#include "stdlib.hpp"

#include "common.hpp"
#include "pod.hpp"
#include "writer.hpp"

typedef Result<Value> (*StdlibFunctionIdPtr)(const Array& params);

struct StdlibFunctionEntry {
  const char* name;
  StdlibFunctionId fun_id;
  StdlibFunctionIdPtr fun_ptr;
};

Result<Value> stdlib_unknown(const Array& params) {
  return ERROR(NotImplemented);
}

Result<void> print_string(const String& s) {
  auto ba = TRY(ByteArray::create(s));

  for (uint64_t i = 0; i < ba.size(); i++) {
    std::cout << TRY(ba[i]);
  }

  return Result<void>();
}

Result<Value> stdlib_print(const Array& params) {
  for (uint64_t i = 0; i < params.size(); i++) {
    Value param = TRY(params.get(i));

    if (i != 0) {
      std::cout << " ";
    }
    if (param.is<String>()) {
      TRY(print_string(*param.to<String>()));
    } else {
      auto s = TRY(write_one(param));
      TRY(print_string(s));
    }
  }

  return Value(TRY(Nil::create()));
}

Result<Value> stdlib_println(const Array& params) {
  TRY(stdlib_print(params));
  std::cout << "\n";

  return Value(TRY(Nil::create()));
}

Result<Value> stdlib_prn(const Array& params) { return ERROR(NotImplemented); }

Result<Value> stdlib_assert(const Array& params) {
  for (uint64_t i = 0; i < params.size(); i++) {
    Value param = TRY(params.get(i));
    if (!param.is<Bool>()) return ERROR(AssertionFailed);
    auto v = param.to<Bool>()->value();
    if (!v) return ERROR(AssertionFailed);
  }

  return Value(TRY(Nil::create()));
}

Result<Value> stdlib_dict(const Array& params) {
  Value d = TRY(Dict::create(params));
  return d;
}

Result<Value> stdlib_list(const Array& params) {
  Value d = TRY(Pair::create(params));
  return d;
}

Result<Value> stdlib_array(const Array& params) {
  Array array_copy = TRY(params.copy());
  return Value(std::move(array_copy));
}

Result<Value> stdlib_get(const Array& params) {
  if (params.size() != 2) return ERROR(ArgumentCountMismatch);
  Value collection = TRY(params.get(0));
  Value key = TRY(params.get(1));
  return TRY(collection.get(key));
}

#define STDLIB_FUNCTION(name, id)                                  \
  [(uint64_t)StdlibFunctionId::id] = {#name, StdlibFunctionId::id, \
                                      stdlib_##name}

static StdlibFunctionEntry function_entries[] = {
    STDLIB_FUNCTION(unknown, Unknown),
    STDLIB_FUNCTION(print, Print),
    STDLIB_FUNCTION(println, PrintLn),
    STDLIB_FUNCTION(prn, Prn),
    STDLIB_FUNCTION(assert, Assert),
    STDLIB_FUNCTION(dict, Dict),
    STDLIB_FUNCTION(list, List),
    STDLIB_FUNCTION(array, Array),
    STDLIB_FUNCTION(get, Get),
    [(uint64_t)StdlibFunctionId::Max] = {0, StdlibFunctionId::Max,
                                         stdlib_unknown},
};

// TODO: this just scans through the array of functions linearly every time.
// It doesn't have much effect at runtime, because such lookup is likely to
// happen on compile-time only. But anyway, this is worth speeding up
// eventually.
StdlibFunctionEntry get_function_entry(const char* name) {
  for (uint64_t i = 1; i < (uint64_t)StdlibFunctionId::Max; i++) {
    if (strcmp(function_entries[i].name, name) == 0) {
      return function_entries[i];
    }
  }
  return function_entries[(uint64_t)StdlibFunctionId::Unknown];
}

Result<StdlibFunctionId> get_stdlib_function(const Symbol& name) {
  const uint64_t bufsize = 256;
  char buf[bufsize];
  if (name.size() + 1 > bufsize) {
    return ERROR(KeyError);
  }

  for (uint64_t i = 0; i < name.size(); i++) {
    buf[i] = (char)TRY(name[i]);
  }
  buf[name.size()] = 0;

  StdlibFunctionId fun_id = get_function_entry(buf).fun_id;
  if (fun_id == StdlibFunctionId::Unknown) {
    return ERROR(KeyError);
  }

  return fun_id;
}

Result<Value> call_stdlib_function(StdlibFunctionId fun_id,
                                   const Array& params) {
  if (fun_id == StdlibFunctionId(0) || fun_id >= StdlibFunctionId::Max) {
    return ERROR(KeyError);
  }

  return function_entries[(uint64_t)fun_id].fun_ptr(params);
}

Result<const char*> get_stdlib_function_name(StdlibFunctionId fun_id) {
  if (fun_id == StdlibFunctionId(0) || fun_id >= StdlibFunctionId::Max) {
    return ERROR(KeyError);
  }

  return function_entries[(uint64_t)fun_id].name;
}