package vm

import (
	"errors"
	"fmt"
	"jinx/pkg/lang/vm/code"
	"jinx/pkg/lang/vm/mem"
	"jinx/pkg/lang/vm/text"
	"jinx/pkg/lang/vm/value"
)

type Error struct {
	Pc   int
	Line int
	Err  error
}

func (e Error) Error() string {
	if e.Line == -1 {
		return fmt.Sprintf("vm error at pc %d, unknown line: %v", e.Pc, e.Err)
	}
	return fmt.Sprintf("vm error at pc %d, line %d: %v", e.Pc, e.Line, e.Err)
}

// Fatal errors

var (
	ErrStackOverflow  = errors.New("stack overflow (max depth: 1000)")
	ErrStackUnderflow = errors.New("local stack underflow")

	ErrReachedMaxCallDepth  = errors.New("reached max call depth (max depth: 1000)")
	ErrReachedRootCallFrame = errors.New("reached root call frame")

	ErrCallBaseCantBeNegative = errors.New("call base cannot be negative")

	ErrEnvNotSet = errors.New("env not set")
)

type ErrLocalIndexOutOfBounds struct {
	Index int
	Len   int
}

func (e ErrLocalIndexOutOfBounds) Error() string {
	return fmt.Sprintf("local index out of bounds: %d (len: %d)", e.Index, e.Len)
}

type ErrStackIndexOutOfBounds struct {
	Index int
	Len   int
}

func (e ErrStackIndexOutOfBounds) Error() string {
	return fmt.Sprintf("stack index out of bounds: %d (len: %d)", e.Index, e.Len)
}

type ErrInvalidOp struct {
	Op uint8
}

func (e ErrInvalidOp) Error() string {
	return fmt.Sprintf("invalid opcode: %d", e.Op)
}

type ErrUnexpectedMemCell struct {
	Ptr      mem.Ptr
	Expected mem.CellKind
	Got      mem.CellKind
}

func (e ErrUnexpectedMemCell) Error() string {
	return fmt.Sprintf("unexpected memory cell at %s: expected %v, got %v", e.Ptr.String(), e.Expected, e.Got)
}

type ErrMemNilCell struct {
	Ptr mem.Ptr
}

func (e ErrMemNilCell) Error() string {
	return fmt.Sprintf("found no value at %s", e.Ptr.String())
}

type ErrCorruptedMemCell struct {
	Ptr mem.Ptr
}

func (e ErrCorruptedMemCell) Error() string {
	return fmt.Sprintf("corrupted memory cell at %s", e.Ptr.String())
}

// Non-fatal errors, which will later be implemented as catchable exceptions

type ErrInvalidOperandType struct {
	Op code.Op
	X  value.Type
}

func (e ErrInvalidOperandType) Error() string {
	return fmt.Sprintf("invalid operand type for op %s: %v", text.OpToString(e.Op), e.X)
}

type ErrInvalidOperandTypes struct {
	Op code.Op
	X  value.Type
	Y  value.Type
}

func (e ErrInvalidOperandTypes) Error() string {
	return fmt.Sprintf("invalid operand types for op %s: %v, %v", text.OpToString(e.Op), e.X, e.Y)
}

type ErrArrayIndexOutOfBounds struct {
	Index int
	Len   int
}

func (e ErrArrayIndexOutOfBounds) Error() string {
	return fmt.Sprintf("array index out of bounds: %d (len: %d)", e.Index, e.Len)
}