#include <cstdint>
#include <unordered_map>
#include <string>
#include <iostream>

#include "cxxopts.hpp"
#include "optional.h"

using FileId = uint64_t;

struct FileDatabase {
  std::unordered_map<std::string, FileId> filename_to_file_id;
  std::unordered_map<FileId, std::string> file_id_to_filename;
};

enum class SymbolKind { Type, Func, Var };
struct SymbolIdx {
  SymbolKind kind;
  union {
    uint64_t type_idx;
    uint64_t func_idx;
    uint64_t var_idx;
  };
};

struct File {
  // Symbols declared in the file.
  std::vector<SymbolIdx> declared_symbols;
  // Symbols which have definitions in the file.
  std::vector<SymbolIdx> defined_symbols;
};

struct TypeDef {};
struct FuncDef {};
struct VarDef {};

struct QueryableEntry {
  const char* const str;
};

// The query database is heavily optimized for fast queries. It is stored
// in-memory.
struct QueryDatabase {
  // Indicies between lookup vectors are related to symbols, ie, index 5 in
  // |qualified_names| matches index 5 in |symbols|.
  std::vector<QueryableEntry> qualified_names;
  std::vector<SymbolIdx> symbols;

  // Raw data storage.
  std::vector<TypeDef> types;
  std::vector<FuncDef> funcs;
  std::vector<VarDef> vars;

  // |files| is indexed by FileId. Retrieve a FileId from a path using
  // |file_locator|.
  FileDatabase file_locator;
  std::vector<File> files;
};




// Task running in a separate process, parsing a file into something we can
// import.
struct ParseTask {};
// Completed parse task that wants to import content into the global database.
// Runs in main process, primary thread. Stops all other threads.
struct IndexImportTask {};
// Completed parse task that wants to update content previously imported into
// the global database. Runs in main process, primary thread. Stops all other
// threads.
//
// Note that this task just contains a set of operations to apply to the global
// database. The operations come from a diff based on the previously indexed
// state in comparison to the newly indexed state.
//
// TODO: We may be able to run multiple freshen and import tasks in parallel if
//       we restrict what ranges of the db they may change.
struct IndexFreshenTask {};
// Task running a query against the global database. Run in main process,
// separate thread.
struct QueryTask {};


// NOTE: When something enters a value into master db, it will have to have a
//       ref count, since multiple parsings could enter it (unless we require
//       that it be defined in that declaration unit!)
struct TaskManager {

};


struct Query {

};

void fail(const std::string& message) {
  std::cerr << "Fatal error: " << message << std::endl;
  std::exit(1);
}

enum class PreferredSymbolLocation {
  Declaration,
  Definition
};
std::istream& operator >> (std::istream& is, PreferredSymbolLocation& obj) {
  std::string content;
  is >> content;

  if (content == "declaration")
    obj = PreferredSymbolLocation::Declaration;
  else if (content == "definition")
    obj = PreferredSymbolLocation::Definition;
  else
    is.setstate(std::ios::failbit);

  return is;
}

// NOTE: If updating this enum, make sure to also update the parser and the
//       help text.
enum class Command {
  Callees,
  Callers,
  FindAllUsages,
  FindInterestingUsages,
  GotoReferenced,
  Hierarchy,
  Outline,
  Search
};

//std::ostream& operator<<(std::ostream& os, const Command& obj) {
  // write obj to stream
//  return os;
//}
std::istream& operator >> (std::istream& is, Command& obj) {
  std::string content;
  is >> content;

  if (content == "callees")
    obj = Command::Callees;
  else if (content == "callers")
    obj = Command::Callers;
  else if (content == "find-all-usages")
    obj = Command::FindAllUsages;
  else if (content == "find-interesting-usages")
    obj = Command::FindInterestingUsages;
  else if (content == "goto-referenced")
    obj = Command::GotoReferenced;
  else if (content == "hierarchy")
    obj = Command::Hierarchy;
  else if (content == "outline")
    obj = Command::Outline;
  else if (content == "search")
    obj = Command::Search;
  else
    is.setstate(std::ios::failbit);

  return is;
}

// TODO: I think we can run libclang multiple times in one process. So we might
//       only need two processes. Still, for perf reasons it would be good if
//       we could stay in one process.
// TODO: allow user to store configuration as json? file in home dir; also
//       allow local overrides (scan up dirs)
// TODO: add opt to dump config when starting (--dump-config)
// TODO: allow user to decide some indexer choices, ie, do we define
// TODO: may want to run indexer in separate process to avoid indexer/compiler crashes?

int main(int argc, char** argv) {
  // cxxopts throws exceptions... replace/rewrite lib?
  try {
    cxxopts::Options options("indexer", "C++ indexer powered by libclang");

    options.add_options()
      ("h,help", "Print help (this output)")
      ("list-commands", "Print information about the query commands")
      ("p,project", "Path to compile_commands.json. Needed for the server, and optionally by clients if there are multiple servers running.")
      ;

    // Server options.
    options.add_options("server")
      ("server", "Flag indicating that the indexer should create an index that can be queried against using separate invocations of this binary (using the --command flag).", cxxopts::value<bool>())
      ("cache-dir", "Path to cache index. Database cache will be restored if present. If not present, the index will be in-memory only.")
      ("threads", "Number of threads to use for indexing and querying tasks.")
      ;

    // Client options.
    options.add_options("client")
      ("c,command", "Execute a query command against the index. See --command-help. Presence of this flag indicates that the indexer is in client mode.", cxxopts::value<Command>())
      ("f,file", "File name to run the index query on", cxxopts::value<std::string>())
      ("l,location", "A symbol location in the active file the query will operate on. Format is line:column, ie, 10:5, for line 10, column 5.", cxxopts::value<std::string>())
      ("preferred-symbol-location", "When looking up symbols, try to return the either the 'declaration' or the 'definition'. Defaults to 'definition'.", cxxopts::value<PreferredSymbolLocation>())
      ;

    options.parse(argc, argv);

    if (options.count("list-commands")) {
      std::cout << R"(Available commands:

  callees:
  callers:
    Emit all functions (with location) that this function calls ("callees") or
    that call this function ("callers"). Requires a location.

  find-all-usages:
    Emit every usage of the given symbol. This is intended to support a rename
    refactoring. This output contains many uninteresting usages of symbols;
    prefer find-interesting-usges. Requires a location.

  find-interesting-usages:
    Emit only usages of the given symbol which are semantically interesting.
    Requires a location.

  goto-referenced:
    Find an associated reference (either definition or declaration) for the
    given symbol. Requires a location.

  hierarchy:
    List the type hierarchy (ie, inherited and derived members) for the given
    method or type. Requires a location.

  outline:
    Emit a file outline, listing all of the symbols in the file.

  search:
    Search for a symbol by name.
)";
      exit(0);
    }

    if (argc == 1 || options.count("help")) {
      std::cout << options.help({ "", "server", "client" }) << std::endl;
      exit(0);
    }
  }
  catch (cxxopts::OptionException exc) {
    fail(exc.what());
  }

  /*
  std::string command;
  for (int i = 0; i < argc; ++i) {
    if (strcmp(argv[i], "--command") == 0) {
      if ((i + 1) >= argc)
        fail("missing --command type");

      command = argv[i + 1];
    }
  }

  if (command == "")
    fail("missing --command switch");



  if (command == "query") {

  }

  std::cout << "Running command " << command;
  */
  return 0;
}