/*
 *  yosys -- Yosys Open SYnthesis Suite
 *
 *  Copyright (C) 2024  Emily Schmidt <emily@yosyshq.com>
 *
 *  Permission to use, copy, modify, and/or distribute this software for any
 *  purpose with or without fee is hereby granted, provided that the above
 *  copyright notice and this permission notice appear in all copies.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

#include "kernel/yosys.h"
#include "kernel/functionalir.h"
#include <cassert>
#include <sstream>
#include <vector>
#include <string>
#include <unordered_map>

USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN

struct SmtScope {
  pool<std::string> used_names;
  dict<IdString, std::string> name_map;

  SmtScope() {}
    
  void reserve(const std::string& name) {
    used_names.insert(name);
  }

  std::string insert(IdString id) {
    std::string name = RTLIL::unescape_id(id);
    if (used_names.count(name) == 0) {
      used_names.insert(name);
      name_map[id] = name;
      return name;
    }
    for (int idx = 0;; ++idx) {
      std::string new_name = name + "_" + std::to_string(idx);
      if (used_names.count(new_name) == 0) {
	used_names.insert(new_name);
	name_map[id] = new_name;
	return new_name;
      }
    }
  }

  std::string operator[](IdString id) {
    if (name_map.count(id)) {
      return name_map[id];
    } else {
      return insert(id);
    }
  }
};

struct SmtWriter {
  std::ostream& stream;

  SmtWriter(std::ostream& out) : stream(out) {}

  void print(const char* fmt, ...) {
    va_list args;
    va_start(args, fmt);
    stream << vstringf(fmt, args);
    va_end(args);
  }
};

template<class NodeNames>
struct SmtPrintVisitor {
  using Node = FunctionalIR::Node;
  NodeNames np;
  SmtScope &scope;

  SmtPrintVisitor(NodeNames np, SmtScope &scope)
    : np(np), scope(scope) {}

  template<class T>
  std::string arg_to_string(T n) { return std::to_string(n); }

  std::string arg_to_string(std::string n) { return n; }

  std::string arg_to_string(Node n) { return np(n); }

  template<typename... Args>
  std::string format(std::string fmt, Args&&... args) {
    std::vector<std::string> arg_strings = { arg_to_string(std::forward<Args>(args))... };
    for (size_t i = 0; i < arg_strings.size(); ++i) {
      std::string placeholder = "%" + std::to_string(i);
      size_t pos = 0;
      while ((pos = fmt.find(placeholder, pos)) != std::string::npos) {
	fmt.replace(pos, placeholder.length(), arg_strings[i]);
	pos += arg_strings[i].length();
      }
    }
    return fmt;
  }
  std::string buf(Node, Node n) { return np(n); }

  std::string slice(Node, Node a, int, int offset, int out_width) {
    return format("(_ extract %1 %2 %0)", np(a), offset, offset + out_width - 1);
  }

  std::string zero_extend(Node, Node a, int, int out_width) {
    return format("((_ zero_extend %1) %0)", np(a), out_width);
  }

  std::string sign_extend(Node, Node a, int, int out_width) {
    return format("((_ sign_extend %1) %0)", np(a), out_width);
  }

  std::string concat(Node, Node a, int, Node b, int) {
    return format("(concat %0 %1)", np(a), np(b));
  }

  std::string add(Node, Node a, Node b, int) {
    return format("(bvadd %0 %1)", np(a), np(b));
  }

  std::string sub(Node, Node a, Node b, int) {
    return format("(bvsub %0 %1)", np(a), np(b));
  }

  std::string bitwise_and(Node, Node a, Node b, int) {
    return format("(bvand %0 %1)", np(a), np(b));
  }

  std::string bitwise_or(Node, Node a, Node b, int) {
    return format("(bvor %0 %1)", np(a), np(b));
  }

  std::string bitwise_xor(Node, Node a, Node b, int) {
    return format("(bvxor %0 %1)", np(a), np(b));
  }

  std::string bitwise_not(Node, Node a, int) {
    return format("(bvnot %0)", np(a));
  }

  std::string unary_minus(Node, Node a, int) {
    return format("(bvneg %0)", np(a));
  }

  std::string reduce_and(Node, Node a, int) {
    return format("(= %0 #b1)", np(a));
  }

  std::string reduce_or(Node, Node a, int) {
    return format("(distinct %0 #b0)", np(a));
  }

  std::string reduce_xor(Node, Node a, int) {
    return format("(bvxor_reduce %0)", np(a));
  }

  std::string equal(Node, Node a, Node b, int) {
    return format("(= %0 %1)", np(a), np(b));
  }

  std::string not_equal(Node, Node a, Node b, int) {
    return format("(distinct %0 %1)", np(a), np(b));
  }

  std::string signed_greater_than(Node, Node a, Node b, int) {
    return format("(bvsgt %0 %1)", np(a), np(b));
  }

  std::string signed_greater_equal(Node, Node a, Node b, int) {
    return format("(bvsge %0 %1)", np(a), np(b));
  }

  std::string unsigned_greater_than(Node, Node a, Node b, int) {
    return format("(bvugt %0 %1)", np(a), np(b));
  }

  std::string unsigned_greater_equal(Node, Node a, Node b, int) {
    return format("(bvuge %0 %1)", np(a), np(b));
  }

  std::string logical_shift_left(Node, Node a, Node b, int, int) {
    return format("(bvshl %0 %1)", np(a), np(b));
  }

  std::string logical_shift_right(Node, Node a, Node b, int, int) {
    return format("(bvlshr %0 %1)", np(a), np(b));
  }

  std::string arithmetic_shift_right(Node, Node a, Node b, int, int) {
    return format("(bvashr %0 %1)", np(a), np(b));
  }

  std::string mux(Node, Node a, Node b, Node s, int) {
    return format("(ite %2 %0 %1)", np(a), np(b), np(s));
  }

  std::string pmux(Node, Node a, Node b, Node s, int, int) {
    // Assume s is a bit vector, combine a and b based on the selection bits
    return format("(pmux %0 %1 %2)", np(a), np(b), np(s));
  }

  std::string constant(Node, RTLIL::Const value) {
    return format("#b%1", value.as_string());
  }

  std::string input(Node, IdString name) {
    return format("%0", scope[name]);
  }

  std::string state(Node, IdString name) {
    return format("%0", scope[name]);
  }

  std::string memory_read(Node, Node mem, Node addr, int, int) {
    return format("(select %0 %1)", np(mem), np(addr));
  }

  std::string memory_write(Node, Node mem, Node addr, Node data, int, int) {
    return format("(store %0 %1 %2)", np(mem), np(addr), np(data));
  }

  std::string undriven(Node, int width) {
    return format("#b%0", std::string(width, '0'));
  }
};
struct SmtModule {
  std::string name;
  SmtScope scope;
  FunctionalIR ir;

  SmtModule(const std::string& module_name, FunctionalIR ir) 
    : name(module_name), ir(std::move(ir)) {}

  void write(std::ostream& out) {
    SmtWriter writer(out);
        
    writer.print("(declare-fun %s () Bool)\n", name.c_str());

    writer.print("(declare-datatypes () ((Inputs (mk_inputs");
    for (const auto& input : ir.inputs()) {
      std::string input_name = scope[input.first];
      writer.print(" (%s (_ BitVec %d))", input_name.c_str(), input.second.width());
    }
    writer.print("))))\n");

    writer.print("(declare-datatypes () ((Outputs (mk_outputs");
    for (const auto& output : ir.outputs()) {
      std::string output_name = scope[output.first];
      writer.print(" (%s (_ BitVec %d))", output_name.c_str(), output.second.width());
    }
    writer.print("))))\n");

    writer.print("(declare-fun state () (_ BitVec 1))\n");

    writer.print("(define-fun %s_step ((state (_ BitVec 1)) (inputs Inputs)) Outputs\n", name.c_str());

    writer.print("  (let (\n");
    for (const auto& input : ir.inputs()) {
      std::string input_name = scope[input.first];
      writer.print("    (%s (%s inputs))\n", input_name.c_str(), input_name.c_str());
    }
    writer.print("  )\n");

    auto node_to_string = [&](FunctionalIR::Node n) { return scope[n.name()]; };
    SmtPrintVisitor<decltype(node_to_string)> visitor(node_to_string, scope);
    writer.print("    (let (\n");
    for (auto it = ir.begin(); it != ir.end(); ++it) {
      const FunctionalIR::Node& node = *it;

      if (ir.inputs().count(node.name()) > 0) {
        continue;
      }
      
      std::string node_name = scope[node.name()];
      std::string node_expr = node.visit(visitor);
      writer.print("      (%s %s)\n", node_name.c_str(), node_expr.c_str());
    }
    writer.print("    )\n");

    writer.print("      (let (\n");
    for (const auto& output : ir.outputs()) {
      std::string output_name = scope[output.first];
      // writer.print("        (%s %s)\n", output_name.c_str(), scope[output_name].c_str());
    }
    writer.print("      )\n");

    writer.print("        (mk_outputs\n");
    for (const auto& output : ir.outputs()) {
      std::string output_name = scope[output.first];
      writer.print("          %s\n", output_name.c_str());
    }
    writer.print("        )\n");
    writer.print("      )\n");
    writer.print("    )\n");
    writer.print("  )\n");
    writer.print(")\n");
  }
};

struct FunctionalSmtBackend : public Backend {
  FunctionalSmtBackend() : Backend("functional_smt2", "Generate SMT-LIB from Functional IR") {}

  void help() override {
    log("\nFunctional SMT Backend.\n\n");
  }

  void execute(std::ostream*& f, std::string filename, std::vector<std::string> args, RTLIL::Design* design) override {
    log_header(design, "Executing Functional SMT Backend.\n");

    size_t argidx = 1;
    extra_args(f, filename, args, argidx, design);

    for (auto module : design->selected_modules()) {
      log("Processing module `%s`.\n", module->name.c_str());
      auto ir = FunctionalIR::from_module(module);
      SmtModule smt(RTLIL::unescape_id(module->name), ir);
      smt.write(*f);
    }
  }
} FunctionalSmtBackend;

PRIVATE_NAMESPACE_END