#include "toy_vm.h"
#include "toy_console_colors.h"

#include "toy_opcodes.h"
#include "toy_value.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//utilities
#define READ_BYTE(vm) \
	vm->routine[vm->routineCounter++]

#define READ_UNSIGNED_INT(vm) \
	*((unsigned int*)(vm->routine + _read_postfix(&(vm->routineCounter), 4)))

#define READ_INT(vm) \
	*((int*)(vm->routine + _read_postfix(&(vm->routineCounter), 4)))

#define READ_FLOAT(vm) \
	*((float*)(vm->routine + _read_postfix(&(vm->routineCounter), 4)))

static inline int _read_postfix(unsigned int* ptr, int amount) {
	int ret = *ptr;
	*ptr += amount;
	return ret;
}

static inline void fix_alignment(Toy_VM* vm) {
	if (vm->routineCounter % 4 != 0) {
		vm->routineCounter += (4 - vm->routineCounter % 4);
	}
}

//instruction handlers
static void processRead(Toy_VM* vm) {
	Toy_ValueType type = READ_BYTE(vm);

	Toy_Value value = TOY_VALUE_TO_NULL();

	switch(type) {
		case TOY_VALUE_NULL: {
			//No-op
			break;
		}

		case TOY_VALUE_BOOLEAN: {
			value = TOY_VALUE_TO_BOOLEAN((bool)READ_BYTE(vm));
			break;
		}

		case TOY_VALUE_INTEGER: {
			fix_alignment(vm);
			value = TOY_VALUE_TO_INTEGER(READ_INT(vm));
			break;
		}

		case TOY_VALUE_FLOAT: {
			fix_alignment(vm);
			value = TOY_VALUE_TO_FLOAT(READ_FLOAT(vm));
			break;
		}

		case TOY_VALUE_STRING: {
			//
			// break;
		}

		case TOY_VALUE_ARRAY: {
			//
			// break;
		}

		case TOY_VALUE_DICTIONARY: {
			//
			// break;
		}

		case TOY_VALUE_FUNCTION: {
			//
			// break;
		}

		case TOY_VALUE_OPAQUE: {
			//
			// break;
		}

		default:
			fprintf(stderr, TOY_CC_ERROR "ERROR: Invalid value type %d found, exiting\n" TOY_CC_RESET, type);
			exit(-1);
	}

	//push onto the stack
	Toy_pushStack(&vm->stack, value);

	//leave the counter in a good spot
	fix_alignment(vm);
}

static void processArithmetic(Toy_VM* vm, Toy_OpcodeType opcode) {
	Toy_Value right = Toy_popStack(&vm->stack);
	Toy_Value left = Toy_popStack(&vm->stack);

	//check types
	if ((!TOY_VALUE_IS_INTEGER(left) && !TOY_VALUE_IS_FLOAT(left)) || (!TOY_VALUE_IS_INTEGER(right) && !TOY_VALUE_IS_FLOAT(right))) {
		fprintf(stderr, TOY_CC_ERROR "ERROR: Invalid types %d and %d passed to processArithmetic, exiting\n" TOY_CC_RESET, left.type, right.type);
		exit(-1);
	}

	//check for divide by zero
	if (opcode == TOY_OPCODE_DIVIDE || opcode == TOY_OPCODE_MODULO) {
		if ((TOY_VALUE_IS_INTEGER(right) && TOY_VALUE_AS_INTEGER(right) == 0) || (TOY_VALUE_IS_FLOAT(right) && TOY_VALUE_AS_FLOAT(right) == 0)) {
			fprintf(stderr, TOY_CC_ERROR "ERROR: Can't divide by zero, exiting\n" TOY_CC_RESET);
			exit(-1);
		}
	}

	//check for modulo by a float
	if (opcode == TOY_OPCODE_MODULO && TOY_VALUE_IS_FLOAT(right)) {
		fprintf(stderr, TOY_CC_ERROR "ERROR: Can't modulo by a float, exiting\n" TOY_CC_RESET);
		exit(-1);
	}

	//coerce ints into floats if needed
	if (TOY_VALUE_IS_INTEGER(left) && TOY_VALUE_IS_FLOAT(right)) {
		left = TOY_VALUE_TO_FLOAT( (float)TOY_VALUE_AS_INTEGER(left) );
	}
	else
	if (TOY_VALUE_IS_FLOAT(left) && TOY_VALUE_IS_INTEGER(right)) {
		right = TOY_VALUE_TO_FLOAT( (float)TOY_VALUE_AS_INTEGER(right) );
	}

	//apply operation
	Toy_Value result = TOY_VALUE_TO_NULL();

	if (opcode == TOY_OPCODE_ADD) {
		result = TOY_VALUE_IS_FLOAT(left) ? TOY_VALUE_TO_FLOAT( TOY_VALUE_AS_FLOAT(left) + TOY_VALUE_AS_FLOAT(right)) : TOY_VALUE_TO_INTEGER( TOY_VALUE_AS_INTEGER(left) + TOY_VALUE_AS_INTEGER(right) );
	}
	else if (opcode == TOY_OPCODE_SUBTRACT) {
		result = TOY_VALUE_IS_FLOAT(left) ? TOY_VALUE_TO_FLOAT( TOY_VALUE_AS_FLOAT(left) - TOY_VALUE_AS_FLOAT(right)) : TOY_VALUE_TO_INTEGER( TOY_VALUE_AS_INTEGER(left) - TOY_VALUE_AS_INTEGER(right) );
	}
	else if (opcode == TOY_OPCODE_MULTIPLY) {
		result = TOY_VALUE_IS_FLOAT(left) ? TOY_VALUE_TO_FLOAT( TOY_VALUE_AS_FLOAT(left) * TOY_VALUE_AS_FLOAT(right)) : TOY_VALUE_TO_INTEGER( TOY_VALUE_AS_INTEGER(left) * TOY_VALUE_AS_INTEGER(right) );
	}
	else if (opcode == TOY_OPCODE_DIVIDE) {
		result = TOY_VALUE_IS_FLOAT(left) ? TOY_VALUE_TO_FLOAT( TOY_VALUE_AS_FLOAT(left) / TOY_VALUE_AS_FLOAT(right)) : TOY_VALUE_TO_INTEGER( TOY_VALUE_AS_INTEGER(left) / TOY_VALUE_AS_INTEGER(right) );
	}
	else if (opcode == TOY_OPCODE_MODULO) {
		result = TOY_VALUE_TO_INTEGER( TOY_VALUE_AS_INTEGER(left) % TOY_VALUE_AS_INTEGER(right) );
	}
	else {
		fprintf(stderr, TOY_CC_ERROR "ERROR: Invalid opcode %d passed to processArithmetic, exiting\n" TOY_CC_RESET, opcode);
		exit(-1);
	}

	//finally
	Toy_pushStack(&vm->stack, result);
}

static void processComparison(Toy_VM* vm, Toy_OpcodeType opcode) {
	Toy_Value right = Toy_popStack(&vm->stack);
	Toy_Value left = Toy_popStack(&vm->stack);

	//most things can be equal, so handle it separately
	if (opcode == TOY_OPCODE_COMPARE_EQUAL) {
		Toy_pushStack(&vm->stack, TOY_VALUE_TO_BOOLEAN(TOY_VALUE_IS_EQUAL(left, right)) );
		return;
	}

	//coerce ints into floats if needed
	if (TOY_VALUE_IS_INTEGER(left) && TOY_VALUE_IS_FLOAT(right)) {
		left = TOY_VALUE_TO_FLOAT( (float)TOY_VALUE_AS_INTEGER(left) );
	}
	else
	if (TOY_VALUE_IS_FLOAT(left) && TOY_VALUE_IS_INTEGER(right)) {
		right = TOY_VALUE_TO_FLOAT( (float)TOY_VALUE_AS_INTEGER(right) );
	}

	//other opcodes
	if (opcode == TOY_OPCODE_COMPARE_LESS) {
		Toy_pushStack(&vm->stack, TOY_VALUE_TO_BOOLEAN(TOY_VALUE_IS_FLOAT(left) ? TOY_VALUE_AS_FLOAT(left) < TOY_VALUE_AS_FLOAT(right) : TOY_VALUE_AS_INTEGER(left) < TOY_VALUE_AS_INTEGER(right)) );
	}
	else if (opcode == TOY_OPCODE_COMPARE_LESS_EQUAL) {
		Toy_pushStack(&vm->stack, TOY_VALUE_TO_BOOLEAN(TOY_VALUE_IS_FLOAT(left) ? TOY_VALUE_AS_FLOAT(left) <= TOY_VALUE_AS_FLOAT(right) : TOY_VALUE_AS_INTEGER(left) <= TOY_VALUE_AS_INTEGER(right)) );
	}
	else if (opcode == TOY_OPCODE_COMPARE_GREATER) {
		Toy_pushStack(&vm->stack, TOY_VALUE_TO_BOOLEAN(TOY_VALUE_IS_FLOAT(left) ? TOY_VALUE_AS_FLOAT(left) > TOY_VALUE_AS_FLOAT(right) : TOY_VALUE_AS_INTEGER(left) > TOY_VALUE_AS_INTEGER(right)) );
	}
	else if (opcode == TOY_OPCODE_COMPARE_GREATER_EQUAL) {
		Toy_pushStack(&vm->stack, TOY_VALUE_TO_BOOLEAN(TOY_VALUE_IS_FLOAT(left) ? TOY_VALUE_AS_FLOAT(left) >= TOY_VALUE_AS_FLOAT(right) : TOY_VALUE_AS_INTEGER(left) >= TOY_VALUE_AS_INTEGER(right)) );
	}
	else {
		fprintf(stderr, TOY_CC_ERROR "ERROR: Invalid opcode %d passed to processComparison, exiting\n" TOY_CC_RESET, opcode);
		exit(-1);
	}
}

static void processLogical(Toy_VM* vm, Toy_OpcodeType opcode) {
	if (opcode == TOY_OPCODE_AND) {
		Toy_Value right = Toy_popStack(&vm->stack);
		Toy_Value left = Toy_popStack(&vm->stack);

		Toy_pushStack(&vm->stack, TOY_VALUE_TO_BOOLEAN( TOY_VALUE_IS_TRUTHY(left) && TOY_VALUE_IS_TRUTHY(right) ));
	}
	else if (opcode == TOY_OPCODE_OR) {
		Toy_Value right = Toy_popStack(&vm->stack);
		Toy_Value left = Toy_popStack(&vm->stack);

		Toy_pushStack(&vm->stack, TOY_VALUE_TO_BOOLEAN( TOY_VALUE_IS_TRUTHY(left) || TOY_VALUE_IS_TRUTHY(right) ));
	}
	else if (opcode == TOY_OPCODE_TRUTHY) {
		Toy_Value top = Toy_popStack(&vm->stack);

		Toy_pushStack(&vm->stack, TOY_VALUE_TO_BOOLEAN( TOY_VALUE_IS_TRUTHY(top) ));
	}
	else if (opcode == TOY_OPCODE_NEGATE) {
		Toy_Value top = Toy_popStack(&vm->stack);

		Toy_pushStack(&vm->stack, TOY_VALUE_TO_BOOLEAN( !TOY_VALUE_IS_TRUTHY(top) ));
	}
	else {
		fprintf(stderr, TOY_CC_ERROR "ERROR: Invalid opcode %d passed to processLogical, exiting\n" TOY_CC_RESET, opcode);
		exit(-1);
	}
}

static void process(Toy_VM* vm) {
	while(true) {
		Toy_OpcodeType opcode = READ_BYTE(vm);

		switch(opcode) {
			case TOY_OPCODE_READ:
				processRead(vm);
				break;

			case TOY_OPCODE_ADD:
			case TOY_OPCODE_SUBTRACT:
			case TOY_OPCODE_MULTIPLY:
			case TOY_OPCODE_DIVIDE:
			case TOY_OPCODE_MODULO:
				processArithmetic(vm, opcode);
				break;

			case TOY_OPCODE_COMPARE_EQUAL:
			case TOY_OPCODE_COMPARE_LESS:
			case TOY_OPCODE_COMPARE_LESS_EQUAL:
			case TOY_OPCODE_COMPARE_GREATER:
			case TOY_OPCODE_COMPARE_GREATER_EQUAL:
				processComparison(vm, opcode);
				break;

			case TOY_OPCODE_AND:
			case TOY_OPCODE_OR:
			case TOY_OPCODE_TRUTHY:
			case TOY_OPCODE_NEGATE: //TODO: squeeze into !=
				processLogical(vm, opcode);
				break;

			case TOY_OPCODE_LOAD:
			case TOY_OPCODE_LOAD_LONG:
			case TOY_OPCODE_DECLARE:
			case TOY_OPCODE_ASSIGN:
			case TOY_OPCODE_ACCESS:
			case TOY_OPCODE_PASS:
			case TOY_OPCODE_ERROR:
			case TOY_OPCODE_EOF:
				fprintf(stderr, TOY_CC_ERROR "ERROR: Invalid opcode %d found, exiting\n" TOY_CC_RESET, opcode);
				exit(-1);

			case TOY_OPCODE_RETURN: //temp terminator, temp position
				//
				return;
		}

		//prepare for the next instruction
		fix_alignment(vm);
	}
}

//exposed functions
void Toy_bindVM(Toy_VM* vm, unsigned char* bytecode, unsigned int bytecodeSize) {
	if (bytecode[0] != TOY_VERSION_MAJOR || bytecode[1] > TOY_VERSION_MINOR) {
		fprintf(stderr, TOY_CC_ERROR "ERROR: Wrong bytecode version found: expected %d.%d.%d found %d.%d.%d, exiting\n" TOY_CC_RESET, TOY_VERSION_MAJOR, TOY_VERSION_MINOR, TOY_VERSION_PATCH, bytecode[0], bytecode[1], bytecode[2]);
		exit(-1);
	}

	if (bytecode[2] != TOY_VERSION_PATCH) {
		fprintf(stderr, TOY_CC_WARN "WARNING: Wrong bytecode version found: expected %d.%d.%d found %d.%d.%d, continuing\n" TOY_CC_RESET, TOY_VERSION_MAJOR, TOY_VERSION_MINOR, TOY_VERSION_PATCH, bytecode[0], bytecode[1], bytecode[2]);
	}

	if (strcmp((char*)(bytecode + 3), TOY_VERSION_BUILD) != 0) {
		fprintf(stderr, TOY_CC_WARN "WARNING: Wrong bytecode build info found: expected '%s' found '%s', continuing\n" TOY_CC_RESET, TOY_VERSION_BUILD, (char*)(bytecode + 3));
	}

	//offset by the header size
	int offset = 3 + strlen(TOY_VERSION_BUILD) + 1;
	if (offset % 4 != 0) {
		offset += 4 - (offset % 4); //ceil
	}

	//delegate
	Toy_bindVMToRoutine(vm, bytecode + offset);

	//cache these
	vm->bc = bytecode;
	vm->bcSize = bytecodeSize;
}

void Toy_bindVMToRoutine(Toy_VM* vm, unsigned char* routine) {
	Toy_resetVM(vm);

	vm->routine = routine;

	//read the header metadata
	vm->routineSize = READ_UNSIGNED_INT(vm);
	vm->paramCount = READ_UNSIGNED_INT(vm);
	vm->jumpsCount = READ_UNSIGNED_INT(vm);
	vm->dataCount = READ_UNSIGNED_INT(vm);
	vm->subsCount = READ_UNSIGNED_INT(vm);

	//read the header addresses
	if (vm->paramCount > 0) {
		vm->paramAddr = READ_UNSIGNED_INT(vm);
	}

	vm->codeAddr = READ_UNSIGNED_INT(vm); //required

	if (vm->jumpsCount > 0) {
		vm->jumpsAddr = READ_UNSIGNED_INT(vm);
	}

	if (vm->dataCount > 0) {
		vm->dataAddr = READ_UNSIGNED_INT(vm);
	}

	if (vm->subsCount > 0) {
		vm->subsAddr = READ_UNSIGNED_INT(vm);
	}

	//preallocate the scope & stack
	vm->stack = Toy_allocateStack();
}

void Toy_runVM(Toy_VM* vm) {
	//TODO: read params into scope

	//prep the routine counter for execution
	vm->routineCounter = vm->codeAddr;

	//begin
	process(vm);
}

void Toy_freeVM(Toy_VM* vm) {
	//clear the stack
	Toy_freeStack(vm->stack);

	//TODO: clear the scope

	//free the bytecode

	free(vm->bc);
	Toy_resetVM(vm);
}

void Toy_resetVM(Toy_VM* vm) {
	vm->bc = NULL;
	vm->bcSize = 0;

	vm->routine = NULL;
	vm->routineSize = 0;

	vm->paramCount = 0;
	vm->jumpsCount = 0;
	vm->dataCount = 0;
	vm->subsCount = 0;

	vm->paramAddr = 0;
	vm->codeAddr = 0;
	vm->jumpsAddr = 0;
	vm->dataAddr = 0;
	vm->subsAddr = 0;

	vm->routineCounter = 0;

	//init the scope & stack
	vm->stack = NULL;
}