/*
 * SPDX-FileCopyrightText: 2025 William Bell
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 */

#include "runtime.h"
#include "../err.h"
#include "../hash_data/hash_data.h"
#include "../translator/translator.h"
#include "declaration/declaration.h"
#include "objects/functions/functions.h"
#include "objects/literals/literals.h"
#include "objects/object.h"
#include "objects/string/string.h"
#include "objects/type/type.h"
#include <fcntl.h>
#include <gc/gc.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

void init_types() {
  BASE_CLASS = init_argon_class("BASE_CLASS");

  init_type();
  init_function_type();
  init_literals();
  init_string_type();

  init_base_field();
  BASE_CLASS->baseObject = ARGON_NULL;
}

int compare_by_order(const void *a, const void *b) {
  const struct node_GC *itemA = (const struct node_GC *)a;
  const struct node_GC *itemB = (const struct node_GC *)b;
  return itemA->order - itemB->order;
}

uint8_t pop_byte(Translated *translated, RuntimeState *state) {
  return *((uint8_t *)darray_get(&translated->bytecode, state->head++));
}

uint64_t pop_bytecode(Translated *translated, RuntimeState *state) {
  uint64_t value = 0;
  for (int i = 0; i < 8; i++) {
    value |= ((uint64_t)pop_byte(translated, state)) << (i * 8);
  }
  return value;
}

void load_const(Translated *translated, RuntimeState *state) {
  uint64_t to_register = pop_byte(translated, state);
  types type = pop_byte(translated, state);
  size_t length = pop_bytecode(translated, state);
  uint64_t offset = pop_bytecode(translated, state);

  void *data = ar_alloc_atomic(length);
  memcpy(data, arena_get(&translated->constants, offset), length);
  ArgonObject *object = ARGON_NULL;
  switch (type) {
  case TYPE_OP_STRING:
    object = init_string_object(data, length);
    break;
  }
  state->registers[to_register] = object;
}

struct hashmap *runtime_hash_table = NULL;

uint64_t runtime_hash(const void *data, size_t len, uint64_t prehash) {
  if (!runtime_hash_table) {
    runtime_hash_table = createHashmap();
  } else {
    void *result = hashmap_lookup(runtime_hash_table, prehash);
    if (result) {
      return (uint64_t)result;
    }
  }
  uint64_t hash = siphash64_bytes(data, len, siphash_key);
  hashmap_insert(runtime_hash_table, prehash, 0, (void *)hash, 0);
  return hash;
}

ArErr load_variable(Translated *translated, RuntimeState *state,
                    struct Stack *stack) {
  int64_t length = pop_bytecode(translated, state);
  int64_t offset = pop_bytecode(translated, state);
  int64_t prehash = pop_bytecode(translated, state);
  int64_t source_location_index = pop_bytecode(translated, state);
  uint64_t hash =
      runtime_hash(arena_get(&translated->constants, offset), length, prehash);
  struct Stack *current_stack = stack;
  while (current_stack) {
    ArgonObject *result = hashmap_lookup_GC(current_stack->scope, hash);
    if (result) {
      state->registers[0] = result;
      return no_err;
    }
    current_stack = current_stack->prev;
  }
  SourceLocation *source_location =
      darray_get(&translated->source_locations, source_location_index);
  ArErr err = create_err(source_location->line, source_location->column,
                         source_location->length, state->path, "Name Error",
                         "name '%.*s' is not defined", (int)length,
                         arena_get(&translated->constants, offset));
  return err;
}

ArErr run_instruction(Translated *translated, RuntimeState *state,
                      struct Stack **stack) {
  OperationType opcode = pop_byte(translated, state);
  switch (opcode) {
  case OP_LOAD_NULL:
    state->registers[pop_byte(translated, state)] = ARGON_NULL;
    break;
  case OP_LOAD_CONST:
    load_const(translated, state);
    break;
  case OP_LOAD_FUNCTION:
    load_argon_function(translated, state, *stack);
    break;
  case OP_IDENTIFIER:
    return load_variable(translated, state, *stack);
  case OP_DECLARE:
    return runtime_declaration(translated, state, *stack);
  case OP_BOOL:;
    uint8_t to_register = pop_byte(translated, state);
    state->registers[to_register] = ARGON_TRUE;
    break;
  case OP_JUMP_IF_FALSE:;
    uint8_t from_register = pop_byte(translated, state);
    uint64_t to = pop_bytecode(translated, state);
    if (state->registers[from_register] == ARGON_FALSE) {
      state->head = to;
    }
    break;
  case OP_JUMP:
    state->head = pop_bytecode(translated, state);
    break;
  case OP_NEW_SCOPE:
    *stack = create_scope(*stack);
    break;
  case OP_POP_SCOPE:;
    // struct node_GC *array =
    //     checked_malloc(sizeof(struct node_GC) * (*stack)->scope->count);
    // size_t j = 0;
    // for (size_t i = 0; i < (*stack)->scope->size; i++) {
    //   struct node_GC *temp = (*stack)->scope->list[i];
    //   while (temp) {
    //     array[j++] = *temp;
    //     temp = temp->next;
    //   }
    // }
    // qsort(array, (*stack)->scope->count, sizeof(struct node_GC),
    //       compare_by_order);
    // for (size_t i = 0; i < (*stack)->scope->count; i++) {
    //   struct node_GC temp = array[i];
    //   printf("%.*s = %.*s\n",
    //            (int)((ArgonObject *)temp.key)->value.as_str.length,
    //            ((ArgonObject *)temp.key)->value.as_str.data,
    //            (int)((ArgonObject *)temp.val)->value.as_str.length,
    //            ((ArgonObject *)temp.val)->value.as_str.data);
    // }
    // free(array);
    *stack = (*stack)->prev;
    break;
  default:
    return create_err(0, 0, 0, NULL, "Runtime Error", "Invalid Opcode %#x",
                      opcode);
  }
  return no_err;
}

RuntimeState init_runtime_state(Translated translated, char *path) {
  return (RuntimeState){
      checked_malloc(translated.registerCount * sizeof(ArgonObject *)), 0, path,
      ARGON_NULL, NULL, NULL};
}

Stack *create_scope(Stack *prev) {
  Stack *stack = ar_alloc(sizeof(Stack));
  stack->scope = createHashmap_GC();
  stack->prev = prev;
  return stack;
}

ArErr runtime(Translated translated, RuntimeState state, Stack *stack) {
  state.head = 0;
  StackFrame *currentStackFrame = checked_malloc(sizeof(StackFrame));
  *currentStackFrame = (StackFrame){translated, state, stack, NULL};
  state.currentStackFramePointer = &currentStackFrame;
  ArErr err = no_err;
  while (currentStackFrame) {
    while (currentStackFrame->state.head <
               currentStackFrame->translated.bytecode.size &&
           !err.exists) {
      err =
          run_instruction(&currentStackFrame->translated,
                          &currentStackFrame->state, &currentStackFrame->stack);
    }
    StackFrame *tempStackFrame = currentStackFrame;
    currentStackFrame = currentStackFrame->previousStackFrame;
    free(tempStackFrame);
  }
  return err;
}