (C) Microsoft Corporation.  All Rights Reserved.
//
//-----------------------------------------------------------------------------
using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;
using System.IO;
using System.Text;
using System.Diagnostics;
using Microsoft.Contracts;
using Microsoft.Boogie.AbstractInterpretation;
using Microsoft.Boogie.Simplify;
using Microsoft.Boogie.VCExprAST;
using Microsoft.Boogie.TypeErasure;

namespace Microsoft.Boogie.Simplify
{
  public abstract class LogProverInterface : ProverInterface
  {
    [NotDelayed]
    protected LogProverInterface(ProverOptions! options,
        string! openComment, string! closeComment,
        string! openActivity, string! closeActivity,
        VCExpressionGenerator! gen)
      ensures this.gen == gen;
    {
      if (options.SeparateLogFiles) {
        this.commonPrefix = new List<string!> ();
      } else {
        this.logFileWriter = options.OpenLog(null);
      }
      this.openCommentString = openComment;
      this.closeCommentString = closeComment;
      this.openActivityString = openActivity;
      this.closeActivityString = closeActivity;
      this.gen = gen;
      this.options = options;
      base();

      if (CommandLineOptions.Clo.ShowEnv != CommandLineOptions.ShowEnvironment.Never) {
        // Emit version comment in the log
        LogCommonComment(CommandLineOptions.Clo.Version);
        LogCommonComment(CommandLineOptions.Clo.Environment);
      }
    }
    
    [StrictReadonly][Additive]
    protected readonly VCExpressionGenerator! gen;

    private TextWriter/*?*/ logFileWriter;
    [Microsoft.Contracts.StrictReadonly]
    private readonly string! openCommentString;
    [Microsoft.Contracts.StrictReadonly]
    private readonly string! closeCommentString;
    [Microsoft.Contracts.StrictReadonly]
    private readonly string! openActivityString;
    [Microsoft.Contracts.StrictReadonly]
    private readonly string! closeActivityString;
    [Microsoft.Contracts.StrictReadonly]
    protected readonly ProverOptions! options;
    [Microsoft.Contracts.StrictReadonly]
    private readonly List<string!>/*?*/ commonPrefix;

    public void LogActivity(string! s) {
      LogActivity(s, false);
    }

    public void LogCommon(string! s) {
      LogActivity(s, true);
    }

    private void LogActivity(string! s, bool common) {
      assume common || !options.SeparateLogFiles || logFileWriter != null;
      if (logFileWriter != null) {
        logFileWriter.Write(openActivityString);
        logFileWriter.Write(s);
        logFileWriter.WriteLine(closeActivityString);
        logFileWriter.Flush();
      }
      if (common && commonPrefix != null) {
        commonPrefix.Add(openActivityString + s + closeActivityString);
      }
    }

    /// <summary>
    /// Write "comment" to logfile, if any, formatted as a comment for the theorem prover at hand.
    /// Assumes that "comment" does not contain any characters that would prematurely terminate
    /// the comment (like, perhaps, a newline or "*/").
    /// </summary>    
    public override void LogComment(string! comment)
    {
      LogComment(comment, false);
    }

    public void LogCommonComment(string! comment)
    {
      LogComment(comment, true);
    }

    private void LogComment(string! comment, bool common)
    {
      assume common || !options.SeparateLogFiles || logFileWriter != null;
      if (logFileWriter != null) {
        logFileWriter.Write(openCommentString);
        logFileWriter.Write(comment);
        logFileWriter.WriteLine(closeCommentString);
        logFileWriter.Flush();
      }
      if (common && commonPrefix != null) {
        commonPrefix.Add(openCommentString + comment + closeCommentString);
      }
    }

    public virtual void NewProblem(string! descName)
    {
      if (commonPrefix != null) {
        if (logFileWriter != null) {
          logFileWriter.Close();
        }
        logFileWriter = options.OpenLog(descName);
        if (logFileWriter != null) {
          foreach (string! s in commonPrefix)
            logFileWriter.WriteLine(s);
        }
      }
      LogComment("Proof obligation: " + descName);
    }

    public override void Close() {
      if (logFileWriter != null) {
        logFileWriter.Close();
        logFileWriter = null;
      }
    }

    public override VCExpressionGenerator! VCExprGen
    {
      get { return this.gen; }
    }
  }
  
  // -----------------------------------------------------------------------------------------------
  // -----------------------------------------------------------------------------------------------
  // -----------------------------------------------------------------------------------------------

  public abstract class ProcessTheoremProver : LogProverInterface
  {
    private static string! _proverPath;

    protected AxiomVCExprTranslator! vcExprTranslator { get {
      return (AxiomVCExprTranslator!)ctx.exprTranslator;
    } }

    protected abstract AxiomVCExprTranslator! SpawnVCExprTranslator();

    protected void FeedNewAxiomsDecls2Prover() throws UnexpectedProverOutputException; {
      if (thmProver == null)
        return;
      foreach (string! s in vcExprTranslator.NewTypeDecls) {
        LogCommon(s);
        thmProver.Feed(s, 0);
      }
      foreach (string! s in vcExprTranslator.NewAxioms) {
        LogBgPush(s);
        thmProver.AddAxioms(s);
      }
    }

    protected static string! CodebaseString() {
      return Path.GetDirectoryName((!)System.Reflection.Assembly.GetExecutingAssembly().Location);
    }

    private static IDictionary<string!, string!>! BackgroundPredicates =
      new Dictionary<string!, string!> ();

    protected static string! GetBackgroundPredicate(string! filename) {
      string res;
      if (!BackgroundPredicates.TryGetValue(filename, out res)) {
        // do we have to lock/synchronise anything?
        string univBackPredPath = Path.Combine(CodebaseString(), filename);
        using (StreamReader reader = new System.IO.StreamReader(univBackPredPath))
        {
          res = reader.ReadToEnd();
        }
        BackgroundPredicates.Add(filename, res);
      }
      return (!)res;
    }

    static void InitializeGlobalInformation(string! proverExe)
      ensures _proverPath != null;
      //throws ProverException, System.IO.FileNotFoundException;
    {
      if (_proverPath == null) {
        // Initialize '_proverPath'
        _proverPath = Path.Combine(CodebaseString(), proverExe);
        string firstTry = _proverPath;
        for (int minorVersion = 5; true; minorVersion--) {
          if (File.Exists(_proverPath)) {
            return;  // all seems good
          }
          if (minorVersion < 0) {
            throw new ProverException("Cannot find executable: " + firstTry);
          }
          _proverPath = Path.Combine(@"c:\Program Files\Microsoft Research\Z3-2." + minorVersion + "\\bin", proverExe);
        }
      }
    }

    [Rep] protected internal ProverProcess thmProver;
    bool currentProverHasBeenABadBoy = false;
    // invariant currentProverHasBeenABadBoy ==> thmProver != null;
    protected int restarts = 0;
    protected DeclFreeProverContext! ctx;
    protected string! BackgroundPredFilename;
    protected ConsoleCancelEventHandler? cancelEvent;
    
    [NotDelayed]
    public ProcessTheoremProver(ProverOptions! options, VCExpressionGenerator! gen, DeclFreeProverContext! ctx,
                                string! proverExe, string! backgroundPred)
      throws UnexpectedProverOutputException;
    {
      BackgroundPredFilename = backgroundPred;
      InitializeGlobalInformation(proverExe);
      this.ctx = ctx;
      base(options, "; ", "", "", "", gen);
      
      // ensure that a VCExprTranslator is available
      // if none exists so far, we have to create a new one
      // from scratch and feed the axioms to it
      if (ctx.exprTranslator == null) {
        AxiomVCExprTranslator tl = SpawnVCExprTranslator();
        ctx.exprTranslator = tl;
        tl.AddAxiom(tl.translate(ctx.Axioms, -1));
        // we clear the lists with new axioms and declarations;
        // they are not needed at this point
        List<string!> x = tl.NewAxioms;
        x = x;  // make the compiler happy: somebody uses the value of x
        x = tl.NewTypeDecls;
      }
    }

    /// <summary>
    /// MSchaef: Allows to Push a VCExpression as Axiom on the prover stack (beta)
    /// </summary>
    public override void PushVCExpression(VCExpr! vc) 
    {
      vcExprTranslator.AddAxiom( vcExprTranslator.translate(vc,1) ); 
    }

    [NoDefaultContract]  // important, since we have no idea what state the object might be in when this handler is invoked
    void ControlCHandler(object o, ConsoleCancelEventArgs a)
    {
      if (thmProver != null) {
        thmProver.Kill();
      }
    }

    public override void Close() {
      if (cancelEvent != null) {
        Console.CancelKeyPress -= cancelEvent;
        cancelEvent = null;
      }
      if (thmProver != null) {
        expose (this) {
          thmProver.Close();
          thmProver = null;
          currentProverHasBeenABadBoy = false;
        }
      }
      base.Close();
    }

    private UnexpectedProverOutputException proverException;

    public override void BeginCheck(string! descriptiveName, VCExpr! vc, ErrorHandler! handler)
    {
      this.NewProblem(descriptiveName);
      this.proverException = null;

      try {
        this.ResurrectProver();
        
        string vcString = vcExprTranslator.translate(vc, 1);

        Helpers.ExtraTraceInformation("Sending data to theorem prover");

        FeedNewAxiomsDecls2Prover();
        string! prelude = ctx.GetProverCommands(false);
        vcString = prelude + vcString;
        LogActivity(vcString);

        assert thmProver != null;
        thmProver.BeginCheck(descriptiveName, vcString);

        if (CommandLineOptions.Clo.RestartProverPerVC) {
          LogComment("Will restart the prover due to /restartProver option");
          currentProverHasBeenABadBoy = true;
        }
      } catch (UnexpectedProverOutputException e) {
        proverException = e;
      }
    }

    public override Outcome CheckOutcome(ErrorHandler! handler)
      throws UnexpectedProverOutputException;
    {
      if (this.thmProver == null) {
        return Outcome.Undetermined;
      }

      if (proverException == null) {
        try {
          ProverProcess.ProverOutcome result = thmProver.CheckOutcome(handler);

          if (options.ForceLogStatus) {
            switch (result) {
            case ProverProcess.ProverOutcome.Valid:
              LogActivity("DBG_WAS_VALID");
              break;
            case ProverProcess.ProverOutcome.NotValid:
              LogActivity("DBG_WAS_INVALID");
              break;
            }
          }

          switch (result) {
          case ProverProcess.ProverOutcome.Valid:
            return Outcome.Valid;
          case ProverProcess.ProverOutcome.TimeOut:
            return Outcome.TimeOut;
          case ProverProcess.ProverOutcome.OutOfMemory:
            return Outcome.OutOfMemory;
          case ProverProcess.ProverOutcome.Inconclusive:
            return Outcome.Undetermined;
          case ProverProcess.ProverOutcome.NotValid:
            return Outcome.Invalid;
          }
        } catch (UnexpectedProverOutputException e) {
          proverException = e;
        }
      }

      assume proverException != null;
      LogComment("***** Unexpected prover output");
      expose (this) {
        currentProverHasBeenABadBoy = true;  // this will cause the next resurrect to restart the prover
      }
      throw proverException;
    }

    protected virtual void ResurrectProver()
      throws UnexpectedProverOutputException;
    {
      expose (this) {
        if (thmProver != null) {
          if (thmProver.HasExited) {
            DateTime now = DateTime.Now;
            LogComment("***** Prover Crashed at or before " + now.ToString("G"));
            
          } else if (CommandLineOptions.Clo.MaxProverMemory > 0 &&
              thmProver.NumFormulasChecked > CommandLineOptions.Clo.MinNumOfProverCalls &&
              thmProver.PeakVirtualMemorySize > CommandLineOptions.Clo.MaxProverMemory)
          {
            LogComment("***** Exceeded memory limit.  Peak memory usage so far: " +
                thmProver.PeakVirtualMemorySize / CommandLineOptions.Megabyte + "MB");
                
          } else if (!currentProverHasBeenABadBoy) {
            // prover is ready to go
            return;
          }
          
          thmProver.Close();
          thmProver = null;
          currentProverHasBeenABadBoy = false;
          restarts++;
        }
        FireUpNewProver();
      }
    }
    
    protected abstract ProverProcess! CreateProverProcess(string! proverPath);
    
    public void LogBgPush(string! s) {
      LogCommon("(BG_PUSH ");
      LogCommon(s);
      LogCommon(")");
    }

    [NoDefaultContract]
    private void FireUpNewProver()
      requires IsExposed;
      requires thmProver == null;
      throws UnexpectedProverOutputException;
    {
      if (cancelEvent == null && CommandLineOptions.Clo.RunningBoogieFromCommandLine) {
        cancelEvent = new ConsoleCancelEventHandler(ControlCHandler);
        Console.CancelKeyPress += cancelEvent;
      }
      thmProver = CreateProverProcess(_proverPath);
      if (restarts == 0) {
        foreach (string! s in thmProver.OptionComments().Split('\n')) {
          LogCommonComment(s);
        }
        foreach (string! parmsetting in thmProver.ParameterSettings) {
          LogCommon(parmsetting);
        }
      }
      foreach (string! parmsetting in thmProver.ParameterSettings) {
        thmProver.Feed(parmsetting, 0);
      }
      thmProver.Feed(GetBackgroundPredicate(BackgroundPredFilename), 3);
      string! incProverCommands = ctx.GetProverCommands(false);
      string! proverCommands = ctx.GetProverCommands(true);
      string! prelude = ctx.GetProverCommands(false);

      if (restarts == 0) {
        // log the stuff before feeding it into the prover, so when it dies
        // and takes Boogie with it, we know what happened
        LogCommon(GetBackgroundPredicate(BackgroundPredFilename));
        LogCommon(prelude);
        LogCommon(proverCommands);

        foreach (string! s in vcExprTranslator.AllTypeDecls)
          LogCommon(s);
        foreach (string! s in vcExprTranslator.AllAxioms)
          LogBgPush(s);

        LogCommonComment("Initialized all axioms.");
      } else {
        LogCommon(incProverCommands);
      }

      thmProver.Feed(prelude, 0);
      thmProver.Feed(proverCommands, 0);

      foreach (string! s in vcExprTranslator.AllTypeDecls)
        thmProver.Feed(s, 0);
      foreach (string! s in vcExprTranslator.AllAxioms)
        thmProver.AddAxioms(s);

      // we have sent everything to the prover and can clear the lists with
      // new axioms and declarations
      List<string!> x = vcExprTranslator.NewAxioms;
      x = x;  // make the compiler happy: somebody uses the value of x
      x = vcExprTranslator.NewTypeDecls;
    }

    public override ProverContext! Context
    {
      get { return this.ctx; }
    }
  }
  
  public class SimplifyTheoremProver : ProcessTheoremProver
  {
    [NotDelayed]
    public SimplifyTheoremProver(ProverOptions! options, VCExpressionGenerator! gen, DeclFreeProverContext! ctx)
      throws UnexpectedProverOutputException;
    {
      base(options, gen, ctx, "simplify.exe", "UnivBackPred2.sx");
    }
    
    protected override ProverProcess! CreateProverProcess(string! proverPath) {
      return new SimplifyProverProcess(proverPath);
    }

    protected override AxiomVCExprTranslator! SpawnVCExprTranslator() {
      return new SimplifyVCExprTranslator(gen);
    }
  }

  // -----------------------------------------------------------------------------------------------
  // -----------------------------------------------------------------------------------------------
  // -----------------------------------------------------------------------------------------------

  public abstract class AxiomVCExprTranslator : VCExprTranslator {
    protected AxiomVCExprTranslator() {
      AllAxioms = new List<string!> ();
      NewAxiomsAttr = new List<string!> ();
      AllTypeDecls = new List<string!> ();
      NewTypeDeclsAttr = new List<string!> ();
    }

    protected AxiomVCExprTranslator(AxiomVCExprTranslator! tl) {
      AllAxioms = new List<string!> (tl.AllAxioms);
      NewAxiomsAttr = new List<string!> (tl.NewAxiomsAttr);
      AllTypeDecls = new List<string!> (tl.AllTypeDecls);
      NewTypeDeclsAttr = new List<string!> (tl.NewTypeDeclsAttr);
    }

    // we store all typing-related axioms that have been sent to the prover
    // so that the prover can be re-initialised in case it dies
    public readonly List<string!>! AllAxioms;
    private List<string!>! NewAxiomsAttr;

    public List<string!>! NewAxioms { get {
      List<string!>! res = NewAxiomsAttr;
      NewAxiomsAttr = new List<string!> ();
      return res;
    } }

    // similarly, a list of declarations that have been sent to the prover
    public readonly List<string!>! AllTypeDecls;
    private List<string!>! NewTypeDeclsAttr;

    public List<string!>! NewTypeDecls { get {
      List<string!>! res = NewTypeDeclsAttr;
      NewTypeDeclsAttr = new List<string!> ();
      return res;
    } }

    public void AddAxiom(string! axiom) {
      AllAxioms.Add(axiom);
      NewAxiomsAttr.Add(axiom);
    }

    public void AddTypeDecl(string! typeDecl) {
      AllTypeDecls.Add(typeDecl);
      NewTypeDeclsAttr.Add(typeDecl);
    }
  }

  // -----------------------------------------------------------------------------------------------
  // -----------------------------------------------------------------------------------------------
  // -----------------------------------------------------------------------------------------------

  public class SimplifyVCExprTranslator : AxiomVCExprTranslator {
    public SimplifyVCExprTranslator(VCExpressionGenerator! gen) {
      Gen = gen;
      TypeAxiomBuilder! axBuilder;
      switch (CommandLineOptions.Clo.TypeEncodingMethod) {
        case CommandLineOptions.TypeEncoding.Arguments:
          axBuilder = new TypeAxiomBuilderArguments (gen);
          break;
        default:
          axBuilder = new TypeAxiomBuilderPremisses (gen);
          break;
      }
      axBuilder.Setup();
      AxBuilder = axBuilder;
      Namer = new UniqueNamer ();
      LitAbstracter = new BigLiteralAbstracter (gen);
    }

    private SimplifyVCExprTranslator(SimplifyVCExprTranslator! tl) {
      base(tl);
      Gen = tl.Gen;
      AxBuilder = (TypeAxiomBuilder)tl.AxBuilder.Clone();
      Namer = (UniqueNamer)tl.Namer.Clone();
      LitAbstracter = (BigLiteralAbstracter)tl.LitAbstracter.Clone();
    }

    public override Object! Clone() {
      return new SimplifyVCExprTranslator(this);
    }

    private readonly VCExpressionGenerator! Gen;
    private readonly TypeAxiomBuilder! AxBuilder;
    private readonly UniqueNamer! Namer;
    private readonly BigLiteralAbstracter! LitAbstracter;

    public override string! translate(VCExpr! expr, int polarity) {
      Let2ImpliesMutator! letImplier = new Let2ImpliesMutator(Gen);

      // handle the types in the VCExpr
      TypeEraser eraser;
      switch (CommandLineOptions.Clo.TypeEncodingMethod) {
        case CommandLineOptions.TypeEncoding.Arguments:
          eraser = new TypeEraserArguments((TypeAxiomBuilderArguments)AxBuilder, Gen);
          break;
        case CommandLineOptions.TypeEncoding.Monomorphic:
          eraser = null;
          break;
        default:
          eraser = new TypeEraserPremisses((TypeAxiomBuilderPremisses)AxBuilder, Gen);
          break;
      }
      VCExpr! exprWithoutTypes = eraser != null ? eraser.Erase(expr, polarity) : expr;

      TermFormulaFlattener! flattener = new TermFormulaFlattener(Gen);
      VCExpr! exprWithLet = flattener.Flatten(exprWithoutTypes);
      VCExpr! exprWithoutLet = letImplier.Mutate(exprWithLet);

      // big integer literals
      VCExpr! exprWithoutBigLits = LitAbstracter.Abstract(exprWithoutLet);
      AddAxiom(SimplifyLikeExprLineariser.ToSimplifyString(LitAbstracter.GetNewAxioms(),
                                                           Namer));

      // type axioms
      VCExpr! axiomsWithLet = flattener.Flatten(AxBuilder.GetNewAxioms());
      VCExpr! axiomsWithoutLet = letImplier.Mutate(axiomsWithLet);

      AddAxiom(SimplifyLikeExprLineariser.ToSimplifyString(axiomsWithoutLet, Namer));
      return SimplifyLikeExprLineariser.ToSimplifyString(exprWithoutBigLits, Namer);
    }
  }

  // -----------------------------------------------------------------------------------------------
  // -----------------------------------------------------------------------------------------------
  // -----------------------------------------------------------------------------------------------

  public class Factory : ProverFactory
  {
    public override object! SpawnProver(ProverOptions! options, object! ctxt)
    {
      return new SimplifyTheoremProver(options,
                                       ((DeclFreeProverContext!)ctxt).ExprGen,
                                       (DeclFreeProverContext!)ctxt);
    }

    public override object! NewProverContext(ProverOptions! options) {
      if (CommandLineOptions.Clo.BracketIdsInVC < 0) {
        CommandLineOptions.Clo.BracketIdsInVC = 1;
      }
      VCExpressionGenerator! gen = new VCExpressionGenerator();
      List<string!>! proverCommands = new List<string!> ();
      proverCommands.Add("all");
      proverCommands.Add("simplify");
      proverCommands.Add("simplifyLike");
      return new DeclFreeProverContext(gen, new VCGenerationOptions(proverCommands));
    }

    public override CommandLineOptions.VCVariety DefaultVCVariety
    {
      get { return CommandLineOptions.VCVariety.BlockNested; }
    }

    // needed to make test7 pass
    public override bool SupportsDags
    {
      get { return true; }
    }
  }
}