/**
 *  Copyright (c) 2014-present, Facebook, Inc.
 *  All rights reserved.
 *
 *  This source code is licensed under both the Apache 2.0 license (found in the
 *  LICENSE file in the root directory of this source tree) and the GPLv2 (found
 *  in the COPYING file in the root directory of this source tree).
 *  You may select, at your option, one of the above-listed licenses.
 */

#include <osquery/database.h>
#include <osquery/flags.h>
#include <osquery/logger.h>
#include <osquery/registry_factory.h>
#include <osquery/tables.h>

#include "osquery/core/json.h"

namespace osquery {

FLAG(bool, disable_caching, false, "Disable scheduled query caching");

CREATE_LAZY_REGISTRY(TablePlugin, "table");

size_t TablePlugin::kCacheInterval = 0;
size_t TablePlugin::kCacheStep = 0;

const std::map<ColumnType, std::string> kColumnTypeNames = {
    {UNKNOWN_TYPE, "UNKNOWN"},
    {TEXT_TYPE, "TEXT"},
    {INTEGER_TYPE, "INTEGER"},
    {BIGINT_TYPE, "BIGINT"},
    {UNSIGNED_BIGINT_TYPE, "UNSIGNED BIGINT"},
    {DOUBLE_TYPE, "DOUBLE"},
    {BLOB_TYPE, "BLOB"},
};

Status TablePlugin::addExternal(const std::string& name,
                                const PluginResponse& response) {
  // Attach the table.
  if (response.size() == 0) {
    // Invalid table route info.
    // Tables must broadcast their column information, this is used while the
    // core is deciding if the extension's route is valid.
    return Status(1, "Invalid route info");
  }

  // Use the SQL registry to attach the name/definition.
  return Registry::call("sql", "sql", {{"action", "attach"}, {"table", name}});
}

void TablePlugin::removeExternal(const std::string& name) {
  // Detach the table name.
  Registry::call("sql", "sql", {{"action", "detach"}, {"table", name}});
}

void TablePlugin::setRequestFromContext(const QueryContext& context,
                                        PluginRequest& request) {
  auto doc = JSON::newObject();
  auto constraints = doc.getArray();

  // The QueryContext contains a constraint map from column to type information
  // and the list of operand/expression constraints applied to that column from
  // the query given.
  for (const auto& constraint : context.constraints) {
    auto child = doc.getObject();
    doc.addRef("name", constraint.first, child);
    constraint.second.serialize(doc, child);
    doc.push(child, constraints);
  }

  doc.add("constraints", constraints);

  if (context.colsUsed) {
    auto colsUsed = doc.getArray();
    for (const auto& columnName : *context.colsUsed) {
      doc.pushCopy(columnName, colsUsed);
    }
    doc.add("colsUsed", colsUsed);
  }

  doc.toString(request["context"]);
}

void TablePlugin::setContextFromRequest(const PluginRequest& request,
                                        QueryContext& context) {
  auto doc = JSON::newObject();
  doc.fromString(request.at("context"));

  if (doc.doc().HasMember("colsUsed")) {
    UsedColumns colsUsed;
    for (const auto& columnName : doc.doc()["colsUsed"].GetArray()) {
      colsUsed.insert(columnName.GetString());
    }
    context.colsUsed = colsUsed;
  }

  if (!doc.doc().HasMember("constraints") ||
      !doc.doc()["constraints"].IsArray()) {
    return;
  }

  // Set the context limit and deserialize each column constraint list.
  for (const auto& constraint : doc.doc()["constraints"].GetArray()) {
    auto column_name = constraint["name"].GetString();
    context.constraints[column_name].deserialize(constraint);
  }
}

Status TablePlugin::call(const PluginRequest& request,
                         PluginResponse& response) {
  response.clear();
  // TablePlugin API calling requires an action.
  if (request.count("action") == 0) {
    return Status(1, "Table plugins must include a request action");
  }

  if (request.at("action") == "generate") {
    // The "generate" action runs the table implementation using a PluginRequest
    // with optional serialized QueryContext and returns the QueryData results
    // as the PluginRequest data.

    // Create a fake table implementation for caching.
    QueryContext context;
    if (request.count("context") > 0) {
      setContextFromRequest(request, context);
    }
    response = generate(context);
  } else if (request.at("action") == "columns") {
    // The "columns" action returns a PluginRequest filled with column
    // information such as name and type.
    response = routeInfo();
  } else {
    return Status(1, "Unknown table plugin action: " + request.at("action"));
  }

  return Status(0, "OK");
}

std::string TablePlugin::columnDefinition() const {
  return osquery::columnDefinition(columns());
}

PluginResponse TablePlugin::routeInfo() const {
  // Route info consists of the serialized column information.
  PluginResponse response;
  for (const auto& column : columns()) {
    response.push_back(
        {{"id", "column"},
         {"name", std::get<0>(column)},
         {"type", columnTypeName(std::get<1>(column))},
         {"op", INTEGER(static_cast<size_t>(std::get<2>(column)))}});
  }
  // Each table name alias is provided such that the core may add the views.
  // These views need to be removed when the backing table is detached.
  for (const auto& alias : aliases()) {
    response.push_back({{"id", "alias"}, {"alias", alias}});
  }

  // Each column alias must be provided, additionally to the column's option.
  // This sets up the value-replacement move within the SQL implementation.
  for (const auto& target : columnAliases()) {
    for (const auto& alias : target.second) {
      response.push_back(
          {{"id", "columnAlias"}, {"name", alias}, {"target", target.first}});
    }
  }

  response.push_back(
      {{"id", "attributes"},
       {"attributes", INTEGER(static_cast<size_t>(attributes()))}});
  return response;
}

static bool cacheAllowed(const TableColumns& cols, const QueryContext& ctx) {
  if (!ctx.useCache()) {
    // The query execution did not request use of the warm cache.
    return false;
  }

  auto uncachable = ColumnOptions::INDEX | ColumnOptions::REQUIRED |
                    ColumnOptions::ADDITIONAL | ColumnOptions::OPTIMIZED;
  for (const auto& column : cols) {
    auto opts = std::get<2>(column) & uncachable;
    if (opts && ctx.constraints.at(std::get<0>(column)).exists()) {
      return false;
    }
  }
  return true;
}

bool TablePlugin::isCached(size_t step, const QueryContext& ctx) const {
  if (FLAGS_disable_caching) {
    return false;
  }

  // Perform the step comparison first, because it's easy.
  return (step < last_cached_ + last_interval_ && cacheAllowed(columns(), ctx));
}

QueryData TablePlugin::getCache() const {
  VLOG(1) << "Retrieving results from cache for table: " << getName();
  // Lookup results from database and deserialize.
  std::string content;
  getDatabaseValue(kQueries, "cache." + getName(), content);
  QueryData results;
  deserializeQueryDataJSON(content, results);
  return results;
}

void TablePlugin::setCache(size_t step,
                           size_t interval,
                           const QueryContext& ctx,
                           const QueryData& results) {
  if (FLAGS_disable_caching || !cacheAllowed(columns(), ctx)) {
    return;
  }

  // Serialize QueryData and save to database.
  std::string content;
  if (serializeQueryDataJSON(results, content)) {
    last_cached_ = step;
    last_interval_ = interval;
    setDatabaseValue(kQueries, "cache." + getName(), content);
  }
}

std::string columnDefinition(const TableColumns& columns) {
  std::map<std::string, bool> epilog;
  bool indexed = false;
  std::vector<std::string> pkeys;

  std::string statement = "(";
  for (size_t i = 0; i < columns.size(); ++i) {
    const auto& column = columns.at(i);
    statement +=
        '`' + std::get<0>(column) + "` " + columnTypeName(std::get<1>(column));
    auto& options = std::get<2>(column);
    if (options & (ColumnOptions::INDEX | ColumnOptions::ADDITIONAL)) {
      if (options & ColumnOptions::INDEX) {
        indexed = true;
      }
      pkeys.push_back(std::get<0>(column));
      epilog["WITHOUT ROWID"] = true;
    }
    if (options & ColumnOptions::HIDDEN) {
      statement += " HIDDEN";
    }
    if (i < columns.size() - 1) {
      statement += ", ";
    }
  }

  // If there are only 'additional' columns (rare), do not attempt a pkey.
  if (!indexed) {
    epilog["WITHOUT ROWID"] = false;
    pkeys.clear();
  }

  // Append the primary keys, if any were defined.
  if (!pkeys.empty()) {
    statement += ", PRIMARY KEY (";
    for (auto pkey = pkeys.begin(); pkey != pkeys.end();) {
      statement += '`' + std::move(*pkey) + '`';
      if (++pkey != pkeys.end()) {
        statement += ", ";
      }
    }
    statement += ')';
  }

  statement += ')';
  for (auto& ei : epilog) {
    if (ei.second) {
      statement += ' ' + std::move(ei.first);
    }
  }
  return statement;
}

std::string columnDefinition(const PluginResponse& response, bool aliases) {
  TableColumns columns;
  // Maintain a map of column to the type, for alias type lookups.
  std::map<std::string, ColumnType> column_types;
  for (const auto& column : response) {
    if (column.count("id") == 0) {
      continue;
    }

    if (column.at("id") == "column" && column.count("name") &&
        column.count("type")) {
      auto options =
          (column.count("op"))
              ? (ColumnOptions)AS_LITERAL(INTEGER_LITERAL, column.at("op"))
              : ColumnOptions::DEFAULT;
      auto column_type = columnTypeName(column.at("type"));
      columns.push_back(make_tuple(column.at("name"), column_type, options));
      if (aliases) {
        column_types[column.at("name")] = column_type;
      }
    } else if (column.at("id") == "columnAlias" && column.count("name") &&
               column.count("target") && aliases) {
      const auto& target = column.at("target");
      if (column_types.count(target) == 0) {
        // No type was defined for the alias target.
        continue;
      }
      columns.push_back(make_tuple(
          column.at("name"), column_types.at(target), ColumnOptions::HIDDEN));
    }
  }
  return columnDefinition(columns);
}

ColumnType columnTypeName(const std::string& type) {
  for (const auto& col : kColumnTypeNames) {
    if (col.second == type) {
      return col.first;
    }
  }
  return UNKNOWN_TYPE;
}

bool ConstraintList::exists(const ConstraintOperatorFlag ops) const {
  if (ops == ANY_OP) {
    return (constraints_.size() > 0);
  } else {
    for (const struct Constraint& c : constraints_) {
      if (c.op & ops) {
        return true;
      }
    }
    return false;
  }
}

bool ConstraintList::matches(const std::string& expr) const {
  // Support each SQL affinity type casting.
  try {
    if (affinity == TEXT_TYPE) {
      return literal_matches<TEXT_LITERAL>(expr);
    } else if (affinity == INTEGER_TYPE) {
      INTEGER_LITERAL lexpr = AS_LITERAL(INTEGER_LITERAL, expr);
      return literal_matches<INTEGER_LITERAL>(lexpr);
    } else if (affinity == BIGINT_TYPE) {
      BIGINT_LITERAL lexpr = AS_LITERAL(BIGINT_LITERAL, expr);
      return literal_matches<BIGINT_LITERAL>(lexpr);
    } else if (affinity == UNSIGNED_BIGINT_TYPE) {
      UNSIGNED_BIGINT_LITERAL lexpr = AS_LITERAL(UNSIGNED_BIGINT_LITERAL, expr);
      return literal_matches<UNSIGNED_BIGINT_LITERAL>(lexpr);
    }
  } catch (const boost::bad_lexical_cast& /* e */) {
    // Unsupported affinity type or unable to cast content type.
  }

  return false;
}

template <typename T>
bool ConstraintList::literal_matches(const T& base_expr) const {
  bool aggregate = true;
  for (size_t i = 0; i < constraints_.size(); ++i) {
    T constraint_expr = AS_LITERAL(T, constraints_[i].expr);
    if (constraints_[i].op == EQUALS) {
      aggregate = aggregate && (base_expr == constraint_expr);
    } else if (constraints_[i].op == GREATER_THAN) {
      aggregate = aggregate && (base_expr > constraint_expr);
    } else if (constraints_[i].op == LESS_THAN) {
      aggregate = aggregate && (base_expr < constraint_expr);
    } else if (constraints_[i].op == GREATER_THAN_OR_EQUALS) {
      aggregate = aggregate && (base_expr >= constraint_expr);
    } else if (constraints_[i].op == LESS_THAN_OR_EQUALS) {
      aggregate = aggregate && (base_expr <= constraint_expr);
    } else {
      // Unsupported constraint. Should match every thing.
      return true;
    }
    if (!aggregate) {
      // Speed up comparison.
      return false;
    }
  }
  return true;
}

std::set<std::string> ConstraintList::getAll(ConstraintOperator op) const {
  std::set<std::string> set;
  for (size_t i = 0; i < constraints_.size(); ++i) {
    if (constraints_[i].op == op) {
      // TODO: this does not apply a distinct.
      set.insert(constraints_[i].expr);
    }
  }
  return set;
}

void ConstraintList::serialize(JSON& doc, rapidjson::Value& obj) const {
  auto expressions = doc.getArray();
  for (const auto& constraint : constraints_) {
    auto child = doc.getObject();
    doc.add("op", static_cast<size_t>(constraint.op), child);
    doc.addRef("expr", constraint.expr, child);
    doc.push(child, expressions);
  }
  doc.add("list", expressions, obj);
  doc.addCopy("affinity", columnTypeName(affinity), obj);
}

void ConstraintList::deserialize(const rapidjson::Value& obj) {
  // Iterate through the list of operand/expressions, then set the constraint
  // type affinity.
  if (!obj.IsObject() || !obj.HasMember("list") || !obj["list"].IsArray()) {
    return;
  }

  for (const auto& list : obj["list"].GetArray()) {
    auto op = static_cast<unsigned char>(JSON::valueToSize(list["op"]));
    Constraint constraint(op);
    constraint.expr = list["expr"].GetString();
    constraints_.push_back(constraint);
  }

  auto affinity_name = (obj.HasMember("affinity") && obj["affinity"].IsString())
                           ? obj["affinity"].GetString()
                           : "UNKNOWN";
  affinity = columnTypeName(affinity_name);
}

bool QueryContext::isColumnUsed(const std::string& colName) const {
  return !colsUsed || colsUsed->find(colName) != colsUsed->end();
}

bool QueryContext::isAnyColumnUsed(
    std::initializer_list<std::string> colNames) const {
  for (auto& colName : colNames) {
    if (isColumnUsed(colName)) {
      return true;
    }
  }
  return false;
}

void QueryContext::useCache(bool use_cache) {
  use_cache_ = use_cache;
}

bool QueryContext::useCache() const {
  return use_cache_;
}

void QueryContext::setCache(const std::string& index, Row _cache) {
  table_->cache[index] = std::move(_cache);
}

void QueryContext::setCache(const std::string& index,
                            const std::string& key,
                            std::string _item) {
  table_->cache[index][key] = std::move(_item);
}

bool QueryContext::isCached(const std::string& index) const {
  return (table_->cache.count(index) != 0);
}

const Row& QueryContext::getCache(const std::string& index) {
  return table_->cache[index];
}

const std::string& QueryContext::getCache(const std::string& index,
                                          const std::string& key) {
  return table_->cache[index][key];
}

bool QueryContext::hasConstraint(const std::string& column,
                                 ConstraintOperator op) const {
  if (constraints.count(column) == 0) {
    return false;
  }
  return constraints.at(column).exists(op);
}

Status QueryContext::expandConstraints(
    const std::string& column,
    ConstraintOperator op,
    std::set<std::string>& output,
    std::function<Status(const std::string& constraint,
                         std::set<std::string>& output)> predicate) {
  for (const auto& constraint : constraints[column].getAll(op)) {
    auto status = predicate(constraint, output);
    if (!status) {
      return status;
    }
  }
  return Status(0);
}
}