// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) 2026, The OpenROAD Authors

#include <memory>
#include <set>
#include <string>
#include <string_view>

#include "boost/json/object.hpp"
#include "boost/json/parse.hpp"
#include "gtest/gtest.h"
#include "odb/db.h"
#include "request_handler.h"
#include "tile_generator.h"
#include "tst/nangate45_fixture.h"

namespace web {
namespace {

// Helper to extract payload as string.
std::string payloadStr(const WebSocketResponse& resp)
{
  return std::string(resp.payload.begin(), resp.payload.end());
}

// Helper to parse a JSON literal into a boost::json::object for tests.
boost::json::object parseObj(std::string_view json)
{
  return boost::json::parse(json).as_object();
}

// ─── TileGenerator::snapAt tests ─────────────────────────────────────────────

class SnapTest : public tst::Nangate45Fixture
{
 protected:
  void SetUp() override
  {
    block_->setDieArea(odb::Rect(0, 0, 100000, 100000));
    block_->setCoreArea(odb::Rect(0, 0, 100000, 100000));
  }

  void makeTileGen()
  {
    tile_gen_ = std::make_unique<TileGenerator>(
        getDb(), /*sta=*/nullptr, getLogger());
  }

  odb::dbInst* placeInst(const char* master_name,
                         const char* inst_name,
                         int x,
                         int y)
  {
    odb::dbMaster* master = lib_->findMaster(master_name);
    EXPECT_NE(master, nullptr);
    odb::dbInst* inst = odb::dbInst::create(block_, master, inst_name);
    inst->setLocation(x, y);
    inst->setPlacementStatus(odb::dbPlacementStatus::PLACED);
    return inst;
  }

  std::unique_ptr<TileGenerator> tile_gen_;
};

TEST_F(SnapTest, NoBlockReturnsNotFound)
{
  // Create a generator with a valid db but then clear the block's die area
  // to create an empty design.
  makeTileGen();
  TileVisibility vis;
  std::set<std::string> layers{"metal1"};
  auto result
      = tile_gen_->snapAt(50000, 50000, 1000, 10, true, true, vis, layers);
  // With an empty design (no instances, no routing), snap should not find
  // anything except possibly the die area edges.
  // We just verify it doesn't crash and returns a valid result.
  EXPECT_TRUE(result.found || !result.found);  // no crash
}

TEST_F(SnapTest, SnapNearInstanceEdge)
{
  // Place an instance at (0,0).  BUF_X16 has a known size in Nangate45.
  placeInst("BUF_X16", "buf1", 0, 0);
  makeTileGen();

  TileVisibility vis;
  std::set<std::string> layers;

  // Query near the origin where the instance is placed.
  // The die area edge is at x=0 and y=0 which should be findable.
  auto result = tile_gen_->snapAt(100, 100, 5000, 50, true, true, vis, layers);
  // Should find at least the die area boundary.
  EXPECT_TRUE(result.found);
  EXPECT_LT(result.distance, 5000);
}

TEST_F(SnapTest, SnapWithHorizontalConstraint)
{
  placeInst("BUF_X16", "buf1", 0, 0);
  makeTileGen();

  TileVisibility vis;
  std::set<std::string> layers;

  // horizontal=true, vertical=false → only horizontal edges (top/bottom)
  auto result
      = tile_gen_->snapAt(50000, 100, 5000, 50, true, false, vis, layers);
  if (result.found) {
    // A horizontal-only snap should return an edge where y1 == y2
    EXPECT_EQ(result.edge.first.y(), result.edge.second.y());
  }
}

TEST_F(SnapTest, SnapWithVerticalConstraint)
{
  placeInst("BUF_X16", "buf1", 0, 0);
  makeTileGen();

  TileVisibility vis;
  std::set<std::string> layers;

  // horizontal=false, vertical=true → only vertical edges (left/right)
  auto result
      = tile_gen_->snapAt(100, 50000, 5000, 50, false, true, vis, layers);
  if (result.found) {
    // A vertical-only snap should return an edge where x1 == x2
    EXPECT_EQ(result.edge.first.x(), result.edge.second.x());
  }
}

TEST_F(SnapTest, SnapAtCenterReportsFarDistance)
{
  makeTileGen();

  TileVisibility vis;
  std::set<std::string> layers;

  // Die area (0,0)-(100000,100000).  At center the nearest edge is 50000 away.
  // Snap always finds the die area edge, but the distance should be large.
  auto result = tile_gen_->snapAt(50000, 50000, 10, 5, true, true, vis, layers);
  EXPECT_TRUE(result.found);
  EXPECT_GE(result.distance, 49000);
}

TEST_F(SnapTest, DieAreaEdgeSnap)
{
  makeTileGen();

  TileVisibility vis;
  std::set<std::string> layers;

  // Die area is (0,0)→(100000,100000).  Bottom edge is at y=0.
  // Query just above the bottom edge.
  auto result = tile_gen_->snapAt(50000, 50, 1000, 10, true, true, vis, layers);
  EXPECT_TRUE(result.found);
  // The bottom edge is horizontal at y=0.
  EXPECT_EQ(result.edge.first.y(), 0);
  EXPECT_EQ(result.edge.second.y(), 0);
}

TEST_F(SnapTest, VisibilityFilterHidesStdcells)
{
  placeInst("BUF_X16", "buf1", 0, 0);
  makeTileGen();

  TileVisibility vis;
  vis.stdcells = true;
  std::set<std::string> layers;

  // With stdcells visible, should find instance edges near origin.
  auto result_visible
      = tile_gen_->snapAt(100, 100, 5000, 50, true, true, vis, layers);

  vis.stdcells = false;
  auto result_hidden
      = tile_gen_->snapAt(100, 100, 5000, 50, true, true, vis, layers);

  // Both may find die area edges, but the instance edges should be different.
  // At minimum, both calls should not crash.
  EXPECT_TRUE(result_visible.found);
  EXPECT_TRUE(result_hidden.found);
}

// ─── handleSnap request handler tests ────────────────────────────────────────

class SnapHandlerTest : public tst::Nangate45Fixture
{
 protected:
  void SetUp() override
  {
    block_->setDieArea(odb::Rect(0, 0, 100000, 100000));
    block_->setCoreArea(odb::Rect(0, 0, 100000, 100000));
    placeInst("BUF_X16", "buf1", 0, 0);
    gen_ = std::make_shared<TileGenerator>(
        getDb(), /*sta=*/nullptr, getLogger());
    tcl_eval_ = std::make_shared<TclEvaluator>(/*interp=*/nullptr, getLogger());
    handler_ = std::make_unique<SelectHandler>(gen_, tcl_eval_);
  }

  odb::dbInst* placeInst(const char* master_name,
                         const char* inst_name,
                         int x,
                         int y)
  {
    odb::dbMaster* master = lib_->findMaster(master_name);
    EXPECT_NE(master, nullptr);
    odb::dbInst* inst = odb::dbInst::create(block_, master, inst_name);
    inst->setLocation(x, y);
    inst->setPlacementStatus(odb::dbPlacementStatus::PLACED);
    return inst;
  }

  std::shared_ptr<TileGenerator> gen_;
  std::shared_ptr<TclEvaluator> tcl_eval_;
  std::unique_ptr<SelectHandler> handler_;
};

TEST_F(SnapHandlerTest, SnapReturnsJson)
{
  WebSocketRequest req;
  req.id = 100;
  req.type = WebSocketRequest::kSnap;
  req.json = parseObj(
      R"({"dbu_x":50000,"dbu_y":50,"radius":1000,"point_threshold":10,"horizontal":true,"vertical":true,"visible_layers":[]})");

  auto resp = handler_->handleSnap(req);
  EXPECT_EQ(resp.id, 100u);
  EXPECT_EQ(resp.type, WebSocketResponse::kJson);  // JSON

  std::string json = payloadStr(resp);
  EXPECT_NE(json.find("\"found\""), std::string::npos);
}

TEST_F(SnapHandlerTest, SnapFoundContainsEdge)
{
  WebSocketRequest req;
  req.id = 101;
  req.type = WebSocketRequest::kSnap;
  // Query near die area bottom edge at y=0.
  req.json = parseObj(
      R"({"dbu_x":50000,"dbu_y":50,"radius":1000,"point_threshold":10,"horizontal":true,"vertical":true,"visible_layers":[]})");

  auto resp = handler_->handleSnap(req);
  EXPECT_EQ(resp.type, WebSocketResponse::kJson);

  std::string json = payloadStr(resp);
  // Should find the die area bottom edge.
  EXPECT_NE(json.find("\"found\":true"), std::string::npos);
  EXPECT_NE(json.find("\"edge\""), std::string::npos);
  EXPECT_NE(json.find("\"is_point\""), std::string::npos);
}

TEST_F(SnapHandlerTest, SnapAlwaysFindsEdgeDueToChipBoundary)
{
  WebSocketRequest req;
  req.id = 102;
  req.type = WebSocketRequest::kSnap;
  // Center of design -- die area edges are always checked so snap always
  // finds something (the closest die boundary).
  req.json = parseObj(
      R"({"dbu_x":50000,"dbu_y":50000,"radius":10,"point_threshold":5,"horizontal":true,"vertical":true,"visible_layers":[]})");

  auto resp = handler_->handleSnap(req);
  EXPECT_EQ(resp.type, WebSocketResponse::kJson);

  std::string json = payloadStr(resp);
  EXPECT_NE(json.find("\"found\":true"), std::string::npos);
  EXPECT_NE(json.find("\"edge\""), std::string::npos);
}

TEST_F(SnapHandlerTest, SnapDispatchesCorrectly)
{
  // Verify that dispatch_request routes SNAP type (even though SNAP goes
  // through SelectHandler, not dispatch_request -- just verify SNAP type
  // is recognized and doesn't error out through the general path).
  WebSocketRequest req;
  req.id = 103;
  req.type = WebSocketRequest::kSnap;
  req.json = parseObj(
      R"({"dbu_x":100,"dbu_y":100,"radius":5000,"point_threshold":50,"horizontal":true,"vertical":true,"visible_layers":[]})");

  auto resp = handler_->handleSnap(req);
  EXPECT_EQ(resp.id, 103u);
  EXPECT_NE(resp.type, WebSocketResponse::kError);  // not error
}

TEST_F(SnapHandlerTest, TechResponseIncludesDbuPerMicron)
{
  // The TECH response should include dbu_per_micron which is needed by the
  // ruler for distance calculations.
  TileHandler tile_handler(gen_);
  SessionState state;
  WebSocketRequest req;
  req.id = 104;
  req.type = WebSocketRequest::kTech;

  auto resp = tile_handler.handleTile(req, state);
  EXPECT_EQ(resp.type, WebSocketResponse::kJson);

  std::string json = payloadStr(resp);
  EXPECT_NE(json.find("\"dbu_per_micron\""), std::string::npos);
}

}  // namespace
}  // namespace web